Sanjiv Sam Gambhir, MD, PhD

All Publications

• Tumor treating fields (TTFields) impairs aberrant glycolysis in glioblastoma as evaluated by [18F]DASA-23, a non-invasive probe of pyruvate kinase M2 (PKM2) expression Neoplasia Patel, C. B., Beinat, C., Xie, Y., Chang, E., Gambhir, S. S. 2021; 23 (1): 58-67

  View details for DOI 10.1016/j.neo.2020.11.003

• Molecular Imaging of Chimeric Antigen Receptor T Cells by ICOS-ImmunoPET. Clinical cancer research : an official journal of the American Association for Cancer Research Simonetta, F., Alam, I. S., Lohmeyer, J. K., Sahaf, B., Good, Z., Chen, W., Xiao, Z., Hirai, T., Scheller, L., Engels, P., Vermesh, O., Robinson, E., Haywood, T., Sathirachinda, A., Baker, J., Malipatlolla, M. B., Schultz, L. M., Spiegel, J. Y., Lee, J. T., Miklos, D. B., Mackall, C. L., Gambhir, S. S., Negrin, R. 2020

  Abstract

  PURPOSE: Immunomonitoring of chimeric antigen receptor (CAR) T cells relies primarily on their quantification in the peripheral blood, which inadequately quantifies their biodistribution and activation status in the tissues. Non-invasive molecular imaging of CAR T cells by positron emission tomography (PET) is a promising approach with the ability to provide spatial, temporal and functional information. Reported strategies rely on the incorporation of reporter transgenes or ex vivo biolabeling, significantly limiting the application of CAR T cell molecular imaging. In the present study, we assessed the ability of antibody-based PET (immunoPET) to non-invasively visualize CAR T cells.EXPERIMENTAL DESIGN: After analyzing human CAR T cells in vitro and ex vivo from patient samples to identify candidate targets for immunoPET, we employed a syngeneic, orthotopic murine tumor model of lymphoma to assess the feasibility of in vivo tracking of CAR T cells by immunoPET using the 89Zr-DFO-anti-ICOS tracer we previously reported.RESULTS: Analysis of human CD19-CAR T cells during activation identified the Inducible T-cell COStimulator (ICOS) as a potential target for immunoPET. In a preclinical tumor model, 89Zr-DFO-ICOS mAb PET-CT imaging detected significantly higher signal in specific bone marrow-containing skeletal sites of CAR T cell treated mice compared with controls. Importantly, administration of ICOS-targeting antibodies at tracer doses did not interfere with CAR T cell persistence and function.CONCLUSIONS: This study highlights the potential of ICOS-immunoPET imaging for monitoring of CAR T cell therapy, a strategy readily applicable to both commercially available and investigational CAR T cells.

  View details for DOI 10.1158/1078-0432.CCR-20-2770

  View details for PubMedID 33087332

• Mitochondrial copper depletion suppresses triple-negative breast cancer in mice. Nature biotechnology Cui, L., Gouw, A. M., LaGory, E. L., Guo, S., Attarwala, N., Tang, Y., Qi, J., Chen, Y., Gao, Z., Casey, K. M., Bazhin, A. A., Chen, M., Hu, L., Xie, J., Fang, M., Zhang, C., Zhu, Q., Wang, Z., Giaccia, A. J., Gambhir, S. S., Zhu, W., Felsher, D. W., Pegram, M. D., Goun, E. A., Le, A., Rao, J. 2020

  Abstract

  Depletion of mitochondrial copper, which shifts metabolism from respiration to glycolysis and reduces energy production, is known to be effective against cancer types that depend on oxidative phosphorylation. However, existing copper chelators are too toxic or ineffective for cancer treatment. Here we develop a safe, mitochondria-targeted, copper-depleting nanoparticle (CDN) and test it against triple-negative breast cancer (TNBC). We show that CDNs decrease oxygen consumption and oxidative phosphorylation, cause a metabolic switch to glycolysis and reduce ATP production in TNBC cells. This energy deficiency, together with compromised mitochondrial membrane potential and elevated oxidative stress, results in apoptosis. CDNs should be less toxic than existing copper chelators because they favorably deprive copper in the mitochondria in cancer cells instead of systemic depletion. Indeed, we demonstrate low toxicity of CDNs in healthy mice. In three mouse models of TNBC, CDN administration inhibits tumor growth and substantially improves survival. The efficacy and safety of CDNs suggest the potential clinical relevance of this approach.

  View details for DOI 10.1038/s41587-020-0707-9

  View details for PubMedID 33077961

• PET reporter gene imaging and ganciclovir-mediated ablation of chimeric antigen receptor T-cells in solid tumors. Cancer research Murty, S., Labanieh, L., Murty, T., Gowrishankar, G., Haywood, T., Alam, I. S., Beinat, C., Robinson, E., Aalipour, A., Klysz, D. D., Cochran, J. R., Majzner, R. G., Mackall, C. L., Gambhir, S. S. 2020

  Abstract

  Imaging strategies to monitor chimeric antigen receptor (CAR) T-cell biodistribution and proliferation harbor the potential to facilitate clinical translation for the treatment of both liquid and solid tumors. Additionally, the potential adverse effects of CAR T-cells highlight the need for mechanisms to modulate CAR T-cell activity. The herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene has previously been translated as a positron emission tomography (PET) reporter gene for imaging of T-cell trafficking in brain tumor patients. The HSV1-TK enzyme can act as a suicide gene of transduced cells through treatment with the prodrug ganciclovir (GCV). Here we report the molecular engineering, imaging, and GCV-mediated destruction of B7H3 CAR T-cells incorporating a mutated version of the HSV1-tk gene (sr39tk) with improved enzymatic activity for GCV. The sr39tk gene did not affect B7H3 CAR T-cell functionality and in vitro and in vivo studies in osteosarcoma models showed no significant effect on B7H3 CAR T-cell antitumor activity. PET/CT imaging with 9-(4-[18F]-fluoro-3-[hydroxymethyl]butyl)guanine [18F]FHBG of B7H3-sr39tk CAR T-cells in an orthotopic model of osteosarcoma revealed tumor homing and systemic immune expansion. Bioluminescence and PET imaging of B7H3-sr39tk CAR T-cells confirmed complete tumor ablation with intraperitoneal GCV administration. This imaging and suicide ablation system can provide insight into CAR T-cell migration and proliferation during clinical trials while serving as a suicide switch to limit potential toxicities.

  View details for DOI 10.1158/0008-5472.CAN-19-3579

  View details for PubMedID 32958548

• Visualization of activated T cells by OX40-immunoPET as a strategy for diagnosis of acute Graft-versus-Host-Disease. Cancer research Alam, I. S., Simonetta, F., Scheller, L., Mayer, A. T., Murty, S., Vermesh, O., Nobashi, T. W., Lohmeyer, J. K., Hirai, T., Baker, J., Lau, K. H., Negrin, R., Gambhir, S. S. 2020

  Abstract

  Graft versus host disease (GvHD) is a major complication of allogeneic hematopoietic cell transplantation (HCT), mediated primarily by donor T cells that become activated and attack host tissues. Non-invasive strategies detecting T cell activation would allow for early diagnosis and possibly more effective management of HCT recipients. Positron emission tomography (PET) imaging is a sensitive and clinically relevant modality ideal for GvHD diagnosis and there is a strong rationale for the use of PET tracers that can monitor T cell activation and expansion with high specificity. The tumor necrosis factor (TNF) receptor superfamily member OX40 (CD134) is a cell surface marker that is highly specific for activated T cells, is upregulated during GvHD, and mediates disease pathogenesis. We recently reported the development of an antibody-based activated T cell imaging agent targeting OX40. In the present study, we visualize the dynamics of OX40 expression in a major histocompatibility complex (MHC)-mismatch mouse model of acute GvHD using OX40-immunoPET. This approach enabled visualization of T cell activation at early stages of disease, prior to overt clinical symptoms with high sensitivity and specificity. This study highlights the potential utility of the OX40 PET imaging as a new strategy for GvHD diagnosis and therapy monitoring.

  View details for DOI 10.1158/0008-5472.CAN-20-1149

  View details for PubMedID 32900772

• Clinical evaluation of (4S)-4-(3-[18F]Fluoropropyl)-L-glutamate (18F-FSPG) for PET/CT imaging in patients with newly diagnosed and recurrent prostate cancer. Clinical cancer research : an official journal of the American Association for Cancer Research Park, S. Y., Na, S. J., Kumar, M., Mosci, C., Wardak, M., Koglin, N., Bullich, S., Mueller, A., Berndt, M., Stephens, A. W., Cho, Y. M., Ahn, H., Chae, S. Y., Kim, H. O., Moon, D. H., Gambhir, S. S., Mittra, E. S. 2020

  Abstract

  PURPOSE: (4S)-4-(3-[18F]Fluoropropyl)-L-glutamic acid (18F-FSPG) is a radiopharmaceutical for PET imaging of system xC - activity, which can be upregulated in prostate cancer. We present data on the first evaluation of newly diagnosed or recurrent prostate cancer patients with this radiopharmaceutical.EXPERIMENTAL DESIGN: Ten primary and ten recurrent prostate cancer patients were enrolled in this prospective multicenter study. After injection of 300 MBq of 18F-FSPG, three whole-body PET/CT scans were obtained. Visual analysis was compared with step-section histopathology when available as well as other imaging studies and clinical outcomes. Metabolic parameters were measured semi-quantitatively. Expression levels of xCT and CD44 were evaluated by immunohistochemistry for patients with available tissue samples.RESULTS: 18F-FSPG PET showed high tumor-to-background ratios with a relatively high tumor detection rate on a per-patient (89%) and per-lobe (87%) basis. The sensitivity was slightly higher with imaging at 105 minutes in comparison to 60 minutes. The SUVmax for cancer was significantly higher than both normal (p < 0.005) and benign pathology (p=0.011), while there was no significant difference between normal and benign pathology (p=0.120). In the setting of recurrence, agreement with standard imaging was demonstrated in 7 of 9 patients (78%) and 13 of 18 lesions (72%), and revealed true local recurrence in a discordant case. 18F-FSPG accumulation showed moderate correlation with CD44 expression.CONCLUSIONS: 18F-FSPG is a promising tumor imaging agent for PET that seems to have favorable biodistribution and high cancer detection rate in patients with prostate cancer. Further studies are warranted to determine the diagnostic value for both initial staging and recurrence, and how it compares to other investigational radiotracers and conventional imaging modalities.

  View details for DOI 10.1158/1078-0432.CCR-20-0644

  View details for PubMedID 32694158

• Synthesis and Characterization of 9-(4-[18F]Fluoro-3-(hydroxymethyl)butyl)-2-(phenylthio)-6-oxopurine as a Novel PET Agent for Mutant Herpes Simplex Virus Type 1 Thymidine Kinase Reporter Gene Imaging. Molecular imaging and biology Fuchigami, T., Haywood, T., Gowrishankar, G., Anders, D., Namavari, M., Wardak, M., Gambhir, S. S. 2020

  Abstract

  PURPOSE: [18F]FHBG has been used as a positron emission tomography (PET) imaging tracer for the monitoring of herpes simplex virus type 1 thymidine kinase (HSV1-tk), a reporter gene for cell and gene therapy in humans. However, this tracer shows inadequate blood-brain barrier (BBB) penetration and, therefore, would be limited for accurate quantification of reporter gene expression in the brain. Here, we report the synthesis and evaluation of 9-(4-[18F]fluoro-3-(hydroxymethyl)butyl)-2(phenylthio)-6-oxopurine ([18F]FHBT) as a new PET tracer for imaging reporter gene expression of HSV1-tk and its mutant HSV1-sr39tk, with the aim of improved BBB penetration.PROCEDURES: [18F]FHBT was prepared by using a tosylate precursor and [18F]KF. The cellular uptake of [18F]FHBT was performed in HSV1-sr39tk-positive (+) or HSV1-sr39tk-negative (-) MDA-MB-231 breast cancer cells. The specificity of [18F]FHBT to assess HSV1-sr39tk expression was evaluated by in vitro blocking studies using 1mM of ganciclovir (GCV). Penetration of [18F]FHBT and [18F]FHBG across the BBB was assessed by dynamic PET imaging studies in normal mice.RESULTS: The tosylate precursor reacted with [18F]KF using Kryptofix2.2.2 followed by deprotection to give [18F]FHBT in 10% radiochemical yield (decay-corrected). The uptake of [18F]FHBT in HSV1-sr39tk (+) cells was significantly higher than that of HSV1-sr39tk (-) cells. In the presence of GCV (1mM), the uptake of [18F]FHBT was significantly decreased, indicating that [18F]FHBT serves as a selective substrate of HSV1-sr39TK. PET images and time-activity curves of [18F]FHBT in the brain regions showed similar initial brain uptakes (~12.75min) as [18F]FHBG (P>0.855). Slower washout of [18F]FHBT was observed at the later time points (17.75 - 57.75 min, P >0.207).CONCLUSIONS: Although [18F]FHBT showed no statistically significant improvement of BBB permeability compared with [18F]FHBG, we have demonstrated that the 2-(phenylthio)-6-oxopurine backbone can serve as a novel scaffold for developing HSV1-tk/HSV1-sr39tk reporter gene imaging agents for additional research in the future.

  View details for DOI 10.1007/s11307-020-01517-5

  View details for PubMedID 32691392

• Isotopically Encoded Nanotags for Multiplexed Ion Beam Imaging. Advanced materials technologies Harmsen, S., Coskun, A. F., Ganesh, S., Nolan, G. P., Gambhir, S. S. 2020; 5 (7)

  Abstract

  High-dimensional profiling of markers and analytes using approaches, such as barcoded fluorescent imaging with repeated labeling and mass cytometry has allowed visualization of biological processes at the single-cell level. To address limitations of sensitivity and mass-channel capacity, a nanobarcoding platform is developed for multiplexed ion beam imaging (MIBI) using secondary ion beam spectrometry that utilizes fabricated isotopically encoded nanotags. Use of combinatorial isotope distributions in 100 nm sized nanotags expands the labeling palette to overcome the spectral bounds of mass channels. As a proof-of-principle, a four-digit (i.e., 0001-1111) barcoding scheme is demonstrated to detect 16 variants of 2H, 19F, 79/81Br, and 127I elemental barcode sets that are encoded in silica nanoparticle matrices. A computational debarcoding method and an automated machine learning analysis approach are developed to extract barcodes for accurate quantification of spatial nanotag distributions in large ion beam imaging areas up to 0.6 mm2. Isotopically encoded nanotags should boost the performance of mass imaging platforms, such as MIBI and other elemental-based bioimaging approaches.

  View details for DOI 10.1002/admt.202000098

  View details for PubMedID 32661501

  View details for PubMedCentralID PMC7357881

• Viral Delivery of CAR Targets to Solid Tumors Enables Effective Cell Therapy. Molecular therapy oncolytics Aalipour, A., Le Boeuf, F., Tang, M., Murty, S., Simonetta, F., Lozano, A. X., Shaffer, T. M., Bell, J. C., Gambhir, S. S. 2020; 17: 232–40

  Abstract

  Chimeric antigen receptor (CAR) Tcell therapy has had limited efficacy for solid tumors, largely due to a lack of selectively and highly expressed surface antigens. To avoid reliance on a tumor's endogenous antigens, here we describe a method of tumor-selective delivery of surface antigens using an oncolytic virus to enable a generalizable CAR Tcell therapy. Using CD19 as our proof of concept, we engineered a thymidine kinase-disrupted vaccinia virus to selectively deliver CD19 to malignant cells, and thus demonstrated potentiation of CD19 CAR Tcell activity against two tumor types invitro. In an immunocompetent model of B16 melanoma, this combination markedly delayed tumor growth and improved median survival compared with antigen-mismatched combinations. We also found that CD19 delivery could improve CAR Tcell activity against tumor cells that express low levels of cognate antigen, suggesting a potential application in counteracting antigen-low escape. This approach highlights the potential of engineering tumors for effective adoptive cell therapy.

  View details for DOI 10.1016/j.omto.2020.03.018

  View details for PubMedID 32346612

• PET imaging of the natural killer cell activation receptor NKp30. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Shaffer, T., Gambhir, S. S., Aalipour, A., Schurch, C. 2020

  Abstract

  Redirecting the immune system in cancer treatment has led to remarkable responses in a subset of patients. Natural killer (NK) cells are innate lymphoid cells being explored as they engage tumor cells in different mechanisms compared to T cells, which could be exploited for treatment of nonresponders to current immunotherapies. NK cell therapies are monitored through measuring peripheral NK cell concentrations or changes in tumor volume over time. The former does not detect NK cells at the tumor site(s), and the latter is inaccurate for immunotherapies because of pseudoprogression. Therefore, new imaging methods are required as companion diagnostics for optimizing immunotherapies. Methods: Here we develop and complete pre-clinical in vivo validation of two antibody-based PET probes specific for NKp30, an activation natural cytotoxicity receptor expressed by human NK cells. Quantitative, multicolor flow cytometry during a variety of NK cell activation conditions was completed on primary human NK cells and the NK92MI cell line. Human renal cell carcinoma (RCC) tumors were stained for the NK cell receptors CD56, NKp30, and NKp46 to determine expression on tumor-infiltrating NK cells. An NKp30 antibody was radiolabeled with 64Cu or 89Zr and evaluated in subcutaneous xenografts and adoptive cell transfer mouse models. Results: Quantitative flow cytometry showed consistent expression of the NKp30 receptor during different activation conditions. NKp30 and NKp46 costained in RCC samples, demonstrating the expression of these receptors on tumor-infiltrating NK cells in human tumors, while tumor cells in one RCC sample expressed the peripheral NK marker CD56. Both PET tracers showed high stability and specificity in vitro and in vivo. Notably, 89Zr- NKp30Ab had higher on-target contrast compared to 64Cu-NKpAb at their respective terminal time points. 64Cu-NKp30Ab delineated NK cell trafficking to the liver and spleen in an adoptive cell transfer model. Conclusion: The consistent expression of NKp30 on NK cells makes it an attractive target for quantitative imaging. Immunofluorescence staining on human RCC samples demonstrated the advantages of NKp30 targeting versus the traditional CD56 for detection of tumor infiltrating NK cells. This work advances PET imaging of NK cells and supports the translation of imaging agents for immunotherapy monitoring.

  View details for DOI 10.2967/jnumed.119.233163

  View details for PubMedID 32532927

• The Project Baseline Health Study: a step towards a broader mission to map human health NPJ DIGITAL MEDICINE Arges, K., Assimes, T., Bajaj, V., Balu, S., Bashir, M. R., Beskow, L., Blanco, R., Califf, R., Campbell, P., Carin, L., Christian, V., Cousins, S., Das, M., Dockery, M., Douglas, P. S., Dunham, A., Eckstrand, J., Fleischmann, D., Ford, E., Fraulo, E., French, J., Gambhir, S. S., Ginsburg, G. S., Green, R. C., Haddad, F., Hernandez, A., Hernandez, J., Huang, E. S., Jaffe, G., King, D., Koweek, L. H., Langlotz, C., Liao, Y. J., Mahaffey, K. W., Marcom, K., Marks, W. J., Maron, D., McCabe, R., McCall, S., McCue, R., Mega, J., Miller, D., Muhlbaier, L. H., Munshi, R., Newby, L., Pak-Harvey, E., Patrick-Lake, B., Pencina, M., Peterson, E. D., Rodriguez, F., Shore, S., Shah, S., Shipes, S., Sledge, G., Spielman, S., Spitler, R., Schaack, T., Swamy, G., Willemink, M. J., Wong, C. A. 2020; 3 (1): 84

  Abstract

  The Project Baseline Health Study (PBHS) was launched to map human health through a comprehensive understanding of both the health of an individual and how it relates to the broader population. The study will contribute to the creation of a biomedical information system that accounts for the highly complex interplay of biological, behavioral, environmental, and social systems. The PBHS is a prospective, multicenter, longitudinal cohort study that aims to enroll thousands of participants with diverse backgrounds who are representative of the entire health spectrum. Enrolled participants will be evaluated serially using clinical, molecular, imaging, sensor, self-reported, behavioral, psychological, environmental, and other health-related measurements. An initial deeply phenotyped cohort will inform the development of a large, expanded virtual cohort. The PBHS will contribute to precision health and medicine by integrating state of the art testing, longitudinal monitoring and participant engagement, and by contributing to the development of an improved platform for data sharing and analysis.

  View details for DOI 10.1038/s41746-020-0290-y

  View details for Web of Science ID 000538242900001

  View details for PubMedID 32550652

  View details for PubMedCentralID PMC7275087

• Molecular Imaging of Infective Endocarditis With 6''-[18F]Fluoromaltotriose Positron Emission Tomography-Computed Tomography. Circulation Wardak, M., Gowrishankar, G., Zhao, X., Liu, Y., Chang, E., Namavari, M., Haywood, T., Gabr, M. T., Neofytou, E., Chour, T., Qin, X., Vilches-Moure, J. G., Hardy, J., Contag, C. H., McConnell, M. V., Wu, J. C., Gambhir, S. S. 2020; 141 (21): 1729–31

  View details for DOI 10.1161/CIRCULATIONAHA.119.043924

  View details for PubMedID 32453662

• Isotopically Encoded Nanotags for Multiplexed Ion Beam Imaging ADVANCED MATERIALS TECHNOLOGIES Harmsen, S., Coskun, A. F., Ganesh, S., Nolan, G. P., Gambhir, S. S. 2020

  View details for DOI 10.1002/admt.202000098

  View details for Web of Science ID 000530513000001

• Imaging activated immune response following therapeutic vaccination in an orthotopic glioma model with Zr-89-DFO-OX40 mAb PET Nobashi, T., Mayer, A., Xiao, Z., Chan, C., Chaney, A., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2020

  View details for Web of Science ID 000568290500003

• A pilot study of F-18-FSPG SiPM-based PET/CT in patients referred for exclusion of active cardiac sarcoidosis and negative or non-diagnostic F-18-FDG PET/CT Duan, H., Hatami, N., Baratto, L., Davidzon, G., Aparici, C., Gambhir, S., Koglin, N., Witteles, R., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2020

  View details for Web of Science ID 000568290501539

• Non-Invasive Photoacoustic Imaging of In Vivo Mice with Erythrocyte Derived Optical Nanoparticles to Detect CAD/MI. Scientific reports Liu, Y., Hanley, T., Chen, H., Long, S. R., Gambhir, S. S., Cheng, Z., Wu, J. C., Fakhri, G. E., Anvari, B., Zaman, R. T. 2020; 10 (1): 5983

  Abstract

  Coronary artery disease (CAD) causes mortality and morbidity worldwide. We used near-infrared erythrocyte-derived transducers (NETs), a contrast agent, in combination with a photoacoustic imaging system to identify the locations of atherosclerotic lesions and occlusion due to myocardial-infarction (MI). NETs (90nm diameter) were fabricated from hemoglobin-depleted mice erythrocyte-ghosts and doped with Indocyanine Green (ICG). Ten weeks old male C57BL/6 mice (n=9) underwent left anterior descending (LAD) coronary artery ligation to mimic vulnerable atherosclerotic plaques and their rupture leading to MI. 150L of NETs (20M ICG,) was IV injected via tail vein 1-hour prior to photoacoustic (PA) and fluorescence in vivo imaging by exciting NETs at 800nm and 650nm, respectively. These results were verified with histochemical analysis. We observed 256-fold higher PA signal from the accumulated NETs in the coronary artery above the ligation. Fluorescence signals were detected in LAD coronary, thymus, and liver. Similar signals were observed when the chest was cut open. Atherosclerotic lesions exhibited inflammatory cells. Liver demonstrated normal portal tract, with no parenchymal necrosis, inflammation, fibrosis, or other pathologic changes, suggesting biocompatibility of NETs. Non-invasively detecting atherosclerotic plaques and stenosis using NETs may lay a groundwork for future clinical detection and improving CAD risk assessment.

  View details for DOI 10.1038/s41598-020-62868-1

  View details for PubMedID 32249814

• Positron emission tomography (PET) imaging of the natural killer (NK) cell activation receptor NKp30. Shaffer, T. M., Aalipour, A., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2020: 102–3

  View details for Web of Science ID 000522837200165

• Integrating genomic features for non-invasive early lung cancer detection. Nature Chabon, J. J., Hamilton, E. G., Kurtz, D. M., Esfahani, M. S., Moding, E. J., Stehr, H., Schroers-Martin, J., Nabet, B. Y., Chen, B., Chaudhuri, A. A., Liu, C. L., Hui, A. B., Jin, M. C., Azad, T. D., Almanza, D., Jeon, Y. J., Nesselbush, M. C., Co Ting Keh, L., Bonilla, R. F., Yoo, C. H., Ko, R. B., Chen, E. L., Merriott, D. J., Massion, P. P., Mansfield, A. S., Jen, J., Ren, H. Z., Lin, S. H., Costantino, C. L., Burr, R., Tibshirani, R., Gambhir, S. S., Berry, G. J., Jensen, K. C., West, R. B., Neal, J. W., Wakelee, H. A., Loo, B. W., Kunder, C. A., Leung, A. N., Lui, N. S., Berry, M. F., Shrager, J. B., Nair, V. S., Haber, D. A., Sequist, L. V., Alizadeh, A. A., Diehn, M. 2020; 580 (7802): 245-251

  Abstract

  Radiologic screening of high-risk adults reduces lung-cancer-related mortality1,2; however, a small minority of eligible individuals undergo such screening in the United States3,4. The availability of blood-based tests could increase screening uptake. Here we introduce improvements to cancer personalized profiling by deep sequencing (CAPP-Seq)5, a method for the analysis of circulating tumour DNA (ctDNA), to better facilitate screening applications. We show that, although levels are very low in early-stage lung cancers, ctDNA is present prior to treatment in most patients and its presence is strongly prognostic. We also find that the majority of somatic mutations in the cell-free DNA (cfDNA) of patients with lung cancer and of risk-matched controls reflect clonal haematopoiesis and are non-recurrent. Compared with tumour-derived mutations, clonal haematopoiesis mutations occur on longer cfDNA fragments and lack mutational signatures that are associated with tobacco smoking. Integrating these findings with other molecular features, we develop and prospectively validate a machine-learning method termed 'lung cancer likelihood in plasma' (Lung-CLiP), which can robustly discriminate early-stage lung cancer patients from risk-matched controls. This approach achieves performance similar to that of tumour-informed ctDNA detection and enables tuning of assay specificity in order to facilitate distinct clinical applications. Our findings establish the potential of cfDNA for lung cancer screening and highlight the importance of risk-matching cases and controls in cfDNA-based screening studies.

  View details for DOI 10.1038/s41586-020-2140-0

  View details for PubMedID 32269342

• ICOS is an indicator of T cell-mediated response to cancer immunotherapy. Cancer research Xiao, Z., Mayer, A. T., Nobashi, T. W., Gambhir, S. S. 2020

  Abstract

  Immunotherapy is innovating clinical cancer management. Nevertheless, only a small fraction of patients benefit from current immunotherapies. To improve clinical management of cancer immunotherapy, it is critical to develop strategies for response monitoring and prediction. In this study, we describe Inducible T cell Costimulator (ICOS) as a conserved mediator of immune response across multiple therapy strategies. ICOS expression was evaluated by flow cytometry, 89Zr-DFO-ICOS mAb PET/CT imaging was performed on Lewis lung cancer models treated with different immunotherapy strategies, and the change in tumor volume was used as a read-out for therapeutic response. ImmunoPET imaging of ICOS enabled sensitive and specific detection of activated T cells and early benchmarking of immune response. A STING agonist was identified as a promising therapeutic approach in this manner. The STING agonist generated significantly stronger immune responses as measured by ICOS ImmunoPET and delayed tumor growth compared to PD-1 checkpoint blockade. More importantly, ICOS ImmunoPET enabled early and robust prediction of therapeutic response across multiple treatment regimens. This data shows that ICOS is an indicator of T cell-mediated immune response and suggests ICOS ImmunoPET as a promising strategy for monitoring, comparing, and predicting immunotherapy success in cancer.

  View details for DOI 10.1158/0008-5472.CAN-19-3265

  View details for PubMedID 32156777

• SP94-Targeted Triblock Copolymer Nanoparticle Delivers Thymidine Kinase-p53-Nitroreductase Triple Therapeutic Gene and Restores Anticancer Function against Hepatocellular Carcinoma in Vivo. ACS applied materials & interfaces Sukumar, U. K., Rajendran, J. C., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. 2020

  Abstract

  Gene-directed enzyme-prodrug therapy (GDEPT) is a promising approach for cancer therapy, but it suffers from poor targeted delivery in vivo. Polyethylenimine (PEI) is a cationic polymer efficient in delivering negatively charged nucleic acids across cell membranes; however, it is highly toxic in vivo. Hence, we efficiently reduced PEI toxicity without compromising its transfection efficiency by conjugating it with poly(d,l-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) as triblock copolymers through a multistep synthetic process. The synthesized nanoparticles showed efficient delivery of loaded nucleic acids to tumor cells in vitro and in vivo in mice. We used this nanoparticle to deliver a rationally engineered thymidine kinase (TK)-p53-nitroreductase (NTR) triple therapeutic gene against hepatocellular carcinoma (HCC), where p53 tumor suppressor gene is mutated in more than 85% of cancers. TK-p53-NTR triple gene therapy restores p53 function and potentiates cancer cell response to delivered prodrugs (ganciclovir (GCV) and CB1954). We used SP94 peptide-functionalized PLGA-PEG-PEI nanoparticles for the optimal delivery of TK-p53-NTR therapeutic gene in vivo. The nanoparticles prepared from the conjugated polymer showed high loading efficiency for the DNA and markedly enhanced TK-NTR-mediated gene therapy upon the simultaneous coexpression of p53 by the concurrent rescue of the endogenous apoptotic pathway in HCC cells of both p53-mutant and wild-type phenotypes in vitro. In vivo delivery of TK-p53-NTR genes by SP94-targeted PLGA-PEG-PEI NP in mice resulted in a strong expression of suicide genes selectively in tumors, and subsequent administration of GCV and CB1954 led to a decline in tumor growth, and established a superior therapeutic outcome against HCC. We demonstrate a highly efficient approach that exogenously supplements p53 to enable synergy with the outcome of TK-NTR suicide gene therapy against HCC.

  View details for DOI 10.1021/acsami.9b20071

  View details for PubMedID 32048820

• Radiotheranostics: a roadmap for future development LANCET ONCOLOGY Herrmann, K., Schwaiger, M., Lewis, J. S., Solomon, S. B., McNeil, B. J., Baumann, M., Gambhir, S. S., Hricak, H., Weissleder, R. 2020; 21 (3): E146–E156

  View details for Web of Science ID 000518470100019

• Evaluation of Glycolytic Response to Multiple Classes of Anti-glioblastoma Drugs by Noninvasive Measurement of Pyruvate Kinase M2 Using [F-18]DASA-23 MOLECULAR IMAGING AND BIOLOGY Beinat, C., Patel, C. B., Xie, Y., Gambhir, S. S. 2020; 22 (1): 124–33

  View details for DOI 10.1007/s11307-019-01353-2

  View details for Web of Science ID 000513265700018

• Carbon-coated FeCo nanoparticles as sensitive magnetic-particle-imaging tracers with photothermal and magnetothermal properties. Nature biomedical engineering Song, G. n., Kenney, M. n., Chen, Y. S., Zheng, X. n., Deng, Y. n., Chen, Z. n., Wang, S. X., Gambhir, S. S., Dai, H. n., Rao, J. n. 2020

  Abstract

  The low magnetic saturation of iron oxide nanoparticles, which are developed primarily as contrast agents for magnetic resonance imaging, limits the sensitivity of their detection using magnetic particle imaging (MPI). Here, we show that FeCo nanoparticles that have a core diameter of 10 nm and bear a graphitic carbon shell decorated with poly(ethylene glycol) provide an MPI signal intensity that is sixfold and fifteenfold higher than the signals from the superparamagnetic iron oxide tracers VivoTrax and Feraheme, respectively, at the same molar concentration of iron. We also show that the nanoparticles have photothermal and magnetothermal properties and can therefore be used for tumour ablation in mice, and that they have high optical absorbance in a broad near-infrared region spectral range (wavelength, 700-1,200 nm), making them suitable as tracers for photoacoustic imaging. As sensitive multifunctional and multimodal imaging tracers, carbon-coated FeCo nanoparticles may confer advantages in cancer imaging and hyperthermia therapy.

  View details for DOI 10.1038/s41551-019-0506-0

  View details for PubMedID 32015409

• Molecular Imaging of Chimeric Antigen Receptor T Cells by ICOS-ImmunoPET Clinical cancer research: an official journal of the American Association for Cancer Research Alam*, I. S., Simonetta*, F. 2020: 1058–68

  Abstract

  Immunomonitoring of chimeric antigen receptor (CAR) T cells relies primarily on their quantification in the peripheral blood, which inadequately quantifies their biodistribution and activation status in the tissues. Noninvasive molecular imaging of CAR T cells by PET is a promising approach with the ability to provide spatial, temporal, and functional information. Reported strategies rely on the incorporation of reporter transgenes or ex vivo biolabeling, significantly limiting the application of CAR T-cell molecular imaging. In this study, we assessed the ability of antibody-based PET (immunoPET) to noninvasively visualize CAR T cells.After analyzing human CAR T cells in vitro and ex vivo from patient samples to identify candidate targets for immunoPET, we employed a syngeneic, orthotopic murine tumor model of lymphoma to assess the feasibility of in vivo tracking of CAR T cells by immunoPET using the 89Zr-DFO-anti-ICOS tracer, which we have previously reported.Analysis of human CD19-CAR T cells during activation identified the Inducible T-cell COStimulator (ICOS) as a potential target for immunoPET. In a preclinical tumor model, 89Zr-DFO-ICOS mAb PET-CT imaging detected significantly higher signal in specific bone marrow-containing skeletal sites of CAR T-cell-treated mice compared with controls. Importantly, administration of ICOS-targeting antibodies at tracer doses did not interfere with CAR T-cell persistence and function.This study highlights the potential of ICOS-immunoPET imaging for monitoring of CAR T-cell therapy, a strategy readily applicable to both commercially available and investigational CAR T cells.See related commentary by Volpe et al., p. 911.

  View details for DOI 10.1158/1078-0432.CCR-20-2770

  View details for PubMedCentralID PMC7887027

• Whole-body tracking of single cells via positron emission tomography. Nature biomedical engineering Jung, K. O., Kim, T. J., Yu, J. H., Rhee, S. n., Zhao, W. n., Ha, B. n., Red-Horse, K. n., Gambhir, S. S., Pratx, G. n. 2020

  Abstract

  In vivo molecular imaging can measure the average kinetics and movement routes of injected cells through the body. However, owing to non-specific accumulation of the contrast agent and its efflux from the cells, most of these imaging methods inaccurately estimate the distribution of the cells. Here, we show that single human breast cancer cells loaded with mesoporous silica nanoparticles concentrating the 68Ga radioisotope and injected into immunodeficient mice can be tracked in real time from the pattern of annihilation photons detected using positron emission tomography, with respect to anatomical landmarks derived from X-ray computed tomography. The cells travelled at an average velocity of 50 mm s-1 and arrested in the lungs 2-3 s after tail-vein injection into the mice, which is consistent with the blood-flow rate. Single-cell tracking could be used to determine the kinetics of cell trafficking and arrest during the earliest phase of the metastatic cascade, the trafficking of immune cells during cancer immunotherapy and the distribution of cells after transplantation.

  View details for DOI 10.1038/s41551-020-0570-5

  View details for PubMedID 32541917

• Initial evaluation of (4S)-4-(3-[18F]fluoropropyl)-L-glutamate (FSPG) PET/CT imaging in patients with head and neck cancer, colorectal cancer, or non-Hodgkin lymphoma. EJNMMI research Park, S. Y., Mosci, C. n., Kumar, M. n., Wardak, M. n., Koglin, N. n., Bullich, S. n., Mueller, A. n., Berndt, M. n., Stephens, A. W., Chin, F. T., Gambhir, S. S., Mittra, E. S. 2020; 10 (1): 100

  Abstract

  (4S)-4-(3-[18F]Fluoropropyl)-L-glutamic acid ([18F]FSPG) measures system xC- transporter activity and shows promise for oncologic imaging. We present data on tumor uptake of this radiopharmaceutical in human subjects with head and neck cancer (HNC), colorectal cancer (CRC), and non-Hodgkin lymphoma (NHL).A total of 15 subjects with HNC (n = 5), CRC (n = 5), or NHL (n = 5) were recruited (mean age 66.2 years, range 44-87 years). 301.4 ± 28.1 MBq (8.1 ± 0.8 mCi) of [18F]FSPG was given intravenously to each subject, and 3 PET/CT scans were obtained 0-2 h post-injection. All subjects also had a positive [18F]FDG PET/CT scan within 1 month prior to the [18F]FSPG PET scan. Semi-quantitative and visual comparisons of the [18F]FSPG and [18F]FDG scans were performed.[18F]FSPG showed strong uptake in all but one HNC subject. The lack of surrounding brain uptake facilitated tumor delineation in the HNC patients. [18F]FSPG also showed tumor uptake in all CRC subjects, but variable uptake in the NHL subjects. While the absolute [18F]FDG SUV values were comparable or higher than [18F]FSPG, the tumor-to-background SUV ratios were greater with [18F]FSPG than [18F]FDG.[18F]FSPG PET/CT showed promising results across 15 subjects with 3 different cancer types. Concordant visualization was mostly observed between [18F]FSPG and [18F]FDG PET/CT images, with some inter- and intra-individual uptake variability potentially reflecting differences in tumor biology. The tumor-to-background ratios were greater with [18F]FSPG than [18F]FDG in the cancer types evaluated. Future studies based on larger numbers of subjects and those with a wider array of primary and recurrent or metastatic tumors are planned to further evaluate the utility of this novel tracer.

  View details for DOI 10.1186/s13550-020-00678-2

  View details for PubMedID 32857284

• Multispectral Photoacoustic Assessment of Thyroid Cancer Nodules In Vivo Kim, J., Park, B., Ha, J., Steinberg, I., Park, E., Choi, W., Hooper, S., Gambhir, S., Lim, D., Kim, C., Oraevsky, A. A., Wang, L. V. SPIE-INT SOC OPTICAL ENGINEERING. 2020

  View details for DOI 10.1117/12.2546616

  View details for Web of Science ID 000558347500001

• Reduction Triggered In Situ Polymerization in Living Mice. Journal of the American Chemical Society Cui, L. n., Vivona, S. n., Smith, B. R., Kothapalli, S. R., Liu, J. n., Ma, X. n., Chen, Z. n., Taylor, M. n., Kierstead, P. H., Fréchet, J. M., Gambhir, S. S., Rao, J. n. 2020

  Abstract

  "Smart" biomaterials that are responsive to physiological or biochemical stimuli have found many biomedical applications for tissue engineering, therapeutics, and molecular imaging. In this work, we describe in situ polymerization of activatable biorthogonal small molecules in response to a reducing environment change in vivo. We designed a carbohydrate linker- and cyanobenzothiazole-cysteine condensation reaction-based small molecule scaffold that can undergo rapid condensation reaction upon physiochemical changes (such as a reducing environment) to form polymers (pseudopolysaccharide). The fluorescent and photoacoustic properties of a fluorophore-tagged condensation scaffold before and after the transformation have been examined with a dual-modality optical imaging method. These results confirmed the in situ polymerization of this probe after both local and systemic administration in living mice.

  View details for DOI 10.1021/jacs.0c07594

  View details for PubMedID 32804495

• Radiotheranostics: a roadmap for future development. The Lancet. Oncology Herrmann, K. n., Schwaiger, M. n., Lewis, J. S., Solomon, S. B., McNeil, B. J., Baumann, M. n., Gambhir, S. S., Hricak, H. n., Weissleder, R. n. 2020; 21 (3): e146–e156

  Abstract

  Radiotheranostics, injectable radiopharmaceuticals with antitumour effects, have seen rapid development over the past decade. Although some formulations are already approved for human use, more radiopharmaceuticals will enter clinical practice in the next 5 years, potentially introducing new therapeutic choices for patients. Despite these advances, several challenges remain, including logistics, supply chain, regulatory issues, and education and training. By highlighting active developments in the field, this Review aims to alert practitioners to the value of radiotheranostics and to outline a roadmap for future development. Multidisciplinary approaches in clinical trial design and therapeutic administration will become essential to the continued progress of this evolving therapeutic approach.

  View details for DOI 10.1016/S1470-2045(19)30821-6

  View details for PubMedID 32135118

• New synthesis of 6''-[18 F]fluoromaltotriose for positron emission tomography (PET) imaging of bacterial infection. Journal of labelled compounds & radiopharmaceuticals Gabr, M. T., Haywood, T. n., Gowrishankar, G. n., Srinivasan, A. n., Gambhir, S. S. 2020

  Abstract

  6''-[18 F]fluoromaltotriose is a positron emission tomography (PET) tracer that can differentiate between bacterial infection and inflammation in vivo. Bacteria-specific uptake of 6''-[18 F]fluoromaltotriose is attributed to the targeting of maltodextrin transporter in bacteria that is absent in mammalian cells. Herein, we report a new synthesis of 6''-[18 F]fluoromaltotriose as a key step for its clinical translation. In comparison to the previously reported synthesis, the new synthesis features unambiguous assignment of the fluorine-18 position on the maltotriose unit. The new method utilizes direct fluorination of 2'',3'',4''-tri-O-acetyl-6''-O-trifyl-α-D-glucopyranosyl-(1-4)-O-2',3',6'-tri-O-acetyl-α-D-glucopyranosyl-(1-4)-1,2,3,6-tetra-O-acetyl-D-glucopyranose followed by basic hydrolysis. Radiolabeling of the new maltotriose triflate precursor proceeds using a single HPLC purification step, which results in shorter reaction time in comparison to the previously reported synthesis. Successful synthesis of 6''-[18 F]fluoromaltotriose has been achieved in 3.5 ± 0.3% radiochemical yield (decay corrected, n=7) and radiochemical purity above 95%. The efficient radiosynthesis of 6''-[18 F]fluoromaltotriose would be critical in advancing this PET tracer into clinical trials for imaging bacterial infections.

  View details for DOI 10.1002/jlcr.3868

  View details for PubMedID 32602175

• Intravital imaging reveals synergistic effect of CAR T-cells and radiation therapy in a preclinical immunocompetent glioblastoma model Oncoimmunology Murty, S., Haile, S. T., Beinat, C., Aalipour, A., Alam, I. S., Murty, T., Shaffer, T. M., Patel, C. B., Graves, E. E., Mackall, C. L., Gambhir, S. S. 2020; 9 (1)

  View details for DOI 10.1080/2162402X.2020.1757360

• Human biodistribution and radiation dosimetry of [18F]DASA-23, a PET probe targeting pyruvate kinase M2. European journal of nuclear medicine and molecular imaging Beinat, C. n., Patel, C. B., Haywood, T. n., Shen, B. n., Naya, L. n., Gandhi, H. n., Holley, D. n., Khalighi, M. n., Iagaru, A. n., Davidzon, G. n., Gambhir, S. S. 2020

  Abstract

  To assess the safety, biodistribution, and radiation dosimetry of the novel positron emission tomography (PET) radiopharmaceutical 1-((2-fluoro-6-[[18F]]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in healthy volunteers.We recruited 5 healthy volunteers who provided a written informed consent. Volunteers were injected with 295.0 ± 8.2 MBq of [18F]DASA-23 intravenously. Immediately following injection, a dynamic scan of the brain was acquired for 15 min. This was followed by serial whole-body PET/MRI scans acquired up to 3 h post-injection. Blood samples were collected at regular intervals, and vital signs monitored pre- and post-radiotracer administration. Regions of interest were drawn around multiple organs, time-activity curves were calculated, and organ uptake and dosimetry were estimated with OLINDA/EXM (version 1.1) software.All subjects tolerated the PET/MRI examination, without adverse reactions to [18F]DASA-23. [18F]DASA-23 passively crossed the blood-brain barrier, followed by rapid clearance from the brain. High accumulation of [18F]DASA-23 was noted in organs such as the gallbladder, liver, small intestine, and urinary bladder, suggesting hepatobiliary and urinary clearance. The effective dose of [18F]DASA-23 was 23.5 ± 5.8 μSv/MBq.We successfully completed a pilot first-in-human study of [18F]DASA-23. Our results indicate that [18F]DASA-23 can be used safely in humans to evaluate pyruvate kinase M2 levels. Ongoing studies are evaluating the ability of [18F]DASA-23 to visualize intracranial malignancies, NCT03539731.ClinicalTrials.gov, NCT03539731 (registered 28 May 2018).

  View details for DOI 10.1007/s00259-020-04687-0

  View details for PubMedID 31938892

• Trop2 is a driver of metastatic prostate cancer with neuroendocrine phenotype via PARP1. Proceedings of the National Academy of Sciences of the United States of America Hsu, E. C., Rice, M. A., Bermudez, A. n., Marques, F. J., Aslan, M. n., Liu, S. n., Ghoochani, A. n., Zhang, C. A., Chen, Y. S., Zlitni, A. n., Kumar, S. n., Nolley, R. n., Habte, F. n., Shen, M. n., Koul, K. n., Peehl, D. M., Zoubeidi, A. n., Gambhir, S. S., Kunder, C. A., Pitteri, S. J., Brooks, J. D., Stoyanova, T. n. 2020

  Abstract

  Resistance to androgen deprivation therapy, or castration-resistant prostate cancer (CRPC), is often accompanied by metastasis and is currently the ultimate cause of prostate cancer-associated deaths in men. Recently, secondary hormonal therapies have led to an increase of neuroendocrine prostate cancer (NEPC), a highly aggressive variant of CRPC. Here, we identify that high levels of cell surface receptor Trop2 are predictive of recurrence of localized prostate cancer. Moreover, Trop2 is significantly elevated in CRPC and NEPC, drives prostate cancer growth, and induces neuroendocrine phenotype. Overexpression of Trop2 induces tumor growth and metastasis while loss of Trop2 suppresses these abilities in vivo. Trop2-driven NEPC displays a significant up-regulation of PARP1, and PARP inhibitors significantly delay tumor growth and metastatic colonization and reverse neuroendocrine features in Trop2-driven NEPC. Our findings establish Trop2 as a driver and therapeutic target for metastatic prostate cancer with neuroendocrine phenotype and suggest that high Trop2 levels could identify cancers that are sensitive to Trop2-targeting therapies and PARP1 inhibition.

  View details for DOI 10.1073/pnas.1905384117

  View details for PubMedID 31932422

• Reconstructed Apoptotic Bodies as Targeted "Nano Decoys" to Treat Intracellular Bacterial Infections within Macrophages and Cancer Cells. ACS nano Bose, R. J., Tharmalingam, N. n., Garcia Marques, F. J., Sukumar, U. K., Natarajan, A. n., Zeng, Y. n., Robinson, E. n., Bermudez, A. n., Chang, E. n., Habte, F. n., Pitteri, S. J., McCarthy, J. R., Gambhir, S. S., Massoud, T. F., Mylonakis, E. n., Paulmurugan, R. n. 2020

  Abstract

  Staphylococcus aureus (S. aureus) is a highly pathogenic facultative anaerobe that in some instances resides as an intracellular bacterium within macrophages and cancer cells. This pathogen can establish secondary infection foci, resulting in recurrent systemic infections that are difficult to treat using systemic antibiotics. Here, we use reconstructed apoptotic bodies (ReApoBds) derived from cancer cells as "nano decoys" to deliver vancomycin intracellularly to kill S. aureus by targeting inherent "eat me" signaling of ApoBds. We prepared ReApoBds from different cancer cells (SKBR3, MDA-MB-231, HepG2, U87-MG, and LN229) and used them for vancomycin delivery. Physicochemical characterization showed ReApoBds size ranges from 80 to 150 nm and vancomycin encapsulation efficiency of 60 ± 2.56%. We demonstrate that the loaded vancomycin was able to kill intracellular S. aureus efficiently in an in vitro model of S. aureus infected RAW-264.7 macrophage cells, and U87-MG (p53-wt) and LN229 (p53-mt) cancer cells, compared to free-vancomycin treatment (P < 0.001). The vancomycin loaded ReApoBds treatment in S. aureus infected macrophages showed a two-log-order higher CFU reduction than the free-vancomycin treatment group. In vivo studies revealed that ReApoBds can specifically target macrophages and cancer cells. Vancomycin loaded ReApoBds have the potential to kill intracellular S. aureus infection in vivo in macrophages and cancer cells.

  View details for DOI 10.1021/acsnano.0c00921

  View details for PubMedID 32347709

• Low-frequency ultrasound-mediated cytokine transfection enhances T cell recruitment at local and distant tumor sites. Proceedings of the National Academy of Sciences of the United States of America Ilovitsh, T. n., Feng, Y. n., Foiret, J. n., Kheirolomoom, A. n., Zhang, H. n., Ingham, E. S., Ilovitsh, A. n., Tumbale, S. K., Fite, B. Z., Wu, B. n., Raie, M. N., Zhang, N. n., Kare, A. J., Chavez, M. n., Qi, L. S., Pelled, G. n., Gazit, D. n., Vermesh, O. n., Steinberg, I. n., Gambhir, S. S., Ferrara, K. W. 2020

  Abstract

  Robust cytotoxic T cell infiltration has proven to be difficult to achieve in solid tumors. We set out to develop a flexible protocol to efficiently transfect tumor and stromal cells to produce immune-activating cytokines, and thus enhance T cell infiltration while debulking tumor mass. By combining ultrasound with tumor-targeted microbubbles, membrane pores are created and facilitate a controllable and local transfection. Here, we applied a substantially lower transmission frequency (250 kHz) than applied previously. The resulting microbubble oscillation was significantly enhanced, reaching an effective expansion ratio of 35 for a peak negative pressure of 500 kPa in vitro. Combining low-frequency ultrasound with tumor-targeted microbubbles and a DNA plasmid construct, 20% of tumor cells remained viable, and ∼20% of these remaining cells were transfected with a reporter gene both in vitro and in vivo. The majority of cells transfected in vivo were mucin 1+/CD45- tumor cells. Tumor and stromal cells were then transfected with plasmid DNA encoding IFN-β, producing 150 pg/106 cells in vitro, a 150-fold increase compared to no-ultrasound or no-plasmid controls and a 50-fold increase compared to treatment with targeted microbubbles and ultrasound (without IFN-β). This enhancement in secretion exceeds previously reported fourfold to fivefold increases with other in vitro treatments. Combined with intraperitoneal administration of checkpoint inhibition, a single application of IFN-β plasmid transfection reduced tumor growth in vivo and recruited efficacious immune cells at both the local and distant tumor sites.

  View details for DOI 10.1073/pnas.1914906117

  View details for PubMedID 32430322

• Two Patient Studies of a Companion Diagnostic Immuno-Positron Emission Tomography (PET) Tracer for Measuring Human CA6 Expression in Cancer for Antibody Drug Conjugate (ADC) Therapy. Molecular imaging Natarajan, A., Srinivas, S. M., Azevedo, C., Greene, L., Bauchet, A., Jouannot, E., Lacoste-Bourgeacq, A., Guizon, I., Cohen, P., Naneix, A., Ilovich, O., Cisneros, J., Rupanarayan, K., Chin, F. T., Iagaru, A., Dirbas, F. M., Karam, A., Gambhir, S. S. 2020; 19: 1536012120939398

  Abstract

  An antigen binding fragment (BFab) derived from a tumor-associated mucin 1-sialoglycotope antigen (CA6) targeting antibody (huDS6) was engineered. We synthesized a companion diagnostic positron emission tomography (PET) tracer by radiolabeling BFab with [64Cu] to measure CA6 expression on cancer tissues prior to anti-human CA6 (huDS6-DM4 antibody-drug conjugate) therapy for ovarian and breast cancer patients. After chemotherapy, the ovarian patient received PET scan with 18F-2-fluoro-2-deoxyglucose ([18F]FDG: 10 mCi), followed by [64Cu]-DOTA-BFab ([64Cu]BFab; 5.5 mCi) 1 week later for PET scanning of CA6 expression and subsequent surgery. The breast cancer patient was treated with chemotherapy before primary tumor resection and subsequent [18F]FDG-PET scan. 4 weeks later the patient received of [64Cu]BFab (11.7 mCi) for CA6 PET scan. Whole body [18F]FDG-PET of the breast cancer patient indicated FDG-avid tumor metastases to the liver, bilateral hila and thoracic spine, but no uptake was observed for the ovarian patient. Each patient was also imaged by PET/CT with [64Cu]BFab at 1 and 24 hours after tracer administration. The [64Cu]BFab tracer was well tolerated by both patients without adverse effects, and no significant tracer uptake was observed in both patients. Immunohistochemistry (IHC) data indicated CA6 expressions were weak to intermediate and matched with the [64Cu]BFab-PET signals.

  View details for DOI 10.1177/1536012120939398

  View details for PubMedID 33104454

• Discovery and Optimization of Small-Molecule Ligands for V-Domain Ig Suppressor of T-Cell Activation (VISTA). Journal of the American Chemical Society Gabr, M. T., Gambhir, S. S. 2020

  Abstract

  V-domain Ig suppressor of T-cell activation (VISTA) is an immune checkpoint that affects the ability of T-cells to attack tumors. A FRET-based high throughput screening identified NSC622608 as the first small-molecule ligand for VISTA. Investigation of the interaction of NSC622608 with VISTA using STD NMR and molecular modeling enabled the identification of a potential binding site in VISTA for NSC622608. Screening NSC622608 against a library of single-point VISTA mutants revealed the key residues in VISTA interacting with NSC622608. Further structural optimization resulted in a lead with submicromolar VISTA binding affinity. The lead compound blocked VISTA signaling in vitro, enhanced T-cell proliferation, and restored T-cell activation in the presence of VISTA-expressing cancer cell lines. This work would enable future development of small molecules targeting VISTA as immunomodulators and imaging probes.

  View details for DOI 10.1021/jacs.0c07276

  View details for PubMedID 32894020

• A mountable toilet system for personalized health monitoring via the analysis of excreta. Nature biomedical engineering Park, S. M., Won, D. D., Lee, B. J., Escobedo, D. n., Esteva, A. n., Aalipour, A. n., Ge, T. J., Kim, J. H., Suh, S. n., Choi, E. H., Lozano, A. X., Yao, C. n., Bodapati, S. n., Achterberg, F. B., Kim, J. n., Park, H. n., Choi, Y. n., Kim, W. J., Yu, J. H., Bhatt, A. M., Lee, J. K., Spitler, R. n., Wang, S. X., Gambhir, S. S. 2020

  Abstract

  Technologies for the longitudinal monitoring of a person's health are poorly integrated with clinical workflows, and have rarely produced actionable biometric data for healthcare providers. Here, we describe easily deployable hardware and software for the long-term analysis of a user's excreta through data collection and models of human health. The 'smart' toilet, which is self-contained and operates autonomously by leveraging pressure and motion sensors, analyses the user's urine using a standard-of-care colorimetric assay that traces red-green-blue values from images of urinalysis strips, calculates the flow rate and volume of urine using computer vision as a uroflowmeter, and classifies stool according to the Bristol stool form scale using deep learning, with performance that is comparable to the performance of trained medical personnel. Each user of the toilet is identified through their fingerprint and the distinctive features of their anoderm, and the data are securely stored and analysed in an encrypted cloud server. The toilet may find uses in the screening, diagnosis and longitudinal monitoring of specific patient populations.

  View details for DOI 10.1038/s41551-020-0534-9

  View details for PubMedID 32251391

• Author Correction: Non-Invasive Photoacoustic Imaging of In Vivo Mice with Erythrocyte Derived Optical Nanoparticles to Detect CAD/MI. Scientific reports Liu, Y. n., Hanley, T. n., Chen, H. n., Long, S. R., Gambhir, S. S., Cheng, Z. n., Wu, J. C., Fakhri, G. E., Anvari, B. n., Zaman, R. T. 2020; 10 (1): 19102

  Abstract

  An amendment to this paper has been published and can be accessed via a link at the top of the paper.

  View details for DOI 10.1038/s41598-020-75966-x

  View details for PubMedID 33127974

• Publisher Correction: A mountable toilet system for personalized health monitoring via the analysis of excreta. Nature biomedical engineering Park, S. M., Won, D. D., Lee, B. J., Escobedo, D. n., Esteva, A. n., Aalipour, A. n., Ge, T. J., Kim, J. H., Suh, S. n., Choi, E. H., Lozano, A. X., Yao, C. n., Bodapati, S. n., Achterberg, F. B., Kim, J. n., Park, H. n., Choi, Y. n., Kim, W. J., Yu, J. H., Bhatt, A. M., Lee, J. K., Spitler, R. n., Wang, S. X., Gambhir, S. S. 2020

  Abstract

  An amendment to this paper has been published and can be accessed via a link at the top of the paper.

  View details for DOI 10.1038/s41551-020-0562-5

  View details for PubMedID 32382068

• Maltotriose-based probes for fluorescence and photoacoustic imaging of bacterial infections. Nature communications Zlitni, A. n., Gowrishankar, G. n., Steinberg, I. n., Haywood, T. n., Sam Gambhir, S. n. 2020; 11 (1): 1250

  Abstract

  Currently, there are no non-invasive tools to accurately diagnose wound and surgical site infections before they become systemic or cause significant anatomical damage. Fluorescence and photoacoustic imaging are cost-effective imaging modalities that can be used to noninvasively diagnose bacterial infections when paired with a molecularly targeted infection imaging agent. Here, we develop a fluorescent derivative of maltotriose (Cy7-1-maltotriose), which is shown to be taken up in a variety of gram-positive and gram-negative bacterial strains in vitro. In vivo fluorescence and photoacoustic imaging studies highlight the ability of this probe to detect infection, assess infection burden, and visualize the effectiveness of antibiotic treatment in E. coli-induced myositis and a clinically relevant S. aureus wound infection murine model. In addition, we show that maltotriose is an ideal scaffold for infection imaging agents encompassing better pharmacokinetic properties and in vivo stability than other maltodextrins (e.g. maltohexose).

  View details for DOI 10.1038/s41467-020-14985-8

  View details for PubMedID 32144257

• Plasmonic and Electrostatic Interactions Enable Uniformly Enhanced Liquid Bacterial Surface-Enhanced Raman Scattering (SERS). Nano letters Tadesse, L. F., Ho, C. S., Chen, D. H., Arami, H. n., Banaei, N. n., Gambhir, S. S., Jeffrey, S. S., Saleh, A. A., Dionne, J. n. 2020

  Abstract

  Surface-enhanced Raman spectroscopy (SERS) is a promising cellular identification and drug susceptibility testing platform, provided it can be performed in a controlled liquid environment that maintains cell viability. We investigate bacterial liquid-SERS, studying plasmonic and electrostatic interactions between gold nanorods and bacteria that enable uniformly enhanced SERS. We synthesize five nanorod sizes with longitudinal plasmon resonances ranging from 670 to 860 nm and characterize SERS signatures of Gram-negative Escherichia coli and Serratia marcescens and Gram-positive Staphylococcus aureus and Staphylococcus epidermidis bacteria in water. Varying the concentration of bacteria and nanorods, we achieve large-area SERS enhancement that is independent of nanorod resonance and bacteria type; however, bacteria with higher surface charge density exhibit significantly higher SERS signal. Using cryo-electron microscopy and zeta potential measurements, we show that the higher signal results from attraction between positively charged nanorods and negatively charged bacteria. Our robust liquid-SERS measurements provide a foundation for bacterial identification and drug testing in biological fluids.

  View details for DOI 10.1021/acs.nanolett.0c03189

  View details for PubMedID 32914987

• Toward the Clinical Development and Validation of a Thy1-Targeted Ultrasound Contrast Agent for the Early Detection of Pancreatic Ductal Adenocarcinoma. Investigative radiology Bam, R. n., Daryaei, I. n., Abou-Elkacem, L. n., Vilches-Moure, J. G., Meuillet, E. J., Lutz, A. n., Marinelli, E. R., Unger, E. C., Gambhir, S. S., Paulmurugan, R. n. 2020

  Abstract

  Early detection of pancreatic ductal adenocarcinoma (PDAC) represents the most significant step toward the treatment of this aggressive lethal disease. Previously, we engineered a preclinical Thy1-targeted microbubble (MBThy1) contrast agent that specifically recognizes Thy1 antigen overexpressed in the vasculature of murine PDAC tissues by ultrasound (US) imaging. In this study, we adopted a single-chain variable fragment (scFv) site-specific bioconjugation approach to construct clinically translatable MBThy1-scFv and test for its efficacy in vivo in murine PDAC imaging, and functionally evaluated the binding specificity of scFv ligand to human Thy1 in patient PDAC tissues ex vivo.We recombinantly expressed the Thy1-scFv with a carboxy-terminus cysteine residue to facilitate its thioether conjugation to the PEGylated MBs presenting with maleimide functional groups. After the scFv-MB conjugations, we tested binding activity of the MBThy1-scFv to MS1 cells overexpressing human Thy1 (MS1Thy1) under liquid shear stress conditions in vitro using a flow chamber setup at 0.6 mL/min flow rate, corresponding to a wall shear stress rate of 100 seconds, similar to that in tumor capillaries. For in vivo Thy1 US molecular imaging, MBThy1-scFv was tested in the transgenic mouse model (C57BL/6J - Pdx1-Cre; KRas; Ink4a/Arf) of PDAC and in control mice (C57BL/6J) with L-arginine-induced pancreatitis or normal pancreas. To facilitate its clinical feasibility, we further produced Thy1-scFv without the bacterial fusion tags and confirmed its recognition of human Thy1 in cell lines by flow cytometry and in patient PDAC frozen tissue sections of different clinical grades by immunofluorescence staining.Under shear stress flow conditions in vitro, MBThy1-scFv bound to MS1Thy1 cells at significantly higher numbers (3.0 ± 0.8 MB/cell; P < 0.01) compared with MBNontargeted (0.5 ± 0.5 MB/cell). In vivo, MBThy1-scFv (5.3 ± 1.9 arbitrary units [a.u.]) but not the MBNontargeted (1.2 ± 1.0 a.u.) produced high US molecular imaging signal (4.4-fold vs MBNontargeted; n = 8; P < 0.01) in the transgenic mice with spontaneous PDAC tumors (2-6 mm). Imaging signal from mice with L-arginine-induced pancreatitis (n = 8) or normal pancreas (n = 3) were not significantly different between the two MB constructs and were significantly lower than PDAC Thy1 molecular signal. Clinical-grade scFv conjugated to Alexa Fluor 647 dye recognized MS1Thy1 cells but not the parental wild-type cells as evaluated by flow cytometry. More importantly, scFv showed highly specific binding to VEGFR2-positive vasculature and fibroblast-like stromal components surrounding the ducts of human PDAC tissues as evaluated by confocal microscopy.Our findings summarize the development and validation of a clinically relevant Thy1-targeted US contrast agent for the early detection of human PDAC by US molecular imaging.

  View details for DOI 10.1097/RLI.0000000000000697

  View details for PubMedID 32569010

• Biodegradable fluorescent nanoparticles for endoscopic detection of colorectal carcinogenesis. Advanced functional materials Rogalla, S., Flisikowski, K., Gorpas, D., Mayer, A. T., Flisikowska, T., Mandella, M. J., Ma, X., Casey, K. M., Felt, S. A., Saur, D., Ntziachristos, V., Schnieke, A., Contag, C. H., Gambhir, S. S., Harmsen, S. 2019; 29 (51)

  Abstract

  Early and comprehensive endoscopic detection of colonic dysplasia - the most clinically significant precursor lesion to colorectal adenocarcinoma - provides an opportunity for timely, minimally-invasive intervention to prevent malignant transformation. Here, the development and evaluation of biodegradable near-infrared fluorescent silica nanoparticles (FSN) is described that have the potential to improve adenoma detection during fluorescence-assisted white-light colonoscopic surveillance in rodent and human-scale models of colorectal carcinogenesis. FSNs are biodegradable (t1/2 of 2.7 weeks), well-tolerated, and enable detection and delineation of adenomas as small as 0.5 mm2 with high tumor-to-background ratios. Furthermore, in the human-scale, APC 1311/+ porcine model, the clinical feasibility and benefit of using FSN-guided detection of colorectal adenomas using video-rate fluorescence-assisted white-light endoscopy is demonstrated. Since nanoparticles of similar size (e.g., 100-150-nm) or composition (i.e., silica, silica/gold hybrid) have already been successfully translated to the clinic, and, clinical fluorescent/white light endoscopy systems are becoming more readily available, there is a viable path towards clinical translation of the proposed strategy for early colorectal cancer detection and prevention in high-risk patients.

  View details for DOI 10.1002/adfm.201904992

  View details for PubMedID 33041743

  View details for PubMedCentralID PMC7546531

• Biodegradable Fluorescent Nanoparticles for Endoscopic Detection of Colorectal Carcinogenesis ADVANCED FUNCTIONAL MATERIALS Rogalla, S., Flisikowski, K., Gorpas, D., Mayer, A. T., Flisikowska, T., Mandella, M. J., Ma, X., Casey, K. M., Felt, S. A., Saur, D., Ntziachristos, V., Schnieke, A., Contag, C. H., Gambhir, S. S., Harmsen, S. 2019; 29 (51)

  View details for DOI 10.1002/adfm.201904992

  View details for Web of Science ID 000516572400007

• EVALUATION OF [18F]DASA-23 FOR NON-INVASIVE MEASUREMENT OF ABERRANTLY EXPRESSED PYRUVATE KINASE M2 IN GLIOMA: FIRST-IN-HUMAN STUDY Patel, C., Beinat, C., Haywood, T., Murty, S., Xie, Y., Recht, L., Nagpal, S., Thomas, R., Khalighi, M., Gandhi, H., Holley, D., Gambhir, S. OXFORD UNIV PRESS INC. 2019: 169

  View details for Web of Science ID 000509478704010

• TUMOR TREATING FIELDS LEADS TO CHANGES IN MEMBRANE PERMEABILITY AND INCREASED PENETRATION BY ANTI-GLIOMA DRUGS Chang, E., Patel, C., Beinat, C., Young, C., Flores, T., Zeng, Y., Joubert, L., Arami, H., Natarajan, A., Sinclair, R., Gambhir, S. OXFORD UNIV PRESS INC. 2019: 93

  View details for Web of Science ID 000509478702048

• Engineering of a novel subnanomolar affinity fibronectin III domain binder targeting human programmed death-ligand 1. Protein engineering, design & selection : PEDS Ramakrishnan, S., Natarajan, A., Chan, C. T., Panesar, P. S., Gambhir, S. S. 2019

  Abstract

  The programmed death-ligand 1 (PD-L1) is a major checkpoint protein that helps cancer cells evade the immune system. A non-invasive imaging agent with rapid clearance rate would be an ideal tool to predict and monitor the efficacy of anti-PD-L1 therapy. The aim of this research was to engineer a subnanomolar, high-affinity fibronectin type 3 domain (FN3)-based small binder targeted against human PD-L1 (hPD-L1) present on tumor cells. A naive yeast G4 library containing the FN3 gene with three binding loop sequences was used to isolate high-affinity binders targeted to purified full-length hPD-L1. The selected binder clones displayed several mutations in the loop regions of the FN3 domain. One unique clone (FN3hPD-L1-01) with a 6x His-tag at the C-terminus had a protein yield of >5mg/L and a protein mass of 12kDa. In vitro binding assays on six different human cancer cell lines (MDA-MB-231, DLD1, U87, 293T, Raji and Jurkat) and murine CT26 colon carcinoma cells stably expressing hPD-L1 showed that CT26/hPD-L1 cells had the highest expression of hPD-L1 in both basal and IFN-gamma-induced states, with a binding affinity of 2.38±0.26nM for FN3hPD-L1-01. The binding ability of FN3hPD-L1-01 was further confirmed by immunofluorescence staining on ex vivo CT26/hPD-L1 tumors sections. The FN3hPD-L1-01 binder represents a novel, small, high-affinity binder for imaging hPD-L1 expression on tumor cells and would aid in earlier imaging of tumors. Future clinical validation studies of the labeled FN3hPD-L1 binder(s) have the potential to monitor immune checkpoint inhibitors therapy and predict responders.

  View details for DOI 10.1093/protein/gzz030

  View details for PubMedID 31612217

• Evaluation of integrin alphavbeta6 cystine knot PET tracers to detect cancer and idiopathic pulmonary fibrosis. Nature communications Kimura, R. H., Wang, L., Shen, B., Huo, L., Tummers, W., Filipp, F. V., Guo, H. H., Haywood, T., Abou-Elkacem, L., Baratto, L., Habte, F., Devulapally, R., Witney, T. H., Cheng, Y., Tikole, S., Chakraborti, S., Nix, J., Bonagura, C. A., Hatami, N., Mooney, J. J., Desai, T., Turner, S., Gaster, R. S., Otte, A., Visser, B. C., Poultsides, G. A., Norton, J., Park, W., Stolowitz, M., Lau, K., Yang, E., Natarajan, A., Ilovich, O., Srinivas, S., Srinivasan, A., Paulmurugan, R., Willmann, J., Chin, F. T., Cheng, Z., Iagaru, A., Li, F., Gambhir, S. S. 2019; 10 (1): 4673

  Abstract

  Advances in precision molecular imaging promise to transform our ability to detect, diagnose and treat disease. Here, we describe the engineering and validation of a new cystine knot peptide (knottin) that selectively recognizes human integrin alphavbeta6 with single-digit nanomolar affinity. We solve its 3D structure by NMR and x-ray crystallography and validate leads with 3 different radiolabels in pre-clinical models of cancer. We evaluate the lead tracer's safety, biodistribution and pharmacokinetics in healthy human volunteers, and show its ability to detect multiple cancers (pancreatic, cervical and lung) in patients at two study locations. Additionally, we demonstrate that the knottin PET tracers can also detect fibrotic lung disease in idiopathic pulmonary fibrosis patients. Our results indicate that these cystine knot PET tracers may have potential utility in multiple disease states that are associated with upregulation of integrin alphavbeta6.

  View details for DOI 10.1038/s41467-019-11863-w

  View details for PubMedID 31611594

• How to Prevent a Leaky Pipeline in Academic Radiology: Insights From a Faculty Survey JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Daldrup-Link, H., Villavasso, K., Zhao, Q., Lu, Y., Ranieri, A., Simard, C., Gambhir, S. 2019; 16 (9): 1220–24

  View details for DOI 10.1016/j.jacr.2019.04.008

  View details for Web of Science ID 000486132000023

• In Vivo Translation of the CIRPI System: Revealing Molecular Pathology of Rabbit Aortic Atherosclerotic Plaques JOURNAL OF NUCLEAR MEDICINE Zaman, R. T., Yousefi, S., Chibana, H., Ikeno, F., Long, S. R., Gambhir, S. S., Chin, F. T., McConnell, M. V., Xing, L., Yeung, A. 2019; 60 (9): 1308–16

  View details for DOI 10.2967/jnumed.118.222471

  View details for Web of Science ID 000484372100026

• Simultaneous transrectal ultrasound and photoacoustic human prostate imaging. Science translational medicine Kothapalli, S., Sonn, G. A., Choe, J. W., Nikoozadeh, A., Bhuyan, A., Park, K. K., Cristman, P., Fan, R., Moini, A., Lee, B. C., Wu, J., Carver, T. E., Trivedi, D., Shiiba, L., Steinberg, I., Huland, D. M., Rasmussen, M. F., Liao, J. C., Brooks, J. D., Khuri-Yakub, P. T., Gambhir, S. S. 2019; 11 (507)

  Abstract

  Imaging technologies that simultaneously provide anatomical, functional, and molecular information are emerging as an attractive choice for disease screening and management. Since the 1980s, transrectal ultrasound (TRUS) has been routinely used to visualize prostatic anatomy and guide needle biopsy, despite limited specificity. Photoacoustic imaging (PAI) provides functional and molecular information at ultrasonic resolution based on optical absorption. Combining the strengths of TRUS and PAI approaches, we report the development and bench-to-bedside translation of an integrated TRUS and photoacoustic (TRUSPA) device. TRUSPA uses a miniaturized capacitive micromachined ultrasonic transducer array for simultaneous imaging of anatomical and molecular optical contrasts [intrinsic: hemoglobin; extrinsic: intravenous indocyanine green (ICG)] of the human prostate. Hemoglobin absorption mapped vascularity of the prostate and surroundings, whereas ICG absorption enhanced the intraprostatic photoacoustic contrast. Future work using the TRUSPA device for biomarker-specific molecular imaging may enable a fundamentally new approach to prostate cancer diagnosis, prognostication, and therapeutic monitoring.

  View details for DOI 10.1126/scitranslmed.aav2169

  View details for PubMedID 31462508

• Microvesicle-mediated delivery of minicircle DNA results in effective gene-directed enzyme prodrug cancer therapy. Molecular cancer therapeutics Kanada, M., Kim, B. D., Hardy, J. W., Bachmann, M. H., Bernard, M. P., Perez, G. I., Zarea, A. A., Ge, T. J., Withrow, A., Ibrahim, S. A., Toomajian, V., Gambhir, S. S., Paulmurugan, R., Contag, C. H., Ronald, J. A. 2019

  Abstract

  An emerging approach for cancer treatment employs the use of extracellular vesicles (EVs), specifically exosomes and microvesicles, as delivery vehicles. We previously demonstrated that microvesicles can functionally deliver plasmid DNA to cells and showed that plasmid size and sequence, in part, determine the delivery efficiency. In this study, delivery vehicles comprised of microvesicles loaded with engineered minicircle (MC) DNA that encodes prodrug converting enzymes were developed as a cancer therapy in mammary carcinoma models. We demonstrated that MCs can be loaded into shed microvesicles with greater efficiency than their parental plasmid counterparts and that microvesicle-mediated MC delivery led to significantly higher and more prolonged transgene expression in recipient cells than microvesicles loaded with the parental plasmid. Microvesicles loaded with MCs encoding a thymidine kinase (TK)/nitroreductase (NTR) fusion protein produced prolonged TK-NTR expression in mammary carcinoma cells. In vivo delivery of TK-NTR and administration of prodrugs led to the effective killing of both targeted cells and surrounding tumor cells via TK-NTR-mediated conversion of co-delivered prodrugs into active cytotoxic agents. In vivo evaluation of the bystander effect in mouse models demonstrated that for effective therapy, at least 1% of tumor cells need to be delivered with TK-NTR-encoding MCs. These results suggest that MC delivery via microvesicles can mediate gene transfer to an extent that enables effective prodrug conversion and tumor cell death such that it comprises a promising approach to cancer therapy.

  View details for DOI 10.1158/1535-7163.MCT-19-0299

  View details for PubMedID 31451563

• Continuous-Wave Coherent Raman Spectroscopy via Plasmonic Enhancement. Scientific reports Monfared, Y. E., Shaffer, T. M., Gambhir, S. S., Hewitt, K. C. 2019; 9 (1): 12092

  Abstract

  In this paper, we report a successful combination of stimulated Raman spectroscopy (SRS) and surface-enhanced Raman scattering (SERS) using cw laser sources and gold/silica nanoparticles with embedded reporter molecules. We describe the preparation method for our gold/silica nanoparticles as well as the effect of probe wavelength, pump and probe power, polarization and sample concentration on the cwSESRS signal. Altogether, a stable ~12 orders of magnitude enhancement in the stimulated Raman signal is achieved because of the amplification of both pump and probe beams, leading to the detection of pico-molar nanoparticle concentrations, comparable to those of SERS. The coherent Raman spectra matches the incoherent conventional Raman spectra of the reporter molecules. Unlike conventional incoherent SERS this approach generates a coherent stimulated signal of microwatt intensities, opening the field to applications requiring a coherent beam, such as Molecular Holography.

  View details for DOI 10.1038/s41598-019-48573-8

  View details for PubMedID 31431666

• Ultrasound/microbubble-mediated targeted delivery of anticancer microRNA-loaded nanoparticles to deep tissues in pigs. Journal of controlled release : official journal of the Controlled Release Society Di Ianni, T., Bose, R. J., Sukumar, U. K., Bachawal, S., Wang, H., Telichko, A., Herickhoff, C., Robinson, E., Baker, S., Vilches-Moure, J. G., Felt, S. A., Gambhir, S. S., Paulmurugan, R., Dahl, J. D. 2019

  Abstract

  In this study, we designed and validated a platform for ultrasound and microbubble-mediated delivery of FDA-approved pegylated poly lactic-co-glycolic acid (PLGA) nanoparticles loaded with anticancer microRNAs (miRNAs) to deep tissues in a pig model. Small RNAs have been shown to reprogram tumor cells and sensitize them to clinically used chemotherapy. To overcome their short intravascular circulation half-life and achieve controlled and sustained release into tumor cells, anticancer miRNAs need to be encapsulated into nanocarriers. Focused ultrasound combined with gas-filled microbubbles provides a noninvasive way to improve the permeability of tumor vasculature and increase the delivery efficiency of drug-loaded particles. A single handheld, curvilinear ultrasound array was used in this study for image-guided therapy with clinical-grade SonoVue contrast agent. First, we validated the platform on phantoms to optimize the microbubble cavitation dose based on acoustic parameters, including peak negative pressure, pulse length, and pulse repetition frequency. We then tested the system in vivo by delivering PLGA nanoparticles co-loaded with antisense-miRNA-21 and antisense-miRNA-10b to pig liver and kidney. Enhanced miRNA delivery was observed (1.9- to 3.7-fold increase) as a result of the ultrasound treatment compared to untreated control regions. Additionally, we used highly fluorescent semiconducting polymer nanoparticles to visually assess nanoparticle extravasation. Fluorescent microscopy suggested the presence of nanoparticles in the extravascular compartment. Hematoxylin and eosin staining of treated tissues did not reveal tissue damage. The results presented in this manuscript suggest that the proposed platform may be used to safely and noninvasively enhance the delivery of miRNA-loaded nanoparticles to target regions in deep organs in large animal models.

  View details for DOI 10.1016/j.jconrel.2019.07.024

  View details for PubMedID 31326463

• Intranasal delivery of targeted polyfunctional gold-iron oxide nanoparticles loaded with therapeutic microRNAs for combined theranostic multimodality imaging and presensitization of glioblastoma to temozolomide. Biomaterials Sukumar, U. K., Bose, R. J., Malhotra, M., Babikir, H. A., Afjei, R., Robinson, E., Zeng, Y., Chang, E., Habte, F., Sinclair, R., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. 2019; 218: 119342

  Abstract

  The prognosis for glioblastoma (GBM) remains depressingly low. The biological barriers of the brain present a major challenge to achieving adequate drug concentrations for GBM therapy. To address this, we explore the potential of the nose-to-brain direct transport pathway to bypass the blood-brain barrier, and to enable targeted delivery of theranostic polyfunctional gold-iron oxide nanoparticles (polyGIONs) surface loaded with therapeutic miRNAs (miR-100 and antimiR-21) to GBMs in mice. These nanoformulations would thus allow presensitization of GBM cells to the systemically delivered chemotherapy drug temozolomide (TMZ), as well as in vivo multimodality molecular and anatomic imaging of nanoparticle delivery, trafficking, and treatment effects. First, we synthesized GIONs coated with beta-cyclodextrin-chitosan (CD-CS) hybrid polymer, and co-loaded with miR-100 and antimiR-21. Then we decorated their surface with PEG-T7 peptide using CD-adamantane host-guest chemistry. The resultant polyGIONs showed efficient miRNA loading with enhanced serum stability. We characterized them for particle size, PDI, polymer functionalization, charge and release using dynamic light scattering analysis, TEM and qRT-PCR. For in vivo intranasal delivery, we used U87-MG GBM cell-derived orthotopic xenograft models in mice. Intranasal delivery resulted in efficient accumulation of Cy5-miRNAs in mice treated with T7-targeted polyGIONs, as demonstrated by in vivo optical fluorescence and MR imaging. We measured the therapeutic response of these FLUC-EGFP labelled U87-MG GBMs using bioluminescence imaging. Overall, there was a significant increase in survival of mice co-treated with T7-polyGIONs loaded with miR-100/antimiR-21 plus systemic TMZ, compared to the untreated control group, or the animals receiving non-targeted polyGIONs-miR-100/antimiR-21, or TMZ alone. Once translated clinically, this novel theranostic nanoformulation and its associated intranasal delivery strategy will have a strong potential to potentiate the effects of TMZ treatment in GBM patients.

  View details for DOI 10.1016/j.biomaterials.2019.119342

  View details for PubMedID 31326657

• Author Correction: Miniature gold nanorods for photoacoustic molecular imaging in the second near-infrared optical window. Nature nanotechnology Chen, Y., Zhao, Y., Yoon, S. J., Gambhir, S. S., Emelianov, S. 2019

  Abstract

  An amendment to this paper has been published and can be accessed via a link at the top of the paper.

  View details for DOI 10.1038/s41565-019-0522-y

  View details for PubMedID 31289408

• Tumor treating fields increases membrane permeability in glioblastoma cells Chang, E., Patel, C., Pohling, C., Young, C., Song, J., Flores, T. A., Zeng, Y., Joubert, L., Arami, H., Natarajan, A., Sinclair, R., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2019

  View details for DOI 10.1158/1538-7445.AM2019-250

  View details for Web of Science ID 000488129901424

• Detection of visually occult metastatic lymph nodes using molecularly targeted fluorescent imaging during surgical resection of pancreatic cancer HPB Tummers, W. S., Miller, S. E., Teraphongphom, N. T., van den Berg, N. S., Hasan, A., Longacre, T. A., Fisher, G. A., Bonsing, B. A., Vahrmeijer, A. L., Gambhir, S. S., Swijnenburg, R., Rosenthal, E. L., Poultsides, G. A. 2019; 21 (7): 883–90

  View details for DOI 10.1016/j.hpb.2018.11.008

  View details for Web of Science ID 000475487400014

• Simultaneous PET/MRI in the Evaluation of Breast and Prostate Cancer Using Combined Na[18F] F and [18F]FDG: a Focus on Skeletal Lesions. Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging Sonni, I., Minamimoto, R., Baratto, L., Gambhir, S. S., Loening, A. M., Vasanawala, S. S., Iagaru, A. 2019

  Abstract

  PURPOSE: The purpose of this study is to prospectively evaluate the performance of sodium 18F]fluoride (Na[18F]F)/2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) simultaneous time-of-flight enabled positron emission tomography (PET)/magnetic resonance imaging (MRI) for the detection of skeletal metastases in selected patients with advanced breast and prostate cancers.PROCEDURE: The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. A total of 74 patients (23 women and 51 men with breast and prostate cancer, respectively) referred for standard-of-care whole-body bone scintigraphy (WBBS) were enrolled in this prospective study. All patients underwent a [99mTc]methyldiphosphonate ([99mTc]MDP) WBBS followed by Na[18F]F/[18F]FDG PET/MRI. Lesions detected by each imaging modality were tabulated and a lesion-based and patient-based analysis was conducted.RESULTS: On a patient-based analysis, [99mTc]MDP WBBS identified skeletal lesions in 37 patients and PET/MRI in 45 patients. On a lesion-based analysis, WBBS identified a total of 81 skeletal lesions, whereas PET/MRI identified 140 lesions. Additionally, PET/MRI showed extra-skeletal lesions in 19 patients, including lymph nodes (16), prostate (4) lung (3), and liver (2) lesions.CONCLUSIONS: The ability of Na[18F]F/[18F]FDG PET/MRI to identify more skeletal lesions than 99mTc-MDP WBBS and to additionally identify extra-skeletal disease may be beneficial for patient care and represent an alternative to the single modalities performed separately. Na[18F]F/[18F]FDG PET/MRI is a promising approach for evaluation of skeletal and extra-skeletal lesions in a selected population of breast and prostate cancer patients.

  View details for DOI 10.1007/s11307-019-01392-9

  View details for PubMedID 31236756

• Photoacoustic clinical imaging. Photoacoustics Steinberg, I., Huland, D. M., Vermesh, O., Frostig, H. E., Tummers, W. S., Gambhir, S. S. 2019; 14: 77–98

  Abstract

  Photoacoustic is an emerging biomedical imaging modality, which allows imaging optical absorbers in the tissue by acoustic detectors (light in - sound out). Such a technique has an immense potential for clinical translation since it allows high resolution, sufficient imaging depth, with diverse endogenous and exogenous contrast, and is free from ionizing radiation. In recent years, tremendous developments in both the instrumentation and imaging agents have been achieved. These opened avenues for clinical imaging of various sites allowed applications such as brain functional imaging, breast cancer screening, diagnosis of psoriasis and skin lesions, biopsy and surgery guidance, the guidance of tumor therapies at the reproductive and urological systems, as well as imaging tumor metastases at the sentinel lymph nodes. Here we survey the various clinical and pre-clinical literature and discuss the potential applications and hurdles that still need to be overcome.

  View details for DOI 10.1016/j.pacs.2019.05.001

  View details for PubMedID 31293884

• Proceedings: Pathways for Successful Translation of New Imaging Agents and Modalities-Phase III Studies JOURNAL OF NUCLEAR MEDICINE Gambhir, S. S., Shankar, L. K., Rosenthal, E., Warram, J. M., Ghesani, M., Hope, T. A., Jacobs, P. M., Jacobson, G. B., Wilson, T., Siegel, B. A. 2019; 60 (6): 736–44

  View details for DOI 10.2967/jnumed.118.219824

  View details for Web of Science ID 000470084400016

• Engineered immune cells as highly sensitive cancer diagnostics NATURE BIOTECHNOLOGY Aalipour, A., Chuang, H., Murty, S., D'Souza, A. L., Park, S., Gulati, G. S., Patel, C. B., Beinat, C., Simonetta, F., Martinic, I., Gowrishankar, G., Robinson, E. R., Aalipour, E., Zhian, Z., Gambhir, S. S. 2019; 37 (5): 531-+

  View details for DOI 10.1038/s41587-019-0064-8

  View details for Web of Science ID 000469110000014

• [F-18]-SuPAR: A Radiofluorinated Probe for Noninvasive Imaging of DNA Damage-Dependent Poly(ADP-ribose) Polymerase Activity BIOCONJUGATE CHEMISTRY Shuhendler, A. J., Cui, L., Chen, Z., Shen, B., Chen, M., James, M. L., Witney, T. H., Bazalova-Carter, M., Gambhir, S. S., Chin, F. T., Graves, E. E., Rao, J. 2019; 30 (5): 1331–42

  Abstract

  Poly(ADP ribose) polymerase (PARP) enzymes generate poly(ADP ribose) post-translational modifications on target proteins for an array of functions centering on DNA and cell stress. PARP isoforms 1 and 2 are critically charged with the surveillance of DNA integrity and are the first line guardians of the genome against DNA breaks. Here we present a novel probe ([18F]-SuPAR) for noninvasive imaging of PARP-1/2 activity using positron emission tomography (PET). [18F]-SuPAR is a radiofluorinated nicotinamide adenine dinucleotide (NAD) analog that can be recognized by PARP-1/2 and incorporated into the long branched polymers of poly(ADP ribose) (PAR). The measurement of PARP-1/2 activity was supported by a reduction of radiotracer uptake in vivo following PARP-1/2 inhibition with talazoparib treatment, a potent PARP inhibitor recently approved by FDA for treatment of breast cancer, as well as ex vivo colocalization of radiotracer analog and poly(ADP ribose). With [18F]-SuPAR, we were able to map the dose- and time-dependent activation of PARP-1/2 following radiation therapy in breast and cervical cancer xenograft mouse models. Tumor response to therapy was determined by [18F]-SuPAR PET within 8 h of administration of a single dose of radiation equivalent to one round of stereotactic ablative radiotherapy.

  View details for DOI 10.1021/acs.bioconjchem.9b00089

  View details for Web of Science ID 000468368300008

  View details for PubMedID 30973715

• Miniature gold nanorods for photoacoustic molecular imaging in the second near-infrared optical window NATURE NANOTECHNOLOGY Chen, Y., Zhao, Y., Yoon, S., Gambhir, S., Emelianov, S. 2019; 14 (5): 465–72

  View details for DOI 10.1038/s41565-019-0392-3

  View details for Web of Science ID 000467053100023

• A Non -Invasive Photoacoustic Imaging th Erythrocyte Derived Optical Nanoparticles to Detect CAD in In Vivo Mice Liu, Y., Hanley, T., Chen, H., Long, S., Gambhir, S., Cheng, Z., Wu, J., El Fakhri, G., Anvari, B., Zaman, R. SOC NUCLEAR MEDICINE INC. 2019

  View details for Web of Science ID 000473116800229

• Evaluation of [18F]DASA-23 for non-invasive measurement of aberrantly expressed pyruvate kinase M2 in glioblastoma: preclinical and first in human studies Beinat, C., Patel, C., Haywood, T., Murty, S., Alam, I., Xie, Y., Gandhi, H., Holley, D., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2019

  View details for Web of Science ID 000473116800052

• Evaluation of Glycolytic Response to Multiple Classes of Anti-glioblastoma Drugs by Noninvasive Measurement of Pyruvate Kinase M2 Using [18F]DASA-23. Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging Beinat, C., Patel, C. B., Xie, Y., Gambhir, S. S. 2019

  Abstract

  PURPOSE: Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, the key process of tumor metabolism. PKM2 is found in high levels in glioblastoma (GBM) cells with marginal expression within healthy brain tissue, rendering it a key biomarker of GBM metabolic re-programming. Our group has reported the development of a novel radiotracer, 1-((2-fluoro- 6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA- 23), to non-invasively detect PKM2 levels with positron emission tomography (PET).PROCEDURE: U87 human GBM cells were treated with the IC50 concentration of various agents used in the treatment of GBM, including alkylating agents (temozolomide, carmustine, lomustine, procarbazine), inhibitor of topoisomerase I (irinotecan), vascular endothelial and epidermal growth factor receptor inhibitors (cediranib and erlotinib, respectively) anti-metabolite (5-fluorouracil), microtubule inhibitor (vincristine), and metabolic agents (dichloroacetate and IDH1 inhibitor ivosidenib). Following drug exposure for three or 6days (n=6 replicates per condition), the radiotracer uptake of [18F]DASA-23 and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) was assessed. Changes in PKM2 protein levels were determined via Western blot and correlated to radiotracer uptake.RESULTS: Significant interactions were found between the treatment agent (n=12 conditions total comprised 11 drugs and vehicle) and the duration of treatment (3- or 6-day exposure to each drug) on the cellular uptake of [18F]DASA-23 (p=0.0001). The greatest change in the cellular uptake of [18F]DASA-23 was found after exposure to alkylating agents (p<0. 0001) followed by irinotecan (p=0. 0012), erlotinib (p=0. 02), and 5-fluorouracil (p=0. 005). Correlation of PKM2 protein levels and [18F]DASA-23 cellular uptake revealed a moderate correlation (r=0.44, p=0.15).CONCLUSIONS: These proof of principle studies emphasize the superiority of [18F]DASA-23 to [18F]FDG in detecting the glycolytic response of GBM to multiple classes of anti-neoplastic drugs in cell culture. A clinical trial evaluating the diagnostic utility of [18F]DASA-23 PET in GBM patients (NCT03539731) is ongoing.

  View details for PubMedID 30989436

• A Novel Engineered Small Protein for Positron Emission Tomography Imaging of Human Programmed Death Ligand-1: Validation in Mouse Models and Human Cancer Tissues. Clinical cancer research : an official journal of the American Association for Cancer Research Natarajan, A., Patel, C. B., Ramakrishnan, S., Panesar, P. S., Long, S. R., Gambhir, S. S. 2019; 25 (6): 1774-1785

  Abstract

  To design and evaluate a small engineered protein binder targeting human programmed death-1 ligand (hPD-L1) in vivo for PET imaging in four mouse tumor models, and in situ in human cancer specimens.Experimental Design: The hPD-L1 protein binder, FN3hPD-L1, was engineered using a 12-kDa human fibronectin type-3 domain (FN3) scaffold. The binder's affinity was assayed in CT26 mouse colon carcinoma cells stably expressing hPD-L1 (CT26/hPD-L1). 64Cu-FN3hPD-L1 was assayed for purity, specific activity, and immunoreactivity. Four groups of NSG mice (n = 3-5/group) were imaged with 64Cu-FN3hPD-L1 PET imaging (1-24 hours postinjection of 3.7 MBq/7 μg of Do-FN3 in 200 μL PBS): Nod SCID Gamma (NSG) mice bearing (i) syngeneic CT26/hPD-L1tumors, (ii) CT26/hPD-L1 tumors blocked (blk) by preinjected nonradioactive FN3hPD-L1 binder, (iii) hPD-L1-negative Raji xenografts, and (iv) MDA-MB-231 xenografts. The FN3hPD-L1 binder staining was evaluated against validated hPD-L1 antibodies by immunostaining in human cancer specimens.FN3hPD-L1 bound hPD-L1 with 1.4 ± 0.3 nmol/L affinity in CT26/hPD-L1 cells. 64Cu-FN3hPD-L1 radiotracer showed >70% yield and >95% purity. 64Cu-FN3hPD-L1 PET imaging of mice bearing CT26/hPD-L1 tumors showed tumor-to-muscle ratios of 5.6 ± 0.9 and 13.1 ± 2.3 at 1 and 4 hours postinjection, respectively. The FN3hPD-L1 binder detected hPD-L1 expression in human tissues with known hPD-L1 expression status based on two validated antibodies.The 64Cu-FN3hPD-L1 radiotracer represents a novel, small, and high-affinity binder for imaging hPD-L1 in tumors. Our data support further exploration and clinical translation of this binder for noninvasive identification of cancer patients who may respond to immune checkpoint blockade therapies.

  View details for DOI 10.1158/1078-0432.CCR-18-1871

  View details for PubMedID 30373750

  View details for PubMedCentralID PMC6420852

• Miniature gold nanorods for photoacoustic molecular imaging in the second near-infrared optical window. Nature nanotechnology Chen, Y., Zhao, Y., Yoon, S. J., Gambhir, S. S., Emelianov, S. 2019

  Abstract

  In photoacoustic imaging, the second near-infrared (NIR-II) window is where tissue generates the least background signal. However, the large size of the few available contrast agents in this spectral range impedes their pharmacokinetics and decreases their thermal stability, leading to unreliable photoacoustic imaging. Here, we report the synthesis of miniaturized gold nanorods absorbing in the NIR-II that are 5-11 times smaller than regular-sized gold nanorods with a similar aspect ratio. Under nanosecond pulsed laser illumination, small nanorods are about 3times more thermally stable and generate 3.5times stronger photoacoustic signal than their absorption-matched larger counterparts. These unexpected findings are confirmed using theoretical and numerical analysis, showing that photoacoustic signal is not only proportional to the optical absorption of the nanoparticle solution but also to the surface-to-volume ratio of the nanoparticles. In living tumour-bearing mice, these small targeted nanorods display a 30% improvement in efficiency of agent delivery to tumours and generate 4.5times greater photoacoustic contrast.

  View details for PubMedID 30833692

• Nanomedicine for Spontaneous Brain Tumors: A Companion Clinical Trial ACS NANO Arami, H., Patel, C. B., Madsen, S. J., Dickinson, P. J., Davis, R. M., Zeng, Y., Sturges, B. K., Woolard, K. D., Habte, F. G., Akin, D., Sinclair, R., Gambhir, S. S. 2019; 13 (3): 2858–69

  View details for DOI 10.1021/acsnano.8b04406

  View details for Web of Science ID 000462950500015

• Detection of Premalignant Gastrointestinal Lesions Using Surface-Enhanced Resonance Raman Scattering-Nanoparticle Endoscopy. ACS nano Harmsen, S., Rogalla, S., Huang, R., Spaliviero, M., Neuschmelting, V., Hayakawa, Y., Lee, Y., Tailor, Y., Toledo-Crow, R., Kang, J. W., Samii, J. M., Karabeber, H., Davis, R. M., White, J. R., van de Rijn, M., Gambhir, S. S., Contag, C. H., Wang, T. C., Kircher, M. F. 2019; 13 (2): 1354–64

  Abstract

  Cancers of the gastrointestinal (GI) tract are among the most frequent and most lethal cancers worldwide. An important reason for this high mortality is that early disease is typically asymptomatic, and patients often present with advanced, incurable disease. Even in high-risk patients who routinely undergo endoscopic screening, lesions can be missed due to their small size or subtle appearance. Thus, current imaging approaches lack the sensitivity and specificity to accurately detect incipient GI tract cancers. Here we report our finding that a single dose of a high-sensitivity surface-enhanced resonance Raman scattering nanoparticle (SERRS-NP) enables reliable detection of precancerous GI lesions in animal models that closely mimic disease development in humans. Some of these animal models have not been used previously to evaluate imaging probes for early cancer detection. The studies were performed using a commercial Raman imaging system, a newly developed mouse Raman endoscope, and finally a clinically applicable Raman endoscope for larger animal studies. We show that this SERRS-NP-based approach enables robust detection of small, premalignant lesions in animal models that faithfully recapitulate human esophageal, gastric, and colorectal tumorigenesis. This method holds promise for much earlier detection of GI cancers than currently possible and could lead therefore to marked reduction of morbidity and mortality of these tumor types.

  View details for PubMedID 30624916

• Assessment of Tumor Redox Status through (S)-4-(3-[F-18] fluoropropyl)-L-Glutamic Acid PET Imaging of System x(c)(-) Activity CANCER RESEARCH McCormick, P. N., Greenwood, H. E., Glaser, M., Maddocks, O. K., Gendron, T., Sander, K., Gowrishankar, G., Hoehne, A., Zhang, T., Shuhendler, A. J., Lewis, D. Y., Berndt, M., Koglin, N., Lythgoe, M. F., Gambhir, S. S., Arstad, E., Witney, T. H. 2019; 79 (4): 853–63

  View details for DOI 10.1158/0008-5472.CAN-18-2634

  View details for Web of Science ID 000458738900017

• In Vivo Translation of the CIRPI System---Revealing Molecular Pathology of Rabbit Aortic Atherosclerotic Plaques. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Zaman, R., Yousufi, S., Chibana, H., Ikeno, F., Long, S. R., Gambhir, S. S., Chin, F. T., McConnell, M. V., Xing, L., Yeung, A. 2019

  Abstract

  Introduction: Thin-cap fibro atheroma (TCFA), unstable lesions in coronary artery disease (CAD), that prones to rupture resulting in substantial morbidity and mortality worldwide. However, their small size and complex morphological/biological features make early detection and risk assessment difficult. To overcome this limitation, we tested our newly developed catheter-based Circumferential-Intravascular-Radioluminescence-Photoacoustic-Imaging (CIRPI) system in vivo rabbit abdominal aorta to detect and characterize TCFA. Methods: The CIRPI system includes a novel optical probe combining circumferential radioluminescence imaging (CRI) and photoacoustic tomography (PAT). The CIRPI system was tested in rabbit abdominal aorta in vivo (WHHL, n = 5) and controls (NZW, n = 2). Rabbits were fasted for 6 hours before 5.55*107 Bq 18F-FDG was injected one hour prior to the imaging procedure. The experiment was done under anesthetic. A bare metal stent was implanted in the dorsal abdominal aorta as landmark, followed by the 7F imaging catheters that were advanced up to the proximal stent edge (PSE). Our CIRPI and clinical OCT were performed using pullback and non-occlusive flushing techniques. Results were verified with histochemical analysis. Results: Our CIRPI system successfully detected the locations and characterized both stable and vulnerable aortic plaques in vivo among all WHHL rabbits. Calcification was detected from the stable plaque (540/560 nm), whereas TCFA exhibited phospholipids/cholesterol (1040 nm, 1210 nm). These findings were verified with clinical OCT showing an area of low attenuation filled with lipids within TCFA. PAT image illustrated broken elastic fiber/collagen that could be verified with the histochemical analysis. All WHHL rabbits exhibited sparse to severe macrophages. However, 4 WHHL rabbits showed both moderate to severe level of calcifications and cholesterol clefts. However, all rabbits exhibited broken elastic fibers and collagen deposition. Control rabbits showed normal wall thickness with no presence of plaque tissue compositions. These findings were verified with the OCT and histochemical analysis. Conclusion: Our novel multi-modality hybrid system has been successfully translated to in vivo evaluation of atherosclerotic plaque structure and biology in a pre-clinical rabbit models. This proposed a paradigm shift that unites molecular and pathologic imaging technologies. Therefore, it may enhance the clinical evaluation of TCFA, as well as expand our understanding of CAD.

  View details for PubMedID 30737298

• Nanomedicine for Spontaneous Brain Tumors: A Companion Clinical Trial. ACS nano Arami, H., Patel, C. B., Madsen, S. J., Dickinson, P. J., Davis, R. M., Zeng, Y., Sturges, B. K., Woolard, K. D., Habte, F. G., Akin, D., Sinclair, R., Gambhir, S. S. 2019

  Abstract

  Nanoparticles' enhanced permeation and retention (EPR) variations due to tumor heterogeneity in naturally occurring brain tumors are commonly neglected in preclinical nanomedicine studies. Recent pathological studies have shown striking similarities between brain tumors in humans and dogs, indicating that canine brain tumors may be a valuable model to evaluate nanoparticles' EPR in this context. We recruited canine clinical cases with spontaneous brain tumors to investigate nanoparticles' EPR in different brain tumor pathologies using surface-enhanced Raman spectroscopy (SERS). We used gold nanoparticles due to their surface plasmon effect that enables their sensitive and microscopic resolution detection using the SERS technique. Raman microscopy of the resected tumors showed heterogeneous EPR of nanoparticles into oligodendrogliomas and meningiomas of different grades, without any detectable traces in necrotic parts of the tumors or normal brain. Raman observations were confirmed by scanning electron microscopy (SEM) and X-ray elemental analyses, which enabled localization of individual nanoparticles embedded in tumor tissues. Our results demonstrate nanoparticles' EPR and its variations in clinically relevant, spontaneous brain tumors. Such heterogeneities should be considered alongside routine preoperative imaging and histopathological analyses in order to accelerate clinical management of brain tumors using nanomedicine approaches.

  View details for PubMedID 30714717

• Detection of visually occult metastatic lymph nodes using molecularly targeted fluorescent imaging during surgical resection of pancreatic cancer. HPB : the official journal of the International Hepato Pancreato Biliary Association Tummers, W. S., Miller, S. E., Teraphongphom, N. T., van den Berg, N. S., Hasan, A., Longacre, T. A., Fisher, G. A., Bonsing, B. A., Vahrmeijer, A. L., Gambhir, S. S., Swijnenburg, R., Rosenthal, E. L., Poultsides, G. A. 2019

  Abstract

  BACKGROUND: Although most patients with PDAC experience distant failure after resection, a significant portion still present with local recurrence. Intraoperative fluorescent imaging can potentially facilitate the visualization of involved peritumoral LNs and guide the locoregional extent of nodal dissection. Here, the efficacy of targeted intraoperative fluorescent imaging was examined in the detection of metastatic lymph nodes (LNs) during resection of pancreatic ductal adenocarcinoma (PDAC).METHODS: A dose-escalation prospective study was performed to assess feasibility of tumor detection within peripancreatic LNs using cetuximab-IRDye800 in PDAC patients. Fluorescent imaging of dissected LNs was analyzed exvivo macroscopically and microscopically and fluorescence was correlated with histopathology.RESULTS: A total of 144 LNs (72 in the low-dose and 72 in the high-dose cohort) were evaluated. Detection of metastatic LNs by fluorescence was better in the low-dose (50mg) cohort, where sensitivity and specificity was 100% and 78% macroscopically, and 91% and 66% microscopically. More importantly, this method was able to detect occult foci of tumor (measuring<5mm) with a sensitivity of 88% (15/17 LNs).CONCLUSION: This study provides proof of concept that intraoperative fluorescent imaging with cetuximab-IRDye800 can facilitate the detection of peripancreatic lymph nodes often containing subclinical foci of disease.

  View details for PubMedID 30723062

• Detection of Premalignant Gastrointestinal Lesions Using Surface-Enhanced Resonance Raman Scattering-Nanoparticle Endoscopy ACS NANO Harmsen, S., Rogalla, S., Huang, R., Spaliviero, M., Neuschmelting, V., Hayakawa, Y., Lee, Y., Tailor, Y., Toledo-Crow, R., Kang, J., Samii, J. M., Karabeber, H., Davis, R. M., White, J. R., van de Rijn, M., Gambhir, S. S., Contag, C. H., Wang, T. C., Kircher, M. F. 2019; 13 (2): 1354–64

  View details for DOI 10.1021/acsnano.8b06808

  View details for Web of Science ID 000460199400038

• First-in-human liver-tumour surgery guided by multispectral fluorescence imaging in the visible and near-infrared-I/II windows. Nature biomedical engineering Hu, Z. n., Fang, C. n., Li, B. n., Zhang, Z. n., Cao, C. n., Cai, M. n., Su, S. n., Sun, X. n., Shi, X. n., Li, C. n., Zhou, T. n., Zhang, Y. n., Chi, C. n., He, P. n., Xia, X. n., Chen, Y. n., Gambhir, S. S., Cheng, Z. n., Tian, J. n. 2019

  Abstract

  The second near-infrared wavelength window (NIR-II, 1,000-1,700 nm) enables fluorescence imaging of tissue with enhanced contrast at depths of millimetres and at micrometre-scale resolution. However, the lack of clinically viable NIR-II equipment has hindered the clinical translation of NIR-II imaging. Here, we describe an optical-imaging instrument that integrates a visible multispectral imaging system with the detection of NIR-II and NIR-I (700-900 nm in wavelength) fluorescence (by using the dye indocyanine green) for aiding the fluorescence-guided surgical resection of primary and metastatic liver tumours in 23 patients. We found that, compared with NIR-I imaging, intraoperative NIR-II imaging provided a higher tumour-detection sensitivity (100% versus 90.6%; with 95% confidence intervals of 89.1%-100% and 75.0%-98.0%, respectively), a higher tumour-to-normal-liver-tissue signal ratio (5.33 versus 1.45) and an enhanced tumour-detection rate (56.41% versus 46.15%). We infer that combining the NIR-I/II spectral windows and suitable fluorescence probes might improve image-guided surgery in the clinic.

  View details for DOI 10.1038/s41551-019-0494-0

  View details for PubMedID 31873212

• Initial experience with a PET/computed tomography system using silicon photomultiplier detectors. Nuclear medicine communications Park, S. Y., Barrato, L. n., Hatami, N. n., Davidzon, G. n., Gambhir, S. S., Iagaru, A. n. 2019

  Abstract

  A PET/computed tomography (CT) that uses silicon photomultiplier (SiPM) technology was installed at our institution. Here, we report the initial use of the new scanner and evaluate the image quality in comparison to standard PET/CT scanners.Seventy-two patients were scanned first using standard PET/CT followed immediately by the new PET/CT system. Images from the new PET/CT system were reconstructed using a conventional [non time-of-flight (TOF)] algorithm, TOF alone and TOF in combination with BSREM. Images from standard PET/CT were reconstructed using clinical standard-of-care settings. Three blinded readers randomly reviewed four datasets (standard, non-TOF, TOF alone, TOF+BSREM) per patient for image quality using a five-point Likert scale. SUV measurements for the single most avid lesion on each dataset were also recorded.Datasets from the new scanner had higher image quality (P < 0.001) and SUV measurements (P < 0.001) compared with the standard scanners, and scores further improved when TOF and BSREM algorithms were added (mean scores for standard, non-TOF, TOF alone and TOF+BSREM were 3.1, 3.9, 4.3 and 5.0, respectively; mean SUVmax for hottest lesion were 8.8, 10.3, 10.7 and 13.3, respectively).The SiPM-based PET/CT system outperforms two standard Bismuth germanium oxide- and Lutetium-yttrium oxyorthosilicate-based scanners in terms of image quality, with further benefits added using TOF and BSREM. This may be beneficial for detecting small lesions and more accurate disease staging.

  View details for DOI 10.1097/MNM.0000000000001088

  View details for PubMedID 31568189

• Improved detection of prostate cancer using a magneto-nanosensor assay for serum circulating autoantibodies. PloS one Xu, L., Lee, J., Hao, S., Ling, X. B., Brooks, J. D., Wang, S. X., Gambhir, S. S. 2019; 14 (8): e0221051

  Abstract

  PURPOSE: To develop a magneto-nanosensor (MNS) based multiplex assay to measure protein and autoantibody biomarkers from human serum for prostate cancer (CaP) diagnosis.MATERIALS AND METHODS: A 4-panel MNS autoantibody assay and a MNS protein assay were developed and optimized in our labs. Using these assays, serum concentration of six biomarkers including prostate-specific antigen (PSA) protein, free/total PSA ratio, as well as four autoantibodies against Parkinson disease 7 (PARK7), TAR DNA-binding protein 43 (TARDBP), Talin 1 (TLN1), and Caldesmon 1 (CALD1) and were analyzed. Human serum samples from 99 patients (50 with non-cancer and 49 with clinically localized CaP) were evaluated.RESULTS: The MNS assay showed excellent performance characteristics and no cross-reactivity. All autoantibody assays showed a statistically significant difference between CaP and non-cancer samples except for PARK7. The most significant difference was the combination of the four autoantibodies as a panel in addition to the free/total PSA ratio. This combination had the highest area under the curve (AUC)- 0.916 in ROC analysis.CONCLUSIONS: Our results suggest that this autoantibody panel along with PSA and free PSA have potential to segregate patients without cancer from those with prostate cancer with higher sensitivity and specificity than PSA alone.

  View details for DOI 10.1371/journal.pone.0221051

  View details for PubMedID 31404106

• Engineered immune cells as highly sensitive cancer diagnostics. Nature biotechnology Aalipour, A. n., Chuang, H. Y., Murty, S. n., D'Souza, A. L., Park, S. M., Gulati, G. S., Patel, C. B., Beinat, C. n., Simonetta, F. n., Martinić, I. n., Gowrishankar, G. n., Robinson, E. R., Aalipour, E. n., Zhian, Z. n., Gambhir, S. S. 2019

  Abstract

  Endogenous biomarkers remain at the forefront of early disease detection efforts, but many lack the sensitivities and specificities necessary to influence disease management. Here, we describe a cell-based in vivo sensor for highly sensitive early cancer detection. We engineer macrophages to produce a synthetic reporter on adopting an M2 tumor-associated metabolic profile by coupling luciferase expression to activation of the arginase-1 promoter. After adoptive transfer in colorectal and breast mouse tumor models, the engineered macrophages migrated to the tumors and activated arginase-1 so that they could be detected by bioluminescence imaging and luciferase measured in the blood. The macrophage sensor detected tumors as small as 25-50 mm3 by blood luciferase measurements, even in the presence of concomitant inflammation, and was more sensitive than clinically used protein and nucleic acid cancer biomarkers. Macrophage sensors also effectively tracked the immunological response in muscle and lung models of inflammation, suggesting the potential utility of this approach in disease states other than cancer.

  View details for PubMedID 30886438

• Engineered Immune Cells as Highly Sensitive Cancer Diagnostics Nature Biotechnology Aalipour, A., Chuang, H., Murty, S., D'Souza, A. L., Park, S., Gulanti, G. S., Patel, C. B., Beinat, C., Simonetta, F., Martinie, I., Gowrishankar, G., Robinson, E. R., Aalipour, E., Zhian, Z., Gambhir, S. S. 2019
• Positron emission tomography reporter gene strategy for use in the central nervous system PNAS Haywood, T., Beinat, C., Gowrishankar, G., Patel, C. B., Alam, I. S., Murty, S., Gambhir, S. S. 2019

  View details for DOI 10.1073/pnas.1901645116

• The characterization of 18F-hGTS13 for molecular imaging of xC- transporter activity with positron emission tomography. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Beinat, C. n., Gowrishankar, G. n., Shen, B. n., Alam, I. S., Robinson, E. n., Haywood, T. n., Patel, C. B., Azevedo, E. C., Castillo, J. n., Ilovich, O. n., Koglin, N. n., Schmitt-Willich, H. n., Berndt, M. n., Mueller, A. n., Zerna, M. n., Srinivasan, A. n., Gambhir, S. S. 2019

  Abstract

  Purpose: The aim of this study was development of an improved positron emission tomography (PET) radiotracer for measuring xC- activity with increased tumor uptake and reduced uptake in inflammatory cells compared to (S)-4-(3-18F-Fluoropropyl)-L-glutamic acid (18F-FSPG). Experimental design: A racemic glutamate derivative, 18F-hGTS13 was evaluated in cell culture and animal tumor models. 18F-hGTS13 was separated into C5-epimers and the corresponding 18F-hGTS13-isomer1 and 18F-hGTS13-isomer2 evaluated in H460 tumor bearing rats. Preliminary studies investigate the cellular uptake of 18F-hGTS13-isomer2 in multiple immune cell populations and states. Results:18F-hGTS13 demonstrated excellent H460 tumor visualization with high tumor-to-background ratios, confirmed by ex vivo biodistribution studies. Tumor associated radioactivity of 18F-hGTS13 (7.5±0.9%ID/g, n = 3) was significantly higher than with 18F-FSPG (4.6±0.7%ID/g, n = 3, P = 0.01). 18F-hGTS13-isomer2 exhibited excellent H460 tumor visualization (6.3±1.1%ID/g, n-3), and significantly reduced uptake in multiple immune cell populations relative to 18F-FSPG. 18F-hGTS13-isomer2 exhibited increased liver uptake relative to 18F-FSPG (4.6±0.8%ID/g vs. 0.7±0.01%ID/g) limiting its application in hepatocellular carcinoma. Conclusion:18F-hGTS13-isomer2 is a new PET radiotracer for molecular imaging of xC- activity which may provide information regarding tumor oxidation states. 18F-hGTS13-isomer2 has potential for clinical translation for imaging cancers of the thorax due to the low background signal in healthy tissue.

  View details for DOI 10.2967/jnumed.119.225870

  View details for PubMedID 31171595

• How to Prevent a Leaky Pipeline in Academic Radiology: Insights From a Faculty Survey. Journal of the American College of Radiology : JACR Daldrup-Link, H. n., Villavasso, K. n., Zhao, Q. n., Lu, Y. n., Ranieri, A. n., Simard, C. n., Gambhir, S. S. 2019

  View details for PubMedID 31092345

• Discussions with Leaders: A Conversation Between Sam Gambhir and Johannes Czernin. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Czernin, J., Gambhir, S. S. 2018; 59 (12): 1783–85

  View details for PubMedID 30510073

• Discussions with Leaders: A Conversation Between Sam Gambhir and Johannes Czernin JOURNAL OF NUCLEAR MEDICINE Czernin, J., Gambhir, S. 2018; 59 (12): 1783–85

  View details for DOI 10.2967/jnumed.118.221648

  View details for Web of Science ID 000452015900005

• Striatal dopamine deficits predict reductions in striatal functional connectivity in major depression: a concurrent 11C-raclopride positron emission tomography and functional magnetic resonance imaging investigation. Translational psychiatry Hamilton, J. P., Sacchet, M. D., Hjornevik, T., Chin, F. T., Shen, B., Kampe, R., Park, J. H., Knutson, B. D., Williams, L. M., Borg, N., Zaharchuk, G., Camacho, M. C., Mackey, S., Heilig, M., Drevets, W. C., Glover, G. H., Gambhir, S. S., Gotlib, I. H. 2018; 8 (1): 264

  Abstract

  Major depressive disorder (MDD) is characterized by the altered integration of reward histories and reduced responding of the striatum. We have posited that this reduced striatal activation in MDD is due to tonically decreased stimulation of striatal dopamine synapses which results in decremented propagation of information along the cortico-striatal-pallido-thalamic (CSPT) spiral. In the present investigation, we tested predictions of this formulation by conducting concurrent functional magnetic resonance imaging (fMRI) and 11C-raclopride positron emission tomography (PET) in depressed and control (CTL) participants. We scanned 16 depressed and 14 CTL participants with simultaneous fMRI and 11C-raclopride PET. We estimated raclopride binding potential (BPND), voxel-wise, and compared MDD and CTL samples with respect to BPND in the striatum. Using striatal regions that showed significant between-group BPND differences as seeds, we conducted whole-brain functional connectivity analysis using the fMRI data and identified brain regions in each group in which connectivity with striatal seed regions scaled linearly with BPND from these regions. We observed increased BPND in the ventral striatum, bilaterally, and in the right dorsal striatum in the depressed participants. Further, we found that as BPND increased in both the left ventral striatum and right dorsal striatum in MDD, connectivity with the cortical targets of these regions (default-mode network and salience network, respectively) decreased. Deficits in stimulation of striatal dopamine receptors in MDD could account in part for the failure of transfer of information up the CSPT circuit in the pathophysiology of this disorder.

  View details for PubMedID 30504860

• Striatal dopamine deficits predict reductions in striatal functional connectivity in major depression: a concurrent C-11-raclopride positron emission tomography and functional magnetic resonance imaging investigation TRANSLATIONAL PSYCHIATRY Hamilton, J., Sacchet, M. D., Hjornevik, T., Chin, F. T., Shen, B., Kampe, R., Park, J., Knutson, B. D., Williams, L. M., Borg, N., Zaharchuk, G., Camacho, M., Mackey, S., Heilig, M., Drevets, W. C., Glover, G. H., Gambhir, S. S., Gotlib, I. H. 2018; 8

  View details for DOI 10.1038/s41398-018-0316-2

  View details for Web of Science ID 000452318900002

• Tracking T Cell Activation By OX40 Immuno-PET: A Novel Strategy for Imaging of Graft Versus Host Disease Simonetta, F., Alam, I. S., Mayer, A. T., Murty, S., Vermesh, O., Hirai, T., Nobashi, T., Lau, K., Gambhir, S. S., Negrin, R. S. AMER SOC HEMATOLOGY. 2018

  View details for DOI 10.1182/blood-2018-99-116483

  View details for Web of Science ID 000454842804170

• Assessment of tumor redox status through (S)-4-(3-[18F]fluoropropyl)-L-glutamic acid positron emission tomography imaging of system xc- activity. Cancer research McCormick, P. N., Greenwood, H. E., Glaser, M., Maddocks, O. D., Gendron, T., Sander, K., Gowrishankar, G., Hoehne, A., Zhang, T., Shuhendler, A. J., Lewis, D. Y., Berndt, M., Koglin, N., Lythgoe, M. F., Gambhir, S. S., Arstad, E., Witney, T. H. 2018

  Abstract

  The cell's endogenous antioxidant system is vital to maintenance of redox homeostasis. Despite its central role in normal and pathophysiology, no non-invasive tools exist to measure this system in patients. The cystine/glutamate antiporter system xc- maintains the balance between intracellular reactive oxygen species and antioxidant production through the provision of cystine, a key precursor in glutathione biosynthesis. Here we show that tumor cell retention of a system xc--specific positron emission tomography radiotracer, (S)-4-(3-[18F]fluoropropyl)-L-glutamic acid ([18F]FSPG), decreases in proportion to levels of oxidative stress following treatment with a range of redox-active compounds. The decrease in [18F]FSPG retention correlated with a depletion of intracellular cystine resulting from increased de novo glutathione biosynthesis, shown through [U-13C6, U-15N2]cystine isotopic tracing. In vivo, treatment with the chemotherapeutic doxorubicin decreased [18F]FSPG tumor uptake in a mouse model of ovarian cancer, coinciding with markers of oxidative stress but preceding tumor shrinkage and decreased glucose utilization. Having already been used in pilot clinical trials, [18F]FSPG PET could be rapidly translated to the clinic as an early redox indicator of tumor response to treatment.

  View details for PubMedID 30401715

• A NOVEL METABOLIC PET TRACER STRATEGY TO DETERMINE EARLY EFFECTS OF TUMOR TREATING FIELDS (TTFIELDS) Patel, C., Beinat, C., Xie, Y., Haywood, T., Murty, S., Chang, E., Gambhir, S. OXFORD UNIV PRESS INC. 2018: 32

  View details for Web of Science ID 000460646300124

• Tumor Cell-Derived Extracellular Vesicle-Coated Nanocarriers: An Efficient Theranostic Platform for the Cancer-Specific Delivery of Anti-miR-21 and Imaging Agents ACS NANO Bose, R. C., Kumar, S., Zeng, Y., Afjei, R., Robinson, E., Lau, K., Bermudez, A., Habte, F., Pitteri, S. J., Sinclair, R., Willmann, J. K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. 2018; 12 (11): 10817–32

  View details for DOI 10.1021/acsnano.8b02587

  View details for Web of Science ID 000451789200022

• COMPARISON OF THREE METABOLIC PET RADIOTRACERS IN GLIOBLASTOMA: CELL CULTURE AND ANIMAL STUDIES Beinat, C., Patel, C., Murty, S., Haywood, T., Park, J., Xie, Y., Gambhir, S. OXFORD UNIV PRESS INC. 2018: 34

  View details for Web of Science ID 000460646300129

• EVALUATION OF GLYCOLYTIC RESPONSE TO SEVEN CLASSES OF ANTI-GLIOBLASTOMA DRUGS BY NON-INVASIVE MEASUREMENT OF PYRUVATE KINASE M2 Beinat, C., Patel, C., Xie, Y., Gambhir, S. OXFORD UNIV PRESS INC. 2018: 33–34

  View details for Web of Science ID 000460646300128

• Surface-Enhanced Raman Scattering Nanoparticles for Multiplexed Imaging of Bladder Cancer Tissue Permeability and Molecular Phenotype ACS NANO Davis, R. M., Kiss, B., Trivedi, D. R., Metzner, T. J., Liao, J. C., Gambhir, S. S. 2018; 12 (10): 9669–79

  View details for DOI 10.1021/acsnano.8b03217

  View details for Web of Science ID 000448751800006

• Emerging Intraoperative Imaging Modalities to Improve Surgical Precision MOLECULAR IMAGING AND BIOLOGY Alam, I. S., Steinberg, I., Vermesh, O., van den Berg, N. S., Rosenthal, E. L., van Dam, G. M., Ntziachristos, V., Gambhir, S. S., Hernot, S., Rogalla, S. 2018; 20 (5): 705–15

  View details for DOI 10.1007/s11307-018-1227-6

  View details for Web of Science ID 000444754000003

• Surface-Enhanced Raman Scattering Nanoparticles for Multiplexed Imaging of Bladder Cancer Tissue Permeability and Molecular Phenotype. ACS nano Davis, R. M., Kiss, B., Trivedi, D. R., Metzner, T. J., Liao, J. C., Gambhir, S. S. 2018

  Abstract

  Bladder cancer has the highest recurrence rate of all cancers due in part to inadequate transurethral resection. Inadequate resection is caused by the inability of cystoscopes to detect invisible lesions during the resection procedure. To improve detection and resection of nonmuscle invasive bladder cancer, we quantified the ability of a surface-enhanced Raman nanoparticle and endoscope system to classify bladder tissue as normal or cancerous. Both antibody-based (active) and tissue permeability-based (passive) targeting mechanisms were evaluated by topically applying nanoparticles to ex vivo human bladder tissue samples. Multiplexed molecular imaging of CD47 and Carbonic Anhydrase 9 tumor proteins gave a receiver operating characteristic area under the curve (ROC AUC of 0.93 (0.75, 1.00). Furthermore, passively targeted nanoparticles enabled tissue classification with an ROC AUC of 0.93 (0.73, 1.00). Passively targeted nanoparticles penetrated 5-fold deeper and bound to tumor tissue at 3.3-fold higher concentrations in cancer compared to normal bladder urothelium, suggesting the existence of an enhanced surface permeability and retention effect in human bladder cancer.

  View details for PubMedID 30203645

• Development and MPI tracking of novel hypoxia-targeted theranostic exosomes. Biomaterials Jung, K. O., Jo, H., Yu, J. H., Gambhir, S. S., Pratx, G. 2018; 177: 139–48

  Abstract

  Treating the hypoxic region of the tumor remains a significant challenge. The goals of this study are to develop an exosome platform that can target regions of tumor hypoxia and that can be monitored invivo using magnetic particle imaging (MPI). Four types of exosomes (generated under hypoxic or normoxic conditions, and with or without exposure to X-ray radiation) were isolated from MDA-MB-231 human breast cancer cells. Exosomes were labeled by DiO, a fluorescent lipophilic tracer, to quantify their uptake by hypoxic cancer cells. Subsequently, the exosomes were modified to carry SPIO (superparamagnetic iron oxide) nanoparticles and Olaparib (PARP inhibitor). FACS and fluorescence microscopy showed that hypoxic cells preferentially take up exosomes released by hypoxic cells, compared with other exosome formulations. In addition, the distribution of SPIO-labeled exosomes was successively imaged invivo using MPI. Finally, the therapeutic efficacy of Olaparib-loaded exosomes was demonstrated by increased apoptosis and slower tumor growth invivo. Our novel theranostic platform could be used as an effective strategy to monitor exosomes invivo and deliver therapeutics to hypoxic tumors.

  View details for PubMedID 29890363

• An intravascular magnetic wire for the high-throughput retrieval of circulating tumour cells in vivo. Nature biomedical engineering Vermesh, O., Aalipour, A., Ge, T. J., Saenz, Y., Guo, Y., Alam, I. S., Park, S. M., Adelson, C. N., Mitsutake, Y., Vilches-Moure, J., Godoy, E., Bachmann, M. H., Ooi, C. C., Lyons, J. K., Mueller, K., Arami, H., Green, A., Solomon, E. I., Wang, S. X., Gambhir, S. S. 2018; 2 (9): 696-705

  Abstract

  The detection and analysis of rare blood biomarkers is necessary for early diagnosis of cancer and to facilitate the development of tailored therapies. However, current methods for the isolation of circulating tumour cells (CTCs) or nucleic acids present in a standard clinical sample of only 5-10 ml of blood provide inadequate yields for early cancer detection and comprehensive molecular profiling. Here, we report the development of a flexible magnetic wire that can retrieve rare biomarkers from the subject's blood in vivo at a much higher yield. The wire is inserted and removed through a standard intravenous catheter and captures biomarkers that have been previously labelled with injected magnetic particles. In a proof-of-concept experiment in a live porcine model, we demonstrate the in vivo labelling and single-pass capture of viable model CTCs in less than 10 s. The wire achieves capture efficiencies that correspond to enrichments of 10-80 times the amount of CTCs in a 5-ml blood draw, and 500-5,000 times the enrichments achieved using the commercially available Gilupi CellCollector.

  View details for DOI 10.1038/s41551-018-0257-3

  View details for PubMedID 30505627

  View details for PubMedCentralID PMC6261517

• Development and MPI tracking of novel hypoxia-targeted theranostic exosomes BIOMATERIALS Jung, K., Jo, H., Yu, J., Gambhir, S., Pratx, G. 2018; 177: 139–48

  View details for DOI 10.1016/j.biomaterials.2018.05.048

  View details for Web of Science ID 000439401700012

• An intravascular magnetic wire for the high-throughput retrieval of circulating tumour cells in vivo NATURE BIOMEDICAL ENGINEERING Vermesh, O., Aalipour, A., Ge, T., Saenz, Y., Guo, Y., Alam, I. S., Park, S., Adelson, C. N., Mitsutake, Y., Vilches-Moure, J., Godoy, E., Bachmann, M. H., Ooi, C., Lyons, J. K., Mueller, K., Arami, H., Green, A., Solomon, E., Wang, S. X., Gambhir, S. S. 2018; 2 (9): 696–705

  View details for DOI 10.1038/s41551-018-0257-3

  View details for Web of Science ID 000444282800014

• The Immunoimaging Toolbox JOURNAL OF NUCLEAR MEDICINE Mayer, A. T., Gambhir, S. S. 2018; 59 (8): 1174–82

  View details for DOI 10.2967/jnumed.116.185967

  View details for Web of Science ID 000440582000003

• Molecular imaging agents for ultrasound CURRENT OPINION IN CHEMICAL BIOLOGY Zlitni, A., Gambhir, S. S. 2018; 45: 113–20

  View details for DOI 10.1016/j.cbpa.2018.03.017

  View details for Web of Science ID 000441686700015

• Quantification of Cerenkov Luminescence Imaging (CLI) Comparable With 3-D PET Standard Measurements MOLECULAR IMAGING Habte, F., Natarajan, A., Paik, D. S., Gambhir, S. 2018; 17

  View details for DOI 10.1177/1536012118788637

  View details for Web of Science ID 000439959300001

• Intraoperative Pancreatic Cancer Detection using Tumor-Specific Multimodality Molecular Imaging. Annals of surgical oncology Tummers, W. S., Miller, S. E., Teraphongphom, N. T., Gomez, A., Steinberg, I., Huland, D. M., Hong, S., Kothapalli, S., Hasan, A., Ertsey, R., Bonsing, B. A., Vahrmeijer, A. L., Swijnenburg, R., Longacre, T. A., Fisher, G. A., Gambhir, S. S., Poultsides, G. A., Rosenthal, E. L. 2018; 25 (7): 1880–88

  Abstract

  BACKGROUND: Operative management of pancreatic ductal adenocarcinoma (PDAC) is complicated by several key decisions during the procedure. Identification of metastatic disease at the outset and, when none is found, complete (R0) resection of primary tumor are key to optimizing clinical outcomes. The use of tumor-targeted molecular imaging, based on photoacoustic and fluorescence optical imaging, can provide crucial information to the surgeon. The first-in-human use of multimodality molecular imaging for intraoperative detection of pancreatic cancer is reported using cetuximab-IRDye800, a near-infrared fluorescent agent that binds to epidermal growth factor receptor.METHODS: A dose-escalation study was performed to assess safety and feasibility of targeting and identifying PDAC in a tumor-specific manner using cetuximab-IRDye800 in patients undergoing surgical resection for pancreatic cancer. Patients received a loading dose of 100mg of unlabeled cetuximab before infusion of cetuximab-IRDye800 (50mg or 100mg). Multi-instrument fluorescence imaging was performed throughout the surgery in addition to fluorescence and photoacoustic imaging ex vivo.RESULTS: Seven patients with resectable pancreatic masses suspected to be PDAC were enrolled in this study. Fluorescence imaging successfully identified tumor with a significantly higher mean fluorescence intensity in the tumor (0.09±0.06) versus surrounding normal pancreatic tissue (0.02±0.01), and pancreatitis (0.04±0.01; p<0.001), with a sensitivity of 96.1% and specificity of 67.0%. The mean photoacoustic signal in the tumor site was 3.7-fold higher than surrounding tissue.CONCLUSIONS: The safety and feasibilty of intraoperative, tumor-specific detection of PDAC using cetuximab-IRDye800 with multimodal molecular imaging of the primary tumor and metastases was demonstrated.

  View details for PubMedID 29667116

• 6"-F-18-Fluoromaltotriose PET Evaluation in Escherichia Coli-Induced Myositis: Is There Uptake Saturation in Control? REPLY JOURNAL OF NUCLEAR MEDICINE Wardak, M., Gowrishankar, G., Gambhir, S. 2018; 59 (7): 1166–67

  View details for DOI 10.2967/jnumed.118.208736

  View details for Web of Science ID 000437237200042

• Intraoperative Pancreatic Cancer Detection using Tumor-Specific Multimodality Molecular Imaging ANNALS OF SURGICAL ONCOLOGY Tummers, W. S., Miller, S. E., Teraphongphom, N. T., Gomez, A., Steinberg, I., Huland, D. M., Hong, S., Kothapalli, S., Hasan, A., Ertsey, R., Bonsing, B. A., Vahrmeijer, A. L., Swijnenburg, R., Longacre, T. A., Fisher, G. A., Gambhir, S. S., Poultsides, G. A., Rosenthal, E. L. 2018; 25 (7): 1880–88

  View details for DOI 10.1245/s10434-018-6453-2

  View details for Web of Science ID 000433907300018

• A novel theranostic strategy for MMP-14 expressing glioblastomas impacts survival Mohanty, S., Chen, Z., Li, K., Morais, G., Klockow, J., Yerneni, K., Pisani, L., Chin, F., Mitra, S., Cheshier, S., Chang, E., Gambhir, S., Rao, J., Loadman, P. M., Falconer, R. A., Daldrup-Link, H. E. AMER ASSOC CANCER RESEARCH. 2018

  View details for DOI 10.1158/1538-7445.AM2018-LB-004

  View details for Web of Science ID 000468818900177

• Positron emission tomography imaging of activated T cells by targeting OX40 reveals spatiotemporal immune dynamics and predicts response to in situ tumor vaccination Mayer, A. T., Alam, I. S., Sagiv-Barfi, I., Wang, K., Vermesh, O., Czerwinski, D. K., Johnson, E. M., James, M. L., Levy, R., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2018

  View details for DOI 10.1158/1538-7445.AM2018-3031

  View details for Web of Science ID 000468819500394

• Advances in Diagnostic and Intraoperative Molecular Imaging of Pancreatic Cancer PANCREAS Tummers, W. S., Willmann, J. K., Bonsing, B. A., Vahrmeijer, A. L., Gambhir, S. S., Swijnenburg, R. 2018; 47 (6): 675–89

  Abstract

  Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. To improve outcomes, there is a critical need for improved tools for detection, accurate staging, and resectability assessment. This could improve patient stratification for the most optimal primary treatment modality. Molecular imaging, used in combination with tumor-specific imaging agents, can improve established imaging methods for PDAC. These novel, tumor-specific imaging agents developed to target specific biomarkers have the potential to specifically differentiate between malignant and benign diseases, such as pancreatitis. When these agents are coupled to various types of labels, this type of molecular imaging can provide integrated diagnostic, noninvasive imaging of PDAC as well as image-guided pancreatic surgery. This review provides a detailed overview of the current clinical imaging applications, upcoming molecular imaging strategies for PDAC, and potential targets for imaging, with an emphasis on intraoperative imaging applications.

  View details for DOI 10.1097/MPA.0000000000001075

  View details for Web of Science ID 000435963800011

  View details for PubMedID 29894417

  View details for PubMedCentralID PMC6003672

• Emerging Intraoperative Imaging Modalities to Improve Surgical Precision. Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging Alam, I. S., Steinberg, I., Vermesh, O., van den Berg, N. S., Rosenthal, E. L., van Dam, G. M., Ntziachristos, V., Gambhir, S. S., Hernot, S., Rogalla, S. 2018

  Abstract

  Intraoperative imaging (IOI) is performed to guide delineation and localization of regions of surgical interest. While oncological surgical planning predominantly utilizes x-ray computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US), intraoperative guidance mainly remains on surgeon interpretation and pathology for confirmation. Over the past decades however, intraoperative guidance has evolved significantly with the emergence of several novel imaging technologies, including fluorescence-, Raman, photoacoustic-, and radio-guided approaches. These modalities have demonstrated the potential to further optimize precision in surgical resection and improve clinical outcomes for patients. Not only can these technologies enhance our understanding of the disease, they can also yield large imaging datasets intraoperatively that can be analyzed by deep learning approaches for more rapid and accurate pathological diagnosis. Unfortunately, many of these novel technologies are still under preclinical or early clinical evaluation. Organizations like the Intra-Operative Imaging Study Group of the European Society for Molecular Imaging (ESMI) support interdisciplinary interactions with the aim to improve technical capabilities in the field, an approach that can succeed only if scientists, engineers, and physicians work closely together with industry and regulatory bodies to resolve roadblocks to clinical translation. In this review, we provide an overview of a variety of novel IOI technologies, discuss their challenges, and present future perspectives on the enormous potential of IOI for oncological surgical navigation.

  View details for PubMedID 29916118

• A Dual-Modality Hybrid Imaging System Harnesses Radioluminescence and Sound to Reveal Molecular Pathology of Atherosclerotic Plaques SCIENTIFIC REPORTS Zaman, R. T., Yousefi, S., Long, S. R., Saito, T., Mandella, M., Qiu, Z., Chen, R., Contag, C. H., Gambhir, S. S., Chin, F. T., Khuri-Yakub, B. T., McConnell, M. V., Shung, K., Xing, L. 2018; 8: 8992

  Abstract

  Atherosclerosis is a progressive inflammatory condition caused by an unstable lesion, called thin-cap fibro atheromata (TCFA) that underlies coronary artery disease (CAD)-one of the leading causes of death worldwide. Therefore, early clinical diagnosis and effective risk stratification is important for CAD management as well as preventing progression to catastrophic events. However, early detection could be difficult due to their small size, motion, obscuring 18F-FDG uptake by adjacent myocardium, and complex morphological/biological features. To overcome these limitations, we developed a catheter-based Circumferential-Intravascular-Radioluminescence-Photoacoustic-Imaging (CIRPI) system that can detect vulnerable plaques in coronary arteries and characterizes them with respect to pathology and biology. Our CIRPI system combined two imaging modalities: Circumferential Radioluminescence Imaging (CRI) and PhotoAcoustic Tomography (PAT) within a novel optical probe. The probe's CaF2:Eu based scintillating imaging window provides a 360° view of human (n = 7) and murine carotid (n = 10) arterial plaques by converting β-particles into visible photons during 18F-FDG decay. A 60× and 63× higher radioluminescent signals were detected from the human and murine plaque inflammations, respectively, compared to the control. The system's photoacoustic imaging provided a comprehensive analysis of the plaque compositions and its morphologic information. These results were further verified with IVIS-200, immunohistochemical analysis, and autoradiography.

  View details for PubMedID 29895966

• The Immuno-Imaging Toolbox. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Mayer, A. T., Gambhir, S. S. 2018

  Abstract

  The recent clinical success of cancer immunotherapy has renewed interest in the development of tools to image the immune system. In general, immunotherapies attempt to enable the body's own immune cells to seek out and destroy malignant disease. Molecular imaging of the cells and molecules which regulate immunity could provide unique insight into the mechanisms of action, and failure, of immunotherapies. In this review, we will collectively refer to the tools applied towards imaging the immune system as the immuno-imaging toolbox. The immuno-imaging toolbox is comprised of imaging hardware, software, and biological wetware which together enable dynamic and non-invasive visualization of immune response. Other recent reviews have focused on specific portions of the immuno-imaging toolbox, including advances in imaging hardware(1) and certain classes of imaging probes(2, 3). Here we will attempt to provide a comprehensive overview of the current state-of-the-art immuno-imaging toolbox with a focus on imaging strategies and their applications towards immunotherapy.

  View details for PubMedID 29794226

• A novel synthesis of 6 ''-[F-18]-fluoromaltotriose as a PET tracer for imaging bacterial infection JOURNAL OF LABELLED COMPOUNDS & RADIOPHARMACEUTICALS Namavari, M., Gowrishankar, G., Srinivasan, A., Gambhir, S. S., Haywood, T., Beinat, C. 2018; 61 (5): 408–14

  View details for DOI 10.1002/jlcr.3601

  View details for Web of Science ID 000431660100001

• Molecular Imaging of Cardiovascular Infections with 6 ''-[F-18]- Fluoromaltotriose PET/CT Wardak, M., Gowrishankar, G., Zhao, X., Namavari, M., Liu, Y., Neofytou, E., Haywood, T., Wu, J., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2018

  View details for Web of Science ID 000467489900037

• The preclinical characterization of [F-18]hGTS13 for imaging of x(C)(-) transporter activity Beinat, C., Gowrishanker, G., Shen, B., Alam, I., Robinson, E., Ilovich, O., Koglin, N., Schmitt-Willich, H., Berndt, M., Mueller, A., Zerna, M., Srinivasan, A., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2018

  View details for Web of Science ID 000467489901109

• A Novel Positron Emission Tomography Reporter Gene/Reporter Probe for the Central Nervous System Haywood, T., Beinat, C., Gowrishankar, G., Patel, C., Alam, I., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2018

  View details for Web of Science ID 000467489900079

• SiPM-based vs LYSO-based Ga-68-DOTA-TATE PET/CT: Comparison of Semi-Quantitative Measurements in Normal Tissues and Lesions Baratto, L., Toriihara, A., Hatami, N., Davidzon, G., Srinivas, S., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2018

  View details for Web of Science ID 000467489900430

• PET imaging of OX40+activated T cells predicts therapeutic response in a murine cancer vaccine model Alam, I., Mayer, A., Sagiv-Barfi, I., Vermesh, O., Wang, K., Johnson, E., Czerwinski, D., James, M. L., Levy, R., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2018

  View details for Web of Science ID 000467489900074

• Prospective Evaluation of Ga-68-RM2 PET/MRI in Patients with Biochemical Recurrence of Prostate Cancer and Negative Findings on Conventional Imaging JOURNAL OF NUCLEAR MEDICINE Minamimoto, R., Sonni, I., Hancock, S., Vasanawala, S., Loening, A., Gambhir, S. S., Iagaru, A. 2018; 59 (5): 803–8

  View details for DOI 10.2967/jnumed.117.197624

  View details for Web of Science ID 000431261700038

• Initial experience with a SiPM-based PET/CT scanner: influence of acquisition time on image quality EJNMMI PHYSICS Sonni, I., Baratto, L., Park, S., Hatami, N., Srinivas, S., Davidzon, G., Gambhir, S., Iagaru, A. 2018; 5: 9

  Abstract

  A newly introduced PET/CT scanner (Discovery Meaningful Insights-DMI, GE Healthcare) includes the silicon photomultiplier (SiPM) with time-of-flight (TOF) technology first used in the GE SIGNA PET/MRI. In this study, we investigated the impact of various acquisition times on image quality using this SiPM-based PET/CT.We reviewed data from 58 participants with cancer who were scanned using the DMI PET/CT scanner. The administered dosages ranged 295.3-429.9 MBq (mean ± SD 356.3 ± 37.4) and imaging started at 71-142 min (mean ± SD 101.41 ± 17.52) after administration of the radiopharmaceutical. The patients' BMI ranged 19.79-46.16 (mean ± SD 26.55 ± 5.53). We retrospectively reconstructed the raw TOF data at 30, 60, 90, and 120 s/bed and at the standard image acquisition time per clinical protocol (180 or 210 s/bed depending on BMI). Each reconstruction was reviewed blindly by two nuclear medicine physicians and scored 1-5 (1-poor, 5-excellent quality). The liver signal-to-noise ratio (SNR) was used as a quantitative measure of image quality.The average scores ± SD of the readers were 2.61 ± 0.83, 3.70 ± 0.92, 4.36 ± 0.82, 4.82 ± 0.39, and 4.91 ± 0.91 for the 30, 60, 90, and 120 s/bed and at standard acquisition time, respectively. Inter-reader agreement on image quality assessment was good, with a weighted kappa of 0.80 (95% CI 0.72-0.81). In the evaluation of the effects of time per bed acquisition on semi-quantitative measurements, we found that the only time point significantly different from the standard time were 30 and 60 s (both with P < 0.001). The effects of dose and BMI were not statistically significant (P = 0.195 and 0.098, respectively). There was a significant positive effect of time on SNR (P < 0.001), as well as a significant negative effect of weight (P < 0.001).Our results suggest that despite significant delays from injection to imaging (due to comparison with standard PET/CT) compared to standard clinical operations and even in a population with average BMI > 25, images can be acquired as fast as 90 s/bed using the SiPM PET/CT and still result in very good image quality (average score > 4).

  View details for PubMedID 29666972

• A blood biomarker for monitoring response to anti-EGFR therapy. Cancer biomarkers : section A of Disease markers Hughes, N. P., Xu, L., Nielsen, C. H., Chang, E., Hori, S. S., Natarajan, A., Lee, S., Kjar, A., Kani, K., Wang, S. X., Mallick, P., Gambhir, S. S. 2018

  Abstract

  BACKGROUND AND OBJECTIVE: To monitor therapies targeted to epidermal growth factor receptors (EGFR) in non-small cell lung cancer (NSCLC), we investigated Peroxiredoxin 6 (PRDX6) as a biomarker of response to anti-EGFR agents.METHODS: We studied cells that are sensitive (H3255, HCC827) or resistant (H1975, H460) to gefitinib. PRDX6 was examined with either gefitinib or vehicle treatment using enzyme-linked immunosorbent assays. We created xenograft models from one sensitive (HCC827) and one resistant cell line (H1975) and monitored serum PRDX6 levels during treatment.RESULTS: PRDX6 levels in cell media from sensitive cell lines increased significantly after gefitinib treatment vs. vehicle, whereas there was no significant difference for resistant lines. PRDX6 accumulation over time correlated positively with gefitinib sensitivity. Serum PRDX6 levels in gefitinib-sensitive xenograft models increased markedly during the first 24 hours of treatment and then decreased dramatically during the following 48 hours. Differences in serum PRDX6 levels between vehicle and gefitinib-treated animals could not be explained by differences in tumor burden.CONCLUSIONS: Our results show that changes in serum PRDX6 during the course of gefitinib treatment of xenograft models provide insight into tumor response and such an approach offers several advantages over imaging-based strategies for monitoring response to anti-EGFR agents.

  View details for PubMedID 29689709

• Smart-Dust-Nanorice for Enhancement of Endogenous Raman Signal, Contrast in Photoacoustic Imaging, and T2-Shortening in Magnetic Resonance Imaging. Small (Weinheim an der Bergstrasse, Germany) Pohling, C., Campbell, J. L., Larson, T. A., Van de Sompel, D., Levi, J., Bachmann, M. H., Bohndiek, S. E., Jokerst, J. V., Gambhir, S. S. 2018: e1703683

  Abstract

  Raman microspectroscopy provides chemo-selective image contrast, sub-micrometer resolution, and multiplexing capabilities. However, it suffers from weak signals resulting in image-acquisition times of up to several hours. Surface-enhanced Raman scattering (SERS) can dramatically enhance signals of molecules in close vicinity of metallic surfaces and overcome this limitation. Multimodal, SERS-active nanoparticles are usually labeled with Raman marker molecules, limiting SERS to the coating material. In order to realize multimodal imaging while acquiring the rich endogenous vibronic information of the specimen, a core-shell particle based on "Nanorice", where a spindle-shaped iron oxide core is encapsulated by a closed gold shell, is developed. An ultrathin layer of silica prevents agglomeration and unwanted chemical interaction with the specimen. This approach provides Raman signal enhancement due to plasmon resonance effects of the shell while the optical absorption in the near-infrared spectral region provides contrast in photoacoustic tomography. Finally, T2-relaxation of a magnetic resonance imaging (MRI) experiment is altered by taking advantage of the iron oxide core. The feasibility for Raman imaging is evaluated by nearfield simulations and experimental studies on the primate cell line COS1. MRI and photoacoustics are demonstrated in agarose phantoms illustrating the promising translational nature of this strategy for clinical applications in radiology.

  View details for DOI 10.1002/smll.201703683

  View details for PubMedID 29635739

• Molecular imaging agents for ultrasound. Current opinion in chemical biology Zlitni, A., Gambhir, S. S. 2018; 45: 113–20

  Abstract

  Ultrasound (US) imaging is a safe, sensitive and affordable imaging modality with a wide usage in the clinic. US signal can be further enhanced by using echogenic contrast agents (UCAs) which amplify the US signal. Developments in UCAs which are targeted to sites of disease allow the use of US imaging to provide molecular information. Unfortunately, traditional UCAs are too large to leave the vascular space limiting the application of molecular US to intravascular markers. In this mini review, we highlight the most recent reports on the application of molecular US imaging in the clinic and summarize the latest nanoparticle platforms used to develop nUCAs. We believe that the highlighted technologies will have a great impact on the evolution of the US imaging field.

  View details for PubMedID 29631121

• Reply: Optimizing Strategies for Immune Checkpoint Imaging with Immuno-PET in Preclinical Study. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Mayer, A. T., Gambhir, S. S. 2018; 59 (4): 711–12

  View details for PubMedID 29348318

• Optimizing Strategies for Immune Checkpoint Imaging with Immuno-PET in Preclinical Study REPLY JOURNAL OF NUCLEAR MEDICINE Mayer, A. T., Gambhir, S. S. 2018; 59 (4): 711–12

  View details for DOI 10.2967/jnumed.117.205153

  View details for Web of Science ID 000428981100042

• Development and Preclinical Validation of a Cysteine Knottin Peptide Targeting Integrin alpha v beta 6 for Near-infrared Fluorescent-guided Surgery in Pancreatic Cancer CLINICAL CANCER RESEARCH Tummers, W. S., Kimura, R. H., Abou-Elkacem, L., Beinat, C., Vahrmeijer, A. L., Swijnenburg, R., Willmann, J. K., Gambhir, S. S. 2018; 24 (7): 1667–76

  View details for DOI 10.1158/1078-0432.CCR-17-2491

  View details for Web of Science ID 000429050000017

• Thy1-Targeted Microbubbles for Ultrasound Molecular Imaging of Pancreatic Ductal Adenocarcinoma CLINICAL CANCER RESEARCH Abou-Elkacem, L., Wang, H., Chowdhury, S. M., Kimura, R. H., Bachawal, S. V., Gambhir, S. S., Tian, L., Willmann, J. K. 2018; 24 (7): 1574–85

  View details for DOI 10.1158/1078-0432.CCR-17-2057

  View details for Web of Science ID 000429050000009

• Tumor characterization by ultrasound-release of multiple protein and microRNA biomarkers, preclinical and clinical evidence PLOS ONE D'Souza, A. L., Chevillet, J. R., Ghanouni, P., Yan, X., Tewari, M., Gambhir, S. S. 2018; 13 (3): e0194268

  Abstract

  We have previously shown that low frequency ultrasound can release biomarkers from cells into the murine circulation enabling an amplification and localization of the released biomarker that could be used as a blood-based method to detect cancer earlier and monitor therapy. In this study, we further demonstrate that this technique could be used for characterization of tumors and/or identification of cellular masses of unknown origin due to the release of multiple protein and nucleic acid biomarkers in cells in culture, mice and patients. We sonicated colon (LS174T) and prostate (LNCaP) cancer cell lines in culture at a low frequency of 1 MHz and show that there were several-fold changes in multiple protein and microRNA (miRNA) abundance with treatment at various intensities and time. This release was dependent on the duration and intensity of the sonication for both cell lines. Significant increased release in biomarkers was also observed following tumor sonication in living mice bearing subcutaneous LS174T cell line xenografts (for proteins and nucleic acids) and in an experimental LS174T liver tumor model (for proteins only). Finally, we demonstrated this methodology of multiple biomarker release in patients undergoing ablation of uterine fibroids using MR guided high intensity focused ultrasound. Two protein biomarkers significantly increased in the plasma after the ultrasound treatment in 21 samples tested. This proof that ultrasound-amplification method works in soft tissue tumor models together with biomarker multiplexing, could allow for an effective non-invasive method for identification, characterization and localization of incidental lesions, cancer and other disease. Pre-treatment quantification of the biomarkers, allows for individualization of quantitative comparisons. This individualization of normal marker levels in this method allows for specificity of the biomarker-increase to each patient, tumor or organ being studied.

  View details for PubMedID 29547636

• A PET imaging approach for determining EGFR mutation status for improved lung cancer patient management SCIENCE TRANSLATIONAL MEDICINE Sun, X., Xiao, Z., Chen, G., Han, Z., Liu, Y., Zhang, C., Sun, Y., Song, Y., Wang, K., Fang, F., Wang, X., Lin, Y., Xu, L., Shao, L., Li, J., Cheng, Z., Gambhir, S., Shen, B. 2018; 10 (431)

  Abstract

  Tumor heterogeneity and changes in epidermal growth factor receptor (EGFR) mutation status over time challenge the design of effective EGFR tyrosine kinase inhibitor (TKI) treatment strategies for non-small cell lung cancer (NSCLC). Therefore, there is an urgent need to develop techniques for comprehensive tumor EGFR profiling in real time, particularly in lung cancer precision medicine trials. We report a positron emission tomography (PET) tracer, N-(3-chloro-4-fluorophenyl)-7-(2-(2-(2-(2-18F-fluoroethoxy) ethoxy) ethoxy) ethoxy)-6-methoxyquinazolin-4-amine (18F-MPG), with high specificity to activating EGFR mutant kinase. We evaluate the feasibility of using 18F-MPG PET for noninvasive imaging and quantification of EGFR-activating mutation status in preclinical models of NSCLC and in patients with primary and metastatic NSCLC tumors. 18F-MPG PET in NSCLC animal models showed a significant correlation (R2 = 0.9050) between 18F-MPG uptake and activating EGFR mutation status. In clinical studies with NSCLC patients (n = 75), the concordance between the detection of EGFR activation by 18F-MPG PET/computed tomography (CT) and tissue biopsy reached 84.29%. There was a greater response to EGFR-TKIs (81.58% versus 6.06%) and longer median progression-free survival (348 days versus 183 days) in NSCLC patients when 18F-MPG PET/CT SUVmax (maximum standard uptake value) was ≥2.23 versus <2.23. Our study demonstrates that 18F-MPG PET/CT is a powerful method for precise quantification of EGFR-activating mutation status in NSCLC patients, and it is a promising strategy for noninvasively identifying patients sensitive to EGFR-TKIs and for monitoring the efficacy of EGFR-TKI therapy.

  View details for PubMedID 29515002

• Toward achieving precision health SCIENCE TRANSLATIONAL MEDICINE Gambhir, S., Ge, T., Vermesh, O., Spitler, R. 2018; 10 (430)

  View details for DOI 10.1126/scitranslmed.aao3612

  View details for Web of Science ID 000426291800005

• Toward achieving precision health. Science translational medicine Gambhir, S. S., Ge, T. J., Vermesh, O., Spitler, R. 2018; 10 (430)

  Abstract

  Health care systems primarily focus on patients after they present with disease, not before. The emerging field of precision health encourages disease prevention and earlier detection by monitoring health and disease based on an individual's risk. Active participation in health care can be encouraged with continuous health-monitoring devices, providing a higher-resolution picture of human health and disease. However, the development of monitoring technologies must prioritize the collection of actionable data and long-term user engagement.

  View details for DOI 10.1126/scitranslmed.aao3612

  View details for PubMedID 29491186

  View details for PubMedCentralID PMC5985668

• [F-18] FSPG-PET reveals increased cystine/glutamate antiporter (xc-) activity in a mouse model of multiple sclerosis JOURNAL OF NEUROINFLAMMATION Hoehne, A., James, M. L., Alam, I. S., Ronald, J. A., Schneider, B., D'Souza, A., Witney, T. H., Andrews, L. E., Cropper, H. C., Behera, D., Gowrishankar, G., Ding, Z., Wyss-Coray, T., Chin, F. T., Biswal, S., Gambhir, S. S. 2018; 15

  View details for DOI 10.1186/s12974-018-1080-1

  View details for Web of Science ID 000425975200001

• [18F]FSPG-PET reveals increased cystine/glutamate antiporter (xc-) activity in a mouse model of multiple sclerosis. Journal of neuroinflammation Hoehne, A., James, M. L., Alam, I. S., Ronald, J. A., Schneider, B., D'Souza, A., Witney, T. H., Andrews, L. E., Cropper, H. C., Behera, D., Gowrishankar, G., Ding, Z., Wyss-Coray, T., Chin, F. T., Biswal, S., Gambhir, S. S. 2018; 15 (1): 55

  Abstract

  The cystine/glutamate antiporter (xc-) has been implicated in several neurological disorders and, specifically, in multiple sclerosis (MS) as a mediator of glutamate excitotoxicity and proinflammatory immune responses. We aimed to evaluate an xc-specific positron emission tomography (PET) radiotracer, (4S)-4-(3-[18F]fluoropropyl)-L-glutamate ([18F]FSPG), for its ability to allow non-invasive monitoring of xc- activity in a mouse model of MS.Experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6 mice by subcutaneous injection of myelin oligodendrocyte glycoprotein (MOG35-55) peptide in complete Freund's adjuvant (CFA) followed by pertussis toxin. Control mice received CFA emulsion and pertussis toxin without MOG peptide, while a separate cohort of naïve mice received no treatment. PET studies were performed to investigate the kinetics and distribution of [18F]FSPG in naïve, control, pre-symptomatic, and symptomatic EAE mice, compared to 18F-fluorodeoxyglucose ([18F]FDG). After final PET scans, each mouse was perfused and radioactivity in dissected tissues was measured using a gamma counter. Central nervous system (CNS) tissues were further analyzed using ex vivo autoradiography or western blot. [18F]FSPG uptake in human monocytes, and T cells pre- and post-activation was investigated in vitro.[18F]FSPG was found to be more sensitive than [18F]FDG at detecting pathological changes in the spinal cord and brain of EAE mice. Even before clinical signs of disease, a small but significant increase in [18F]FSPG signal was observed in the spinal cord of EAE mice compared to controls. This increase in PET signal became more pronounced in symptomatic EAE mice and was confirmed by ex vivo biodistribution and autoradiography. Likewise, in the brain of symptomatic EAE mice, [18F]FSPG uptake was significantly higher than controls, with the largest changes observed in the cerebellum. Western blot analyses of CNS tissues revealed a significant correlation between light chain of xc- (xCT) protein levels, the subunit of xc- credited with its transporter activity, and [18F]FSPG-PET signal. In vitro [18F]FSPG uptake studies suggest that both activated monocytes and T cells contribute to the observed in vivo PET signal.These data highlight the promise of [18F]FSPG-PET as a technique to provide insights into neuroimmune interactions in MS and the in vivo role of xc- in the development and progression of this disease, thus warranting further investigation.

  View details for DOI 10.1186/s12974-018-1080-1

  View details for PubMedID 29471880

  View details for PubMedCentralID PMC5822551

• Eradication of spontaneous malignancy by local immunotherapy. Science translational medicine Sagiv-Barfi, I., Czerwinski, D. K., Levy, S., Alam, I. S., Mayer, A. T., Gambhir, S. S., Levy, R. 2018; 10 (426)

  Abstract

  It has recently become apparent that the immune system can cure cancer. In some of these strategies, the antigen targets are preidentified and therapies are custom-made against these targets. In others, antibodies are used to remove the brakes of the immune system, allowing preexisting T cells to attack cancer cells. We have used another noncustomized approach called in situ vaccination. Immunoenhancing agents are injected locally into one site of tumor, thereby triggering a T cell immune response locally that then attacks cancer throughout the body. We have used a screening strategy in which the same syngeneic tumor is implanted at two separate sites in the body. One tumor is then injected with the test agents, and the resulting immune response is detected by the regression of the distant, untreated tumor. Using this assay, the combination of unmethylated CG-enriched oligodeoxynucleotide (CpG)-a Toll-like receptor 9 (TLR9) ligand-and anti-OX40 antibody provided the most impressive results. TLRs are components of the innate immune system that recognize molecular patterns on pathogens. Low doses of CpG injected into a tumor induce the expression of OX40 on CD4+ T cells in the microenvironment in mouse or human tumors. An agonistic anti-OX40 antibody can then trigger a T cell immune response, which is specific to the antigens of the injected tumor. Remarkably, this combination of a TLR ligand and an anti-OX40 antibody can cure multiple types of cancer and prevent spontaneous genetically driven cancers.

  View details for DOI 10.1126/scitranslmed.aan4488

  View details for PubMedID 29386357

  View details for PubMedCentralID PMC5997264

• Dosimetry Prediction for Clinical Translation of 64Cu-Pembrolizumab ImmunoPET Targeting Human PD-1 Expression. Scientific reports Natarajan, A., Patel, C. B., Habte, F., Gambhir, S. S. 2018; 8 (1): 633

  Abstract

  The immune checkpoint programmed death 1 receptor (PD-1) expressed on some tumor-infiltrating lymphocytes, and its ligand (PD-L1) expressed on tumor cells, enable cancers to evade the immune system. Blocking PD-1 with the monoclonal antibody pembrolizumab is a promising immunotherapy strategy. Thus, noninvasively quantifying the presence of PD-1 expression in the tumor microenvironment prior to initiation of immune checkpoint blockade may identify the patients likely to respond to therapy. We have developed a 64Cu-pembrolizumab radiotracer and evaluated human dosimetry. The tracer was utilized to image hPD-1 levels in two subcutaneous mouse models: (a) 293 T/hPD-1 cells xenografted into NOD-scid IL-2Rγnull mice (NSG/293 T/hPD-1) and (b) human peripheral blood mononuclear cells engrafted into NSG bearing A375 human melanoma tumors (hNSG/A375). In each mouse model two cohorts were evaluated (hPD-1 blockade with pembrolizumab [blk] and non-blocked [nblk]), for a total of four groups (n = 3-5/group). The xenograft-to-muscle ratio in the NSG/293 T/hPD-1 model at 24 h was significantly increased in the nblk group (7.0 ± 0.5) compared to the blk group (3.4 ± 0.9), p = 0.01. The radiotracer dosimetry evaluation (PET/CT ROI-based and ex vivo) in the hNSG/A375 model revealed the highest radiation burden to the liver. In summary, we validated the 64Cu-pembrolizumab tracer's specific hPD-1 receptor targeting and predicted human dosimetry.

  View details for DOI 10.1038/s41598-017-19123-x

  View details for PubMedID 29330552

• Thy1-Targeted Microbubbles for Ultrasound Molecular Imaging of Pancreatic Ductal Adenocarcinoma. Clinical cancer research : an official journal of the American Association for Cancer Research Abou-Elkacem, L. n., Wang, H. n., Chowdhury, S. M., Kimura, R. H., Bachawal, S. V., Gambhir, S. S., Tian, L. n., Willmann, J. K. 2018

  Abstract

  To engineer a dual human and murine Thy1-binding single-chain-antibody ligand (Thy1-scFv) for contrast microbubble-enhanced ultrasound molecular imaging of pancreatic ductal adenocarcinoma (PDAC). Thy1-scFv were engineered using yeast-surface-display techniques. Binding to soluble human and murine Thy1 and to Thy1-expressing cells was assessed by flow cytometry. Thy1-scFv was then attached to gas-filled microbubbles to create MB Thy1-scFv. Thy1 binding of MB Thy1-scFv to Thy1-expressing cells was evaluated under flow shear stress conditions in flow-chamber experiments. MB scFv-scrambled and MB Non-targeted were used as negative controls. All microbubble types were tested in both orthotopic human PDAC xenografts and transgenic PDAC mice in vivo. Results: Thy1-scFv had a K D of 3.4±0.36 nM for human and 9.2±1.7 nM for murine Thy1 and showed binding to both soluble and cellularly expressed Thy1. MB Thy1-scFv attached to Thy1 with high affinity compared to negative control microbubbles P<0.01) as assessed by flow cytometry. Similarly, flow-chamber studies showed significantly (P<0.01) higher binding of MB Thy1-scFv (3.0±0.81 MB/cell) to Thy1-expressing cells than MB scFv-scrambled (0.57±0.53) and MB Non-targeted (0.43±0.53). In vivo ultrasound molecular imaging using MB Thy1-scFv demonstrated significantly higher signal (P<0.01) in both orthotopic (5.32±1.59 a.u.) and transgenic PDAC (5.68±2.5 a.u.) mice compared to chronic pancreatitis (0.84±0.6 a.u.) and normal pancreas (0.67±0.71 a.u.). Ex vivo immunofluorescence confirmed significantly (P<0.01) increased Thy1 expression in PDAC compared to chronic pancreatitis and normal pancreas tissue. Conclusions: A dual human and murine Thy1-binding scFv was designed to generate contrast microbubbles to allow PDAC detection with ultrasound.

  View details for PubMedID 29301827

• The Utility of [18F]DASA-23 for Molecular Imaging of Prostate Cancer with Positron Emission Tomography Molecular Imaging and Biology Beinat, C., Haywood, T., Chen, Y., Patel, C. B., Alam, I. S., Murty, S., Gambhir, S. S. 2018; 20 (6)

  View details for DOI 10.1007/s11307-018-1194-y

• A blood biomarker for monitoring response to anti-EGFR therapy CANCER BIOMARKERS Hughes, N. P., Xu, L., Nielsen, C. H., Chang, E., Hori, S. S., Natarajan, A., Lee, S., Kjaer, A., Kani, K., Wang, S. X., Mallick, P., Gambhir, S. 2018; 22 (2): 333–44

  View details for DOI 10.3233/CBM-171149

  View details for Web of Science ID 000437251500016

• An intravascular magnetic wire for the high-throughput retrieval of circulating tumour cells in vivo. Nature biomedical engineering Vermesh, O., Aalipour, A., Ge, T. J., Saenz, Y., Guo, Y., Alam, I. S., Park, S., Adelson, C. N., Mitsutake, Y., Vilches-Moure, J., Godoy, E., Bachmann, M., Ooi, C. C., Lyons, J. K., Mueller, K., Arami, H., Green, A., Solomon, E. I., Wang, S. X., Gambhir, S. S. 2018; 2: 696–705

  Abstract

  The detection and analysis of rare blood biomarkers is necessary for early cancer diagnosis and to facilitate the development of tailored therapies. However, current methods for the isolation of circulating tumor cells (CTCs) or nucleic acids present in a standard clinical sample of only 5-10 mL of blood provide inadequate yields for early cancer detection and comprehensive molecular profiling. We have developed a flexible magnetic wire that can retrieve rare biomarkers from the subject's blood in vivo at a much higher yield. The wire is inserted and removed through a standard intravenous catheter and captures biomarkers that have been previously labeled with injected magnetic particles. In a proof-of-concept experiment in a live porcine model, we demonstrate the in vivo labeling and single-pass capture of viable model CTCs in less than 10 seconds. The wire achieves capture efficiencies that correspond to enrichments of 10-80 times the amount of CTCs in a 5-mL blood draw, and to 500-5,000 times the enrichments achieved by the commercially available Gilupi CellCollector.

  View details for PubMedID 30524876

• A Novel Engineered Small Protein for Positron Emission Tomography Imaging of Human Programmed Death Ligand-1 : Validation in Mouse Models and Human Cancer Tissues Clinical Cancer Res Natarajan, A., Patel, C. B., Ramakrishnan, S., Panesar, P. S., Long, S. R., Gambhir, S. S. 2018

  View details for DOI 10.1158/1078-0432.CCR-18-1871

• Role of Imaging in Early-Phase Trials NOVEL DESIGNS OF EARLY PHASE TRIALS FOR CANCER THERAPEUTICS Greene, L., Srinivas, S., Park, S., Hatami, N., Nobashi, T., Baratto, L., Toriihara, A., Gambhir, S. S., Kummar, S., Takimoto, C. 2018: 129–49

  View details for DOI 10.1016/B978-0-12-812512-0.00010-5

  View details for Web of Science ID 000464871500011

• Tumor Cell-Derived Extracellular Vesicle-Coated Nanocarriers: An Efficient Theranostic Platform for the Cancer-Specific Delivery of Anti-miR-21 and Imaging Agents. ACS nano Jc Bose, R. n., Uday Kumar, S. n., Zeng, Y. n., Afjei, R. n., Robinson, E. n., Lau, K. n., Bermudez, A. n., Habte, F. n., Pitteri, S. J., Sinclair, R. n., Willmann, J. K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. n. 2018

  Abstract

  MicroRNAs are critical regulators of cancer initiation, progression, and dissemination. Extensive evidence suggests that the inhibition of over-expressed oncogenic miRNA function can be a robust strategy for anticancer therapy. However, in vivo targeted delivery of miRNA therapeutics to various types of cancers remains a major challenge. Inspired by their natural synthesis and cargo delivery capabilities, researchers have exploited tumor cell-derived extracellular vesicles (TEVs) for the cancer-targeted delivery of therapeutics and theranostics. Here, we investigate a TEV-based nanoplatform for multimodal miRNA delivery and phototherapy treatments as well as the magnetic resonance imaging of cancer. We demonstrated loading of anti-miR-21 that blocks the function of endogenous oncogenic miR-21 over-expressed in cancer cells into and subsequent delivery by TEVs derived from 4T1 cells. We also produced Cy5-anti-miR-21-loaded TEVs from two other cancer cell lines (HepG2 and SKBR3) and confirmed their robust homologous and heterologous transfection efficiency and intracellular Cy5-anti-miR-21 delivery. Additionally, TEV-mediated anti-miR-21 delivery attenuated doxorubicin (DOX) resistance in breast cancer cells with a 3-fold higher cell kill efficiency than in cells treated with DOX alone. We then investigated TEVs as a biomimetic source for the functionalization of gold-iron oxide nanoparticles (GIONs) and demonstrated nanotheranostic properties of TEV-GIONs in vitro. TEV-GIONs demonstrated excellent T2 contrast in in vitro magnetic resonance (MR) imaging and resulted in efficient photothermal effect in 4T1 cells. We also evaluated the biodistribution and theranostic property of anti-miR-21 loaded TEV-GIONs in vivo by labeling with indocyanine green near-infrared dye. We further validated the tumor specific accumulation of TEV-GIONs using MR imaging. Our findings demonstrate that the distribution pattern of the TEV-anti-miR-21-GIONs correlated well with the tumor-targeting capability as well as the activity and efficacy obtained in response to doxorubicin combination treatments. TEVs and TEV-GIONs are promising nanotheranostics for future applications in cancer molecular imaging and therapy.

  View details for PubMedID 30346694

• Tumor treating fields increases membrane permeability in glioblastoma cells. Cell death discovery Chang, E. n., Patel, C. B., Pohling, C. n., Young, C. n., Song, J. n., Flores, T. A., Zeng, Y. n., Joubert, L. M., Arami, H. n., Natarajan, A. n., Sinclair, R. n., Gambhir, S. S. 2018; 4: 113

  Abstract

  Glioblastoma is the most common yet most lethal of primary brain cancers with a one-year post-diagnosis survival rate of 65% and a five-year survival rate of barely 5%. Recently the U.S. Food and Drug Administration approved a novel fourth approach (in addition to surgery, radiation therapy, and chemotherapy) to treating glioblastoma; namely, tumor treating fields (TTFields). TTFields involves the delivery of alternating electric fields to the tumor but its mechanisms of action are not fully understood. Current theories involve TTFields disrupting mitosis due to interference with proper mitotic spindle assembly. We show that TTFields also alters cellular membrane structure thus rendering it more permeant to chemotherapeutics. Increased membrane permeability through the imposition of TTFields was shown by several approaches. For example, increased permeability was indicated through increased bioluminescence with TTFields exposure or with the increased binding and ingress of membrane-associating reagents such as Dextran-FITC or ethidium D or with the demonstration by scanning electron microscopy of augmented number and sizes of holes on the cellular membrane. Further investigations showed that increases in bioluminescence and membrane hole production with TTFields exposure disappeared by 24 h after cessation of alternating electric fields thus demonstrating that this phenomenom is reversible. Preliminary investigations showed that TTFields did not induce membrane holes in normal human fibroblasts thus suggesting that the phenomenom was specific to cancer cells. With TTFields, we present evidence showing augmented membrane accessibility by compounds such as 5-aminolevulinic acid, a reagent used intraoperatively to delineate tumor from normal tissue in glioblastoma patients. In addition, this mechanism helps to explain previous reports of additive and synergistic effects between TTFields and other chemotherapies. These findings have implications for the design of combination therapies in glioblastoma and other cancers and may significantly alter standard of care strategies for these diseases.

  View details for PubMedID 30534421

• The Immuno-Imaging Toolbox Journal of Nuclear Medicine Mayer, A. T., Gambhir, S. S. 2018; 59 (8): 1174-1182
• [18F]FSPG-PET Reveals Increased Cystine/Glutamate Antiporter (xc-) Activity in a Mouse Model of Multiple Sclerosis Journal of Neuroinflammation Hoehne, A., James, M. L., Alam, I. S., Ronald, J. A., Schneider, B., D'Souza, A., Witney, T. H., Andrews, L. E., Cropper, H. C., Behera, D., Gowrishankar, G., Ding, Z., Wyss-Coray, T., Chin, F. T., Biswal, S., Gambhir, S. S. 2018; 15 (1): 55
• Tumor Treating Fields Increases Membrane Permeability in Glioblastoma Cells Cell Death Discovery Chang, E., Patel, C. B., Pohling, C., Young, C., Song, J., Flores, T., Zeng, Y., Joubert, L. M., Arami, H., Natarajan, A., Sinclair, R., Gambhir, S. S. 2018; 4

  View details for DOI 10.1038/s41420-018-0130-x

• Immune Cell Therapy and Imaging of Glioblastoma Glioblastoma: State-of-the-Art Clinical Neuroimaging Murty, S., Gambhir, S. S. edited by Iv, M., Wintermark, M., Massoud, T. D. Nova Science Publishers. 2018
• Ferumoxytol-based Dual-modality Imaging Probe for Detection of Stem Cell Transplant Rejection. Nanotheranostics Li, K. n., Chan, C. T., Nejadnik, H. n., Lenkov, O. D., Wolterman, C. n., Paulmurugan, R. n., Yang, H. n., Gambhir, S. S., Daldrup-Link, H. E. 2018; 2 (4): 306–19

  Abstract

  Purpose: Stem cell transplants are an effective approach to repair large bone defects. However, comprehensive techniques to monitor the fate of transplanted stem cells in vivo are lacking. Such strategies would enable corrective interventions at an early stage and greatly benefit the development of more successful tissue regeneration approaches. In this study, we designed and synthesized a dual-modality imaging probe (Feru-AFC) that can simultaneously localize transplanted stem cells and diagnose immune rejection-induced apoptosis at an early stage in vivo. Methods: We used a customized caspase-3 cleavable peptide-dye conjugate to modify the surface of clinically approved ferumoxytol nanoparticles (NPs) to generate the dual-modality imaging probe with fluorescence "light-up" feature. We labeled both mouse mesenchymal stem cells (mMSCs, matched) and pig mesenchymal stem cells (pMSCs, mismatched) with the probe and transplanted the labeled cells with biocompatible scaffold at the calvarial defects in mice. We then employed intravital microscopy (IVM) and magnetic resonance imaging (MRI) to investigate the localization, engraftment, and viability of matched and mismatched stem cells, followed by histological analyses to evaluate the results obtained from in vivo studies. Results: The Feru-AFC NPs showed good cellular uptake efficiency in the presence of lipofectin without cytotoxicity to mMSCs and pMSCs. The fluorescence of Feru-AFC NPs was turned on inside apoptotic cells due to the cleavage of peptide by activated caspase-3 and subsequent release of fluorescence dye molecules. Upon transplantation at the calvarial defects in mice, the intense fluorescence from the cleaved Feru-AFC NPs in apoptotic pMSCs was observed with a concomitant decrease in the overall cell number from days 1 to 6. In contrast, the Feru-AFC NP-treated mMSCs exhibited minimum fluorescence and the cell number also remained similar. Furthermore, in vivo MRI of the Feru-AFC NP-treated mMSC and pMSCs transplants could clearly indicate the localization of matched and mismatched cells, respectively. Conclusions: We successfully developed a dual-modality imaging probe for evaluation of the localization and viability of transplanted stem cells in mouse calvarial defects. Using ferumoxytol NPs as the platform, our Feru-AFC NPs are superparamagnetic and display a fluorescence "light-up" signature upon exposure to activated caspase-3. The results show that the probe is a promising tool for long-term stem cell tracking through MRI and early diagnosis of immune rejection-induced apoptosis through longitudinal fluorescence imaging.

  View details for DOI 10.7150/ntno.26389

  View details for PubMedID 29977742

  View details for PubMedCentralID PMC6030766

• Imaging activated T cells predicts response to cancer vaccines. The Journal of clinical investigation Alam, I. S., Mayer, A. T., Sagiv-Barfi, I. n., Wang, K. n., Vermesh, O. n., Czerwinski, D. K., Johnson, E. M., James, M. L., Levy, R. n., Gambhir, S. S. 2018

  Abstract

  In situ cancer vaccines are under active clinical investigation, given their reported ability to eradicate both local and disseminated malignancies. Intratumoral vaccine administration is thought to activate a T cell-mediated immune response, which begins in the treated tumor and cascades systemically. In this study, we describe a PET tracer (64Cu-DOTA-AbOX40) that enabled noninvasive and longitudinal imaging of OX40, a cell-surface marker of T cell activation. We report the spatiotemporal dynamics of T cell activation following in situ vaccination with CpG oligodeoxynucleotide in a dual tumor-bearing mouse model. We demonstrate that OX40 imaging was able to predict tumor responses on day 9 after treatment on the basis of tumor tracer uptake on day 2, with greater accuracy than both anatomical and blood-based measurements. These studies provide key insights into global T cell activation following local CpG treatment and indicate that 64Cu-DOTA-AbOX40 is a promising candidate for monitoring clinical cancer immunotherapy strategies.

  View details for PubMedID 29596062

• Quantification of Cerenkov Luminescence Imaging (CLI) Comparable With 3-D PET Standard Measurements. Molecular imaging Habte, F., Natarajan, A., Paik, D. S., Gambhir, S. S. 2018; 17: 1536012118788637

  Abstract

  Cerenkov luminescence imaging (CLI) is commonly performed using two-dimensional (2-D) conventional optical imaging systems for its cost-effective solution. However, quantification of CLI comparable to conventional three-dimensional positron emission tomography (PET) is challenging using these systems due to both the high attenuation of Cerenkov radiation (CR) on mouse tissue and nonexisting depth resolution of CLI using 2-D imaging systems (2-D CLI). In this study, we developed a model that estimates effective tissue attenuation coefficient and corrects the tissue attenuation of CLI signal intensity independent of tissue depth and size. To evaluate this model, we used several thin slices of ham as a phantom and placed a radionuclide (89Zr and 64Cu) inside the phantom at different tissue depths and sizes (2, 7, and 12 mm). We performed 2-D CLI and MicroPET/CT (Combined small animal PET and Computed Tomography (CT)) imaging of the phantom and in vivo mouse model after administration of 89Zr tracer. Estimates of the effective tissue attenuation coefficient (mueff) for 89Zr and 64Cu were 2.4 and 2.6 cm-1, respectively. The computed unit conversion factor to %ID/g from 2-D CLI signal was 2.74 * 10-3 muCi/radiance estimated from phantom study. After applying tissue attenuation correction and unit conversion to the in vivo animal study, an average quantification difference of 10% for spleen and 35% for liver was obtained compared to PET measurements. The proposed model provides comparable quantification accuracy to standard PET system independent of deep tissue CLI signal attenuation.

  View details for PubMedID 30043654

• Reply: 6"-18F-Fluoromaltotriose PET Evaluation in Escherichia-Coli-Induced Myositis: is there Uptake Saturation in Control? Journal of nuclear medicine : official publication, Society of Nuclear Medicine Wardak, M. n., Gowrishankar, G. n., Gambhir, S. S. 2018

  View details for PubMedID 29653976

• Intraoperative Molecular Imaging in Lung Cancer: The State of the Art and the Future. Molecular therapy : the journal of the American Society of Gene Therapy Rogalla, S. n., Joosten, S. C., Alam, I. S., Gambhir, S. S., Vermesh, O. n. 2018; 26 (2): 338–41

  View details for PubMedID 29398484

• The Utility of [18F]DASA-23 for Molecular Imaging of Prostate Cancer with Positron Emission Tomography. Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging Beinat, C. n., Haywood, T. n., Chen, Y. S., Patel, C. B., Alam, I. S., Murty, S. n., Gambhir, S. S. 2018

  Abstract

  There is a strong, unmet need for superior positron emission tomography (PET) imaging agents that are able to measure biochemical processes specific to prostate cancer. Pyruvate kinase M2 (PKM2) catalyzes the concluding step in glycolysis and is a key regulator of tumor growth and metabolism. Elevation of PKM2 expression was detected in Gleason 8-10 tumors compared to Gleason 6-7 carcinomas, indicating that PKM2 may potentially be a marker of aggressive prostate cancer. We have recently reported the development of a PKM2-specific radiopharmaceutical [18F]DASA-23 and herein describe its evaluation in cell culture and preclinical models of prostate cancer.The cellular uptake of [18F]DASA-23 was evaluated in a panel of prostate cancer cell lines and compared to that of [18F]FDG. The specificity of [18F]DASA-23 to measure PKM2 levels in cell culture was additionally confirmed through the use of PKM2-specific siRNA. PET imaging studies were then completed utilizing subcutaneous prostate cancer xenografts using either PC3 or DU145 cells in mice.[18F]DASA-23 uptake values over 60-min incubation period in PC3, LnCAP, and DU145 respectively were 23.4 ± 4.5, 18.0 ± 2.1, and 53.1 ± 4.6 % tracer/mg protein. Transient reduction in PKM2 protein expression with siRNA resulted in a 50.1 % reduction in radiotracer uptake in DU145 cells. Small animal PET imaging revealed 0.86 ± 0.13 and 1.6 ± 0.2 % ID/g at 30 min post injection of radioactivity in DU145 and PC3 subcutaneous tumor bearing mice respectively.Herein, we evaluated a F-18-labeled PKM2-specific radiotracer, [18F]DASA-23, for the molecular imaging of prostate cancer with PET. [18F]DASA-23 revealed rapid and extensive uptake levels in cellular uptake studies of prostate cancer cells; however, there was only modest tumor uptake when evaluated in mouse subcutaneous tumor models.

  View details for PubMedID 29736561

• Development and preclinical validation of a cysteine knottin peptide targeting Integrin αvβ6 for near-infrared fluorescent-guided surgery in pancreatic cancer. Clinical cancer research : an official journal of the American Association for Cancer Research Tummers, W. S., Kimura, R. H., Abou-Elkacem, L. n., Vahrmeijer, A. L., Swijnenburg, R. J., Willmann, J. K., Gambhir, S. S. 2018

  Abstract

  Intraoperative near-infrared fluorescence (NIRF) imaging could help stratification for the proper primary treatment for patients with pancreatic ductal adenocarcinoma (PDAC), and achieve complete resection since it allows visualization of cancer in real time. Integrin αvβ6, a target specific for PDAC, is present in >90% of patients, and is able to differentiate between pancreatitis and PDAC. A clinically translatable αvβ6-targeting NIRF agent was developed, based on a previously developed cysteine knottin peptide for PET imaging, R01-MG, and validated in preclinical mouse models.The applicability of the agent was tested for cell and tissue binding characteristics using cell-based plate assays, subcutaneous and orthotopic pancreatic models, and a transgenic mouse model of PDAC development (Pdx1-Cre tg/+;KRas LSL G12D/+;Ink4a/Arf). IRDye800CW was conjugated to R01-MG in a 1:1 ratio. R01-MG-IRDye800, was compared to a control peptide and IRDye800 alone.In subcutaneous tumor models a significantly higher tumor-to-background ratio (TBR) was seen in BxPC-3 tumors (2.5±0.1) compared to MiaPaCa-2 (1.2±0.1) (p<0.001), and to the control peptide (1.6±0.4) (p<0.005). In an orthotopic tumor model tumor-specific uptake of R01-MG-IRDye800 was shown compared to IRDye800 alone (TBR 2.7 versus 0.86). The fluorescent signal in tumors of transgenic mice was significantly higher, TBR of 3.6±0.94, compared to the normal pancreas of wild type controls, TBR of 1.0±0.17 (p<0.001).R01-MG-IRDye800 shows specific targeting to αvβ6, and holds promise as a diagnostic and therapeutic tool to recognize PDAC for fluorescence-guided surgery. This agent can help improve the stratification of patients for a potentially curative, margin-negative resection.

  View details for PubMedID 29298796

• A novel synthesis of 6''-[18 F]-fluoromaltotriose as a PET tracer for imaging bacterial infection. Journal of labelled compounds & radiopharmaceuticals Namavari, M. n., Gowrishankar, G. n., Srinivasan, A. n., Gambhir, S. S. 2018

  Abstract

  The aim of this study was to develop a positron emission tomography (PET) tracer to visualize and monitor therapeutic response to bacterial infections. In our continued efforts to find maltose based PET tracers that can image bacterial infections, we have designed and prepared 6''-[18 F]fluoromaltotriose as a second generation PET imaging tracer targeting the maltodextrin transporter of bacteria. We have developed methods to synthesize 6''-deoxy-6''-[18 F]fluoro-α-D-glucopyranosyl-(1-4)-O-α-D-glucopyranosyl-(1-4)-O-D-glucopyranose (6''-[18 F]-fluoromaltotriose) as a bacterial infection PET imaging agent. 6''-[18 F]fluoromaltotriose was prepared from precursor, 2'',3'',4''-tri-O-acetyl-6''-O-nosyl-α-D-glucopyranosyl-(1-4)-O-2',3',6'-tri-O-acetyl-α-D-glucopyranosyl-(1-4)-1,2,3,6-tetra-O-acetyl-D-glucopyranose (per-O-acetyl-6''-O-nosyl-maltotriose 4). This method utilizes the reaction between precursor 4 and anhydrous [18 F]KF/Kryptofix 2.2.2 in Dimethylformamide (DMF) at 85o C for 10 minutes to yield per-O-acetyl-6''-deoxy-6-'' [18 F]-fluoromaltotriose (7). Successive acidic and basic hydrolysis of the acetyl protecting groups in 7 produced 6''-[18 F]fluoromaltotriose (8). Also, cold 6''- [19 F]fluoromaltotriose was prepared from per-O-acetyl-6''-hydroxymaltotriose via a DAST reaction followed by a basic hydrolysis. A successful synthesis of 6''-[18 F]-fluoromaltotriose has been accomplished in 8±1.2 % radiochemical yield (decay corrected). Total synthesis time was 120 min. Serum stability of 6''-[18 F]fluoromaltotriose at 37o C indicated that 6''-[18 F]-fluoromaltotriose remained intact up to 2 h. In conclusion, we have successfully synthesized 6''-[18 F]-fluoromaltotriose via direct fluorination of an appropriate precursor of a protected maltotriose.

  View details for PubMedID 29314161

• Tomographic magnetic particle imaging of cancer targeted nanoparticles. Nanoscale Arami, H., Teeman, E., Troksa, A., Bradshaw, H., Saatchi, K., Tomitaka, A., Gambhir, S. S., Häfeli, U. O., Liggitt, D., Krishnan, K. M. 2017; 9 (47): 18723-18730

  Abstract

  Magnetic Particle Imaging (MPI) is an emerging, whole body biomedical imaging technique, with sub-millimeter spatial resolution and high sensitivity to a biocompatible contrast agent consisting of an iron oxide nanoparticle core and a biofunctionalized shell. Successful application of MPI for imaging of cancer depends on the nanoparticles (NPs) accumulating at tumors at sufficient levels relative to other sites. NPs' physiochemical properties such as size, crystallographic structure and uniformity, surface coating, stability, blood circulation time and magnetization determine the efficacy of their tumor accumulation and MPI signal generation. Here, we address these criteria by presenting strategies for the synthesis and surface functionalization of efficient MPI tracers, that can target a typical murine brain cancer model and generate three dimensional images of these tumors with very high signal-to-noise ratios (SNR). Our results showed high contrast agent sensitivities that enabled us to detect 1.1 ng of iron (SNR ∼ 3.9) and enhance the spatial resolution to about 600 μm. The biodistribution of these NPs was also studied using near-infrared fluorescence (NIRF) and single-photon emission computed tomography (SPECT) imaging. NPs were mainly accumulated in the liver and spleen and did not show any renal clearance. This first pre-clinical study of cancer targeted NPs imaged using a tomographic MPI system in an animal model paves the way to explore new nanomedicine strategies for cancer diagnosis and therapy, using clinically safe magnetic iron oxide nanoparticles and MPI.

  View details for DOI 10.1039/c7nr05502a

  View details for PubMedID 29165498

• SURFACE-ENHANCED RAMAN SPECTROSCOPY (SERS) FOR INTRAOPERATIVE BRAIN TUMOR IMAGING AND PHOTOTHERMAL THERAPY Arami, H., Chang, E., Patel, C. B., Madsen, S., Davis, R., Sinclair, R., Gambhir, S. S. OXFORD UNIV PRESS INC. 2017: 159

  View details for Web of Science ID 000415152503011

• Future cancer research priorities in the USA: a Lancet Oncology Commission. The Lancet. Oncology Jaffee, E. M., Dang, C. V., Agus, D. B., Alexander, B. M., Anderson, K. C., Ashworth, A., Barker, A. D., Bastani, R., Bhatia, S., Bluestone, J. A., Brawley, O., Butte, A. J., Coit, D. G., Davidson, N. E., Davis, M., DePinho, R. A., Diasio, R. B., Draetta, G., Frazier, A. L., Futreal, A., Gambhir, S. S., Ganz, P. A., Garraway, L., Gerson, S., Gupta, S., Heath, J., Hoffman, R. I., Hudis, C., Hughes-Halbert, C., Ibrahim, R., Jadvar, H., Kavanagh, B., Kittles, R., Le, Q. T., Lippman, S. M., Mankoff, D., Mardis, E. R., Mayer, D. K., McMasters, K., Meropol, N. J., Mitchell, B., Naredi, P., Ornish, D., Pawlik, T. M., Peppercorn, J., Pomper, M. G., Raghavan, D., Ritchie, C., Schwarz, S. W., Sullivan, R., Wahl, R., Wolchok, J. D., Wong, S. L., Yung, A. 2017; 18 (11): e653-e706

  Abstract

  We are in the midst of a technological revolution that is providing new insights into human biology and cancer. In this era of big data, we are amassing large amounts of information that is transforming how we approach cancer treatment and prevention. Enactment of the Cancer Moonshot within the 21st Century Cures Act in the USA arrived at a propitious moment in the advancement of knowledge, providing nearly US$2 billion of funding for cancer research and precision medicine. In 2016, the Blue Ribbon Panel (BRP) set out a roadmap of recommendations designed to exploit new advances in cancer diagnosis, prevention, and treatment. Those recommendations provided a high-level view of how to accelerate the conversion of new scientific discoveries into effective treatments and prevention for cancer. The US National Cancer Institute is already implementing some of those recommendations. As experts in the priority areas identified by the BRP, we bolster those recommendations to implement this important scientific roadmap. In this Commission, we examine the BRP recommendations in greater detail and expand the discussion to include additional priority areas, including surgical oncology, radiation oncology, imaging, health systems and health disparities, regulation and financing, population science, and oncopolicy. We prioritise areas of research in the USA that we believe would accelerate efforts to benefit patients with cancer. Finally, we hope the recommendations in this report will facilitate new international collaborations to further enhance global efforts in cancer control.

  View details for DOI 10.1016/S1470-2045(17)30698-8

  View details for PubMedID 29208398

  View details for PubMedCentralID PMC6178838

• A Pixel Pitch-Matched Ultrasound Receiver for 3-D Photoacoustic Imaging With Integrated Delta-Sigma Beamformer in 28-nm UTBB FD-SOI. IEEE journal of solid-state circuits Chen, M. C., Perez, A. P., Kothapalli, S. R., Cathelin, P., Cathelin, A., Gambhir, S. S., Murmann, B. 2017; 52 (11): 2843-2856

  Abstract

  This paper presents a pixel pitch-matched readout chip for 3-D photoacoustic (PA) imaging, featuring a dedicated signal conditioning and delta-sigma modulation integrated within a pixel area of 250 µm by 250 µm. The proof-of-concept receiver was implemented in an STMicroelectronics's 28-nm Fully Depleted Silicon On Insulator technology, and interfaces to a 4 × 4 subarray of capacitive micromachined ultrasound transducers (CMUTs). The front-end signal conditioning in each pixel employs a coarse/fine gain tuning architecture to fulfill the 90-dB dynamic range requirement of the application. The employed delta-sigma beamforming architecture obviates the need for area-consuming Nyquist ADCs and thereby enables an efficient in-pixel A/D conversion. The per-pixel switched-capacitor ΔΣ modulator leverages slewing-dominated and area-optimized inverter-based amplifiers. It occupies only 1/4th of the pixel, and its area compares favorably with state-of-the-art designs that offer the same SNR and bandwidth. The modulator's measured peak signal-to-noise-and-distortion ratio is 59.9 dB for a 10-MHz input bandwidth, and it consumes 6.65 mW from a 1-V supply. The overall subarray beamforming approach improves the area per channel by 7.4 times and the single-channel SNR by 8 dB compared to prior art with similar delay resolution and power dissipation. The functionality of the designed chip was evaluated within a PA imaging experiment, employing a flip-chip bonded 2-D CMUT array.

  View details for DOI 10.1109/JSSC.2017.2749425

  View details for PubMedID 31303662

  View details for PubMedCentralID PMC6625768

• A Pixel Pitch-Matched Ultrasound Receiver for 3-D Photoacoustic Imaging With Integrated Delta-Sigma Beamformer in 28-nm UTBB FD-SOI Chen, M., Perez, A., Kothapalli, S., Cathelin, P., Cathelin, A., Gambhir, S., Murmann, B. IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. 2017: 2843–56

  View details for DOI 10.1109/JSSC.2017.2749425

  View details for Web of Science ID 000413941800005

• SYNERGISTIC INHIBITION OF GLIOMA CELL PROLIFERATION BY WITHAFERIN A AND TUMOR TREATING FIELDS Chang, E., Pohling, C., Beygui, N., Patel, C. B., Rosenberg, J., Ha, D., Gambhir, S. S. OXFORD UNIV PRESS INC. 2017: 61–62

  View details for Web of Science ID 000415152501067

• Imaging of T cells in patients with recurrent glioblastoma TRANSLATIONAL CANCER RESEARCH Gambhir, S. 2017; 6: S291–S292

  View details for DOI 10.21037/tcr.2017.08.27

  View details for Web of Science ID 000413569400042

• A PET Imaging Strategy to Visualize Activated T Cells in Acute Graft-versus-Host Disease Elicited by Allogenic Hematopoietic Cell Transplant. Cancer research Ronald, J. A., Kim, B., Gowrishankar, G., Namavari, M., Alam, I. S., D'Souza, A., Nishikii, H., Chuang, H., Ilovich, O., Lin, C., Reeves, R., Shuhendler, A., Hoehne, A., Chan, C. T., Baker, J., Yaghoubi, S. S., VanBrocklin, H. F., Hawkins, R., Franc, B. L., Jivan, S., Slater, J. B., Verdin, E. F., Gao, K. T., Benjamin, J., Negrin, R., Gambhir, S. S. 2017; 77 (11): 2893-2902

  Abstract

  A major barrier to successful use of allogeneic hematopoietic cell transplantation is acute graft-versus-host disease (aGVHD), a devastating condition that arises when donor T cells attack host tissues. With current technologies, aGVHD diagnosis is typically made after end-organ injury and often requires invasive tests and tissue biopsies. This affects patient prognosis as treatments are dramatically less effective at late disease stages. Here, we show that a novel PET radiotracer, 2'-deoxy-2'-[18F]fluoro-9-β-D-arabinofuranosylguanine ([18F]F-AraG), targeted toward two salvage kinase pathways preferentially accumulates in activated primary T cells. [18F]F-AraG PET imaging of a murine aGVHD model enabled visualization of secondary lymphoid organs harboring activated donor T cells prior to clinical symptoms. Tracer biodistribution in healthy humans showed favorable kinetics. This new PET strategy has great potential for early aGVHD diagnosis, enabling timely treatments and improved patient outcomes. [18F]F-AraG may be useful for imaging activated T cells in various biomedical applications. Cancer Res; 77(11); 2893-902. ©2017 AACR.

  View details for DOI 10.1158/0008-5472.CAN-16-2953

  View details for PubMedID 28572504

• F-FTC-146 in humans. Journal of nuclear medicine Hjørnevik, T., Cipriano, P. W., Shen, B., Hyung Park, J., Gulaka, P., Holley, D., Gandhi, H., Yoon, D., Mittra, E. S., Zaharchuk, G., Gambhir, S. S., McCurdy, C. R., Chin, F. T., Biswal, S. 2017

  Abstract

  The purpose of this study is to assess safety, biodistribution and radiation dosimetry in humans for the highly selective sigma-1 receptor (S1R) positron emission tomography (PET) agent (18)F-6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ((18)F-FTC-146). Methods: Ten healthy volunteers (HV; five female, five male; age: 34.3 ± 6.5 years) were recruited, and written informed consent was obtained from all participants. Series of whole-body PET/magnetic resonance imaging (PET/MRI) examinations were acquired for up to three hours after injection (357.2 ± 48.8 MBq). Blood samples were collected and standard vital signs (heart rate, pulse oximetry, and body temperature) were monitored at regular intervals. Regions-of-interest were delineated, time-activity curves were calculated, and organ uptake and dosimetry was estimated using PMOD 3.7 and Organ Linear Internal Dose Assessment (OLINDA). Results: All subjects tolerated the PET/MRI examination well, and no adverse reactions to (18)F-FTC-146 were reported. High accumulation of (18)F-FTC-146 was observed in S1R dense organs such as the pancreas and spleen, moderate uptake in the brain and myocardium, and low uptake in bone and muscle. High uptake was also observed in the kidneys and bladder, indicating renal tracer clearance. The effective dose (ED) of (18)F-FTC-146 was 0.0259 ± 0.0034 mSv/MBq (range: 0.0215-0.0301 mSv/MBq). Conclusion: First-in-human studies with clinical-grade (18)F-FTC-146 were successful. Injection of (18)F-FTC-146 is safe, and absorbed doses are acceptable. The potential of (18)F-FTC-146 as an imaging agent for a variety of neuroinflammatory diseases is currently under investigation.

  View details for DOI 10.2967/jnumed.117.192641

  View details for PubMedID 28572487

• A Model-Based Personalized Cancer Screening Strategy for Detecting Early-Stage Tumors Using Blood-Borne Biomarkers CANCER RESEARCH Hori, S. S., Lutz, A. M., Paulmurugan, R., Gambhir, S. S. 2017; 77 (10): 2570-2584

  Abstract

  An effective cancer blood biomarker screening strategy must distinguish aggressive from non-aggressive tumors at an early, intervenable time. However, for blood-based strategies to be useful, the quality and quantiy of the biomarker shed into the blood and its relationship to tumor growth or progression must be validated. To study how blood biomarker levels correlate with early-stage viable tumor growth in an mouse model of human cancer, we monitored early tumor growth of engineered human ovarian cancer cells (A2780) implanted orthotopically into nude mice. Biomarker shedding was monitored by serial blood sampling, while tumor viability and volume was monitored by bioluminescence imaging and ultrasound imaging. From these metrics we developed a mathematical model of cancer biomarker kinetics in different compartments that accounts for biomarker shedding from tumor and healthy cells, biomarker entry into vasculature, biomarker elimination from plasma and subject-specific tumor growth. We validated the model in a separate set of mice where subject-specific tumor growth rates were accurately predicted. To illustrate clinical translation of this strategy, we allometrically scaled model parameters from mouse to human and used parameters for PSA shedding and prostate cancer. In this manner, we found that blood biomarker sampling data alone was capable of enabling the detection and discrimination of simulated aggressive (2-month tumor doubling time) and non-aggressive (18-month tumor doubling time) tumors as early as 7.2 months and 8.9 years before clinical imaging, respectively. Our model and screening strategy offer broad impact in their applicability to any solid cancer and the biomarkers they shed, thereby allowing a distinction between aggressive vs. non-aggressive tumors using blood biomarker sampling data alone.

  View details for DOI 10.1158/0008-5472.CAN-16-2904

  View details for Web of Science ID 000401252900003

  View details for PubMedID 28283654

• F-Fluoromaltotriose: A Second Generation PET Tracer Targeting the Maltodextrin Transporter in Bacteria. Journal of nuclear medicine Gowrishankar, G., Hardy, J., Wardak, M., Namavari, M., Reeves, R., Neofytou, E., Srinivasan, A., Wu, J., Contag, C., Gambhir, S. 2017

  Abstract

  Purpose: 6"-(18)F-fluoromaltotriose is a novel positron emission tomography (PET) tracer that can potentially be used to image and localize most bacterial infections, much like 2-deoxy-2-(18)F-fluoro-D-glucose ((18)F-FDG) has been used to image and localize many cancers. However, unlike (18)F-FDG, 6"-(18)F-fluoromaltotriose is not taken up by inflammatory lesions and appears to be specific to bacterial infections by targeting the maltodextrin transporter that is expressed in most Gram-positive and Gram-negative strains of bacteria. Materials and Methods: 6"-(18)F-fluoromaltotriose was synthesized with high radiochemical purity and evaluated in several clinically relevant bacterial strains incultures in vitro and in living mice. Results: 6"-(18)F-fluoromaltotriose was taken up in both Gram-positive and Gram-negative bacterial strains. 6"-[(18)F]-fluoromaltotriose was also able to detect Pseudomonas aeruginosa in a clinically relevant mouse model of wound infection. The utility of 6"-(18)F-fluoromaltotriose to help monitor antibiotic therapies was also evaluated in rats. Conclusion: 6"-(18)F-fluoromaltotriose is a promising new tracer that has significant diagnostic utility, with the potential to change the clinical management of patients suffering from infectious diseases of bacterial origin.

  View details for DOI 10.2967/jnumed.117.191452

  View details for PubMedID 28490473

• Regulatory Aspects of Optical Methods and Exogenous Targets for Cancer Detection CANCER RESEARCH Tummers, W. S., Warram, J. M., Tipirneni, K. E., Fengler, J., Jacobs, P., Shankar, L., Henderson, L., Ballard, B., Pogue, B. W., Weichert, J. P., Bouvet, M., Sorger, J., Contag, C. H., Frangioni, J. V., Tweedle, M. F., Basilion, J. P., Gambhir, S. S., Rosenthal, E. L. 2017; 77 (9): 2197-2206

  Abstract

  Considerable advances in cancer-specific optical imaging have improved the precision of tumor resection. In comparison to traditional imaging modalities, this technology is unique in its ability to provide real-time feedback to the operating surgeon. Given the significant clinical implications of optical imaging, there is an urgent need to standardize surgical navigation tools and contrast agents to facilitate swift regulatory approval. Because fluorescence-enhanced surgery requires a combination of both device and drug, each may be developed in conjunction, or separately, which are important considerations in the approval process. This report is the result of a one-day meeting held on May 4, 2016 with officials from the National Cancer Institute, the FDA, members of the American Society of Image-Guided Surgery, and members of the World Molecular Imaging Society, which discussed consensus methods for FDA-directed human testing and approval of investigational optical imaging devices as well as contrast agents for surgical applications. The goal of this workshop was to discuss FDA approval requirements and the expectations for approval of these novel drugs and devices, packaged separately or in combination, within the context of optical surgical navigation. In addition, the workshop acted to provide clarity to the research community on data collection and trial design. Reported here are the specific discussion items and recommendations from this critical and timely meeting. Cancer Res; 77(9); 2197-206. ©2017 AACR.

  View details for DOI 10.1158/0008-5472.CAN-16-3217

  View details for Web of Science ID 000400270100004

  View details for PubMedID 28428283

• Towards clinically translatable in vivo nanodiagnostics. Nature reviews. Materials Park, S. M., Aalipour, A., Vermesh, O., Yu, J. H., Gambhir, S. S. 2017; 2 (5)

  Abstract

  Nanodiagnostics as a field makes use of fundamental advances in nanobiotechnology to diagnose, characterize and manage disease at the molecular scale. As these strategies move closer to routine clinical use, a proper understanding of different imaging modalities, relevant biological systems and physical properties governing nanoscale interactions is necessary to rationally engineer next-generation bionanomaterials. In this Review, we analyse the background physics of several clinically relevant imaging modalities and their associated sensitivity and specificity, provide an overview of the materials currently used for in vivo nanodiagnostics, and assess the progress made towards clinical translation. This work provides a framework for understanding both the impressive progress made thus far in the nanodiagnostics field as well as presenting challenges that must be overcome to obtain widespread clinical adoption.

  View details for DOI 10.1038/natrevmats.2017.14

  View details for PubMedID 29876137

  View details for PubMedCentralID PMC5985817

• Harnessing Radioluminescence and Sound to Reveal Molecular Pathology of Atherosclerotic Plaques Zaman, R., Yousefi, S., Long, S., Contag, C., Gambhir, S., Khuri-Yakub, B., Xing, L. SOC NUCLEAR MEDICINE INC. 2017

  View details for Web of Science ID 000404949900032

• SiPM PET/CT vs. Standard PET/CT: A Pilot Study Comparing Semi-Quantitative Measurements in Normal Tissues and Lesions Baratto, L., Park, S., Hatami, N., Davidzon, G., Srinivas, S., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2017

  View details for Web of Science ID 000404949902041

• Initial Experience with a New PET/CT System Using SiPM Detectors: Image Quality Comparison with Standard PET/CT Park, S., Baratto, L., Hatami, N., Davidzon, G., Srinivas, S., Gambhir, S., Lagaru, A. SOC NUCLEAR MEDICINE INC. 2017

  View details for Web of Science ID 000404949906122

• Natural product-inspired agents and their anticancer activity against glioblastoma multiforme cells Kumar, V., Banister, S., Kaufman, H., Vittimberga, J., Jacobo, S., Gambhir, S., Malhotra, S. AMER CHEMICAL SOC. 2017

  View details for Web of Science ID 000430569104415

• Practical Immuno-PET Radiotracer Design Considerations for Human Immune Checkpoint Imaging JOURNAL OF NUCLEAR MEDICINE Mayer, A. T., Natarajan, A., Gordon, S. R., Maute, R. L., McCracken, M. N., Ring, A. M., Weissman, I. L., Gambhir, S. S. 2017; 58 (4): 538-546

  Abstract

  Immune checkpoint blockade has emerged as a promising cancer treatment paradigm. Unfortunately, there are still a large number of patients and malignancies that do not respond to therapy. A major barrier to validating biomarkers for the prediction and monitoring of responders to clinical checkpoint blockade has been the lack of imaging tools to accurately assess dynamic immune checkpoint expression. Here, we sought to optimize noninvasive immuno-PET imaging of human programmed death-ligand 1 (PD-L1) expression, in a preclinical model, using a small high-affinity engineered protein scaffold (HAC-PD1). Six HAC-PD1 radiotracer variants were developed and used in preclinical imaging and biodistribution studies to assess their ability to detect human PD-L1 expression in vivo. Radiotracer design modifications included chelate, glycosylation, and radiometal. HACA-PD1 was adopted as the naming convention for aglycosylated tracer variants. NOD scid γ-(NSG) mice were inoculated with subcutaneous tumors engineered to either be constitutively positive (CT26 hPD-L1) or be negative (ΔmPD-L1 CT26) for human PD-L1 expression. When the tumors had grown to an average size of 1 cm in diameter, mice were injected with 0.75-2.25 MBq (∼10 μg) of an engineered radiotracer variant and imaged. At 1 h after injection, organs were harvested for biodistribution. Of the practical immuno-PET tracer modifications considered, glycosylation was the most prominent design factor affecting tracer uptake, specificity, and clearance. In imaging studies, aglycosylated (64)Cu-NOTA-HACA-PD1 most accurately visualized human PD-L1 expression in vivo. We reasoned that because of the scaffold's small size (14 kDa), its pharmacokinetics may be suitable for labeling with the short-lived and widely clinically available radiometal (68)Ga. At 1 h after injection, (68)Ga-NOTA-HACA-PD1 and (68)Ga-DOTA-HACA-PD1 exhibited promising target-to-background ratios in ex vivo biodistribution studies (12.3 and 15.2 tumor-to-muscle ratios, respectively). Notably, all HAC-PD1 radiotracer variants enabled much earlier detection of human PD-L1 expression (1 h after injection) than previously reported radiolabeled antibodies (>24 h after injection). This work provides a template for assessing immuno-PET tracer design parameters and supports the translation of small engineered protein radiotracers for imaging human immune checkpoints.

  View details for DOI 10.2967/jnumed.116.177659

  View details for Web of Science ID 000398249600012

  View details for PubMedCentralID PMC5373501

• Ultrasound Molecular Imaging With BR55 in Patients With Breast and Ovarian Lesions: First-in-Human Results. Journal of clinical oncology Willmann, J. K., Bonomo, L., Carla Testa, A., Rinaldi, P., Rindi, G., Valluru, K. S., Petrone, G., Martini, M., Lutz, A. M., Gambhir, S. S. 2017: JCO2016708594-?

  Abstract

  Purpose We performed a first-in-human clinical trial on ultrasound molecular imaging (USMI) in patients with breast and ovarian lesions using a clinical-grade contrast agent (kinase insert domain receptor [KDR] -targeted contrast microbubble [MBKDR]) that is targeted at the KDR, one of the key regulators of neoangiogenesis in cancer. The aim of this study was to assess whether USMI using MBKDR is safe and allows assessment of KDR expression using immunohistochemistry (IHC) as the gold standard. Methods Twenty-four women (age 48 to 79 years) with focal ovarian lesions and 21 women (age 34 to 66 years) with focal breast lesions were injected intravenously with MBKDR (0.03 to 0.08 mL/kg of body weight), and USMI of the lesions was performed starting 5 minutes after injection up to 29 minutes. Blood pressure, ECG, oxygen levels, heart rate, CBC, and metabolic panel were obtained before and after MBKDR administration. Persistent focal MBKDR binding on USMI was assessed. Patients underwent surgical resection of the target lesions, and tissues were stained for CD31 and KDR by IHC. Results USMI with MBKDR was well tolerated by all patients without safety concerns. Among the 40 patients included in the analysis, KDR expression on IHC matched well with imaging signal on USMI in 93% of breast and 85% of ovarian malignant lesions. Strong KDR-targeted USMI signal was present in 77% of malignant ovarian lesions, with no targeted signal seen in 78% of benign ovarian lesions. Similarly, strong targeted signal was seen in 93% of malignant breast lesions with no targeted signal present in 67% of benign breast lesions. Conclusion USMI with MBKDR is clinically feasible and safe, and KDR-targeted USMI signal matches well with KDR expression on IHC. This study lays the foundation for a new field of clinical USMI in cancer.

  View details for DOI 10.1200/JCO.2016.70.8594

  View details for PubMedID 28291391

• F]FTC-146. Molecular imaging and biology Shen, B., Park, J. H., Hjørnevik, T., Cipriano, P. W., Yoon, D., Gulaka, P. K., Holly, D., Behera, D., Avery, B. A., Gambhir, S. S., McCurdy, C. R., Biswal, S., Chin, F. T. 2017

  Abstract

  Sigma-1 receptors (S1Rs) play an important role in many neurological disorders. Simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) with S1R radioligands may provide valuable information for diagnosing and guiding treatment for these diseases. Our previously reported S1R radioligand, [(18)F]FTC-146, demonstrated high affinity for the S1R (K i = 0.0025 nM) and excellent selectivity for the S1R over the sigma-2 receptor (S2Rs; K i = 364 nM) across several species (from mouse to non-human primate). Herein, we report the clinical-grade radiochemistry filed with exploratory Investigational New Drug (eIND) and first-in-human PET/MRI evaluation of [(18)F]FTC-146.[(18)F]FTC-146 is prepared via a direct [(18)F] fluoride nucleophilic radiolabeling reaction and formulated in 0.9 % NaCl containing no more than 10 % ethanol through sterile filtration. Quality control (QC) was performed based on USP 823 before doses were released for clinical use. The safety and whole body biodistribution of [(18)F]FTC-146 were evaluated using a simultaneous PET/MR scanner in two representative healthy human subjects.[(18)F]FTC-146 was synthesized with a radiochemical yield of 3.3 ± 0.7 % and specific radioactivity of 8.3 ± 3.3 Ci/μmol (n = 10, decay corrected to EOB). Both radiochemical and chemical purities were >95 %; the prepared doses were stable for 4 h at ambient temperature. All QC test results met specified clinical criteria. The in vivo PET/MRI investigations showed that [(18)F]FTC-146 rapidly crossed the blood brain barrier and accumulated in S1R-rich regions of the brain. There were also radioactivity distributed in the peripheral organs, i.e., the lungs, spleen, pancreas, and thyroid. Furthermore, insignificant uptake of [(18)F]FTC-146 was observed in cortical bone and muscle.A reliable and automated radiosynthesis for providing routine clinical-grade [(18)F]FTC-146 for human studies was established in a modified GE TRACERlab FXFN. PET/MRI demonstrated the initial tracer biodistribution in humans, and clinical studies investigating different S1R-related diseases are in progress.

  View details for DOI 10.1007/s11307-017-1064-z

  View details for PubMedID 28280965

• Development of Novel ImmunoPET Tracers to Image Human PD-1 Checkpoint Expression on Tumor-Infiltrating Lymphocytes in a Humanized Mouse Model. Molecular imaging and biology Natarajan, A., Mayer, A. T., Reeves, R. E., Nagamine, C. M., Gambhir, S. S. 2017

  Abstract

  It is well known that cancers exploit immune checkpoints (programmed death 1 receptor (PD-1) and its ligand (PD-L1)) to evade anti-tumor immune responses. Although immune checkpoint (IC) blockade is a promising approach, not all patients respond. Hence, imaging of tumor-infiltrating lymphocytes (TILs) is of high specific interest, as they are known to express PD-1 during activation and subsequent exhaustion in the tumor microenvironment and are thought to be potentially predictive of therapeutic responses to IC blockade.We developed immune-tracers for positron emission tomography (PET) to image hPD-1 status of human peripheral blood mononuclear cells (hPBMCs) adoptively transferred to NOD-scid IL-2Rγ(null) (NSG) mice (hNSG) bearing A375 human skin melanoma tumors. The anti-PD-1 human antibody (IgG; keytruda) was labeled with either Zr-89 or Cu-64 radiometals to image PD-1-expressing human TILs in vivo.[(89)Zr] Keytruda (groups = 2; NSG-ctl (control) and hNSG-nblk (non-blocking), n = 3-5, 3.2 ± 0.4 MBq/15-16 μg/200 μl) and [(64)Cu] Keytruda (groups = 3; NSG-ctl, NSG-blk (blocking), and hNSG-nblk; n = 4, 7.4 ± 0.4 MBq /20-25 μg/200 μl) were administered in mice. PET-CT scans were performed over 1-144 h ([(89)Zr] Keytruda) and 1-48 h ([(64)Cu] Keytruda) on mice. hNSG mice exhibited a high tracer uptake in the spleen, lymphoid organs and tumors. At 24 h, human TILs homing into melanoma of hNSG-nblk mice exhibited high signal (mean %ID/g ± SD) of 3.8 ± 0.4 ([(89)Zr] Keytruda), and 6.4 ± 0.7 ([(64)Cu] Keytruda), which was 1.5- and 3-fold higher uptake compared to NSG-ctl mice (p = 0.01), respectively. Biodistribution measurements of hNSG-nblk mice performed at 144 h ([(89)Zr] Keytruda) and 48 h ([(64)Cu] Keytruda) p.i. revealed tumor to muscle ratios as high as 45- and 12-fold, respectively.Our immunoPET study clearly demonstrates specific imaging of human PD-1-expressing TILs within the tumor and lymphoid tissues. This suggests these anti-human-PD-1 tracers could be clinically translatable to monitor cancer treatment response to IC blockade therapy.

  View details for DOI 10.1007/s11307-017-1060-3

  View details for PubMedID 28247187

• F]DASA-23 for Imaging Tumor Glycolysis Through Noninvasive Measurement of Pyruvate Kinase M2. Molecular imaging and biology Beinat, C., Alam, I. S., James, M. L., Srinivasan, A., Gambhir, S. S. 2017

  Abstract

  A hallmark of cancer is metabolic reprogramming, which is exploited by cancer cells to ensure rapid growth and survival. Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key step in tumor metabolism and growth. Recently, we reported the radiosynthesis of the first positron emission tomography tracer for visualizing PKM2 in vivo-i.e., [(11)C]DASA-23. Due to the highly promising imaging results obtained with [(11)C]DASA-23 in rodent model glioblastoma, we set out to generate an F-18-labeled version of this tracer, with the end goal of clinical translation in mind. Herein, we report the radiosynthesis of 1-((2-fluoro-6-[(18)F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([(18)F]DASA-23) and our initial investigation of its binding properties in cancer cells.We synthesized [(18)F]DASA-23 via fluorination of 1-((2-fluoro-6-nitrophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine (10) with K[(18)F]F/K2.2.2 in N,N-dimethylformamide at 110 °C for 20 min. Subsequently, we evaluated uptake of [(18)F]DASA-23 in HeLa cervical adenocarcinoma cells and in vitro stability in human and mouse serum.We successfully prepared [(18)F]DASA-23 in 2.61 ± 1.54 % radiochemical yield (n = 10, non-decay corrected at end of synthesis) with a specific activity of 2.59 ± 0.44 Ci/μmol. Preliminary cell uptake experiments revealed high uptake in HeLa cells, which was effectively blocked by pretreating cells with the structurally distinct PKM2 activator, TEPP-46. [(18)F]DASA-23 remained intact in human and mouse serum up to 120 min.Herein, we have identified a F-18-labeled PKM2 specific radiotracer which shows potential for in vivo imaging. The promising cell uptake results reported herein warrant the further evaluation of [(18)F]DASA-23 for its ability to detect and monitor cancer noninvasively.

  View details for DOI 10.1007/s11307-017-1068-8

  View details for PubMedID 28236227

• Nanomaterials for In Vivo Imaging. Chemical reviews Smith, B. R., Gambhir, S. S. 2017; 117 (3): 901-986

  Abstract

  In vivo imaging, which enables us to peer deeply within living subjects, is producing tremendous opportunities both for clinical diagnostics and as a research tool. Contrast material is often required to clearly visualize the functional architecture of physiological structures. Recent advances in nanomaterials are becoming pivotal to generate the high-resolution, high-contrast images needed for accurate, precision diagnostics. Nanomaterials are playing major roles in imaging by delivering large imaging payloads, yielding improved sensitivity, multiplexing capacity, and modularity of design. Indeed, for several imaging modalities, nanomaterials are now not simply ancillary contrast entities, but are instead the original and sole source of image signal that make possible the modality's existence. We address the physicochemical makeup/design of nanomaterials through the lens of the physical properties that produce contrast signal for the cognate imaging modality-we stratify nanomaterials on the basis of their (i) magnetic, (ii) optical, (iii) acoustic, and/or (iv) nuclear properties. We evaluate them for their ability to provide relevant information under preclinical and clinical circumstances, their in vivo safety profiles (which are being incorporated into their chemical design), their modularity in being fused to create multimodal nanomaterials (spanning multiple different physical imaging modalities and therapeutic/theranostic capabilities), their key properties, and critically their likelihood to be clinically translated.

  View details for DOI 10.1021/acs.chemrev.6b00073

  View details for PubMedID 28045253

• Detection of Stem Cell Transplant Rejection with Ferumoxytol MR Imaging: Correlation of MR Imaging Findings with Those at Intravital Microscopy. Radiology Daldrup-Link, H. E., Chan, C., Lenkov, O., Taghavigarmestani, S., Nazekati, T., Nejadnik, H., Chapelin, F., Khurana, A., Tong, X., Yang, F., Pisani, L., Longaker, M., Gambhir, S. S. 2017: 161139-?

  Abstract

  Purpose To determine whether endogenous labeling of macrophages with clinically applicable nanoparticles enables noninvasive detection of innate immune responses to stem cell transplants with magnetic resonance (MR) imaging. Materials and Methods Work with human stem cells was approved by the institutional review board and the stem cell research oversight committee, and animal experiments were approved by the administrative panel on laboratory animal care. Nine immunocompetent Sprague-Dawley rats received intravenous injection of ferumoxytol, and 18 Jax C57BL/6-Tg (Csf1r-EGFP-NGFR/FKBP1A/TNFRSF6) 2Bck/J mice received rhodamine-conjugated ferumoxytol. Then, 48 hours later, immune-matched or mismatched stem cells were implanted into osteochondral defects of the knee joints of experimental rats and calvarial defects of Jax mice. All animals underwent serial MR imaging and intravital microscopy (IVM) up to 4 weeks after surgery. Macrophages of Jax C57BL/6-Tg (Csf1r-EGFP-NGFR/FKBP1A/TNFRSF6) 2Bck/J mice express enhanced green fluorescent protein (GFP), which enables in vivo correlation of ferumoxytol enhancement at MR imaging with macrophage quantities at IVM. All quantitative data were compared between experimental groups by using a mixed linear model and t tests. Results Immune-mismatched stem cell implants demonstrated stronger ferumoxytol enhancement than did matched stem cell implants. At 4 weeks, T2 values of mismatched implants were significantly lower than those of matched implants in osteochondral defects of female rats (mean, 10.72 msec for human stem cells and 11.55 msec for male rat stem cells vs 15.45 msec for sex-matched rat stem cells; P = .02 and P = .04, respectively) and calvarial defects of recipient mice (mean, 21.7 msec vs 27.1 msec, respectively; P = .0444). This corresponded to increased recruitment of enhanced GFP- and rhodamine-ferumoxytol-positive macrophages into stem cell transplants, as visualized with IVM and histopathologic examination. Conclusion Endogenous labeling of macrophages with ferumoxytol enables noninvasive detection of innate immune responses to stem cell transplants with MR imaging. (©) RSNA, 2017 Online supplemental material is available for this article.

  View details for DOI 10.1148/radiol.2017161139

  View details for PubMedID 28128708

• Reporter gene imaging of targeted T cell immunotherapy in recurrent glioma. Science translational medicine Keu, K. V., Witney, T. H., Yaghoubi, S., Rosenberg, J., Kurien, A., Magnusson, R., Williams, J., Habte, F., Wagner, J. R., Forman, S., Brown, C., Allen-Auerbach, M., Czernin, J., Tang, W., Jensen, M. C., Badie, B., Gambhir, S. S. 2017; 9 (373)

  Abstract

  High-grade gliomas are aggressive cancers that often become rapidly fatal. Immunotherapy using CD8(+) cytotoxic T lymphocytes (CTLs), engineered to express both herpes simplex virus type 1 thymidine kinase (HSV1-TK) and interleukin-13 (IL-13) zetakine chimeric antigen receptor (CAR), is a treatment strategy with considerable potential. To optimize this and related immunotherapies, it would be helpful to monitor CTL viability and trafficking to glioma cells. We show that noninvasive positron emission tomography (PET) imaging with 9-[4-[(18)F]fluoro-3-(hydroxymethyl)butyl]guanine ([(18)F]FHBG) can track HSV1-tk reporter gene expression present in CAR-engineered CTLs. [(18)F]FHBG imaging was safe and enabled the longitudinal imaging of T cells stably transfected with a PET reporter gene in patients. Further optimization of this imaging approach for monitoring in vivo cell trafficking should greatly benefit various cell-based therapies for cancer.

  View details for DOI 10.1126/scitranslmed.aag2196

  View details for PubMedID 28100832

  View details for PubMedCentralID PMC5260938

• Withaferin A and its potential role in glioblastoma (GBM) JOURNAL OF NEURO-ONCOLOGY Dhami, J., Chang, E., Gambhir, S. S. 2017; 131 (2): 201-211

  Abstract

  Within the Ayurvedic medical tradition of India, Ashwagandha (Withania somnifera) is a well-known herb. A large number of withanolides have been isolated from both its roots and its leaves and many have been assessed for their pharmacological activities. Amongst them, Withaferin A is one of its most bioactive phytoconstituents. Due to the lactonal steroid's potential to modulate multiple oncogenic pathways, Withaferin A has gained much attention as a possible anti-neoplastic agent. This review focuses on the use of Withaferin A alone, or in combination with other treatments, as a newer option for therapy against the most aggressive variant of brain tumors, Glioblastoma. We survey the various studies that delineate Withaferin A's anticancer mechanisms, its toxicity profiles, its pharmacokinetics and pharmacodynamics and its immuno-modulating properties.

  View details for DOI 10.1007/s11060-016-2303-x

  View details for Web of Science ID 000394342500001

  View details for PubMedID 27837436

• Imaging B-Cells in a Mouse of Multiple Sclerosis Using 64Cu-Rituximab-PET Journal of Nuclear Medicine James, M. L., Hoehne, A., Mayer, A. T., Lechtenburg, K., Moreno, M., Gowrishankar, G., Illovich, O., Natarajan, A., Johnson, E. M., Nguyen , J., Quach, L., Han, M., Buckwalter, M., Chandra, S., Gambhir, S. S. 2017; 58 (11): 1845-1851
• Capture and Genetic Analysis of Circulating Tumor Cells Using a Magnetic Separation Device (Magnetic Sifter) CIRCULATING TUMOR CELLS: METHODS AND PROTOCOLS Ooi, C., Park, S., Wong, D. J., Gambhir, S. S., Wang, S. X., Magbanua, M. J., Park, J. W. 2017; 1634: 153–62

  View details for DOI 10.1007/978-1-4939-7144-2_12

  View details for Web of Science ID 000449398600014

• On-Target Probes for Early Detection Nature Biomedical Engineering Hori, S. S., Tummers, W. S., Gambhir, S. S. 2017; 1: 1-3

  View details for DOI 10.1038/s41551-017-0062

• Towards clinically translatable in vivo nanodiagnostics Nature Reviews Materials Park, S., Aalipour, A., Vermesh, O., Yu, J., Gambhir, S. S. 2017; 2

  View details for DOI 10.1038/natrevmats.2017.14

• Multigene Profiling of Single Circulating Tumor Cells Molecular & Cellular Oncology Park, S., Wong, D., Ooi, C., Nesvet, J., Nair, V. S., Wang, S. X., Gambhir, S. S. 2017; 4 (2): e1289295

  Abstract

  Numerous techniques for isolating circulating tumor cells (CTCs) have been developed. Concurrently, single-cell techniques that can reveal molecular components of CTCs have become widely available. We discuss how the combination of isolation and multigene profiling of single CTCs in our platform can facilitate eventual translation to the clinic.

  View details for DOI 10.1080/23723556.2017.1289295

  View details for PubMedCentralID PMC5383366

• High-throughput full-length single-cell mRNA-seq of rare cells. PloS one Ooi, C. C., Mantalas, G. L., Koh, W. n., Neff, N. F., Fuchigami, T. n., Wong, D. J., Wilson, R. J., Park, S. M., Gambhir, S. S., Quake, S. R., Wang, S. X. 2017; 12 (11): e0188510

  Abstract

  Single-cell characterization techniques, such as mRNA-seq, have been applied to a diverse range of applications in cancer biology, yielding great insight into mechanisms leading to therapy resistance and tumor clonality. While single-cell techniques can yield a wealth of information, a common bottleneck is the lack of throughput, with many current processing methods being limited to the analysis of small volumes of single cell suspensions with cell densities on the order of 107 per mL. In this work, we present a high-throughput full-length mRNA-seq protocol incorporating a magnetic sifter and magnetic nanoparticle-antibody conjugates for rare cell enrichment, and Smart-seq2 chemistry for sequencing. We evaluate the efficiency and quality of this protocol with a simulated circulating tumor cell system, whereby non-small-cell lung cancer cell lines (NCI-H1650 and NCI-H1975) are spiked into whole blood, before being enriched for single-cell mRNA-seq by EpCAM-functionalized magnetic nanoparticles and the magnetic sifter. We obtain high efficiency (> 90%) capture and release of these simulated rare cells via the magnetic sifter, with reproducible transcriptome data. In addition, while mRNA-seq data is typically only used for gene expression analysis of transcriptomic data, we demonstrate the use of full-length mRNA-seq chemistries like Smart-seq2 to facilitate variant analysis of expressed genes. This enables the use of mRNA-seq data for differentiating cells in a heterogeneous population by both their phenotypic and variant profile. In a simulated heterogeneous mixture of circulating tumor cells in whole blood, we utilize this high-throughput protocol to differentiate these heterogeneous cells by both their phenotype (lung cancer versus white blood cells), and mutational profile (H1650 versus H1975 cells), in a single sequencing run. This high-throughput method can help facilitate single-cell analysis of rare cell populations, such as circulating tumor or endothelial cells, with demonstrably high-quality transcriptomic data.

  View details for PubMedID 29186152

  View details for PubMedCentralID PMC5706670

• A Pixel-Pitch-Matched Ultrasound Receiver for 3D Photoacoustic Imaging with Integrated Delta-Sigma Beamformer in 28nm UTBB FDSOI Chen, M., Perez, A., Kothapalli, S., Cathelin, P., Cathelin, A., Gambhir, S., Murmann, B., IEEE IEEE. 2017: 456

  View details for Web of Science ID 000403393800192

• Fdg Pet-CT Suvmax And Circulating Tumor Microemboli Identify Recurrence In Patients With Non-Small Cell Lung Cancer Nair, V. S., Carlsson, F., Carlsson, A., Jamali, M., Keu, K., Vasanawala, M., Shrager, J., Loo, B. W., Horng, G., Kuschner, W., Gambhir, S. S., Kuhn, P. AMER THORACIC SOC. 2017

  View details for Web of Science ID 000400372500266

• Capture and Genetic Analysis of Circulating Tumor Cells Using a Magnetic Separation Device (Magnetic Sifter). Methods in molecular biology (Clifton, N.J.) Ooi, C. C., Park, S. M., Wong, D. J., Gambhir, S. S., Wang, S. X. 2017; 1634: 153–62

  Abstract

  Circulating tumor cells (CTCs) are currently widely studied for their potential application as part of a liquid biopsy. These cells are shed from the primary tumor into the circulation, and are postulated to provide insight into the molecular makeup of the actual tumor in a minimally invasive manner. However, they are extremely rare in blood, with typical concentrations of 1-100 in a milliliter of blood; hence, a need exists for a rapid and high-purity method for isolating CTCs from whole blood. Here, we describe the application of a microfabricated magnetic sifter toward isolation of CTCs from whole blood at volumetric flow rates of 10 mL/h, along with the use of a PDMS-based nanowell system for single-cell gene expression profiling. This method allows rapid isolation of CTCs and subsequent integration with downstream genetic profiling methods for clinical applications such as targeted therapy, therapy monitoring, or further biological studies.

  View details for PubMedID 28819848

• Synergistic inhibition of glioma cell proliferation by Withaferin A and tumor treating fields. Journal of neuro-oncology Chang, E. n., Pohling, C. n., Beygui, N. n., Patel, C. B., Rosenberg, J. n., Ha, D. H., Gambhir, S. S. 2017

  Abstract

  Glioblastoma (GBM) is the most aggressive and lethal form of brain cancer. Standard therapies are non-specific and often of limited effectiveness; thus, efforts are underway to uncover novel, unorthodox therapies against GBM. In previous studies, we investigated Withaferin A, a steroidal lactone from Ayurvedic medicine that inhibits proliferation in cancers including GBM. Another novel approach, tumor treating fields (TTFields), is thought to disrupt mitotic spindle formation and stymie proliferation of actively dividing cells. We hypothesized that combining TTFields with Withaferin A would synergistically inhibit proliferation in glioblastoma. Human glioblastoma cells (GBM2, GBM39, U87-MG) and human breast adenocarcinoma cells (MDA-MB-231) were isolated from primary tumors. The glioma cell lines were genetically engineered to express firefly luciferase. Proliferative potential was assessed either by bioluminescence imaging or cell counting via hemocytometer. TTFields (4 V/cm) significantly inhibited growth of the four cancer cell lines tested (n = 3 experiments per time point, four measurements per sample, p < 0.02 at least; 2-way ANOVA, control vs. treatment). The combination of Withaferin A (10-100 nM) with TTFields significantly inhibited the growth of the glioma cells to a degree beyond that of Withaferin A or TTFields alone. The interaction of the Withaferin A and TTFields on glioma cells was found to be synergistic in nature (p < 0.01, n = 3 experiments). These findings were validated by both bioluminescence and hemocytometric measurements. The combination of Withaferin A with TTFields represents a novel approach to treat GBM in a manner that is likely better than either treatment alone and that is synergistic.

  View details for PubMedID 28681243

• A novel theranostic strategy for MMP-14 expressing glioblastomas impacts survival. Molecular cancer therapeutics Mohanty, S. n., Chen, Z. n., Li, K. n., Morais, G. R., Klockow, J. n., Yerneni, K. n., Pisani, L. n., Chin, F. T., Mitra, S. n., Cheshier, S. n., Chang, E. n., Gambhir, S. S., Rao, J. n., Loadman, P. M., Falconer, R. A., Daldrup-Link, H. E. 2017

  Abstract

  Glioblastoma (GBM) has a dismal prognosis. Evidence from preclinical tumor models and human trials indicates the role of GBM initiating cells (GIC) in GBM drug resistance. Here, we propose a new treatment option with tumor enzyme-activatable, combined therapeutic and diagnostic (theranostic) nanoparticles, which caused specific toxicity against GBM tumor cells and GICs. The theranostic cross-linked iron oxide nanoparticles (CLIO) were conjugated to a highly potent vascular disrupting agent (ICT) and secured with a matrix-metalloproteinase (MMP-14) cleavable peptide. Treatment with CLIO-ICT disrupted tumor vasculature of MMP-14 expressing GBM, induced GIC apoptosis and significantly impaired tumor growth. In addition, the iron core of CLIO-ICT enabled in vivo drug tracking with MR imaging. Treatment with CLIO-ICT plus temozolomide achieved tumor remission and significantly increased survival of human GBM bearing mice by more than 2 fold compared to treatment with temozolomide alone. Thus, we present a novel therapeutic strategy with significant impact on survival and great potential for clinical translation.

  View details for PubMedID 28659432

• Imaging B cells in a mouse model of multiple sclerosis using (64)Cu-Rituximab-PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Hoehne, A. n., Mayer, A. T., Lechtenberg, K. n., Moreno, M. n., Gowrishankar, G. n., Ilovich, O. n., Natarajan, A. n., Johnson, E. M., Nguyen, J. n., Quach, L. n., Han, M. n., Buckwalter, M. n., Chandra, S. n., Gambhir, S. S. 2017

  Abstract

  B lymphocytes are a key pathological feature of multiple sclerosis (MS), and are becoming an important therapeutic target for this condition. Currently, there is no approved technique to non-invasively visualize B cells in the central nervous system (CNS) to monitor MS disease progression and response to therapies. Here we evaluated (64)Cu-Rituximab, a radiolabeled antibody specifically targeting the human B cell marker CD20, for its ability to image B cells in a mouse model of MS using positron emission tomography (PET). Methods: To model CNS infiltration by B cells, experimental autoimmune encephalomyelitis (EAE) was induced in transgenic mice that express human CD20 on B cells. EAE mice were given subcutaneous injections of Myelin Oligodendrocyte Glycoprotein fragment1-125 (MOG1-125) emulsified in complete Freund's adjuvant. Control mice received complete Freund's adjuvant alone. PET imaging of EAE and control mice was performed 1, 4, and 19h following (64)Cu-Rituximab administration. Mice were perfused and sacrificed after final PET scan, and radioactivity in dissected tissues was measured with a gamma-counter. CNS tissues from these mice were immunostained to quantify B cells or further analyzed via digital autoradiography. Results: Lumbar spinal cord PET signal was significantly higher in EAE mice compared to controls at all evaluated time points (e.g., 1h post-injection: 5.44 ± 0.37 vs. 3.33 ± 0.20 %ID/g, p<0.05). (64)Cu-Rituximab-PET signal in brain regions ranged between 1.74 ± 0.11 and 2.93 ± 0.15 %ID/g for EAE mice compared to 1.25±0.08 and 2.24±0.11%ID/g for controls, p<0.05 for all regions except striatum and thalamus at 1h post-injection. Similarly, ex vivo biodistribution results revealed notably higher (64)Cu-Rituximab uptake in brain and spinal cord of huCD20tg EAE, and B220 immunostaining verified that increased (64)Cu-Rituximab uptake in CNS tissues corresponded with elevated B cells. Conclusion: B cells can be detected in the CNS of EAE mice using (64)Cu-Rituximab-PET. Results from these studies warrant further investigation of (64)Cu-Rituximab in EAE models and consideration of use in MS patients to evaluate its potential for detecting and monitoring B cells in the progression and treatment of this disease. These results represent an initial step toward generating a platform to evaluate B cell-targeted therapeutics en route to the clinic.

  View details for PubMedID 28687602

• The Exosome Total Isolation Chip. ACS nano Liu, F. n., Vermesh, O. n., Mani, V. n., Ge, T. J., Madsen, S. J., Sabour, A. n., Hsu, E. C., Gowrishankar, G. n., Kanada, M. n., Jokerst, J. V., Sierra, R. G., Chang, E. n., Lau, K. n., Sridhar, K. n., Bermudez, A. n., Pitteri, S. J., Stoyanova, T. n., Sinclair, R. n., Nair, V. S., Gambhir, S. S., Demirci, U. n. 2017

  Abstract

  Circulating tumor-derived extracellular vesicles (EVs) have emerged as a promising source for identifying cancer biomarkers for early cancer detection. However, the clinical utility of EVs has thus far been limited by the fact that most EV isolation methods are tedious, nonstandardized, and require bulky instrumentation such as ultracentrifugation (UC). Here, we report a size-based EV isolation tool called ExoTIC (exosome total isolation chip), which is simple, easy-to-use, modular, and facilitates high-yield and high-purity EV isolation from biofluids. ExoTIC achieves an EV yield ∼4-1000-fold higher than that with UC, and EV-derived protein and microRNA levels are well-correlated between the two methods. Moreover, we demonstrate that ExoTIC is a modular platform that can sort a heterogeneous population of cancer cell line EVs based on size. Further, we utilize ExoTIC to isolate EVs from cancer patient clinical samples, including plasma, urine, and lavage, demonstrating the device's broad applicability to cancers and other diseases. Finally, the ability of ExoTIC to efficiently isolate EVs from small sample volumes opens up avenues for preclinical studies in small animal tumor models and for point-of-care EV-based clinical testing from fingerprick quantities (10-100 μL) of blood.

  View details for DOI 10.1021/acsnano.7b04878

  View details for PubMedID 29090896

• Prospective Evaluation of 68Ga-RM2 PET/MRI in Patients with Biochemical Recurrence of Prostate Cancer and Negative Conventional Imaging. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Minamimoto, R. n., Sonni, I. n., Hancock, S. n., Vasanawala, S. n., Loening, A. n., Gambhir, S. S., Iagaru, A. n. 2017

  Abstract

  Purpose:68Ga-labeled DOTA-4-amino-1-carboxymethyl-piperidine-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (68Ga-RM2) is a synthetic bombesin receptor antagonist that targets gastrin-releasing peptide receptors (GRPr). GRPr proteins are highly overexpressed in several human tumors, including prostate cancer. We present data from the use of 68Ga-RM2 in patients with biochemical recurrence (BCR) of prostate cancer (PC) and negative conventional imaging (CI). Methods: We enrolled 32 men with BCR PC, 59-83 year-old (mean±standard deviation (SD): 68.7±6.4). Imaging started at 40-69 minutes (mean±SD: 50.5±6.8) after injection of 133.2-151.7 MBq (mean±SD: 140.6±7.4) of 68Ga-RM2 using a time-of-flight (TOF)-enabled simultaneous positron emission tomography (PET) / magnetic resonance imaging (MRI) scanner. T1-weighted (T1w), T2-weighted (T2w) and diffusion-weighted images (DWI) were acquired. Results: All patients had rising prostate specific antigen (PSA) (range: 0.3-119.0 ng/mL; mean±SD: 10.1 ± 21.3) and negative CI (CT or MRI, and 99mTc MDP bone scan) prior to enrollment. The observed 68Ga-RM2 PET detection rate was 71.8%. 68Ga-RM2 PET identified recurrent prostate cancer in 23 of the 32 participants, while the simultaneous MRI scan identified findings compatible with recurrent prostate cancer in 11 of the 32 patients. PSA velocity (PSAv) values were 0.32±0.59 ng/ml/year (range: 0.04-1.9) in patients with negative PET scans and 2.51±2.16 ng/ml/year (range: 0.13-8.68) in patients with positive PET scans (P: 0.006). Conclusion:68Ga-RM2 PET can be used for assessment of GRPr expression in patients with BCR PC. High uptake in multiple areas compatible with cancer lesions suggests that 68Ga-RM2 is a promising PET radiopharmaceutical for localization of disease in participants with BCR PC and negative CI.

  View details for PubMedID 29084827

• Deactivated CRISPR Associated Protein 9 for Minor-Allele Enrichment in Cell-Free DNA. Clinical chemistry Aalipour, A. n., Dudley, J. C., Park, S. M., Murty, S. n., Chabon, J. J., Boyle, E. A., Diehn, M. n., Gambhir, S. S. 2017

  Abstract

  Cell-free DNA (cfDNA) diagnostics are emerging as a new paradigm of disease monitoring and therapy management. The clinical utility of these diagnostics is relatively limited by a low signal-to-noise ratio, such as with low allele frequency (AF) mutations in cancer. While enriching for rare alleles to increase their AF before sample analysis is one strategy that can greatly improve detection capability, current methods are limited in their generalizability, ease of use, and applicability to point mutations.Leveraging the robust single-base-pair specificity and generalizability of the CRISPR associated protein 9 (Cas9) system, we developed a deactivated Cas9 (dCas9)-based method of minor-allele enrichment capable of efficient single-target and multiplexed enrichment. The dCas9 protein was complexed with single guide RNAs targeted to mutations of interest and incubated with cfDNA samples containing mutant strands at low abundance. Mutation-bound dCas9 complexes were isolated, dissociated, and the captured DNA purified for downstream use.Targeting the 3 most common epidermal growth factor receptor mutations (exon 19 deletion, T790M, L858R) found in nonsmall-cell lung cancer (NSCLC), we achieved >20-fold increases in AF and detected mutations by use of qPCR at an AF of 0.1%. In a cohort of 18 NSCLC patient-derived cfDNA samples, our method enabled detection of 8 out of 13 mutations that were otherwise undetected by qPCR.The dCas9 method provides important application of the CRISPR/Cas9 system outside the realm of genome editing and can provide a step forward for the detection capability of cfDNA diagnostics.

  View details for PubMedID 29038154

• Longitudinal Monitoring of Antibody Responses against Tumor Cells Using Magneto-nanosensors with a Nanoliter of Blood. Nano letters Lee, J. R., Chan, C. T., Ruderman, D. n., Chuang, H. Y., Gaster, R. S., Atallah, M. n., Mallick, P. n., Lowe, S. W., Gambhir, S. S., Wang, S. X. 2017; 17 (11): 6644–52

  Abstract

  Each immunoglobulin isotype has unique immune effector functions. The contribution of these functions in the elimination of pathogens and tumors can be determined by monitoring quantitative temporal changes in isotype levels. Here, we developed a novel technique using magneto-nanosensors based on the effect of giant magnetoresistance (GMR) for longitudinal monitoring of total and antigen-specific isotype levels with high precision, using as little as 1 nL of serum. Combining in vitro serologic measurements with in vivo imaging techniques, we investigated the role of the antibody response in the regression of firefly luciferase (FL)-labeled lymphoma cells in spleen, kidney, and lymph nodes in a syngeneic Burkitt's lymphoma mouse model. Regression status was determined by whole body bioluminescent imaging (BLI). The magneto-nanosensors revealed that anti-FL IgG2a and total IgG2a were elevated and sustained in regression mice compared to non-regression mice (p < 0.05). This platform shows promise for monitoring immunotherapy, vaccination, and autoimmunity.

  View details for PubMedID 28990786

• Engineering Intracellularly Retained Gaussia Luciferase Reporters for Improved Biosensing and Molecular Imaging Applications. ACS chemical biology Gaur, S. n., Bhargava-Shah, A. n., Hori, S. n., Afjei, R. n., Sekar, T. V., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. n. 2017

  Abstract

  Gaussia luciferase (GLUC) is a bioluminescent reporter protein of increasing importance. As a secretory protein, it has increased sensitivity in vitro and in vivo (∼20 000-fold, and ∼1000-fold, respectively) over its competitor, secreted alkaline phosphatase. Unfortunately, this same advantageous secretory nature of GLUC limits its usefulness for many other possible intracellular applications, e.g., imaging signaling pathways in intact cells, in vivo imaging, and in developing molecular imaging biosensors to study protein-protein interactions and protein folding. Hence, to widen the research applications of GLUC, we developed engineered variants that increase its intracellular retention both by modifying the N-terminal secretory signal peptide and by tagging additional sequences to its C-terminal region. We found that when GLUC was expressed in mammalian cells, its N-terminal secretory signal peptide comprising amino acids 1-16 was essential for GLUC folding and functional activity in addition to its inherent secretory property. Modification of the C-terminus of GLUC by tagging a four amino acid (KDEL) endoplasmic reticulum targeting peptide in multiple repeats significantly improved its intracellular retention, with little impact on its folding and enzymatic activity. We used stable cells expressing this engineered GLUC with KDEL repeats to monitor chemically induced endoplasmic reticulum stress on cells. Additionally, we engineered an apoptotic sensor using modified variants of GLUC containing a four amino acid caspase substrate peptide (DEVD) between the GLUC protein and the KDEL repeats. Its use in cell culture resulted in increased GLUC secretion in the growth medium when cells were treated with the chemotherapeutic drugs doxorubicin, paclitaxel, and carboplatin. We thus successfully engineered a new variant GLUC protein that is retained inside cells rather than secreted extracellularly. We validated this novel reporter by incorporating it in biosensors for detection of cellular endoplasmic reticulum stress and caspase activation. This new molecularly engineered enzymatic reporter has the potential for widespread applications in biological research.

  View details for PubMedID 28767220

• Future cancer research priorities in the USA: A Lancet Oncology Commission Future cancer research priorities in the USA: A Lancet Oncology Commission Jaffee, E. M., Dang, C. V., Agus, D. B., Alexaner, B. M., Anderson, K. C., Ashworth, A., Barker, A. D., Bastani, R., Bhatia, S., Bluestone, J. A., Brawley, O., Butte, A. J., Coit, D. G., Davidson, N. E., Davis, M., DePinho, R. A., Diasio, R. B., Draetta, G., Frazier, A. L., Futreal, A., Gambhir, S. S., Ganz, P. A., Garraway, L., Gerson, S., Gupta, S., et al 2017; 18 (11): E653-E706
• A First Report on [18F]FPRGD2 PET/CT Imaging in Multiple Myeloma. Contrast media & molecular imaging Withofs, N. n., Cousin, F. n., De Prijck, B. n., Bonnet, C. n., Hustinx, R. n., Gambhir, S. S., Beguin, Y. n., Caers, J. n. 2017; 2017: 6162845

  Abstract

  An observational study was set up to assess the feasibility of [18F]FPRGD2 PET/CT for imaging patients with multiple myeloma (MM) and to compare its detection rate with low dose CT alone and combined [18F]NaF/[18F]FDG PET/CT images. Four patients (2 newly diagnosed patients and 2 with relapsed MM) were included and underwent whole-body PET/CT after injection of [18F]FPRGD2. The obtained images were compared with results of low dose CT and already available results of a combined [18F]NaF/[18F]FDG PET/CT. In total, 81 focal lesions (FLs) were detected with PET/CT and an underlying bone destruction or fracture was seen in 72 (89%) or 8 (10%) FLs, respectively. Fewer FLs (54%) were detected by [18F]FPRGD2 PET/CT compared to low dose CT (98%) or [18F]NaF/[18F]FDG PET/CT (70%) and all FLs detected with [18F]FPRGD2 PET were associated with an underlying bone lesion. In one newly diagnosed patient, more [18F]FPRGD2 positive lesions were seen than [18F]NaF/[18F]FDG positive lesions. This study suggests that [18F]FPRGD2 PET/CT might be less useful for the detection of myeloma lesions in patients with advanced disease as all FLs with [18F]FPRGD2 uptake were already detected with CT alone.

  View details for PubMedID 29097930

  View details for PubMedCentralID PMC5612716

• Visualizing Nerve Injury in a Neuropathic Pain Model with [(18)F]FTC-146 PET/MRI. Theranostics Shen, B. n., Behera, D. n., James, M. L., Reyes, S. T., Andrews, L. n., Cipriano, P. W., Klukinov, M. n., Lutz, A. B., Mavlyutov, T. n., Rosenberg, J. n., Ruoho, A. E., McCurdy, C. R., Gambhir, S. S., Yeomans, D. C., Biswal, S. n., Chin, F. T. 2017; 7 (11): 2794–2805

  Abstract

  The ability to locate nerve injury and ensuing neuroinflammation would have tremendous clinical value for improving both the diagnosis and subsequent management of patients suffering from pain, weakness, and other neurologic phenomena associated with peripheral nerve injury. Although several non-invasive techniques exist for assessing the clinical manifestations and morphological aspects of nerve injury, they often fail to provide accurate diagnoses due to limited specificity and/or sensitivity. Herein, we describe a new imaging strategy for visualizing a molecular biomarker of nerve injury/neuroinflammation, i.e., the sigma-1 receptor (S1R), in a rat model of nerve injury and neuropathic pain. The two-fold higher increase of S1Rs was shown in the injured compared to the uninjured nerve by Western blotting analyses. With our novel S1R-selective radioligand, [(18)F]FTC-146 (6-(3-[(18)F]fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one), and positron emission tomography-magnetic resonance imaging (PET/MRI), we could accurately locate the site of nerve injury created in the rat model. We verified the accuracy of this technique by ex vivo autoradiography and immunostaining, which demonstrated a strong correlation between accumulation of [(18)F]FTC-146 and S1R staining. Finally, pain relief could also be achieved by blocking S1Rs in the neuroma with local administration of non-radioactive [(19)F]FTC-146. In summary, [(18)F]FTC-146 S1R PET/MR imaging has the potential to impact how we diagnose, manage and treat patients with nerve injury, and thus warrants further investigation.

  View details for PubMedID 28824716

• Cancer Diagnostics: On-target Probes for Early Detection Nature Biomedical Engineering Hori, S. S., Willemieke, S., Tummers, S., Gambhir, S. S. 2017; 1 (0062): 1-3
• [F-18]GE-180 PET Detects Reduced Microglia Activation After LM11A-31 Therapy in a Mouse Model of Alzheimer's Disease THERANOSTICS James, M. L., Belichenko, N. P., Shuhendler, A. J., Hoehne, A., Andrews, L. E., Condon, C., Nguyen, T. V., Reiser, V., Jones, P., Trigg, W., Rao, J., Gambhir, S. S., Longo, F. M. 2017; 7 (6): 1422-1436

  Abstract

  Microglial activation is a key pathological feature of Alzheimer's disease (AD). PET imaging of translocator protein 18 kDa (TSPO) is a strategy to detect microglial activation in vivo. Here we assessed flutriciclamide ([(18)F]GE-180), a new second-generation TSPO-PET radiotracer, for its ability to monitor response to LM11A-31, a novel AD therapeutic in clinical trials. AD mice displaying pathology were treated orally with LM11A-31 for 3 months. Subsequent [(18)F]GE-180-PET imaging revealed significantly lower signal in cortex and hippocampus of LM11A-31-treated AD mice compared to those treated with vehicle, corresponding with decreased levels of TSPO immunostaining and microglial Iba1 immunostaining. In addition to detecting decreased microglial activation following LM11A-31 treatment, [(18)F]GE-180 identified activated microglia in AD mice with greater sensitivity than another second-generation TSPO radiotracer, [(18)F]PBR06. Together, these data demonstrate the promise of [(18)F]GE-180 as a potentially sensitive tool for tracking neuroinflammation in AD mice and for monitoring therapeutic modulation of microglial activation.

  View details for DOI 10.7150/thno.17666

  View details for PubMedID 28529627

• 18F-FDG silicon photomultiplier PET/CT: A pilot study comparing semi-quantitative measurements with standard PET/CT. PloS one Baratto, L., Park, S. Y., Hatami, N., Davidzon, G., Srinivas, S., Gambhir, S. S., Iagaru, A. 2017; 12 (6)

  Abstract

  To evaluate if the new Discovery Molecular Insights (DMI) PET/CT scanner provides equivalent results compared to the standard of care PET/CT scanners (GE Discovery 600 or GE Discovery 690) used in our clinic and to explore any possible differences in semi-quantitative measurements.The local Institutional Review Board approved the protocol and written informed consent was obtained from each patient. Between September and November 2016, 50 patients underwent a single 18F-FDG injection and two scans: the clinical standard PET/CT followed immediately by the DMI PET/CT scan. We measured SUVmax and SUVmean of different background organs and up to four lesions per patient from data acquired using both scanners.DMI PET/CT identified all the 107 lesions detected by standard PET/CT scanners, as well as additional 37 areas of focal increased 18F-FDG uptake. The SUVmax values for all 107 lesions ranged 1.2 to 14.6 (mean ± SD: 2.8 ± 2.8), higher on DMI PET/CT compared with standard of care PET/CT. The mean lesion:aortic arch SUVmax ratio and mean lesion:liver SUVmax ratio were 0.2-15.2 (mean ± SD: 3.2 ± 2.6) and 0.2-8.5 (mean ± SD: 1.9 ± 1.4) respectively, higher on DMI PET/CT than standard PET/CT. These differences were statistically significant (P value < 0.0001) and not correlated to the delay in acquisition of DMI PET data (P < 0.0001).Our study shows high performance of the new DMI PET/CT scanner. This may have a significant role in diagnosing and staging disease, as well as for assessing and monitoring responses to therapies.

  View details for DOI 10.1371/journal.pone.0178936

  View details for PubMedID 28582472

• Molecular profiling of single circulating tumor cells from lung cancer patients PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Park, S., Wong, D. J., Ooi, C. C., Kurtz, D. M., Vermesh, O., Aalipour, A., Suh, S., Pian, K. L., Chabon, J. J., Lee, S. H., Jamali, M., Say, C., Carter, J. N., Lee, L. P., Kuschner, W. G., Schwartz, E. J., Shrager, J. B., Neal, J. W., Wakelee, H. A., Diehn, M., Nair, V. S., Wang, S. X., Gambhir, S. S. 2016; 113 (52): E8379-E8386

  Abstract

  Circulating tumor cells (CTCs) are established cancer biomarkers for the "liquid biopsy" of tumors. Molecular analysis of single CTCs, which recapitulate primary and metastatic tumor biology, remains challenging because current platforms have limited throughput, are expensive, and are not easily translatable to the clinic. Here, we report a massively parallel, multigene-profiling nanoplatform to compartmentalize and analyze hundreds of single CTCs. After high-efficiency magnetic collection of CTC from blood, a single-cell nanowell array performs CTC mutation profiling using modular gene panels. Using this approach, we demonstrated multigene expression profiling of individual CTCs from non-small-cell lung cancer (NSCLC) patients with remarkable sensitivity. Thus, we report a high-throughput, multiplexed strategy for single-cell mutation profiling of individual lung cancer CTCs toward minimally invasive cancer therapy prediction and disease monitoring.

  View details for DOI 10.1073/pnas.1608461113

  View details for PubMedID 27956614

• Practical ImmunoPET radiotracer design considerations for human immune checkpoint imaging. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Mayer, A. T., Natarajan, A., Gordon, S., Maute, R., McCracken, M., Ring, A., Weissman, I., Gambhir, S. S. 2016

  Abstract

  Immune checkpoint blockade has emerged as a promising cancer treatment paradigm. Unfortunately, there are still a large number of patients and malignancies that do not respond to therapy. A major barrier to validating biomarkers for the prediction and monitoring of responders to clinical checkpoint blockade has been the lack of imaging tools to accurately assess dynamic immune checkpoint expression. Here, we sought to optimize noninvasive immuno-PET imaging of human programmed death-ligand 1 (PD-L1) expression, in a preclinical model, using a small high-affinity engineered protein scaffold (HAC-PD1). Six HAC-PD1 radiotracer variants were developed and used in preclinical imaging and biodistribution studies to assess their ability to detect human PD-L1 expression in vivo. Radiotracer design modifications included chelate, glycosylation, and radiometal. HACA-PD1 was adopted as the naming convention for aglycosylated tracer variants. NOD scid γ-(NSG) mice were inoculated with subcutaneous tumors engineered to either be constitutively positive (CT26 hPD-L1) or be negative (ΔmPD-L1 CT26) for human PD-L1 expression. When the tumors had grown to an average size of 1 cm in diameter, mice were injected with 0.75-2.25 MBq (∼10 μg) of an engineered radiotracer variant and imaged. At 1 h after injection, organs were harvested for biodistribution. Of the practical immuno-PET tracer modifications considered, glycosylation was the most prominent design factor affecting tracer uptake, specificity, and clearance. In imaging studies, aglycosylated (64)Cu-NOTA-HACA-PD1 most accurately visualized human PD-L1 expression in vivo. We reasoned that because of the scaffold's small size (14 kDa), its pharmacokinetics may be suitable for labeling with the short-lived and widely clinically available radiometal (68)Ga. At 1 h after injection, (68)Ga-NOTA-HACA-PD1 and (68)Ga-DOTA-HACA-PD1 exhibited promising target-to-background ratios in ex vivo biodistribution studies (12.3 and 15.2 tumor-to-muscle ratios, respectively). Notably, all HAC-PD1 radiotracer variants enabled much earlier detection of human PD-L1 expression (1 h after injection) than previously reported radiolabeled antibodies (>24 h after injection). This work provides a template for assessing immuno-PET tracer design parameters and supports the translation of small engineered protein radiotracers for imaging human immune checkpoints.

  View details for PubMedID 27980047

• A Clinical Wide-Field Fluorescence Endoscopic Device for Molecular Imaging Demonstrating Cathepsin Protease Activity in Colon Cancer. Molecular imaging and biology Sensarn, S., Zavaleta, C. L., Segal, E., Rogalla, S., Lee, W., Gambhir, S. S., Bogyo, M., Contag, C. H. 2016; 18 (6): 820-829

  Abstract

  Early and effective detection of cancers of the gastrointestinal tract will require novel molecular probes and advances in instrumentation that can reveal functional changes in dysplastic and malignant tissues. Here, we describe adaptation of a wide-field clinical fiberscope to perform wide-field fluorescence imaging while preserving its white-light capability for the purpose of providing wide-field fluorescence imaging capability to point-of-care microscopes.We developed and used a fluorescent fiberscope to detect signals from a quenched probe, BMV109, that becomes fluorescent when cleaved by, and covalently bound to, active cathepsin proteases. Cathepsins are expressed in inflammation- and tumor-associated macrophages as well as directly from tumor cells and are a promising target for cancer imaging. The fiberscope has a 1-mm outer diameter enabling validation via endoscopic exams in mice, and therefore we evaluated topically applied BMV109 for the ability to detect colon polyps in an azoxymethane-induced colon tumor model in mice.This wide-field endoscopic imaging device revealed consistent and clear fluorescence signals from BMV109 that specifically localized to the polypoid regions as opposed to the normal adjacent colon tissue (p < 0.004) in the murine colon carcinoma model.The sensitivity of detection of BMV109 with the fluorescence fiberscope suggested utility of these tools for early detection at hard-to-reach sites. The fiberscope was designed to be used in conjunction with miniature, endoscope-compatible fluorescence microscopes for dual wide-field and microscopic cancer detection.

  View details for PubMedID 27154508

• Clinically Approved Nanoparticle Imaging Agents JOURNAL OF NUCLEAR MEDICINE Thakor, A. S., Jokerst, J. V., Ghanouni, P., Campbell, J. L., Mittra, E., Gambhir, S. S. 2016; 57 (12): 1833–37

  View details for DOI 10.2967/jnumed.116.181362

  View details for Web of Science ID 000389106800005

• A Clinical Wide-Field Fluorescence Endoscopic Device for Molecular Imaging Demonstrating Cathepsin Protease Activity in Colon Cancer MOLECULAR IMAGING AND BIOLOGY Sensarn, S., Zavaleta, C. L., Segal, E., Rogalla, S., Lee, W., Gambhir, S. S., Bogyo, M., Contag, C. H. 2016; 18 (6): 820–29

  View details for DOI 10.1007/s11307-016-0956-7

  View details for Web of Science ID 000387367100004

• Can multispectral optoacoustic tomography replace sentinel lymph biopsy in melanoma? Annals of translational medicine Leong, S. P., Kothapalli, S., Gambhir, S. S. 2016; 4 (24): 517-?

  View details for DOI 10.21037/atm.2016.12.31

  View details for PubMedID 28149879

  View details for PubMedCentralID PMC5233521

• Clinically Approved Nanoparticle Imaging Agents. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Thakor, A. S., Jokerst, J. V., Ghanouni, P., Campbell, J., Mittra, E., Gambhir, S. S. 2016

  Abstract

  Nanoparticles are a new class of imaging agent used for both anatomic and molecular imaging. Nanoparticle-based imaging exploits the signal intensity, stability, and biodistribution behavior of submicron-diameter molecular imaging agents. This review focuses on nanoparticles used in human medical imaging, with an emphasis on radionuclide imaging and MRI. Newer nanoparticle platforms are also discussed in relation to theranostic and multimodal uses.

  View details for PubMedID 27738007

• A transgenic mouse model expressing an ER alpha folding biosensor reveals the effects of Bisphenol A on estrogen receptor signaling SCIENTIFIC REPORTS Sekar, T. V., Foygel, K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. 2016; 6

  Abstract

  Estrogen receptor-α (ERα) plays an important role in normal and abnormal physiology of the human reproductive system by interacting with the endogenous ligand estradiol (E2). However, other ligands, either analogous or dissimilar to E2, also bind to ERα. This may create unintentional activation of ER signaling in reproductive tissues that can lead to cancer development. We developed a transgenic mouse model that constitutively expresses a firefly luciferase (FLuc) split reporter complementation biosensor (NFLuc-ER-LBDG521T-CFLuc) to simultaneously evaluate the dynamics and potency of ligands that bind to ERα. We first validated this model using various ER ligands, including Raloxifene, Diethylstilbestrol, E2, and 4-hydroxytamoxifen, by employing FLuc-based optical bioluminescence imaging of living mice. We then used the model to investigate the carcinogenic property of Bisphenol A (BPA), an environmental estrogen, by long-term exposure at full and half environmental doses. We showed significant carcinogenic effects on female animals while revealing activated downstream ER signaling as measured by bioluminescence imaging. BPA induced tumor-like outgrowths in female transgenic mice, histopathologically confirmed to be neoplastic and epithelial in origin. This transgenic mouse model expressing an ERα folding-biosensor is useful in evaluation of estrogenic ligands and their downstream effects, and in studying environmental estrogen induced carcinogenesis in vivo.

  View details for DOI 10.1038/srep34788

  View details for PubMedID 27721470

• A Cystine Knot Peptide Targeting Integrin alpha(v)beta(6) for Photoacoustic and Fluorescence Imaging of Tumors in Living Subjects JOURNAL OF NUCLEAR MEDICINE Zhang, C., Kimura, R., Abou-Elkacem, L., Levi, J., Xu, L., Gambhir, S. S. 2016; 57 (10): 1629-1634

  Abstract

  Photoacoustic imaging is a nonionizing biomedical imaging modality with higher resolution and imaging depth than fluorescence imaging, which has greater sensitivity. The combination of the 2 imaging modalities could improve the detection of cancer. Integrin αvβ6 is a cell surface marker overexpressed in many different cancers. Here, we report the development and evaluation of a dye-labeled cystine knot peptide, which selectively recognizes integrin αvβ6 with high affinity, for photoacoustic and fluorescence imaging. The new dual-modality probe may find clinical application in cancer diagnosis and intraoperative imaging of integrin αvβ6-positive tumors.An engineered cystine knot peptide, R01, that recognizes integrin αvβ6 was labeled with Atto 740 (A740) and evaluated for its specific cell uptake and its sensitivity threshold. A740-R01 was injected via the tail vein into nude mice xenografted with A431 (integrin αvβ6-positive) or 293T (integrin αvβ6-negative) tumors. Photoacoustic and fluorescence scans of tumors were acquired before and at 0.5, 1, 2, and 4 h after injection of A740-R01. Dynamic photoacoustic scans of various normal organs were also acquired. Ex vivo fluorescence imaging of tissues was performed 1 h after injection.The A740-R01 demonstrated integrin αvβ6-dependent binding to A431 cells in culture. Sensitivity studies indicated that the probe may potentially detect lesions as small as 1 or 6 mm(3) by fluorescence or photoacoustic imaging, respectively. The photoacoustic and fluorescence signals of A431 xenografts at 1 h after injection were 1.87 ± 0.25 arbitrary units (AU) and 8.27 ± 0.87 AU, respectively. Target specificity was confirmed by low tumor uptake in 293T tumors at 1 h after injection (1.07 ± 0.15 AU and 1.10 ± 0.14 AU for photoacoustic and fluorescence signals, respectively). A740-R01 exhibited hepatobiliary clearance marked by high uptake in the liver, spleen, and intestine but low uptake in the kidneys.A740-R01 specifically targeted integrin αvβ6 with low nanomolar affinity. A740-R01 was able to detect integrin αvβ6 both in vitro and in vivo by photoacoustic and fluorescence imaging. A740-R01 is able to detect αvβ6-positive tumors in living subjects and may have clinical application in cancer diagnosis and real-time image-guided surgery.

  View details for DOI 10.2967/jnumed.115.169383

  View details for Web of Science ID 000384961900031

  View details for PubMedID 27230926

• Quantitative photoacoustic image reconstruction improves accuracy in deep tissue structures. Biomedical optics express Mastanduno, M. A., Gambhir, S. S. 2016; 7 (10): 3811-3825

  Abstract

  Photoacoustic imaging (PAI) is emerging as a potentially powerful imaging tool with multiple applications. Image reconstruction for PAI has been relatively limited because of limited or no modeling of light delivery to deep tissues. This work demonstrates a numerical approach to quantitative photoacoustic image reconstruction that minimizes depth and spectrally derived artifacts. We present the first time-domain quantitative photoacoustic image reconstruction algorithm that models optical sources through acoustic data to create quantitative images of absorption coefficients. We demonstrate quantitative accuracy of less than 5% error in large 3 cm diameter 2D geometries with multiple targets and within 22% error in the largest size quantitative photoacoustic studies to date (6cm diameter). We extend the algorithm to spectral data, reconstructing 6 varying chromophores to within 17% of the true values. This quantitiative PA tomography method was able to improve considerably on filtered-back projection from the standpoint of image quality, absolute, and relative quantification in all our simulation geometries. We characterize the effects of time step size, initial guess, and source configuration on final accuracy. This work could help to generate accurate quantitative images from both endogenous absorbers and exogenous photoacoustic dyes in both preclinical and clinical work, thereby increasing the information content obtained especially from deep-tissue photoacoustic imaging studies.

  View details for DOI 10.1364/BOE.7.003811

  View details for PubMedID 27867695

  View details for PubMedCentralID PMC5102520

• Quantitative photoacoustic image reconstruction improves accuracy in deep tissue structures BIOMEDICAL OPTICS EXPRESS Mastanduno, M. A., Gambhir, S. S. 2016; 7 (10): 3811-3825

  View details for DOI 10.1364/BOE.7.003811

  View details for Web of Science ID 000385418200001

• Imaging approaches to optimize molecular therapies SCIENCE TRANSLATIONAL MEDICINE Weissleder, R., Schwaiger, M. C., Gambhir, S. S., Hricak, H. 2016; 8 (355)

  Abstract

  Imaging, including its use for innovative tissue sampling, is slowly being recognized as playing a pivotal role in drug development, clinical trial design, and more effective delivery and monitoring of molecular therapies. The challenge is that, while a considerable number of new imaging technologies and new targeted tracers have been developed for cancer imaging in recent years, the technologies are neither evenly distributed nor evenly implemented. Furthermore, many imaging innovations are not validated and are not ready for widespread use in drug development or in clinical trial designs. Inconsistent and often erroneous use of terminology related to quantitative imaging biomarkers has also played a role in slowing their development and implementation. We examine opportunities for, and challenges of, the use of imaging biomarkers to facilitate development of molecular therapies and to accelerate progress in clinical trial design. In the future, in vivo molecular imaging, image-guided tissue sampling for mutational analyses ("high-content biopsies"), and noninvasive in vitro tests ("liquid biopsies") will likely be used in various combinations to provide the best possible monitoring and individualized treatment plans for cancer patients.

  View details for DOI 10.1126/scitranslmed.aaf3936

  View details for Web of Science ID 000384015200001

  View details for PubMedID 27605550

• Multimodality Molecular Imaging of Cardiac Cell Transplantation: Part II. In Vivo Imaging of Bone Marrow Stromal Cells in Swine with PET/CT and MR Imaging. Radiology Parashurama, N., Ahn, B., Ziv, K., Ito, K., Paulmurugan, R., Willmann, J. K., Chung, J., Ikeno, F., Swanson, J. C., Merk, D. R., Lyons, J. K., Yerushalmi, D., Teramoto, T., Kosuge, H., Dao, C. N., Ray, P., Patel, M., Chang, Y., Mahmoudi, M., Cohen, J. E., Goldstone, A. B., Habte, F., Bhaumik, S., Yaghoubi, S., Robbins, R. C., Dash, R., Yang, P. C., Brinton, T. J., Yock, P. G., McConnell, M. V., Gambhir, S. S. 2016; 280 (3): 826-836

  Abstract

  Purpose To quantitatively determine the limit of detection of marrow stromal cells (MSC) after cardiac cell therapy (CCT) in swine by using clinical positron emission tomography (PET) reporter gene imaging and magnetic resonance (MR) imaging with cell prelabeling. Materials and Methods Animal studies were approved by the institutional administrative panel on laboratory animal care. Seven swine received 23 intracardiac cell injections that contained control MSC and cell mixtures of MSC expressing a multimodality triple fusion (TF) reporter gene (MSC-TF) and bearing superparamagnetic iron oxide nanoparticles (NP) (MSC-TF-NP) or NP alone. Clinical MR imaging and PET reporter gene molecular imaging were performed after intravenous injection of the radiotracer fluorine 18-radiolabeled 9-[4-fluoro-3-(hydroxyl methyl) butyl] guanine ((18)F-FHBG). Linear regression analysis of both MR imaging and PET data and nonlinear regression analysis of PET data were performed, accounting for multiple injections per animal. Results MR imaging showed a positive correlation between MSC-TF-NP cell number and dephasing (dark) signal (R(2) = 0.72, P = .0001) and a lower detection limit of at least approximately 1.5 × 10(7) cells. PET reporter gene imaging demonstrated a significant positive correlation between MSC-TF and target-to-background ratio with the linear model (R(2) = 0.88, P = .0001, root mean square error = 0.523) and the nonlinear model (R(2) = 0.99, P = .0001, root mean square error = 0.273) and a lower detection limit of 2.5 × 10(8) cells. Conclusion The authors quantitatively determined the limit of detection of MSC after CCT in swine by using clinical PET reporter gene imaging and clinical MR imaging with cell prelabeling. (©) RSNA, 2016 Online supplemental material is available for this article.

  View details for DOI 10.1148/radiol.2016151150

  View details for PubMedID 27332865

• Multimodality Molecular Imaging of Cardiac Cell Transplantation: Part I. Reporter Gene Design, Characterization, and Optical in Vivo Imaging of Bone Marrow Stromal Cells after Myocardial Infarction. Radiology Parashurama, N., Ahn, B., Ziv, K., Ito, K., Paulmurugan, R., Willmann, J. K., Chung, J., Ikeno, F., Swanson, J. C., Merk, D. R., Lyons, J. K., Yerushalmi, D., Teramoto, T., Kosuge, H., Dao, C. N., Ray, P., Patel, M., Chang, Y., Mahmoudi, M., Cohen, J. E., Goldstone, A. B., Habte, F., Bhaumik, S., Yaghoubi, S., Robbins, R. C., Dash, R., Yang, P. C., Brinton, T. J., Yock, P. G., McConnell, M. V., Gambhir, S. S. 2016; 280 (3): 815-825

  Abstract

  Purpose To use multimodality reporter-gene imaging to assess the serial survival of marrow stromal cells (MSC) after therapy for myocardial infarction (MI) and to determine if the requisite preclinical imaging end point was met prior to a follow-up large-animal MSC imaging study. Materials and Methods Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care. Mice (n = 19) that had experienced MI were injected with bone marrow-derived MSC that expressed a multimodality triple fusion (TF) reporter gene. The TF reporter gene (fluc2-egfp-sr39ttk) consisted of a human promoter, ubiquitin, driving firefly luciferase 2 (fluc2), enhanced green fluorescent protein (egfp), and the sr39tk positron emission tomography reporter gene. Serial bioluminescence imaging of MSC-TF and ex vivo luciferase assays were performed. Correlations were analyzed with the Pearson product-moment correlation, and serial imaging results were analyzed with a mixed-effects regression model. Results Analysis of the MSC-TF after cardiac cell therapy showed significantly lower signal on days 8 and 14 than on day 2 (P = .011 and P = .001, respectively). MSC-TF with MI demonstrated significantly higher signal than MSC-TF without MI at days 4, 8, and 14 (P = .016). Ex vivo luciferase activity assay confirmed the presence of MSC-TF on days 8 and 14 after MI. Conclusion Multimodality reporter-gene imaging was successfully used to assess serial MSC survival after therapy for MI, and it was determined that the requisite preclinical imaging end point, 14 days of MSC survival, was met prior to a follow-up large-animal MSC study. (©) RSNA, 2016 Online supplemental material is available for this article.

  View details for DOI 10.1148/radiol.2016140049

  View details for PubMedID 27308957

• Glioblastoma Multiforme Recurrence: An Exploratory Study of (18)F FPPRGD2 PET/CT. Radiology Iagaru, A., Mosci, C., Mittra, E., Zaharchuk, G., Fischbein, N., Harsh, G., Li, G., Nagpal, S., Recht, L., Gambhir, S. S. 2016; 280 (1): 328-?

  View details for DOI 10.1148/radiol.2016164020

  View details for PubMedID 27322985

• Glioblastoma Multiforme Recurrence Response RADIOLOGY Iagaru, A., Gambhir, S. 2016; 280 (1): 326–27

  View details for Web of Science ID 000378721900042

• Characterization of Physiologic F-18 FSPG Uptake in Healthy Volunteers RADIOLOGY Mosci, C., Kumar, M., Smolarz, K., Koglin, N., Stephens, A. W., Schwaiger, M., Gambhir, S. S., Mittra, E. S. 2016; 279 (3): 898-905

  Abstract

  Purpose To evaluate the normal biodistribution and kinetics of (S)-4-(3-[18F]fluoropropyl)-l-glutamic acid ((18)F FSPG) in healthy volunteers and to compare (18)F FSPG mean and maximum standardized uptake values (SUVmean and SUVmax, respectively) with those of (18)F fluorodeoxyglucose (FDG) across a variety of organs. Materials and Methods This protocol was reviewed and approved by all appropriate regulatory authorities. An 8-mCi (±10%) dose of (18)F FSPG was given to five subjects (three women, two men), and seven whole-body positron emission tomography (PET) scans were performed 5, 10, 20, 30, 45, 150, and 240 minutes after injection. Regions of interest were analyzed on the resultant (18)F FSPG images to evaluate the kinetics of this radiotracer. The images obtained 45 minutes after injection were used to measure SUVmean and SUVmax in additional regions of the body. These values were compared with similar values obtained with (18)F FDG PET published previously. Descriptive statistics, including average and standard deviation across the five subjects, were used. (18)F FSPG SUVmean and SUVmax were compared. Results On the (18)F FSPG images obtained 45 minutes after injection, there was only low-grade background activity in the majority of analyzed regions. Prominent activity was seen throughout the pancreas. Clearance of the radiotracer through the kidneys and collection in the bladder also were seen. SUV quantification shows notable differences between (18)F FSPG and (18)F FDG in the pancreas ((18)F FSPG SUVmean, 8.2; (18)F FDG SUVmean, 1.3), stomach ((18)F FSPG SUVmax, 3.6; (18)F FDG SUVmax, 1.6), and brain ((18)F FSPG SUVmean, 0.08; (18)F FDG SUVmean, 7.8). The kinetic data showed rapid clearance of the radiotracer from the blood pool and most organs, except the pancreas. Conclusion (18)F FSPG is a PET radiopharmaceutical characterized by rapid clearance from most healthy tissues, except the pancreas and kidneys. A consistent biodistribution pattern was observed with low background uptake. The physiologic uptake of this new radiotracer throughout the body is described in more detail, which is important for improved interpretative accuracy and understanding potential clinical applications. (©) RSNA, 2016.

  View details for DOI 10.1148/radiol.2015142000

  View details for Web of Science ID 000378719700028

  View details for PubMedID 26785040

• Pilot prospective evaluation of F-18-FPPRGD(2) PET/CT in patients with cervical and ovarian cancer EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Minamimoto, R., Karam, A., Jamali, M., Barkhodari, A., Gambhir, S. S., Dorigo, O., Iagaru, A. 2016; 43 (6): 1047-1055

  Abstract

  We report the effect of antiangiogenic therapy on the biodistribution of (18)F-FPPRGD2 (a surrogate biomarker of integrin αvβ3 expression), and the potential of (18)F-FPPRGD2 to predict the prognosis in patients with cervical cancer and ovarian cancer in this clinical scenario.Data from six women, age range 30 - 59 years (mean ± SD 44.0 ± 12.5 years), who had undergone a (18)F-FPPRGD2 PET/CT scan and bevacizumab-containing therapy were prospectively collected and analyzed. We compared baseline (18)F-FPPRGD2 and (18)F-FDG uptake in the lesions and tumor-to-background (T/B) ratios. The maximum and mean (18)F-FPPRGD2 standardized uptake values (SUVmax and SUVmean) were recorded for 13 normal organs, as well as in all the identified malignant lesions on the pretreatment scan and the 1-week post-treatment scan. We also measured changes in (18)F-FPPRGD2 uptake from before to 1 week after treatment, and compared them to the changes in (18)F-FDG uptake from before to 6 weeks after treatment. Treatment outcomes were correlated with these changes.The uptake in lesions and T/B ratio of (18)F-FPPRGD2 were lower than those of (18)F-FDG (SUVmax 3.7 ± 1.3 vs. 6.0 ± 1.8, P < 0.001; SUVmean 2.6 ± 0.7 vs. 4.2 ± 1.3, P < 0.001; T/B ratio based on SUVmax 2.4 ± 1.0 vs. 2.6 ± 1.0, P < 0.04; T/B ratio based on SUVmean 1.9 ± 0.6 vs. 2.4 ± 1.0, P < 0.003). One patient did not return for the follow-up scan and in another patient no lesions were identified on the pretreatment scan. (18)F-FPPRGD2 uptake in lesions in the remaining four patients had significantly changed 1 week after treatment (SUVmean 3.3 ± 1.0 vs. 2.7 ± 1.0, P < 0.001), while uptake in all normal tissues analyzed was not affected by treatment. One patient with clinical disease progression had a decrease in lesional (18)F-FPPRGD2 SUVmean of 1.6 % and in (18)F-FDG SUVmean of 9.4 %. Two patients with a clinical complete response to treatment had decreases in lesional (18)F-FPPRGD2 SUVmean of 25.2 % and 25.0 % and in (18)F-FDG SUVmean of 6.1 % and 71.8 %. One patient with a clinical partial response had a decrease in lesional (18)F-FPPRGD2 SUVmean of 7.9 % and in (18)F-FDG SUVmean of 76.4 %.This pilot study showed that (18)F-FPPRGD2 and (18)F-FDG provide independent information about the biology of ovarian and cervical cancers. Bevacizumab-containing therapy does not affect (18)F-FPPRGD2 uptake in normal organs, but does result in statistically significant changes in lesions. In addition, (18)F-FPPRGD2 may have potential for early prediction of response to such treatments. These preliminary findings have to be confirmed in larger studies.

  View details for DOI 10.1007/s00259-015-3263-7

  View details for Web of Science ID 000374972900008

  View details for PubMedID 26611425

• Protein biomarkers on tissue as imaged via MALDI mass spectrometry: A systematic approach to study the limits of detection PROTEOMICS van de Ven, S. M., Bemis, K. D., Lau, K., Adusumilli, R., Kota, U., Stolowitz, M., Vitek, O., Mallick, P., Gambhir, S. S. 2016; 16 (11-12): 1660-1669

  Abstract

  MALDI mass spectrometry imaging (MSI) is emerging as a tool for protein and peptide imaging across tissue sections. Despite extensive study, there does not yet exist a baseline study evaluating the potential capabilities for this technique to detect diverse proteins in tissue sections. In this study, we developed a systematic approach for characterizing MALDI-MSI workflows in terms of limits of detection, coefficients of variation, spatial resolution, and the identification of endogenous tissue proteins. Our goal was to quantify these figures of merit for a number of different proteins and peptides, in order to gain more insight in the feasibility of protein biomarker discovery efforts using this technique. Control proteins and peptides were deposited in serial dilutions on thinly sectioned mouse xenograft tissue. Using our experimental setup, coefficients of variation were <30% on tissue sections and spatial resolution was 200 μm (or greater). Limits of detection for proteins and peptides on tissue were in the micromolar to millimolar range. Protein identification was only possible for proteins present in high abundance in the tissue. These results provide a baseline for the application of MALDI-MSI towards the discovery of new candidate biomarkers and a new benchmarking strategy that can be used for comparing diverse MALDI-MSI workflows.

  View details for DOI 10.1002/pmic.201500515

  View details for Web of Science ID 000379049100008

  View details for PubMedID 26970438

• Alk5 inhibition increases delivery of macromolecular and protein-bound contrast agents to tumors. JCI insight Daldrup-Link, H. E., Mohanty, S., Ansari, C., Lenkov, O., Shaw, A., Ito, K., Hong, S. H., Hoffmann, M., Pisani, L., Boudreau, N., Gambhir, S. S., Coussens, L. M. 2016; 1 (6)

  Abstract

  Limited transendothelial permeability across tumor microvessels represents a significant bottleneck in the development of tumor-specific diagnostic agents and theranostic drugs. Here, we show an approach to increase transendothelial permeability of macromolecular and nanoparticle-based contrast agents via inhibition of the type I TGF-β receptor, activin-like kinase 5 (Alk5), in tumors. Alk5 inhibition significantly increased tumor contrast agent delivery and enhancement on imaging studies, while healthy organs remained relatively unaffected. Imaging data correlated with significantly decreased tumor interstitial fluid pressure, while tumor vascular density remained unchanged. This immediately clinically translatable concept involving Alk5 inhibitor pretreatment prior to an imaging study could be leveraged for improved tumor delivery of macromolecular and nanoparticle-based imaging probes and, thereby, facilitate development of more sensitive imaging tests for cancer diagnosis, enhanced tumor characterization, and personalized, image-guided therapies.

  View details for PubMedID 27182558

• Alk5 inhibition increases delivery of macromolecular and protein-bound contrast agents to tumors JCI INSIGHT Daldrup-Link, H. E., Mohanty, S., Ansari, C., Lenkov, O., Shaw, A., Ito, K., Hong, S., Hoffmann, M., Pisani, L., Boudreau, N., Gambhir, S., Coussens, L. M. 2016; 1 (6)

  View details for DOI 10.1172/jci.insight.85608

  View details for Web of Science ID 000387111300001

• Imaging of tumor-associated system xC-activity with 18F-fluoropropylglutamate (18F-FSPG) PET/CT for intracranial malignancies Sonni, I., Minamimoto, R., Jamali, M., Hatami, N., Berndt, M., Koglin, N., Stephens, A., Iagaru, A., Chin, F., Gambhir, S., Mittra, E. SOC NUCLEAR MEDICINE INC. 2016

  View details for Web of Science ID 000442211000182

• [(18)F]FPRGD2 PET/CT imaging of integrin avß3 levels in patients with locally advanced rectal carcinoma. European journal of nuclear medicine and molecular imaging Withofs, N., Martinive, P., Vanderick, J., Bletard, N., Scagnol, I., Mievis, F., Giacomelli, F., Coucke, P., Delvenne, P., Cataldo, D., Gambhir, S. S., Hustinx, R. 2016; 43 (4): 654-662

  Abstract

  Our primary objective was to determine if [(18)F]FPRGD2 PET/CT performed at baseline and/or after chemoradiotherapy (CRT) could predict tumour regression grade (TRG) in locally advanced rectal cancer (LARC). Secondary objectives were to compare baseline [(18)F]FPRGD2 and [(18)F]FDG uptake, to evaluate the correlation between posttreatment [(18)F]FPRGD2 uptake and tumour microvessel density (MVD) and to determine if [(18)F]FPRGD2 and FDG PET/CT could predict disease-free survival.Baseline [(18)F]FPRGD2 and FDG PET/CT were performed in 32 consecutive patients (23 men, 9 women; mean age 63 ± 8 years) with LARC before starting any therapy. A posttreatment [(18)F]FPRGD2 PET/CT scan was performed in 24 patients after the end of CRT (median interval 7 weeks, range 3 - 15 weeks) and before surgery (median interval 4 days, range 1 - 15 days).All LARC showed uptake of both [(18)F]FPRGD2 (SUVmax 5.4 ± 1.5, range 2.7 - 9) and FDG (SUVmax 16.5 ± 8, range 7.1 - 36.5). There was a moderate positive correlation between [(18)F]FPRGD2 and FDG SUVmax (Pearson's r = 0.49, p = 0.0026). There was a moderate negative correlation between baseline [(18)F]FPRGD2 SUVmax and the TRG (Spearman's r = -0.37, p = 0.037), and a [(18)F]FPRGD2 SUVmax of >5.6 identified all patients with a complete response (TRG 0; AUC 0.84, 95 % CI 0.68 - 1, p = 0.029). In the 24 patients who underwent a posttreatment [(18)F]FPRGD2 PET/CT scan the response index, calculated as [(SUVmax1 - SUVmax2)/SUVmax1] × 100 %, was not associated with TRG. Post-treatment [(18)F]FPRGD2 uptake was not correlated with tumour MVD. Neither [(18)F]FPRGD2 nor FDG uptake predicted disease-free survival.Baseline [(18)F]FPRGD2 uptake was correlated with the pathological response in patients with LARC treated with CRT. However, the specificity was too low to consider its clinical routine use.

  View details for DOI 10.1007/s00259-015-3219-y

  View details for PubMedID 26490751

• [F-18]FPRGD(2) PET/CT imaging of integrin alpha(v)beta(3) levels in patients with locally advanced rectal carcinoma EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Withofs, N., Martinive, P., Vanderick, J., Bletard, N., Scagnol, I., Mievis, F., Giacomelli, F., Coucke, P., Delvenne, P., Cataldo, D., Gambhir, S. S., Hustinx, R. 2016; 43 (4): 654-662

  View details for DOI 10.1007/s00259-015-3219-y

  View details for Web of Science ID 000371074100007

• Pilot Comparison of Ga-68-RM2 PET and Ga-68-PSMA-11 PET in Patients with Biochemically Recurrent Prostate Cancer JOURNAL OF NUCLEAR MEDICINE Minamimoto, R., Hancock, S., Schneider, B., Chin, F. T., Jamali, M., Loening, A., Vasanawala, S., Gambhir, S. S., Iagaru, A. 2016; 57 (4): 557-562

  Abstract

  Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)] ((68)Ga-PSMA-11) is a PET tracer that can detect prostate cancer relapses and metastases by binding to the extracellular domain of PSMA.(68)Ga-labeled DOTA-4-amino-1-carboxymethyl-piperidine-d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 ((68)Ga-RM2) is a synthetic bombesin receptor antagonist that targets gastrin-releasing peptide receptors. We present pilot data on the biodistribution of these PET tracers in a small cohort of patients with biochemically recurrent prostate cancer.Seven men (mean age ± SD, 74.3 ± 5.9 y) with biochemically recurrent prostate cancer underwent both(68)Ga-PSMA-11 PET/CT and(68)Ga-RM2 PET/MRI scans. SUVmaxand SUVmeanwere recorded for normal tissues and areas of uptake outside the expected physiologic biodistribution.All patients had a rising level of prostate-specific antigen (mean ± SD, 13.5 ± 11.5) and noncontributory results on conventional imaging.(68)Ga-PSMA-11 had the highest physiologic uptake in the salivary glands and small bowel, with hepatobiliary and renal clearance noted, whereas(68)Ga-RM2 had the highest physiologic uptake in the pancreas, with renal clearance noted. Uptake outside the expected physiologic biodistribution did not significantly differ between(68)Ga-PSMA-11 and(68)Ga-RM2; however,(68)Ga-PSMA-11 localized in a lymph node and seminal vesicle in a patient with no abnormal(68)Ga-RM2 uptake. Abdominal periaortic lymph nodes were more easily visualized by(68)Ga-RM2 in two patients because of lack of interference by radioactivity in the small intestine.(68)Ga-PSMA-11 and(68)Ga-RM2 had distinct biodistributions in this small cohort of patients with biochemically recurrent prostate cancer. Additional work is needed to understand the expression of PSMA and gastrin-releasing peptide receptors in different types of prostate cancer.

  View details for DOI 10.2967/jnumed.115.168393

  View details for PubMedID 26659347

• Comparison of Deconvolution Filters for Photoacoustic Tomography PLOS ONE de Sompel, D. V., Sasportas, L. S., Jokerst, J. V., Gambhir, S. S. 2016; 11 (3)

  View details for DOI 10.1371/journal.pone.0152597

  View details for Web of Science ID 000373121800099

• Mesoporous silica nanoparticles for ultrasound/magnetic resonance imaging and therapeutic drug delivery for stem cell therapy Kempen, P., Campbell, J., Greasley, S., Jones, J., Gambhir, S., Sinclair, R., Jokerst, J. AMER CHEMICAL SOC. 2016

  View details for Web of Science ID 000431903805079

• Tumor Molecular Imaging with Nanoparticles ENGINEERING Cheng, Z., Yan, X., Sun, X., Shen, B., Gambhir, S. 2016; 2 (1): 132–40

  View details for DOI 10.1016/J.ENG.2016.01.027

  View details for Web of Science ID 000389355500031

• Comparison of Deconvolution Filters for Photoacoustic Tomography. PloS one Van de Sompel, D., Sasportas, L. S., Jokerst, J. V., Gambhir, S. S. 2016; 11 (3)

  Abstract

  In this work, we compare the merits of three temporal data deconvolution methods for use in the filtered backprojection algorithm for photoacoustic tomography (PAT). We evaluate the standard Fourier division technique, the Wiener deconvolution filter, and a Tikhonov L-2 norm regularized matrix inversion method. Our experiments were carried out on subjects of various appearances, namely a pencil lead, two man-made phantoms, an in vivo subcutaneous mouse tumor model, and a perfused and excised mouse brain. All subjects were scanned using an imaging system with a rotatable hemispherical bowl, into which 128 ultrasound transducer elements were embedded in a spiral pattern. We characterized the frequency response of each deconvolution method, compared the final image quality achieved by each deconvolution technique, and evaluated each method's robustness to noise. The frequency response was quantified by measuring the accuracy with which each filter recovered the ideal flat frequency spectrum of an experimentally measured impulse response. Image quality under the various scenarios was quantified by computing noise versus resolution curves for a point source phantom, as well as the full width at half maximum (FWHM) and contrast-to-noise ratio (CNR) of selected image features such as dots and linear structures in additional imaging subjects. It was found that the Tikhonov filter yielded the most accurate balance of lower and higher frequency content (as measured by comparing the spectra of deconvolved impulse response signals to the ideal flat frequency spectrum), achieved a competitive image resolution and contrast-to-noise ratio, and yielded the greatest robustness to noise. While the Wiener filter achieved a similar image resolution, it tended to underrepresent the lower frequency content of the deconvolved signals, and hence of the reconstructed images after backprojection. In addition, its robustness to noise was poorer than that of the Tikhonov filter. The performance of the Fourier filter was found to be the poorest of all three methods, based on the reconstructed images' lowest resolution (blurriest appearance), generally lowest contrast-to-noise ratio, and lowest robustness to noise. Overall, the Tikhonov filter was deemed to produce the most desirable image reconstructions.

  View details for DOI 10.1371/journal.pone.0152597

  View details for PubMedID 27031832

  View details for PubMedCentralID PMC4816281

• AshwaMAX and Withaferin A inhibits gliomas in cellular and murine orthotopic models. Journal of neuro-oncology Chang, E., Pohling, C., Natarajan, A., Witney, T. H., Kaur, J., Xu, L., Gowrishankar, G., D'Souza, A. L., Murty, S., Schick, S., Chen, L., Wu, N., Khaw, P., Mischel, P., Abbasi, T., Usmani, S., Mallick, P., Gambhir, S. S. 2016; 126 (2): 253-64

  Abstract

  Glioblastoma multiforme (GBM) is an aggressive, malignant cancer Johnson and O'Neill (J Neurooncol 107: 359-364, 2012). An extract from the winter cherry plant (Withania somnifera ), AshwaMAX, is concentrated (4.3 %) for Withaferin A; a steroidal lactone that inhibits cancer cells Vanden Berghe et al. (Cancer Epidemiol Biomark Prev 23: 1985-1996, 2014). We hypothesized that AshwaMAX could treat GBM and that bioluminescence imaging (BLI) could track oral therapy in orthotopic murine models of glioblastoma. Human parietal-cortical glioblastoma cells (GBM2, GBM39) were isolated from primary tumors while U87-MG was obtained commercially. GBM2 was transduced with lentiviral vectors that express Green Fluorescent Protein (GFP)/firefly luciferase fusion proteins. Mutational, expression and proliferative status of GBMs were studied. Intracranial xenografts of glioblastomas were grown in the right frontal regions of female, nude mice (n = 3-5 per experiment). Tumor growth was followed through BLI. Neurosphere cultures (U87-MG, GBM2 and GBM39) were inhibited by AshwaMAX at IC50 of 1.4, 0.19 and 0.22 µM equivalent respectively and by Withaferin A with IC50 of 0.31, 0.28 and 0.25 µM respectively. Oral gavage, every other day, of AshwaMAX (40 mg/kg per day) significantly reduced bioluminescence signal (n = 3 mice, p < 0.02, four parameter non-linear regression analysis) in preclinical models. After 30 days of treatment, bioluminescent signal increased suggesting onset of resistance. BLI signal for control, vehicle-treated mice increased and then plateaued. Bioluminescent imaging revealed diffuse growth of GBM2 xenografts. With AshwaMAX, GBM neurospheres collapsed at nanomolar concentrations. Oral treatment studies on murine models confirmed that AshwaMAX is effective against orthotopic GBM. AshwaMAX is thus a promising candidate for future clinical translation in patients with GBM.

  View details for DOI 10.1007/s11060-015-1972-1

  View details for PubMedID 26650066

• A Cystine Knot Peptide Targeting Integrin αvβ6 for Photoacoustic and Fluorescence Imaging of Tumors in Living Subjects. Journal of Nuclear Medicine Zhang, C., Kimura, R., Abou-Elkacem, L., Levi, J., Xu, L., Gambhir, S. S. 2016: 1629-1634
• Engineered PD-1 variants as immunotherapies for cancer Gordon, S. R., Maute, R., Mayer, A., McCracken, M., Natarajan, A., Guo, N., Kimura, R., Tsai, J. M., Manglik, A., Kruse, A., Gambhir, S., Weissman, I. L., Ring, A. M. AMER ASSOC CANCER RESEARCH. 2016

  View details for DOI 10.1158/2326-6074.CRICIMTEATIAACR15-B101

  View details for Web of Science ID 000375484400088

• Artificial MicroRNAs as Novel Secreted Reporters for Cell Monitoring in Living Subjects. PloS one Ronald, J. A., D'Souza, A. L., Chuang, H., Gambhir, S. S. 2016; 11 (7)

  Abstract

  Reporter genes are powerful technologies that can be used to directly inform on the fate of transplanted cells in living subjects. Imaging reporter genes are often employed to quantify cell number, location(s), and viability with various imaging modalities. To complement this, reporters that are secreted from cells can provide a low-cost, in vitro diagnostic test to monitor overall cell viability at relatively high frequency without knowing the locations of all cells. Whereas protein-based secretable reporters have been developed, an RNA-based reporter detectable with amplification inherent PCR-based assays has not been previously described. MicroRNAs (miRNAs) are short non-coding RNAs (18-22 nt) that regulate mRNA translation and are being explored as relatively stable blood-based disease biomarkers. We developed an artificial miRNA-based secreted reporter, called Sec-miR, utilizing a coding sequence that is not expressed endogenously and does not have any known vertebrate target. Sec-miR was detectable in both the cells and culture media of transiently transfected cells. Cells stably expressing Sec-miR also reliably secreted it into the culture media. Mice implanted with parental HeLa cells or HeLa cells expressing both Sec-miR and the bioluminescence imaging (BLI) reporter gene Firefly luciferase (FLuc) were monitored over time for tumor volume, FLuc signal via BLI, and blood levels of Sec-miR. Significantly (p<0.05) higher Sec-miR was found in the blood of mice bearing Sec-miR-expressing tumors compared to parental cell tumors at 21 and 28 days after implantation. Importantly, blood Sec-miR reporter levels after day 21 showed a trend towards correlation with tumor volume (R2 = 0.6090; p = 0.0671) and significantly correlated with FLuc signal (R2 = 0.7067; p<0.05). Finally, we could significantly (p<0.01) amplify Sec-miR secretion into the cell media by chaining together multiple Sec-miR copies (4 instead of 1 or 2) within an expression cassette. Overall, we show that a novel complement of BLI together with a unique Sec-miR reporter adds an in vitro RNA-based diagnostic to enhance the monitoring of transplanted cells. While Sec-miR was not as sensitive as BLI for monitoring cell number, it may be more sensitive than clinically-relevant positron emission tomography (PET) reporter assays. Future work will focus on improving cell detectability via improved secretion of Sec-miR reporters from cells and more sensitive detection platforms, as well as, exploring other miRNA sequences to allow multiplexed monitoring of more than one cell population at a time. Continued development may lead to more refined and precise monitoring of cell-based therapies.

  View details for DOI 10.1371/journal.pone.0159369

  View details for PubMedID 27442530

  View details for PubMedCentralID PMC4956193

• AshwaMAX and Withaferin A inhibits gliomas in cellular and murine orthotopic models JOURNAL OF NEURO-ONCOLOGY Chang, E., Pohling, C., Natarajan, A., Witney, T. H., Kaur, J., Xu, L., Gowrishankar, G., D'Souza, A. L., Murty, S., Schick, S., Chen, L., Wu, N., Khaw, P., Mischel, P., Abbasi, T., Usmani, S., Mallick, P., Gambhir, S. S. 2016; 126 (2): 253-264

  Abstract

  Glioblastoma multiforme (GBM) is an aggressive, malignant cancer Johnson and O'Neill (J Neurooncol 107: 359-364, 2012). An extract from the winter cherry plant (Withania somnifera ), AshwaMAX, is concentrated (4.3 %) for Withaferin A; a steroidal lactone that inhibits cancer cells Vanden Berghe et al. (Cancer Epidemiol Biomark Prev 23: 1985-1996, 2014). We hypothesized that AshwaMAX could treat GBM and that bioluminescence imaging (BLI) could track oral therapy in orthotopic murine models of glioblastoma. Human parietal-cortical glioblastoma cells (GBM2, GBM39) were isolated from primary tumors while U87-MG was obtained commercially. GBM2 was transduced with lentiviral vectors that express Green Fluorescent Protein (GFP)/firefly luciferase fusion proteins. Mutational, expression and proliferative status of GBMs were studied. Intracranial xenografts of glioblastomas were grown in the right frontal regions of female, nude mice (n = 3-5 per experiment). Tumor growth was followed through BLI. Neurosphere cultures (U87-MG, GBM2 and GBM39) were inhibited by AshwaMAX at IC50 of 1.4, 0.19 and 0.22 µM equivalent respectively and by Withaferin A with IC50 of 0.31, 0.28 and 0.25 µM respectively. Oral gavage, every other day, of AshwaMAX (40 mg/kg per day) significantly reduced bioluminescence signal (n = 3 mice, p < 0.02, four parameter non-linear regression analysis) in preclinical models. After 30 days of treatment, bioluminescent signal increased suggesting onset of resistance. BLI signal for control, vehicle-treated mice increased and then plateaued. Bioluminescent imaging revealed diffuse growth of GBM2 xenografts. With AshwaMAX, GBM neurospheres collapsed at nanomolar concentrations. Oral treatment studies on murine models confirmed that AshwaMAX is effective against orthotopic GBM. AshwaMAX is thus a promising candidate for future clinical translation in patients with GBM.

  View details for DOI 10.1007/s11060-015-1972-1

  View details for Web of Science ID 000368728300005

• Pilot Preclinical and Clinical Evaluation of (4S)-4-(3-[18F]Fluoropropyl)-L-Glutamate (18F-FSPG) for PET/CT Imaging of Intracranial Malignancies. PloS one Mittra, E. S., Koglin, N., Mosci, C., Kumar, M., Hoehne, A., Keu, K. V., Iagaru, A. H., Mueller, A., Berndt, M., Bullich, S., Friebe, M., Schmitt-Willich, H., Gekeler, V., Fels, L. M., Bacher-Stier, C., Moon, D. H., Chin, F. T., Stephens, A. W., Dinkelborg, L. M., Gambhir, S. S. 2016; 11 (2)

  Abstract

  (S)-4-(3-[18F]Fluoropropyl)-L-glutamic acid (18F-FSPG) is a novel radiopharmaceutical for Positron Emission Tomography (PET) imaging. It is a glutamate analogue that can be used to measure xC- transporter activity. This study was performed to assess the feasibility of 18F-FSPG for imaging orthotopic brain tumors in small animals and the translation of this approach in human subjects with intracranial malignancies.For the small animal study, GS9L glioblastoma cells were implanted into brains of Fischer rats and studied with 18F-FSPG, the 18F-labeled glucose derivative 18F-FDG and with the 18F-labeled amino acid derivative 18F-FET. For the human study, five subjects with either primary or metastatic brain cancer were recruited (mean age 50.4 years). After injection of 300 MBq of 18F-FSPG, 3 whole-body PET/Computed Tomography (CT) scans were obtained and safety parameters were measured. The three subjects with brain metastases also had an 18F-FDG PET/CT scan. Quantitative and qualitative comparison of the scans was performed to assess kinetics, biodistribution, and relative efficacy of the tracers.In the small animals, the orthotopic brain tumors were visualized well with 18F-FSPG. The high tumor uptake of 18F-FSPG in the GS9L model and the absence of background signal led to good tumor visualization with high contrast (tumor/brain ratio: 32.7). 18F-FDG and 18F-FET showed T/B ratios of 1.7 and 2.8, respectively. In the human pilot study, 18F-FSPG was well tolerated and there was similar distribution in all patients. All malignant lesions were positive with 18F-FSPG except for one low-grade primary brain tumor. In the 18F-FSPG-PET-positive tumors a similar T/B ratio was observed as in the animal model.18F-FSPG is a novel PET radiopharmaceutical that demonstrates good uptake in both small animal and human studies of intracranial malignancies. Future studies on larger numbers of subjects and a wider array of brain tumors are planned.ClinicalTrials.gov NCT01186601.

  View details for DOI 10.1371/journal.pone.0148628

  View details for PubMedID 26890637

  View details for PubMedCentralID PMC4758607

• Multiscale Framework for Imaging Radiolabeled Therapeutics. Molecular pharmaceutics Natarajan, A., Türkcan, S., Gambhir, S. S., Pratx, G. 2015; 12 (12): 4554-4560

  Abstract

  The resistance of a tumor to a drug is the result of bulk properties of the tumor tissue as well as phenotypic variations displayed by single cells. Here, we show that radioisotopic detection methods, commonly used for tracking the tissue distribution of drug compounds, can be extended to the single-cell level to image the same molecule over a range of physical scales. The anticancer drug rituximab was labeled with short-lived radionuclides ((89)Zr/(64)Cu) and its accumulation at the organ level was imaged using PET in a humanized transgenic mouse model of non-Hodgkin's lymphoma. To capture the distribution of the drug at a finer scale, tissue sections and single living cells were imaged using radioluminescence microscopy (RLM), a novel method that can detect radionuclides with single-cell resolution. In vivo PET images (24 h postinjection) showed that [(89)Zr]rituximab targeted the intended site of human CD20 expression, the spleen. Within this organ, RLM was used to resolve radiotracer accumulation in the splenic red pulp. In a separate study, RLM highlighted marked differences between single cells, with binding of the radiolabeled antibody ranging from background levels to 1200 radionuclides per cell. Overall, RLM images demonstrated significantly higher spatial resolution and sensitivity than conventional storage-phosphor autoradiography. In conclusion, this combination of PET and RLM provides a unique opportunity for exploring the molecular mechanism of drugs by tracking the same molecule over multiple physical scales, ranging from single living cells to organs substructures and entire living subjects.

  View details for DOI 10.1021/acs.molpharmaceut.5b00392

  View details for PubMedID 26460685

• Dynamic Noninvasive Genomic Monitoring for Outcome Prediction in Diffuse Large B-Cell Lymphoma Kurtz, D. M., Scherer, F., Newman, A. M., Lovejoy, A. F., Klass, D. M., Chabon, J. J., Gambhir, S., Diehn, M., Alizadeh, A. A. AMER SOC HEMATOLOGY. 2015

  View details for Web of Science ID 000368019000194

• Further validation to support clinical translation of [(18)F]FTC-146 for imaging sigma-1 receptors. EJNMMI research Shen, B., James, M. L., Andrews, L., Lau, C., Chen, S., Palner, M., Miao, Z., Arksey, N. C., Shuhendler, A. J., Scatliffe, S., Kaneshige, K., Parsons, S. M., McCurdy, C. R., Salehi, A., Gambhir, S. S., Chin, F. T. 2015; 5 (1): 49-?

  Abstract

  This study aims to further evaluate the specificity and selectivity of [(18)F]FTC-146 and obtain additional data to support its clinical translation.The binding of [(19)F]FTC-146 to vesicular acetylcholine transporter (VAChT) was evaluated using [(3)H]vesamicol and PC12(A123.7) cells in an in vitro binding assay. The uptake and kinetics of [(18)F]FTC-146 in S1R-knockout mice (S1R-KO) compared to wild-type (WT) littermates was assessed using dynamic positron emission tomography (PET) imaging. Ex vivo autoradiography and histology were conducted using a separate cohort of S1R-KO/WT mice, and radiation dosimetry was calculated from WT mouse data (extrapolated for human dosing). Toxicity studies in Sprague-Dawley rats were performed with a dose equivalent to 250× the anticipated clinical dose of [(19)F]FTC-146 mass.VAChT binding assay results verified that [(19)F]FTC-146 displays negligible affinity for VAChT (K i = 450 ± 80 nM) compared to S1R. PET images demonstrated significantly higher tracer uptake in WT vs. S1R-KO brain (4.57 ± 1.07 vs. 1.34 ± 0.4 %ID/g at 20-25 min, n = 4, p < 0.05). In S1R-KO mice, it was shown that rapid brain uptake and clearance 10 min post-injection, which are consistent with previous S1R-blocking studies in mice. Three- to fourfold higher tracer uptake was observed in WT relative to S1R-KO mouse brains by ex vivo autoradiography. S1R staining coincided well with the autoradiographic data in all examined brain regions (r (2) = 0.85-0.95). Biodistribution results further demonstrated high [(18)F]FTC-146 accumulation in WT relative to KO mouse brain and provided quantitative information concerning tracer uptake in S1R-rich organs (e.g., heart, lung, pancreas) for WT mice vs. age-matched S1R-KO mice. The maximum allowed dose per scan in humans as extrapolated from mouse dosimetry was 33.19 mCi (1228.03 MBq). No significant toxicity was observed even at a 250X dose of the maximum carrier mass [(19)F]FTC-146 expected to be injected for human studies.Together, these data indicate that [(18)F]FTC-146 binds specifically to S1Rs and is a highly promising radiotracer ready for clinical translation to investigate S1R-related diseases.

  View details for DOI 10.1186/s13550-015-0122-2

  View details for PubMedID 26384292

  View details for PubMedCentralID PMC4573970

• Imaging patients with breast and prostate cancers using combined 18F NaF/18F FDG and TOF simultaneous PET/ MRI. EJNMMI physics Iagaru, A., Minamimoto, R., Jamali, M., Barkodhodari, A., Gambhir, S. S., Vasanawala, S. 2015; 2: A65-?

  View details for DOI 10.1186/2197-7364-2-S1-A65

  View details for PubMedID 26956325

  View details for PubMedCentralID PMC4798635

• Multiscale Framework for Imaging Radio labeled Therapeutics MOLECULAR PHARMACEUTICS Natarajan, A., Tuerkcan, S., Gambhir, S. S., Pratx, G. 2015; 12 (12): 4554-4560

  View details for DOI 10.1021/acs.molpharmaceur.5b00392

  View details for Web of Science ID 000366151500036

  View details for PubMedID 26460685

• Prospective Comparison of 99mTc-MDP Scintigraphy, Combined 18F-NaF and 18F-FDG PET/CT, and Whole-Body MRI in Patients with Breast and Prostate Cancer. Journal of nuclear medicine Minamimoto, R., Loening, A., Jamali, M., Barkhodari, A., Mosci, C., Jackson, T., Obara, P., Taviani, V., Gambhir, S. S., Vasanawala, S., Iagaru, A. 2015; 56 (12): 1862-1868

  Abstract

  We prospectively evaluated the combined (18)F-NaF/(18)F-FDG PET/CT in patients with breast and prostate cancers, and compared the results to (99m)Tc MDP bone scintigraphy (BS) and whole-body MRI (WBMRI).30 patients (15 women with breast cancer and 15 men with prostate cancer) referred for standard of care BS were prospectively enrolled in this study. (18)F-NaF/(18)F-FDG PET/CT and WBMRI were performed following BS. WBMRI protocol consisted of both non-contrast enhanced and contrast enhanced sequences. Lesions detected with each test were tabulated and the results were compared.For extra skeletal lesions, (18)F-/(18)F-FDG PET/CT and WBMRI had no statistically significant differences in sensitivity (92.9% vs 92.9%, P = 1.00), PPV (81.3% vs 86.7%, P = 0.68) and accuracy (76.5% vs 82.4%, P = 0.56). However, (18)F-/(18)F-FDG PET/CT showed significantly higher sensitivity and accuracy than WBMRI (96.2% vs 81.4%, P<0.001, 89.8% vs 74.7%, P = 0.01) and BS (96.2% vs 64.6%, P<0.001, 89.8% vs 65.9%, P<0.001) for the detection of skeletal lesions. Overall, (18)F-/(18)F-FDG PET/CT showed higher sensitivity and accuracy than WBMRI (95.7% vs 83.3%, P<0.002, 87.6% vs 76.0%, P< 0.02), but not statistically significant when compared to a combination of WBMRI and BS (95.7% vs 91.6%, P = 0.17, 87.6% vs 83.0%, P = 0.53). (18)F-/(18)F-FDG PET/CT showed no significant difference with a combination of (18)F-/(18)F-FDG PET/CT and WBMRI. No statistically significant differences in PPV were noted among the 3 examinations.The (18)F NaF/(18)F FDG PET/CT is superior to WBMRI and (99m)Tc-MDP scintigraphy for evaluation of skeletal disease extent. Further, (18)F NaF/(18)F FDG PET/CT and WBMRI detected extra-skeletal disease that may change the management of these patients. The (18)F NaF/(18)F FDG PET/CT provide similar diagnostic ability with combination of WBMRI and BS in patients with breast and prostate cancers. Larger cohorts are needed in order to confirm these preliminary findings, ideally using the newly introduced simultaneous PET/MRI scanners.

  View details for DOI 10.2967/jnumed.115.162610

  View details for PubMedID 26405167

• Photoacoustic Tomography Detects Early Vessel Regression and Normalization During Ovarian Tumor Response to the Antiangiogenic Therapy Trebananib. Journal of nuclear medicine Bohndiek, S. E., Sasportas, L. S., Machtaler, S., Jokerst, J. V., Hori, S., Gambhir, S. S. 2015; 56 (12): 1942-1947

  Abstract

  The primary aim of this study was to assess the potential of in vivo photoacoustic tomography (PAT) for direct functional measurement of ovarian tumor response to anti-angiogenic therapy.In vivo studies were performed with institutional animal care and use committee approval. We used an orthotopic mouse model of ovarian cancer treated with Trebananib (n = 9) or vehicle (n = 9). Tumor-bearing mice were randomized into Trebananib or vehicle groups at day 10 and dosed on days 12, 15 and 18 post implantation. PAT and blood draws were performed at day 10, then 24 hours after each drug dose. Tumors were excised for histopathology following the final studies on day 19. Data analysis to test for statistical significance was performed blinded.Blockade of angiopoietin signaling using Trebananib resulted in reduced total hemoglobin-weighted PA signal (n = 9, P = 0.01) and increased oxyhemoglobin-weighted PA signal (n = 9, P<0.01). The latter observation indicated normalization of the residual tumor vessels, which was also implied by low levels of angiopoietin 1 in serum biomarker profiling (0.76±0.12ng/mL). These non-invasive measures reflected a 30% reduction in microvessel density and increased vessel maturation in ex vivo sections.PAT is able to evaluate both vessel regression and normalization in response to Trebananib. Non-invasive imaging data was supported by modulation of serum markers in vitro and ex vivo histopathology.

  View details for DOI 10.2967/jnumed.115.160002

  View details for PubMedID 26315834

• (18)F-FPRGD2 PET/CT imaging of musculoskeletal disorders. Annals of nuclear medicine Withofs, N., Charlier, E., Simoni, P., Alvarez-Miezentseva, V., Mievis, F., Giacomelli, F., Mella, C., Gambhir, S. S., Malaise, O., de Seny, D., Malaise, M., Hustinx, R. 2015; 29 (10): 839-847

  Abstract

  This work reports on musculoskeletal uptake of (18)F-FPRGD2, targeting the integrin αvβ3, in patients who had undergone (18)F-FPRGD2 positron emission tomography combined with computed tomography (PET/CT) for oncologic purposes.Whole-body (18)F-FPRGD2 PET/CT images of 62 cancer patients were retrospectively reviewed to detect foci of musculoskeletal (18)F-FPRGD2 uptake. For 37 patients, a FDG PET/CT performed in clinical settings was available. In each joint with an abnormal uptake, the maximum standardized uptake value (SUVmax) was estimated.A total of 260 musculoskeletal foci of (18)F-FPRGD2 uptake were detected. Most common sites of uptake were joints and discs (n = 160; 61.5 %), entheses (osteotendinous and osteoligamentous junctions; n = 55; 21.2 %) and recent fractures (n = 18; 6.9 %). In addition, 27 (10.4 %) miscellaneous foci were detected. Out of the 146 lesions for which a FDG PET was available, 63 % showed both (18)F-FPRGD2 and FDG uptake, 33.6 % did not show FDG avidity and 3.4 % showed only FDG uptake. The uptake intensity of the 92 lesions positive with (18)F-FPRGD2 and FDG was similar with both radiopharmaceuticals, but the target-to-background (blood pool or muscle) ratios were significantly higher with (18)F-FPRGD2 than with FDG (p < 0.0001).The (18)F-FPRGD2 uptake in joints, spine degenerative diseases and tendons was highly prevalent in our population. Up to one-third of (18)F-FPRGD2 foci showed no FDG uptake suggesting that (18)F-FPRGD2 signal may not be related to inflammatory angiogenesis only.

  View details for DOI 10.1007/s12149-015-1011-5

  View details for PubMedID 26254227

• Engineering high-affinity PD-1 variants for optimized immunotherapy and immuno-PET imaging. Proceedings of the National Academy of Sciences of the United States of America Maute, R. L., Gordon, S. R., Mayer, A. T., McCracken, M. N., Natarajan, A., Ring, N. G., Kimura, R., Tsai, J. M., Manglik, A., Kruse, A. C., Gambhir, S. S., Weissman, I. L., Ring, A. M. 2015; 112 (47): E6506-14

  Abstract

  Signaling through the immune checkpoint programmed cell death protein-1 (PD-1) enables tumor progression by dampening antitumor immune responses. Therapeutic blockade of the signaling axis between PD-1 and its ligand programmed cell death ligand-1 (PD-L1) with monoclonal antibodies has shown remarkable clinical success in the treatment of cancer. However, antibodies have inherent limitations that can curtail their efficacy in this setting, including poor tissue/tumor penetrance and detrimental Fc-effector functions that deplete immune cells. To determine if PD-1:PD-L1-directed immunotherapy could be improved with smaller, nonantibody therapeutics, we used directed evolution by yeast-surface display to engineer the PD-1 ectodomain as a high-affinity (110 pM) competitive antagonist of PD-L1. In contrast to anti-PD-L1 monoclonal antibodies, high-affinity PD-1 demonstrated superior tumor penetration without inducing depletion of peripheral effector T cells. Consistent with these advantages, in syngeneic CT26 tumor models, high-affinity PD-1 was effective in treating both small (50 mm(3)) and large tumors (150 mm(3)), whereas the activity of anti-PD-L1 antibodies was completely abrogated against large tumors. Furthermore, we found that high-affinity PD-1 could be radiolabeled and applied as a PET imaging tracer to efficiently distinguish between PD-L1-positive and PD-L1-negative tumors in living mice, providing an alternative to invasive biopsy and histological analysis. These results thus highlight the favorable pharmacology of small, nonantibody therapeutics for enhanced cancer immunotherapy and immune diagnostics.

  View details for DOI 10.1073/pnas.1519623112

  View details for PubMedID 26604307

  View details for PubMedCentralID PMC4664306

• Glioblastoma Multiforme Recurrence: An Exploratory Study of F-18 FPPRGD(2) PET/CT1 RADIOLOGY Iagaru, A., Mosci, C., Mittra, E., Zaharchuk, G., Fischbein, N., Harsh, G., Li, G., Nagpal, S., Recht, L., Gambhir, S. S. 2015; 277 (2): 497-506

  Abstract

  Purpose To prospectively evaluate fluorine 18 ((18)F) 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2) positron emission tomography (PET) in patients with glioblastoma multiforme (GBM). Materials and Methods The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. (18)F FPPRGD2 uptake was measured semiquantitatively in the form of maximum standardized uptake values (SUVmax) and uptake volumes before and after treatment with bevacizumab. Vital signs and laboratory results were collected before, during, and after the examinations. A nonparametric version of multivariate analysis of variance was used to assess safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare SUVmax. Results A total of 17 participants (eight men, nine women; age range, 25-65 years) were enrolled prospectively. (18)F FPPRGD2 PET/computed tomography (CT), (18)F fluorodeoxyglucose (FDG) PET/CT, and brain magnetic resonance (MR) imaging were performed within 3 weeks, prior to the start of bevacizumab therapy. In eight of the 17 patients (47%), (18)F FPPRGD2 PET/CT was repeated 1 week after the start of bevacizumab therapy; six patients (35%) underwent (18)F FPPRGD2 PET/CT a third time 6 weeks after starting bevacizumab therapy. There were no changes in vital signs, electrocardiographic findings, or laboratory values that qualified as adverse events. One patient (6%) had recurrent GBM identified only on (18)F FPPRGD2 PET images, and subsequent MR images enabled confirmation of recurrence. Of the 17 patients, 14 (82%) had recurrent GBM identified on (18)F FPPRGD2 PET and brain MR images, while (18)F FDG PET enabled identification of recurrence in 13 (76%) patients. Two patients (12%) had no recurrent GBM. Conclusion (18)F FPPRGD2 is a safe PET radiopharmaceutical that has increased uptake in GBM lesions. Larger cohorts are required to confirm these preliminary findings. (©) RSNA, 2015 Online supplemental material is available for this article.

  View details for DOI 10.1148/radiol.2015141550

  View details for Web of Science ID 000368435100026

• Biodistribution of the (18)F-FPPRGD2 PET radiopharmaceutical in cancer patients: an atlas of SUV measurements. European journal of nuclear medicine and molecular imaging Minamimoto, R., Jamali, M., Barkhodari, A., Mosci, C., Mittra, E., Shen, B., Chin, F., Gambhir, S. S., Iagaru, A. 2015; 42 (12): 1850-1858

  Abstract

  The aim of this study was to investigate the biodistribution of 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) ((18)F-FPPRGD2) in cancer patients and to compare its uptake in malignant lesions with (18)F-FDG uptake.A total of 35 patients (11 men, 24 women, mean age 52.1 ± 10.8 years) were enrolled prospectively and had (18)F-FPPRGD2 PET/CT prior to treatment. Maximum standardized uptake values (SUVmax) and mean SUV (SUVmean) were measured in 23 normal tissues in each patient, as well as in known or suspected cancer lesions. Differences between (18)F-FPPRGD2 uptake and (18)F-FDG uptake were also evaluated in 28 of the 35 patients.Areas of high (18)F-FPPRGD2 accumulation (SUVmax range 8.9 - 94.4, SUVmean range 7.1 - 64.4) included the bladder and kidneys. Moderate uptake (SUVmax range 2.1 - 6.3, SUVmean range 1.1 - 4.5) was found in the choroid plexus, salivary glands, thyroid, liver, spleen, pancreas, small bowel and skeleton. Compared with (18)F-FDG, (18)F-FPPRGD2 showed higher tumor-to-background ratio in brain lesions (13.4 ± 8.5 vs. 1.1 ± 0.5, P < 0.001), but no significant difference in body lesions (3.2 ± 1.9 vs. 4.4 ± 4.2, P = 0.10). There was no significant correlation between the uptake values (SUVmax and SUVmean) for (18)F FPPRGD2 and those for (18)F-FDG.The biodistribution of (18)F-FPPRGD2 in cancer patients is similar to that of other RGD dimer peptides and it is suitable for clinical use. The lack of significant correlation between (18)F-FPPRGD2 and (18)F-FDG uptake confirms that the information provided by each PET tracer is different.

  View details for DOI 10.1007/s00259-015-3096-4

  View details for PubMedID 26062933

• Novel Radiotracer for ImmunoPET Imaging of PD-1 Checkpoint Expression on Tumor Infiltrating Lymphocytes. Bioconjugate chemistry Natarajan, A., Mayer, A. T., Xu, L., Reeves, R. E., Gano, J., Gambhir, S. S. 2015; 26 (10): 2062-2069

  Abstract

  Immune checkpoint signaling through the programmed death 1 (PD-1) axis to its ligand (PD-L1) significantly dampens anti-tumor immune responses. Cancer patients treated with checkpoint inhibitors that block this suppressive signaling have exhibited objective response rates of 20-40% for advanced solid tumors, lymphomas, and malignant melanomas. This represents a tremendous advance in cancer treatment. Unfortunately, all patients do not respond to immune checkpoint blockade. Recent findings suggest that patients with tumor infiltrating lymphocytes (TILs) expressing PD-1 may be most likely to respond to αPD-1/PD-L1 checkpoint inhibitors. There is a compelling need for diagnostic and prognostic imaging tools to assess the PD-1 status of TILs in vivo. Here we have developed a novel immunoPET tracer to image PD-1 expressing TILs in a transgenic mouse model bearing melanoma. A (64)Cu labeled anti-mouse antibody (IgG) PD-1 immuno positron emission tomography (PET) tracer was developed to detect PD-1 expressing murine TILs. Quality control of the tracer showed >95% purity by HPLC and >70% immunoreactivity in an in vitro cell binding assay. ImmunoPET scans were performed over 1-48 h on Foxp3+.LuciDTR4 mice bearing B16-F10 melanoma tumors. Mice receiving anti-PD-1 tracer (200 ± 10 μCi/10-12 μg/200 μL) revealed high tracer uptake in lymphoid organs and tumors. BLI images of FoxP3(+) CD4(+) Tregs known to express PD-1 confirmed lymphocyte infiltration of tumors at the time of PET imaging. Biodistribution measurements performed at 48 h revealed a high (11×) tumor to muscle uptake ratio of the PET tracer (p < 0.05). PD-1 tumors exhibited 7.4 ± 0.7%ID/g tracer uptake and showed a 2× fold signal decrease when binding was blocked by unlabeled antibody. To the best of our knowledge this data is the first report to image PD-1 expression in living subjects with PET. This radiotracer has the potential to assess the prognostic value of PD-1 in preclinical models of immunotherapy and may ultimately aid in predicting response to therapies targeting immune checkpoints.

  View details for DOI 10.1021/acs.bioconjchem.5b00318

  View details for PubMedID 26307602

• PET imaging of tumor glycolysis downstream of hexokinase through noninvasive measurement of pyruvate kinase M2. Science translational medicine Witney, T. H., James, M. L., Shen, B., Chang, E., Pohling, C., Arksey, N., Hoehne, A., Shuhendler, A., Park, J., Bodapati, D., Weber, J., Gowrishankar, G., Rao, J., Chin, F. T., Gambhir, S. S. 2015; 7 (310): 310ra169-?

  Abstract

  Cancer cells reprogram their metabolism to meet increased biosynthetic demands, commensurate with elevated rates of replication. Pyruvate kinase M2 (PKM2) catalyzes the final and rate-limiting step in tumor glycolysis, controlling the balance between energy production and the synthesis of metabolic precursors. We report here the synthesis and evaluation of a positron emission tomography (PET) radiotracer, [(11)C]DASA-23, that provides a direct noninvasive measure of PKM2 expression in preclinical models of glioblastoma multiforme (GBM). In vivo, orthotopic U87 and GBM39 patient-derived tumors were clearly delineated from the surrounding normal brain tissue by PET imaging, corresponding to exclusive tumor-associated PKM2 expression. In addition, systemic treatment of mice with the PKM2 activator TEPP-46 resulted in complete abrogation of the PET signal in intracranial GBM39 tumors. Together, these data provide the basis for the clinical evaluation of imaging agents that target this important gatekeeper of tumor glycolysis.

  View details for DOI 10.1126/scitranslmed.aac6117

  View details for PubMedID 26491079

• Diketopyrrolopyrrole-Based Semiconducting Polymer Nanoparticles for In Vivo Photoacoustic Imaging. Advanced materials Pu, K., Mei, J., Jokerst, J. V., Hong, G., Antaris, A. L., Chattopadhyay, N., Shuhendler, A. J., Kurosawa, T., Zhou, Y., Gambhir, S. S., Bao, Z., Rao, J. 2015; 27 (35): 5184-5190

  Abstract

  Diketopyrrolopyrrole-based semiconducting polymer nanoparticles with high photostability and strong photoacoustic brightness are designed and synthesized, which results in 5.3-fold photoacoustic signal enhancement in tumor xenografts after systemic administration.

  View details for DOI 10.1002/adma.201502285

  View details for PubMedID 26247171

  View details for PubMedCentralID PMC4567488

• 18F-FDG PET Imaging Utilization in the National Lung Screening Trial Nair, V. S., Sundaram, V., Gould, M. K., Gambhir, S. S., Desai, M. ELSEVIER SCIENCE INC. 2015: S396–S397

  View details for Web of Science ID 000370365101407

• A Systematic Comparison of 18F-C-SNAT to Established Radiotracer Imaging Agents for the Detection of Tumor Response to Treatment. Clinical cancer research Witney, T. H., Hoehne, A., Reeves, R. E., Ilovich, O., Namavari, M., Shen, B., Chin, F. T., Rao, J., Gambhir, S. S. 2015; 21 (17): 3896-3905

  Abstract

  An early readout of tumor response to therapy through measurement of drug or radiation-induced cell death may provide important prognostic indications and improved patient management. It has been shown that the uptake of (18)F-C-SNAT can be used to detect early response to therapy in tumors by positron emission tomography (PET) via a mechanism of caspase-3-triggered nanoaggregation.Here, we compared the preclinical utility of (18)F-C-SNAT for the detection of drug-induced cell death to clinically evaluated radiotracers, (18)F-FDG, (99m)Tc-Annexin V, and (18)F-ML-10 in tumor cells in culture, and in tumor-bearing mice in vivo.In drug-treated lymphoma cells, (18)F-FDG, (99m)Tc-Annexin V, and (18)F-C-SNAT cell-associated radioactivity correlated well to levels of cell death (R(2) > 0.8; P < 0.001), with no correlation measured for (18)F-ML-10 (R(2) = 0.05; P > 0.05). A similar pattern of response was observed in two human NSCLC cell lines following carboplatin treatment. EL-4 tumor uptake of (99m)Tc-Annexin V and (18)F-C-SNAT were increased 1.4- and 2.1-fold, respectively, in drug-treated versus naïve control animals (P < 0.05), although (99m)Tc-Annexin V binding did not correlate to ex vivo TUNEL staining of tissue sections. A differential response was not observed with either (18)F-FDG or (18)F-ML-10.We have demonstrated here that (18)F-C-SNAT can sensitively detect drug-induced cell death in murine lymphoma and human NSCLC. Despite favorable image contrast obtained with (18)F-C-SNAT, the development of next-generation derivatives, using the same novel and promising uptake mechanism, but displaying improved biodistribution profiles, are warranted for maximum clinical utility. Clin Cancer Res; 21(17); 3896-905. ©2015 AACR.

  View details for DOI 10.1158/1078-0432.CCR-14-3176

  View details for PubMedID 25972517

  View details for PubMedCentralID PMC4558304

• Androgen Receptor Splice Variants Dimerize to Transactivate Target Genes CANCER RESEARCH Xu, D., Zhan, Y., Qi, Y., Cao, B., Bai, S., Xu, W., Gambhir, S. S., Lee, P., Sartor, O., Flemington, E. K., Zhang, H., Hu, C., Dong, Y. 2015; 75 (17): 3663-3671

  Abstract

  Constitutively active androgen receptor splice variants (AR-V) lacking the ligand-binding domain have been implicated in the pathogenesis of castration-resistant prostate cancer and in mediating resistance to newer drugs that target the androgen axis. AR-V regulates expression of both canonical AR targets and a unique set of cancer-specific targets that are enriched for cell-cycle functions. However, little is known about how AR-V controls gene expression. Here, we report that two major AR-Vs, termed AR-V7 and AR(v567es), not only homodimerize and heterodimerize with each other but also heterodimerize with full-length androgen receptor (AR-FL) in an androgen-independent manner. We found that heterodimerization of AR-V and AR-FL was mediated by N- and C-terminal interactions and by the DNA-binding domain of each molecule, whereas AR-V homodimerization was mediated only by DNA-binding domain interactions. Notably, AR-V dimerization was required to transactivate target genes and to confer castration-resistant cell growth. Our results clarify the mechanism by which AR-Vs mediate gene regulation and provide a pivotal pathway for rational drug design to disrupt AR-V signaling as a rational strategy for the effective treatment of advanced prostate cancer.

  View details for DOI 10.1158/0008-5472.CAN-15-0381

  View details for Web of Science ID 000361917100021

  View details for PubMedID 26060018

  View details for PubMedCentralID PMC4558376

• Combined F-18-NaF and F-18-FDG PET/CT in the Evaluation of Sarcoma Patients CLINICAL NUCLEAR MEDICINE Jackson, T., Mosci, C., von Eyben, R., Mittra, E., Ganjoo, K., Biswal, S., Gambhir, S. S., Iagaru, A. 2015; 40 (9): 720-724

  Abstract

  The combined administration of F-NaF and F-FDG in a single PET/CT scan has the potential to improve patient convenience and cancer detection. Here we report the use of this approach for patients with sarcomas.This is a retrospective review of 21 patients (12 men, 9 women; age, 19-66 years) with biopsy-proven sarcomas who had separate F-NaF PET/CT, F-FDG PET/CT, and combined F-NaF/F-FDG PET/CT scans for evaluation of malignancy. Two board-certified nuclear medicine physicians and 1 board-certified musculoskeletal radiologist were randomly assigned to review the scans. Results were analyzed for sensitivity and specificity, using linear regression and receiver operating characteristics.A total of 13 patients had metastatic disease on F-NaF PET/CT, F-FDG PET/CT, and combined F-NaF/F-FDG PET/CT. Skeletal disease was more extensive on the F-NaF PET/CT scan than on the F-FDG PET/CT in 3 patients, whereas in 1 patient, F-FDG PET/CT showed skeletal disease and the F-NaF PET/CT was negative. Extraskeletal lesions were detected on both F-FDG and combined F-NaF/F-FDG PET/CT in 20 patients, with 1 discordant finding in the lung.The combined F-NaF/F-FDG PET/CT scan allows for accurate evaluation of sarcoma patients. Further evaluation of this proposed imaging modality is warranted to identify the most suitable clinical scenarios, including initial treatment strategy and evaluation of response to therapy.

  View details for DOI 10.1097/RLU.0000000000000845

  View details for Web of Science ID 000359668600005

  View details for PubMedID 26053718

• Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics. Proceedings of the National Academy of Sciences of the United States of America Inci, F., Filippini, C., Baday, M., Ozen, M. O., Calamak, S., Durmus, N. G., Wang, S., Hanhauser, E., Hobbs, K. S., Juillard, F., Kuang, P. P., Vetter, M. L., Carocci, M., Yamamoto, H. S., Takagi, Y., Yildiz, U. H., Akin, D., Wesemann, D. R., Singhal, A., Yang, P. L., Nibert, M. L., Fichorova, R. N., Lau, D. T., Henrich, T. J., Kaye, K. M., Schachter, S. C., Kuritzkes, D. R., Steinmetz, L. M., Gambhir, S. S., Davis, R. W., Demirci, U. 2015; 112 (32): E4354-63

  Abstract

  Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE(2)RD), which addresses all these impediments on a single platform. The NE(2)RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE(2)RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE(2)RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients' homes.

  View details for DOI 10.1073/pnas.1510824112

  View details for PubMedID 26195743

  View details for PubMedCentralID PMC4538635

• Radiation Dosimetry Study of [(89)Zr]rituximab Tracer for Clinical Translation of B cell NHL Imaging using Positron Emission Tomography. Molecular imaging and biology Natarajan, A., Gambhir, S. S. 2015; 17 (4): 539-547

  Abstract

  We evaluated the dosimetry of [(89)Zr]rituximab, an anti-CD20 immunoPET tracer to image B cell non-Hodgkin's lymphoma (NHL) using a humanized transgenic mouse model that expresses human CD20 transgenic mice (huCD20TM).Rituximab was conjugated to desferrioxamine (Df) for radiolabeling of Zirconium-89. [(89)Zr]rituximab (2.8 ± 0.2 MBq) was tail vein-injected into huCD20T mice. Positron emission tomography (PET)/CT imaging was performed on the two groups of mice (blocking = 2 mg/kg pre-dose of rituximab and non-blocking; n = 5) at eight time points (1, 4, 24, 48, 72, 96, 120, and 168 h) post injection.The novel [(89)Zr]rituximab PET tracer had good immunoreactivity, was stable in human serum, and was able to specifically target human CD20 in mice. The human equivalents of highest dose (mean ± SD) organs with and without pre-dose are liver (345 ± 284 μSv/MBq) and spleen (1165 ± 149 μSv/MBq), respectively.Dosimetry of the human patient whole-body dose was found to be 145 MBq per annum, and the patient dose-limiting organ will be the liver (with rituximab pre-dose blocking) and spleen for non-blocking. The [(89)Zr]rituximab (t½ = 78.4 h) imaging of B cell NHL patients could permit the observation of targeting lesions in NHL patients over an extended period due to longer half-life as compared to the [(64)Cu] rituximab (t½ = 12.7 h).

  View details for DOI 10.1007/s11307-014-0810-8

  View details for PubMedID 25500766

  View details for PubMedCentralID PMC4465424

• Gene expression profiling of individual circulating tumor cells from non-small cell lung cancer (NSCLC) patients via integrated nanotechnologies Park, S., Wong, D. J., Ooi, C., Nair, V. S., Vermesh, O., Lee, S., Suh, S., Lee, L. P., Wang, S. X., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2015

  View details for DOI 10.1158/1538-7445.AM2015-LB-280

  View details for Web of Science ID 000371597100372

• Isolation and Characterization of a Monobody with a Fibronectin Domain III Scaffold That Specifically Binds EphA2 PLOS ONE Park, S., Park, S., Kim, D., Pyo, A., Kimura, R. H., Sathirachinda, A., Choy, H. E., Min, J., Gambhir, S. S., Hong, Y. 2015; 10 (7)

  Abstract

  Monobodies are binding scaffold proteins originating from a human fibronectin domain III (Fn3) scaffold that can be easily engineered with specificity and affinity. Human EphA2 (hEphA2) is an early detection marker protein for various tumors including lung, breast, and colon cancer. In this study, we isolated two hEphA2-specific monobodies (E1 and E10) by screening a yeast surface display library. They showed the same amino acid sequence except in the DE loop and had high affinity (~2 nM Kd) against hEphA2. E1 bound only hEphA2 and mEphA2, although it bound hEphA2 with an affinity 2-fold higher than that of mEphA2. However, E10 also bound the mEphA6 and mEphA8 homologs as well as hEphA2 and mEphA2. Thus, E1 but not E10 was highly specific for hEphA2. E1 specifically bound human cells and xenograft tumor tissues expressing hEphA on the cell surface. In vivo optical imaging showed strong targeting of Cy5.5-labeled E1 to mouse tumor tissue induced by PC3 cells, a human prostate cancer cell line that expresses a high level of hEphA2. In conclusion, the highly specific monobody E1 is useful as a hEphA2 probe candidate for in vivo diagnosis and therapy.

  View details for DOI 10.1371/journal.pone.0132976

  View details for Web of Science ID 000358197600194

  View details for PubMedCentralID PMC4503726

• Development and Validation of an Immuno-PET Tracer as a Companion Diagnostic Agent for Antibody-Drug Conjugate Therapy to Target the CA6 Epitope. Radiology Ilovich, O., Natarajan, A., Hori, S., Sathirachinda, A., Kimura, R., Srinivasan, A., Gebauer, M., Kruip, J., Focken, I., Lange, C., Carrez, C., Sassoon, I., Blanc, V., Sarkar, S. K., Gambhir, S. S. 2015; 276 (1): 191-198

  Abstract

  Purpose To develop and compare three copper 64 ((64)Cu)-labeled antibody fragments derived from a CA6-targeting antibody (huDS6) as immuno-positron emission tomography (immuno-PET)-based companion diagnostic agents for an antibody-drug conjugate by using huDS6. Materials and Methods Three antibody fragments derived from huDS6 were produced, purified, conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and evaluated in the following ways: (a) the affinity of the fragments and the DOTA conjugates was measured via flow cytometry, (b) the stability of the labeled fragments was determined ex vivo in human serum over 24 hours, and (c) comparison of the in vivo imaging potential of the fragments was evaluated in mice bearing subcutaneous CA6-positive and CA6-negative xenografts by using serial PET imaging and biodistribution. Isotype controls with antilysozyme and anti-DM4 B-Fabs and blocking experiments with an excess of either B-Fab or huDS6 were used to determine the extent of the antibody fragment (64)Cu-DOTA-B-Fab binding specificity. Immunoreactivity and tracer kinetics were evaluated by using cellular uptake and 48-hour imaging experiments, respectively. Statistical analyses were performed by using t tests, one-way analysis of variance, and Wilcoxon and Mann-Whitney tests. Results The antibody fragment (64)Cu-DOTA-B-Fab was more than 95% stable after 24 hours in human serum, had an immunoreactivity of more than 70%, and allowed differentiation between CA6-positive and CA6-negative tumors in vivo as early as 6 hours after injection, with a 1.7-fold uptake ratio between tumors. Isotype and blocking studies experiments showed tracer-specific uptake in antigen-positive tumors, despite some nonspecific uptake in both tumor models. Conclusion Three antibody fragments were produced and examined as potential companion diagnostic agents. (64)Cu-DOTA-B-Fab is a stable and effective immuno-PET tracer for CA6 imaging in vivo. (©) RSNA, 2015 Online supplemental material is available for this article.

  View details for DOI 10.1148/radiol.15140058

  View details for PubMedID 25734548

• Early detection of sporadic pancreatic cancer: summative review. Pancreas Chari, S. T., Kelly, K., Hollingsworth, M. A., Thayer, S. P., Ahlquist, D. A., Andersen, D. K., Batra, S. K., Brentnall, T. A., Canto, M., Cleeter, D. F., Firpo, M. A., Gambhir, S. S., Go, V. L., Hines, O. J., Kenner, B. J., Klimstra, D. S., Lerch, M. M., Levy, M. J., Maitra, A., Mulvihill, S. J., Petersen, G. M., Rhim, A. D., Simeone, D. M., Srivastava, S., Tanaka, M., Vinik, A. I., Wong, D. 2015; 44 (5): 693-712

  Abstract

  Pancreatic cancer (PC) is estimated to become the second leading cause of cancer death in the United States by 2020. Early detection is the key to improving survival in PC. Addressing this urgent need, the Kenner Family Research Fund conducted the inaugural Early Detection of Sporadic Pancreatic Cancer Summit Conference in 2014 in conjunction with the 45th Anniversary Meeting of the American Pancreatic Association and Japan Pancreas Society. This seminal convening of international representatives from science, practice, and clinical research was designed to facilitate challenging interdisciplinary conversations to generate innovative ideas leading to the creation of a defined collaborative strategic pathway for the future of the field. An in-depth summary of current efforts in the field, analysis of gaps in specific areas of expertise, and challenges that exist in early detection is presented within distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. In addition, an overview of efforts in familial PC is presented in an addendum to this article. It is clear from the summit deliberations that only strategically designed collaboration among investigators, institutions, and funders will lead to significant progress in early detection of sporadic PC.

  View details for DOI 10.1097/MPA.0000000000000368

  View details for PubMedID 25931254

  View details for PubMedCentralID PMC4467589

• Early Detection of Sporadic Pancreatic Cancer Summative Review PANCREAS Chari, S. T., Kelly, K., Hollingsworth, M. A., Thayer, S. P., Ahlquist, D. A., Andersen, D. K., Batra, S. K., Brentnall, T. A., Canto, M., Cleeter, D. F., Firpo, M. A., Gambhir, S. S., Go, V. L., Hines, O. J., Kenner, B. J., Klimstra, D. S., Lerch, M. M., Levy, M. J., Maitra, A., Mulvihill, S. J., Petersen, G. M., Rhim, A. D., Simeone, D. M., Srivastava, S., Tanaka, M., Vinik, A. I., Wong, D. 2015; 44 (5): 693-712

  Abstract

  Pancreatic cancer (PC) is estimated to become the second leading cause of cancer death in the United States by 2020. Early detection is the key to improving survival in PC. Addressing this urgent need, the Kenner Family Research Fund conducted the inaugural Early Detection of Sporadic Pancreatic Cancer Summit Conference in 2014 in conjunction with the 45th Anniversary Meeting of the American Pancreatic Association and Japan Pancreas Society. This seminal convening of international representatives from science, practice, and clinical research was designed to facilitate challenging interdisciplinary conversations to generate innovative ideas leading to the creation of a defined collaborative strategic pathway for the future of the field. An in-depth summary of current efforts in the field, analysis of gaps in specific areas of expertise, and challenges that exist in early detection is presented within distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. In addition, an overview of efforts in familial PC is presented in an addendum to this article. It is clear from the summit deliberations that only strategically designed collaboration among investigators, institutions, and funders will lead to significant progress in early detection of sporadic PC.

  View details for DOI 10.1097/MPA.0000000000000368

  View details for Web of Science ID 000360629300003

  View details for PubMedCentralID PMC4467589

• Predictive Modeling of Drug Response in Non-Hodgkin's Lymphoma PLOS ONE Frieboes, H. B., Smith, B. R., Wang, Z., Kotsuma, M., Ito, K., Day, A., Cahill, B., Flinders, C., Mumenthaler, S. M., Mallick, P., Simbawa, E., Al-Fhaid, A. S., Mahmoud, S. R., Gambhir, S. S., Cristini, V. 2015; 10 (6)

  Abstract

  We combine mathematical modeling with experiments in living mice to quantify the relative roles of intrinsic cellular vs. tissue-scale physiological contributors to chemotherapy drug resistance, which are difficult to understand solely through experimentation. Experiments in cell culture and in mice with drug-sensitive (Eµ-myc/Arf-/-) and drug-resistant (Eµ-myc/p53-/-) lymphoma cell lines were conducted to calibrate and validate a mechanistic mathematical model. Inputs to inform the model include tumor drug transport characteristics, such as blood volume fraction, average geometric mean blood vessel radius, drug diffusion penetration distance, and drug response in cell culture. Model results show that the drug response in mice, represented by the fraction of dead tumor volume, can be reliably predicted from these inputs. Hence, a proof-of-principle for predictive quantification of lymphoma drug therapy was established based on both cellular and tissue-scale physiological contributions. We further demonstrate that, if the in vitro cytotoxic response of a specific cancer cell line under chemotherapy is known, the model is then able to predict the treatment efficacy in vivo. Lastly, tissue blood volume fraction was determined to be the most sensitive model parameter and a primary contributor to drug resistance.

  View details for DOI 10.1371/journal.pone.0129433

  View details for Web of Science ID 000355979500143

  View details for PubMedID 26061425

  View details for PubMedCentralID PMC4464754

• Cu-64-Labeled Divalent Cystine Knot Peptide for Imaging Carotid Atherosclerotic Plaques JOURNAL OF NUCLEAR MEDICINE Jiang, L., Tu, Y., Kimura, R. H., Habte, F., Chen, H., Cheng, K., Shi, H., Gambhir, S. S., Cheng, Z. 2015; 56 (6): 939-944

  Abstract

  The rupture of vulnerable atherosclerotic plaques that lead to stroke and myocardial infarction may be induced by macrophage infiltration and augmented by the expression of integrin αvβ3. Indeed, atherosclerotic angiogenesis may be a promising marker of inflammation. In this study, an engineered integrin αvβ3-targeting PET probe, (64)Cu-NOTA-3-4A, derived from a divalent knottin miniprotein was evaluated in a mouse model for carotid atherosclerotic plaques.Atherosclerotic plaques in BALB/C mice, maintained on a high-fat diet, were induced with streptozotocin injection and carotid artery ligation and verified by MR imaging. Knottin 3-4A was synthesized by solid-phase peptide synthesis chemistry and coupled to 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) before radiolabeling with (64)Cu. PET probe stability in mouse serum was evaluated. Mice with carotid atherosclerotic plaques were injected via the tail vein with (64)Cu-NOTA-3-4A or (18)F-FDG, followed by small-animal PET/CT imaging at different time points. Receptor targeting specificity of the probe was verified by coinjection of c(RGDyK) administered in molar excess. Subsequently, carotid artery dissection and immunofluorescence staining were performed to evaluate target expression.(64)Cu-NOTA-3-4A was synthesized in high radiochemical purity and yield and demonstrated molecular stability in both phosphate-buffered saline and mouse serum at 4 h. Small-animal PET/CT showed that (64)Cu-NOTA-3-4A accumulated at significantly higher levels in the neovasculature of carotid atherosclerotic plaques (7.41 ± 1.44 vs. 0.67 ± 0.23 percentage injected dose/gram, P < 0.05) than healthy or normal vessels at 1 h after injection. (18)F-FDG also accumulated in atherosclerotic lesions at 0.5 and 1 h after injection but at lower plaque-to-normal tissue ratios than (64)Cu-NOTA-3-4A. For example, plaque-to-normal carotid artery ratios for (18)F-FDG and (64)Cu-NOTA-3-4A at 1 h after injection were 3.75 and 14.71 (P < 0.05), respectively. Furthermore, uptake of (64)Cu-NOTA-3-4A in atherosclerotic plaques was effectively blocked (∼90% at 1 h after injection) by coinjection of c(RGDyK). Immunostaining confirmed integrin αvβ3 expression in both the infiltrating macrophages and the neovasculature of atherosclerotic plaques.(64)Cu-NOTA-3-4A demonstrates specific accumulation in carotid atherosclerotic plaques in which macrophage infiltration and angiogenesis are responsible for elevated integrin αvβ3 levels. Therefore, (64)Cu-NOTA-3-4A may demonstrate clinical utility as a PET probe for atherosclerosis imaging or for the evaluation of therapies used to treat atherosclerosis.

  View details for DOI 10.2967/jnumed.115.155176

  View details for Web of Science ID 000355570300026

  View details for PubMedID 25908832

• Development of a High-Throughput Molecular Imaging-Based Orthotopic Hepatocellular Carcinoma Model CUREUS Hwang, G. L., van den Bosch, M. A., Kim, Y. I., Katzenberg, R., Willmann, J. K., Paulmurugan, R., Gambhir, S. S., Hofmann, L. 2015; 7 (6)

  View details for DOI 10.7759/cureus.281

  View details for Web of Science ID 000453603500009

• Development of a High-Throughput Molecular Imaging-Based Orthotopic Hepatocellular Carcinoma Model. Cureus Hwang, G. L., van den Bosch, M. A., Kim, Y. I., Katzenberg, R., Willmann, J. K., Paulmurugan, R., Gambhir, S. S., Hofmann, L. 2015; 7 (6)

  Abstract

  We have developed a novel orthotopic rat hepatocellular (HCC) model and have assessed the ability to use bioluminescence imaging (BLI), positron emission tomography (PET), and ultrasound for early tumor detection and monitoring of disease progression.  Briefly, rat HCC cells were stably transfected with click beetle red as a reporter gene for BLI. Tumor cells were injected under direct visualization into the left or middle lobe of the liver in 37 rats. In six animals, serial PET, BLI, and ultrasound imaging were performed at 10-time points in 28 days. The remainder of the animals underwent PET imaging at 14 days. Tumor implantation was successful in 34 of 37 animals (91.9%). In the six animals that underwent serial imaging, tumor formation was first detected with BLI on Day 4 with continued increase through Day 21, and hypermetabolic activity on PET was first noted on Days 14-15 with continued increase through Day 28. PET activity was seen on Day 14 in the 28 other animals that demonstrated tumor development. Anatomic tumor formation was detected with ultrasound at Days 10-12 with continued growth through Day 28. The first metastases were detected by PET after Day 24.        We have successfully developed and validated a novel orthotopic HCC small animal model that permits longitudinal assessment of change in tumor size using molecular imaging techniques. BLI is the most sensitive imaging method for detection of early tumor formation and growth. This model permits high-throughput in vivo evaluation of image-guided therapies.

  View details for DOI 10.7759/cureus.281

  View details for PubMedID 26180705

  View details for PubMedCentralID PMC4494575

• Glioblastoma Multiforme Recurrence: An Exploratory Study of (18)F FPPRGD2 PET/CT. Radiology Iagaru, A., Mosci, C., Mittra, E., Zaharchuk, G., Fischbein, N., Harsh, G., Li, G., Nagpal, S., Recht, L., Gambhir, S. S. 2015: 141550

  Abstract

  Purpose To prospectively evaluate fluorine 18 ((18)F) 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2) positron emission tomography (PET) in patients with glioblastoma multiforme (GBM). Materials and Methods The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. (18)F FPPRGD2 uptake was measured semiquantitatively in the form of maximum standardized uptake values (SUVmax) and uptake volumes before and after treatment with bevacizumab. Vital signs and laboratory results were collected before, during, and after the examinations. A nonparametric version of multivariate analysis of variance was used to assess safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare SUVmax. Results A total of 17 participants (eight men, nine women; age range, 25-65 years) were enrolled prospectively. (18)F FPPRGD2 PET/computed tomography (CT), (18)F fluorodeoxyglucose (FDG) PET/CT, and brain magnetic resonance (MR) imaging were performed within 3 weeks, prior to the start of bevacizumab therapy. In eight of the 17 patients (47%), (18)F FPPRGD2 PET/CT was repeated 1 week after the start of bevacizumab therapy; six patients (35%) underwent (18)F FPPRGD2 PET/CT a third time 6 weeks after starting bevacizumab therapy. There were no changes in vital signs, electrocardiographic findings, or laboratory values that qualified as adverse events. One patient (6%) had recurrent GBM identified only on (18)F FPPRGD2 PET images, and subsequent MR images enabled confirmation of recurrence. Of the 17 patients, 14 (82%) had recurrent GBM identified on (18)F FPPRGD2 PET and brain MR images, while (18)F FDG PET enabled identification of recurrence in 13 (76%) patients. Two patients (12%) had no recurrent GBM. Conclusion (18)F FPPRGD2 is a safe PET radiopharmaceutical that has increased uptake in GBM lesions. Larger cohorts are required to confirm these preliminary findings. (©) RSNA, 2015 Online supplemental material is available for this article.

  View details for DOI 10.1148/radiol.2015141550

  View details for PubMedID 25965900

• Semiquantitative Analysis of the Biodistribution of the Combined F-18-NaF and F-18-FDG Administration for PET/CT Imaging JOURNAL OF NUCLEAR MEDICINE Minamimoto, R., Mosci, C., Jamali, M., Barkhodari, A., Habte, F., Jackson, T., Mittra, E., Gambhir, S. S., Iagaru, A. 2015; 56 (5): 688-694

  Abstract

  In this study we evaluated the biodistribution of the (18)F-/(18)F-FDG administration compared to separate (18)F-NaF and (18)F-FDG. We also estimated the interaction of (18)F-NaF and (18)F-FDG in the (18)F-/(18)F-FDG administration by semiquantitative analysis.We retrospectively analyzed data of 49 patients (male 39, female 10; mean ± SD age: 59.3 ± 15.2 years) who had separate (18)F-FDG PET/CT and (18)F-NaF PET/CT, as well as the (18)F-/(18)F-FDG PET/CT sequentially. The most common primary diagnosis was prostate cancer (n = 28), followed by sarcoma (n = 9) and breast cancer (n = 6). The mean standardized uptake values (SUVmean) were recorded for 18 organs in all patients, while maximum SUV (SUVmax) and SUVmean were recorded for all the identified malignant lesions. We also estimated the (18)F-/(18)F-FDG uptake by sum of (18)F-FDG uptake and adjusted (18)F-NaF uptake based on the ratio of (18)F-NaF injected dose in (18)F-/(18)F-FDG PET/CT. Lastly, we compared the results in order to explore the interaction of (18)F-FDG and (18)F-NaF uptake in the (18)F-/(18)F-FDG scan.The (18)F-/(18)F-FDG uptake in the cerebral cortex, cerebellum, parotid grand, myocardium and bowel mostly reflect the (18)F-FDG uptake, while the uptake in the other analyzed structures is influenced by both the (18)F-FDG and the (18)F-NaF uptake. The (18)F-/(18)F-FDG uptake in extra skeletal lesions shows no significant difference when compared to the uptake from the separate (18)F-FDG scan. The (18)F-/(18)F-FDG uptake in skeletal lesions reflected mostly the (18)F-NaF uptake. Tumor to background (T/B) ratio of (18)F-/(18)F-FDG in extra skeletal lesions showed no significant difference when compared with that from (18)F-FDG alone (P = 0.73). For skeletal lesions, T/B ratio of (18)F-/(18)F-FDG was lower than that from (18)F-NaF alone (P <0.001); however, this difference did not result in missed skeletal lesions on the (18)F-/(18)F-FDG scan.The understanding of the biodistribution of radiopharmaceuticals and the lesions uptake of the (18)F-/(18)F-FDG scan, as well as the variations compared to the uptake on the separate (18)F-FDG PET/CT and (18)F-NaF PET/CT are valuable for more in depth evaluation of the combined scanning technique.

  View details for DOI 10.2967/jnumed.115.153767

  View details for Web of Science ID 000353831000013

  View details for PubMedID 25840978

• Imaging poly(ADP ribose) polymerase-1 activity for personalized cancer medicine using a novel PET tracer Shuhendler, A., Cui, L., Lin, J., Shen, B., James, M., Witney, T., Chattopadhyay, N., Gambhir, S., Chin, F., Rao, J. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738800003

• PET Imaging Carotid Atherosclerostic Plaque Using Divalent Knottin Jiang, L., Tu, Y., Kimura, R., Habte, F., Chen, H., Cheng, K., Shi, H., Gambhir, S., Cheng, Z. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738801112

• Antibody mimics, fibronectin domain III for EphA2-targeting as a probe in murine tumor model Park, S., Hong, Y., Park, S., Kimura, R., Min, J., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738802114

• Physiological distribution of Ga-68-DOTA-TATE: an atlas of standardized uptake values Moradi, F., Minamimoto, R., Jamali, M., Barkhodari, A., Quon, A., Mittra, E., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738802255

• F-18 FPPRGD(2) PET as a Surrogate Biomarker of Integrin alpha(v)beta(3) Expression Before and After Anti-angiogenesis Treatment 18 Minamimoto, R., Jamali, M., Barkhodari, A., Mosci, C., Mittra, E., Shen, B., Chin, F., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738801280

• Prospective evaluation of Tc-99m MDP scintigraphy, F-18 NaF/F-18 FDG PET/CT and WBMRI in patients with breast and prostate cancers Iagaru, A., Minamimoto, R., Mosci, C., Jamali, M., Barkhodari, A., Loening, A., Taviani, V., Mittra, E., Gambhir, S., Vasanawala, S. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738802275

• Imaging of tumor-associated system x(C)(-) activity with 18F-fluoropropylglutamate (FSPG) PET/CT for intracranial malignancies. Mittra, E., Minamimoto, R., Barkhodari, A., Jamali, M., Schneider, B., Koglin, N., Berndt, M., Stephens, A., Chin, F., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2015

  View details for Web of Science ID 000358738803222

• Optical coherence contrast imaging using gold nanorods in living mice eyes CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY de la Zerda, A., Prabhulkar, S., Perez, V. L., Ruggeri, M., Paranjape, A. S., Habte, F., Gambhir, S. S., Awdeh, R. M. 2015; 43 (4): 358-366

  Abstract

  Optical coherence tomography (OCT) is a powerful imaging modality to visualize tissue structures, with axial image pixel resolution as high as 1.6 μm in tissue. However, OCT is intrinsically limited to providing structural information as the OCT contrast is produced by optically scattering tissues.Gold nanorods (GNRs) were injected into the anterior chamber (AC) and cornea of mice eyes which could create a significant OCT signal and hence could be used as a contrast agent for in vivo OCT imaging.A dose of 30 nM of GNRs (13 nm in diameter and 45 nm in length) were injected to the AC of mice eyes and produced an OCT contrast nearly 50-fold higher than control mice injected with saline. Furthermore, the lowest detectable concentration of GNRs in living mice AC was experimentally estimated to be as low as 120 pM.The high sensitivity and low toxicity of GNRs brings great promise for OCT to uniquely become a high-resolution molecular imaging modality.

  View details for DOI 10.1111/ceo.12299

  View details for Web of Science ID 000356810200009

  View details for PubMedID 24533647

• A Real-Time Clinical Endoscopic System for Intraluminal, Multiplexed Imaging of Surface-Enhanced Raman Scattering Nanoparticles PLOS ONE Garai, E., Sensarn, S., Zavaleta, C. L., Loewke, N. O., Rogalla, S., Mandella, M. J., Felt, S. A., Friedland, S., Liu, J. T., Gambhir, S. S., Contag, C. H. 2015; 10 (4)

  Abstract

  The detection of biomarker-targeting surface-enhanced Raman scattering (SERS) nanoparticles (NPs) in the human gastrointestinal tract has the potential to improve early cancer detection; however, a clinically relevant device with rapid Raman-imaging capability has not been described. Here we report the design and in vivo demonstration of a miniature, non-contact, opto-electro-mechanical Raman device as an accessory to clinical endoscopes that can provide multiplexed molecular data via a panel of SERS NPs. This device enables rapid circumferential scanning of topologically complex luminal surfaces of hollow organs (e.g., colon and esophagus) and produces quantitative images of the relative concentrations of SERS NPs that are present. Human and swine studies have demonstrated the speed and simplicity of this technique. This approach also offers unparalleled multiplexing capabilities by simultaneously detecting the unique spectral fingerprints of multiple SERS NPs. Therefore, this new screening strategy has the potential to improve diagnosis and to guide therapy by enabling sensitive quantitative molecular detection of small and otherwise hard-to-detect lesions in the context of white-light endoscopy.

  View details for DOI 10.1371/journal.pone.0123185

  View details for Web of Science ID 000353711600032

  View details for PubMedID 25923788

  View details for PubMedCentralID PMC4414592

• Synthesis of [(18)F]-labelled Maltose Derivatives as PET Tracers for Imaging Bacterial Infection. Molecular imaging and biology Namavari, M., Gowrishankar, G., Hoehne, A., Jouannot, E., Gambhir, S. S. 2015; 17 (2): 168-176

  Abstract

  To develop novel positron emission tomography (PET) agents for visualization and therapy monitoring of bacterial infections.It is known that maltose and maltodextrins are energy sources for bacteria. Hence, (18)F-labelled maltose derivatives could be a valuable tool for imaging bacterial infections. We have developed methods to synthesize 4-O-(α-D-glucopyranosyl)-6-deoxy-6-[(18)F]fluoro-D-glucopyranoside (6-[(18)F]fluoromaltose) and 4-O-(α-D-glucopyranosyl)-1-deoxy-1-[(18)F]fluoro-D-glucopyranoside (1-[(18)F]fluoromaltose) as bacterial infection PET imaging agents. 6-[(18)F]fluoromaltose was prepared from precursor 1,2,3-tri-O-acetyl-4-O-(2',3',-di-O-acetyl-4',6'-benzylidene-α-D-glucopyranosyl)-6-deoxy-6-nosyl-D-glucopranoside (5). The synthesis involved the radio-fluorination of 5 followed by acidic and basic hydrolysis to give 6-[(18)F]fluoromaltose. In an analogous procedure, 1-[(18)F]fluoromaltose was synthesized from 2,3, 6-tri-O-acetyl-4-O-(2',3',4',6-tetra-O-acetyl-α-D-glucopyranosyl)-1-deoxy-1-O-triflyl-D-glucopranoside (9). Stability of 6-[(18)F]fluoromaltose in phosphate-buffered saline (PBS) and human and mouse serum at 37 °C was determined. Escherichia coli uptake of 6-[(18)F]fluoromaltose was examined.A reliable synthesis of 1- and 6-[(18)F]fluoromaltose has been accomplished with 4-6 and 5-8 % radiochemical yields, respectively (decay-corrected with 95 % radiochemical purity). 6-[(18)F]fluoromaltose was sufficiently stable over the time span needed for PET studies (∼96 % intact compound after 1-h and ∼65 % after 2-h incubation in serum). Bacterial uptake experiments indicated that E. coli transports 6-[(18)F]fluoromaltose. Competition assays showed that the uptake of 6-[(18)F]fluoromaltose was completely blocked by co-incubation with 1 mM of the natural substrate maltose.We have successfully synthesized 1- and 6-[(18)F]fluoromaltose via direct fluorination of appropriate protected maltose precursors. Bacterial uptake experiments in E. coli and stability studies suggest a possible application of 6-[(18)F]fluoromaltose as a new PET imaging agent for visualization and monitoring of bacterial infections.

  View details for DOI 10.1007/s11307-014-0793-5

  View details for PubMedID 25277604

• Detecting cancers through tumor-activatable minicircles that lead to a detectable blood biomarker. Proceedings of the National Academy of Sciences of the United States of America Ronald, J. A., Chuang, H., Dragulescu-Andrasi, A., Hori, S. S., Gambhir, S. S. 2015; 112 (10): 3068-3073

  Abstract

  Earlier detection of cancers can dramatically improve the efficacy of available treatment strategies. However, despite decades of effort on blood-based biomarker cancer detection, many promising endogenous biomarkers have failed clinically because of intractable problems such as highly variable background expression from nonmalignant tissues and tumor heterogeneity. In this work we present a tumor-detection strategy based on systemic administration of tumor-activatable minicircles that use the pan-tumor-specific Survivin promoter to drive expression of a secretable reporter that is detectable in the blood nearly exclusively in tumor-bearing subjects. After systemic administration we demonstrate a robust ability to differentiate mice bearing human melanoma metastases from tumor-free subjects for up to 2 wk simply by measuring blood reporter levels. Cumulative change in reporter levels also identified tumor-bearing subjects, and a receiver operator-characteristic curve analysis highlighted this test's performance with an area of 0.918 ± 0.084. Lung tumor burden additionally correlated (r(2) = 0.714; P < 0.05) with cumulative reporter levels, indicating that determination of disease extent was possible. Continued development of our system could improve tumor detectability dramatically because of the temporally controlled, high reporter expression in tumors and nearly zero background from healthy tissues. Our strategy's highly modular nature also allows it to be iteratively optimized over time to improve the test's sensitivity and specificity. We envision this system could be used first in patients at high risk for tumor recurrence, followed by screening high-risk populations before tumor diagnosis, and, if proven safe and effective, eventually may have potential as a powerful cancer-screening tool for the general population.

  View details for DOI 10.1073/pnas.1414156112

  View details for PubMedID 25713388

  View details for PubMedCentralID PMC4364239

• F-18-FPRGD2 PET/CT Imaging of Integrin alpha(v)beta(3) in Renal Carcinomas: Correlation with Histopathology JOURNAL OF NUCLEAR MEDICINE Withofs, N., Signolle, N., Somja, J., Lovinfosse, P., Nzaramba, E. M., Mievis, F., Giacomelli, F., Waltregny, D., Cataldo, D., Gambhir, S. S., Hustinx, R. 2015; 56 (3): 361-364

  Abstract

  This study aimed to correlate (18)F-FB-mini-PEG-E[c(RGDyK)](2) ((18)F-FPRGD2) uptake to integrin αvβ3 expression and angiogenesis in renal tumors.(18)F-FPRGD2 PET/CT was performed on 27 patients before surgical resection (median 4 d) of a renal mass. The (18)F-FPRGD2 uptake was compared with integrin αvβ3, CD31, CD105, and Ki-67 using immunohistochemistry; with placental growth factor and vascular endothelial growth factor receptors 1 and 2 using reverse transcription polymerase chain reaction; and with vascular endothelial growth factor A isoforms using enzyme-linked immunosorbent assay.Overall, (18)F-FPRGD2 uptake significantly correlated (P < 0.0001) with integrin αvβ3 expression in renal masses. However, it correlated only with integrin αvβ3-positive vessels in the group of papillary carcinomas whereas it correlated with integrin αvβ3 expression by tumor cells in the clear cell carcinoma group.(18)F-FPRGD2 uptake reflects the expression of integrin αvβ3 in renal tumors but represents angiogenesis only when tumor cells do not express the integrin.

  View details for DOI 10.2967/jnumed.114.149021

  View details for Web of Science ID 000350631700032

• Detection of Osseous Metastasis by 18F-NaF/18F-FDG PET/CT Versus CT Alone. Clinical nuclear medicine Sampath, S. C., Sampath, S. C., Mosci, C., Lutz, A. M., Willmann, J. K., Mittra, E. S., Gambhir, S. S., Iagaru, A. 2015; 40 (3): e173-7

  Abstract

  Sodium fluoride PET (F-NaF) has recently reemerged as a valuable method for detection of osseous metastasis, with recent work highlighting the potential of coadministered F-NaF and F-FDG PET/CT in a single combined imaging examination. We further examined the potential of such combined examinations by comparing dual tracer F-NaF/F-FDG PET/CT with CT alone for detection of osseous metastasis.Seventy-five participants with biopsy-proven malignancy were consecutively enrolled from a single center and underwent combined F-NaF/F-FDG PET/CT and diagnostic CT scans. PET/CT as well as CT only images were reviewed in blinded fashion and compared with the results of clinical, imaging, or histological follow-up as a truth standard.Sensitivity of the combined F-NaF/F-FDG PET/CT was higher than that of CT alone (97.4% vs 66.7%). CT and F-NaF/F-FDG PET/CT were concordant in 73% of studies. Of 20 discordant cases, F-NaF/F-FDG PET/CT was correct in 19 (95%). Three cases were interpreted concordantly but incorrectly, and all 3 were false positives. A single case of osseous metastasis was detected by CT alone, but not by F-NaF/F-FDG PET/CT.Combined F-NaF/F-FDG PET/CT outperforms CT alone and is highly sensitive and specific for detection of osseous metastases. The concordantly interpreted false-positive cases demonstrate the difficulty of distinguishing degenerative from malignant disease, whereas the single case of metastasis seen on CT but not PET highlights the need for careful review of CT images in multimodality studies.

  View details for DOI 10.1097/RLU.0000000000000560

  View details for PubMedID 25140557

• 18F-FPRGD2 PET/CT imaging of integrin avß3 in renal carcinomas: correlation with histopathology. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Withofs, N., Signolle, N., Somja, J., Lovinfosse, P., Nzaramba, E. M., Mievis, F., Giacomelli, F., Waltregny, D., Cataldo, D., Gambhir, S. S., Hustinx, R. 2015; 56 (3): 361-364

  Abstract

  This study aimed to correlate (18)F-FB-mini-PEG-E[c(RGDyK)](2) ((18)F-FPRGD2) uptake to integrin αvβ3 expression and angiogenesis in renal tumors.(18)F-FPRGD2 PET/CT was performed on 27 patients before surgical resection (median 4 d) of a renal mass. The (18)F-FPRGD2 uptake was compared with integrin αvβ3, CD31, CD105, and Ki-67 using immunohistochemistry; with placental growth factor and vascular endothelial growth factor receptors 1 and 2 using reverse transcription polymerase chain reaction; and with vascular endothelial growth factor A isoforms using enzyme-linked immunosorbent assay.Overall, (18)F-FPRGD2 uptake significantly correlated (P < 0.0001) with integrin αvβ3 expression in renal masses. However, it correlated only with integrin αvβ3-positive vessels in the group of papillary carcinomas whereas it correlated with integrin αvβ3 expression by tumor cells in the clear cell carcinoma group.(18)F-FPRGD2 uptake reflects the expression of integrin αvβ3 in renal tumors but represents angiogenesis only when tumor cells do not express the integrin.

  View details for DOI 10.2967/jnumed.114.149021

  View details for PubMedID 25655629

• Detection of osseous metastasis by 18F-NaF/18F-FDG PET/CT versus CT alone. Clinical nuclear medicine Sampath, S. C., Sampath, S. C., Mosci, C., Lutz, A. M., Willmann, J. K., Mittra, E. S., Gambhir, S. S., Iagaru, A. 2015; 40 (3): e173-7

  Abstract

  Sodium fluoride PET (F-NaF) has recently reemerged as a valuable method for detection of osseous metastasis, with recent work highlighting the potential of coadministered F-NaF and F-FDG PET/CT in a single combined imaging examination. We further examined the potential of such combined examinations by comparing dual tracer F-NaF/F-FDG PET/CT with CT alone for detection of osseous metastasis.Seventy-five participants with biopsy-proven malignancy were consecutively enrolled from a single center and underwent combined F-NaF/F-FDG PET/CT and diagnostic CT scans. PET/CT as well as CT only images were reviewed in blinded fashion and compared with the results of clinical, imaging, or histological follow-up as a truth standard.Sensitivity of the combined F-NaF/F-FDG PET/CT was higher than that of CT alone (97.4% vs 66.7%). CT and F-NaF/F-FDG PET/CT were concordant in 73% of studies. Of 20 discordant cases, F-NaF/F-FDG PET/CT was correct in 19 (95%). Three cases were interpreted concordantly but incorrectly, and all 3 were false positives. A single case of osseous metastasis was detected by CT alone, but not by F-NaF/F-FDG PET/CT.Combined F-NaF/F-FDG PET/CT outperforms CT alone and is highly sensitive and specific for detection of osseous metastases. The concordantly interpreted false-positive cases demonstrate the difficulty of distinguishing degenerative from malignant disease, whereas the single case of metastasis seen on CT but not PET highlights the need for careful review of CT images in multimodality studies.

  View details for DOI 10.1097/RLU.0000000000000560

  View details for PubMedID 25140557

• PET Imaging of Translocator Protein (18 kDa) in a Mouse Model of Alzheimer's Disease Using N-(2,5-Dimethoxybenzyl)-2-18F-Fluoro-N-(2-Phenoxyphenyl)Acetamide. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Belichenko, N. P., Nguyen, T. V., Andrews, L. E., Ding, Z., Liu, H., Bodapati, D., Arksey, N., Shen, B., Cheng, Z., Wyss-Coray, T., Gambhir, S. S., Longo, F. M., Chin, F. T. 2015; 56 (2): 311-316

  Abstract

  Herein we aimed to evaluate the utility of N-(2,5-dimethoxybenzyl)-2-(18)F-fluoro-N-(2-phenoxyphenyl)acetamide ((18)F-PBR06) for detecting alterations in translocator protein (TSPO) (18 kDa), a biomarker of microglial activation, in a mouse model of Alzheimer's disease (AD).Wild-type (wt) and AD mice (i.e., APP(L/S)) underwent (18)F-PBR06 PET imaging at predetermined time points between the ages of 5-6 and 15-16 mo. MR images were fused with PET/CT data to quantify (18)F-PBR06 uptake in the hippocampus and cortex. Ex vivo autoradiography and TSPO/CD68 immunostaining were also performed using brain tissue from these mice.PET images showed significantly higher accumulation of (18)F-PBR06 in the cortex and hippocampus of 15- to 16-mo-old APP(L/S) mice than age-matched wts (cortex/muscle: 2.43 ± 0.19 vs. 1.55 ± 0.15, P < 0.005; hippocampus/muscle: 2.41 ± 0.13 vs. 1.55 ± 0.12, P < 0.005). And although no significant difference was found between wt and APP(L/S) mice aged 9-10 mo or less using PET (P = 0.64), we were able to visualize and quantify a significant difference in (18)F-PBR06 uptake in these mice using autoradiography (cortex/striatum: 1.13 ± 0.04 vs. 0.96 ± 0.01, P < 0.05; hippocampus/striatum: 1.266 ± 0.003 vs. 1.096 ± 0.017, P < 0.001). PET results for 15- to 16-mo-old mice correlated well with autoradiography and immunostaining (i.e., increased (18)F-PBR06 uptake in brain regions containing elevated CD68 and TSPO staining in APP(L/S) mice, compared with wts).(18)F-PBR06 shows great potential as a tool for visualizing TSPO/microglia in the progression and treatment of AD.

  View details for DOI 10.2967/jnumed.114.141648

  View details for PubMedID 25613536

• Sol-Gel Synthesis and Electrospraying of Biodegradable (P2O5)(55)-(CaO)(30)-(Na2O)(15) Glass Nanospheres as a Transient Contrast Agent for Ultrasound Stem Cell Imaging ACS NANO Foroutan, F., Jokerst, J. V., Gambhir, S. S., Vermesh, O., Kim, H., Knowles, J. C. 2015; 9 (2): 1868-1877

  Abstract

  Ultrasound imaging is a powerful tool in medicine because of the millisecond temporal resolution and submillimeter spatial resolution of acoustic imaging. However, the current generation of acoustic contrast agents is primarily limited to vascular targets due to their large size. Nanosize particles have the potential to be used as a contrast agent for ultrasound molecular imaging. Silica-based nanoparticles have shown promise here; however, their slow degradation rate may limit their applications as a contrast agent. Phosphate-based glasses are an attractive alternative with controllable degradation rate and easily metabolized degradation components in the body. In this study, biodegradable P2O5-CaO-Na2O phosphate-based glass nanospheres (PGNs) were synthesized and characterized as contrast agents for ultrasound imaging. The structure of the PGNs was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), (31)P magic angle spinning nuclear magnetic resonance ((31)P MAS NMR), and Fourier transform infrared (FTIR) spectroscopy. The SEM images indicated a spherical shape with a diameter size range of 200-500 nm. The XRD, (31)P NMR, and FTIR results revealed the amorphous and glassy nature of PGNs that consisted of mainly Q(1) and Q(2) phosphate units. We used this contrast to label mesenchymal stem cells and determined in vitro and in vivo detection limits of 5 and 9 μg/mL, respectively. Cell counts down to 4000 could be measured with ultrasound imaging with no cytoxicity at doses needed for imaging. Importantly, ion-release studies confirmed these PGNs biodegrade into aqueous media with degradation products that can be easily metabolized in the body.

  View details for DOI 10.1021/nn506789y

  View details for PubMedID 25625373

• 18F-FAZA PET Imaging Response Tracks the Reoxygenation of Tumors in Mice upon Treatment with the Mitochondrial Complex I Inhibitor BAY 87-2243. Clinical cancer research Chang, E., Liu, H., Unterschemmann, K., Ellinghaus, P., Liu, S., Gekeler, V., Cheng, Z., Berndorff, D., Gambhir, S. S. 2015; 21 (2): 335-346

  Abstract

  We describe a noninvasive PET imaging method that monitors early therapeutic efficacy of BAY 87-2243, a novel small-molecule inhibitor of mitochondrial complex I as a function of hypoxia-inducible factor-1α (HIF1α) activity.Four PET tracers [(18)F-FDG, (18)F-Fpp(RGD)2, (18)F-FLT, and (18)F-FAZA] were assessed for uptake into tumor xenografts of drug-responsive (H460, PC3) or drug-resistant (786-0) carcinoma cells. Mice were treated with BAY 87-2243 or vehicle. At each point, RNA from treated and vehicle H460 tumor xenografts (n = 3 each) was isolated and analyzed for target genes.Significant changes in uptake of (18)F-FAZA, (18)F-FLT, and (18)F-Fpp(RGD)2 (P < 0.01) occurred with BAY 87-2243 treatment with (18)F-FAZA being the most prominent. (18)F-FDG uptake was unaffected. (18)F-FAZA tumor uptake declined by 55% to 70% (1.21% ± 0.10%ID/g to 0.35 ± 0.1%ID/g; n = 6, vehicle vs. treatment) in both H460 (P < 0.001) and PC3 (P < 0.05) xenografts 1 to 3 days after drug administration. (18)F-FAZA uptake in 786-0 xenografts was unaffected. Decline occurred before significant differences in tumor volume, thus suggesting (18)F-FAZA decrease reflected early changes in tumor metabolism. BAY 87-2243 reduced expression of hypoxia-regulated genes CA IX, ANGPTL4, and EGLN-3 by 99%, 93%, and 83%, respectively (P < 0.001 for all), which corresponds with reduced (18)F-FAZA uptake upon drug treatment. Heterogeneous expression of genes associated with glucose metabolism, vessel density, and proliferation was observed.Our studies suggest suitability of (18)F-FAZA-PET as an early pharmacodynamic monitor on the efficacy of anticancer agents that target the mitochondrial complex I and intratumor oxygen levels (e.g., BAY 87-2243). Clin Cancer Res; 21(2); 335-46. ©2014 AACR.

  View details for DOI 10.1158/1078-0432.CCR-14-0217

  View details for PubMedID 25381339

  View details for PubMedCentralID PMC4297600

• A multimodal imaging agent for intrinsic surface enhanced Raman scattering of biological tissue Conference on Plasmonics in Biology and Medicine XII Pohling, C. B., Campbell, J. L., Larson, T. A., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2015

  View details for DOI 10.1117/12.2077890

  View details for Web of Science ID 000353615600006

• Validation of 64Cu-DOTA-rituximab injection preparation under good manufacturing practices: a PET tracer for imaging of B-cell non-Hodgkin lymphoma. Molecular imaging Natarajan, A., Arksey, N., Iagaru, A., Chin, F. T., Gambhir, S. S. 2015; 14

  View details for DOI 10.2310/7290.2014.00055

  View details for PubMedID 25762106

• A Magnetic Bead-Based Sensor for the Quantification of Multiple Prostate Cancer Biomarkers. PloS one Jokerst, J. V., Chen, Z., Xu, L., Nolley, R., Chang, E., Mitchell, B., Brooks, J. D., Gambhir, S. S. 2015; 10 (9): e0139484

  Abstract

  Novel biomarker assays and upgraded analytical tools are urgently needed to accurately discriminate benign prostatic hypertrophy (BPH) from prostate cancer (CaP). To address this unmet clinical need, we report a piezeoelectric/magnetic bead-based assay to quantitate prostate specific antigen (PSA; free and total), prostatic acid phosphatase, carbonic anhydrase 1 (CA1), osteonectin, IL-6 soluble receptor (IL-6sr), and spondin-2. We used the sensor to measure these seven proteins in serum samples from 120 benign prostate hypertrophy patients and 100 Gleason score 6 and 7 CaP using serum samples previously collected and banked. The results were analyzed with receiver operator characteristic curve analysis. There were significant differences between BPH and CaP patients in the PSA, CA1, and spondin-2 assays. The highest AUC discrimination was achieved with a spondin-2 OR free/total PSA operation-the area under the curve was 0.84 with a p value below 10-6. Some of these data seem to contradict previous reports and highlight the importance of sample selection and proper assay building in the development of biomarker measurement schemes. This bead-based system offers important advantages in assay building including low cost, high throughput, and rapid identification of an optimal matched antibody pair.

  View details for DOI 10.1371/journal.pone.0139484

  View details for PubMedID 26421725

  View details for PubMedCentralID PMC4589536

• A Magnetic Bead-Based Sensor for the Quantification of Multiple Prostate Cancer Biomarkers. PloS one Jokerst, J. V., Chen, Z., Xu, L., Nolley, R., Chang, E., Mitchell, B., Brooks, J. D., Gambhir, S. S. 2015; 10 (9)

  Abstract

  Novel biomarker assays and upgraded analytical tools are urgently needed to accurately discriminate benign prostatic hypertrophy (BPH) from prostate cancer (CaP). To address this unmet clinical need, we report a piezeoelectric/magnetic bead-based assay to quantitate prostate specific antigen (PSA; free and total), prostatic acid phosphatase, carbonic anhydrase 1 (CA1), osteonectin, IL-6 soluble receptor (IL-6sr), and spondin-2. We used the sensor to measure these seven proteins in serum samples from 120 benign prostate hypertrophy patients and 100 Gleason score 6 and 7 CaP using serum samples previously collected and banked. The results were analyzed with receiver operator characteristic curve analysis. There were significant differences between BPH and CaP patients in the PSA, CA1, and spondin-2 assays. The highest AUC discrimination was achieved with a spondin-2 OR free/total PSA operation-the area under the curve was 0.84 with a p value below 10-6. Some of these data seem to contradict previous reports and highlight the importance of sample selection and proper assay building in the development of biomarker measurement schemes. This bead-based system offers important advantages in assay building including low cost, high throughput, and rapid identification of an optimal matched antibody pair.

  View details for DOI 10.1371/journal.pone.0139484

  View details for PubMedID 26421725

  View details for PubMedCentralID PMC4589536

• Parts per billion detection of uranium with a porphyrinoid-containing nanoparticle and in vivo photoacoustic imaging ANALYST Ho, I., Sessler, J. L., Gambhir, S. S., Jokerst, J. V. 2015; 140 (11): 3731-3737

  Abstract

  Chemical tools that can report radioactive isotopes would be of interest to the defense community. Here we report ∼250 nm polymeric nanoparticles containing porphyrinoid macrocycles with and without pre-complexed depleted uranium and demonstrate that the latter species may be detected easily and with high sensitivity via photoacoustic imaging. The porphyrinoid macrocycles used in the present study are non-aromatic in the absence of the uranyl cation, but aromatic after cation complexation. We solubilized both the freebase and metalated forms of the macrocycles in poly(lactic-co-glycolic acid) and found a peak in the photoacoustic spectrum at 910 nm excitation in the case of the uranyl complex. The signal was stable for at least 15 minutes and allowed detection of uranium concentrations down to 6.2 ppb (5.7 nM) in vitro and 0.57 ppm (19 fCi; 0.52 μM) in vivo. To the best of our knowledge, this is the first report of a nanoparticle that detects an actinide cation via photoacoustic imaging.

  View details for DOI 10.1039/c5an00207a

  View details for PubMedID 25854506

• Validation of 64Cu-DOTA-rituximab injection preparation under good manufacturing practices: a PET tracer for imaging of B-cell non-Hodgkin lymphoma. Molecular imaging Natarajan, A., Arksey, N., Iagaru, A., Chin, F. T., Gambhir, S. S. 2015; 14

  Abstract

  AbstractManufacturing of 64Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-rituximab injection under good manufacturing practices (GMP) was validated for imaging of patients with CD20+ B-cell non-Hodgkin lymphoma. Rituximab was purified by size exclusion high performance liquid chromatography (HPLC) and conjugated to DOTA-mono-(N-hydroxysuccinimidyl) ester. 64CuCl2, buffers, reagents, and other raw materials were obtained as high-grade quality. Following a semi-automated synthesis of 64Cu-DOTA-rituximab, a series of quality control tests was performed. The product was further tested in vivo using micro-positron emission tomography/computed tomography (PET/CT) to assess targeting ability towards human CD20 in transgenic mice. Three batches of 64Cu-DOTA-rituximab final product were prepared as per GMP specifications. The radiolabeling yield from these batches was 93.1 ± 5.8%; these provided final product with radiopharmaceutical yield, purity, and specific activity of 59.2 ± 5.1% (0.9 ± 0.1 GBq of 64Cu), > 95% (by HPLC and radio-thin layer chromatography), and 229.4 ± 43.3 GBq/µmol (or 1.5 ± 0.3 MBq/µg), respectively. The doses passed apyrogenicity and human serum stability specifications, were sterile up to 14 days, and retained > 60% immunoreactivity. In vivo micro-PET/CT mouse images at 24 hours postinjection showed that the tracer targeted the intended sites of human CD20 expression. Thus, we have validated the manufacturing of GMP grade 64Cu-DOTA-rituximab for injection in the clinical setting.

  View details for DOI 10.2310/7290.2014.00055

  View details for PubMedID 25762106

• Theranostic mesoporous silica nanoparticles biodegrade after pro-survival drug delivery and ultrasound/magnetic resonance imaging of stem cells. Theranostics Kempen, P. J., Greasley, S., Parker, K. A., Campbell, J. L., Chang, H., Jones, J. R., Sinclair, R., Gambhir, S. S., Jokerst, J. V. 2015; 5 (6): 631-642

  Abstract

  Increasing cell survival in stem cell therapy is an important challenge for the field of regenerative medicine. Here, we report theranostic mesoporous silica nanoparticles that can increase cell survival through both diagnostic and therapeutic approaches. First, the nanoparticle offers ultrasound and MRI signal to guide implantation into the peri-infarct zone and away from the most necrotic tissue. Second, the nanoparticle serves as a slow release reservoir of insulin-like growth factor (IGF)-a protein shown to increase cell survival. Mesenchymal stem cells labeled with these nanoparticles had detection limits near 9000 cells with no cytotoxicity at the 250 µg/mL concentration required for labeling. We also studied the degradation of the nanoparticles and showed that they clear from cells in approximately 3 weeks. The presence of IGF increased cell survival up to 40% (p<0.05) versus unlabeled cells under in vitro serum-free culture conditions.

  View details for DOI 10.7150/thno.11389

  View details for PubMedID 25825602

• A correlative optical microscopy and scanning electron microscopy approach to locating nanoparticles in brain tumors. Micron Kempen, P. J., Kircher, M. F., de la Zerda, A., Zavaleta, C. L., Jokerst, J. V., Mellinghoff, I. K., Gambhir, S. S., Sinclair, R. 2015; 68: 70-76

  Abstract

  The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy.

  View details for DOI 10.1016/j.micron.2014.09.004

  View details for PubMedID 25464144

  View details for PubMedCentralID PMC4262686

• Simultaneous Whole-Body Time-of-Flight F-18-FDG PET/MRI A Pilot Study Comparing SUVmax With PET/CT and Assessment of MR Image Quality CLINICAL NUCLEAR MEDICINE Iagaru, A., Mittra, E., Minamimoto, R., Jamali, M., Levin, C., Quon, A., Gold, G., Herfkens, R., Vasanawala, S., Gambhir, S. S., Zaharchuk, G. 2015; 14 (1): 1-8

  Abstract

  The recent introduction of hybrid PET/MRI scanners in clinical practice has shown promising initial results for several clinical scenarios. However, the first generation of combined PET/MRI lacks time-of-flight (TOF) technology. Here we report the results of the first patients to be scanned on a completely novel fully integrated PET/MRI scanner with TOF.We analyzed data from patients who underwent a clinically indicated F FDG PET/CT, followed by PET/MRI. Maximum standardized uptake values (SUVmax) were measured from F FDG PET/MRI and F FDG PET/CT for lesions, cerebellum, salivary glands, lungs, aortic arch, liver, spleen, skeletal muscle, and fat. Two experienced radiologists independently reviewed the MR data for image quality.Thirty-six patients (19 men, 17 women, mean [±standard deviation] age of 61 ± 14 years [range: 27-86 years]) with a total of 69 discrete lesions met the inclusion criteria. PET/CT images were acquired at a mean (±standard deviation) of 74 ± 14 minutes (range: 49-100 minutes) after injection of 10 ± 1 mCi (range: 8-12 mCi) of F FDG. PET/MRI scans started at 161 ± 29 minutes (range: 117 - 286 minutes) after the F FDG injection. All lesions identified on PET from PET/CT were also seen on PET from PET/MRI. The mean SUVmax values were higher from PET/MRI than PET/CT for all lesions. No degradation of MR image quality was observed.The data obtained so far using this investigational PET/MR system have shown that the TOF PET system is capable of excellent performance during simultaneous PET/MR with routine pulse sequences. MR imaging was not compromised. Comparison of the PET images from PET/CT and PET/MRI show no loss of image quality for the latter. These results support further investigation of this novel fully integrated TOF PET/MRI instrument.

  View details for Web of Science ID 000346633400023

• Syntheses and Discovery of a Novel Class of Cinnamic Hydroxamates as Histone Deacetylase Inhibitors by Multimodality Molecular Imaging in Living Subjects CANCER RESEARCH CHAN, C. T., Qi, J., Smith, W., Paranol, R., Mazitschek, R., West, N., Reeves, R., Chiosis, G., Schreiber, S. L., Bradner, J. E., Paulmurugan, R., Gambhir, S. S. 2014; 74 (24): 7475-7486

  Abstract

  Histone deacetylases (HDAC) that regulate gene expression are being explored as cancer therapeutic targets. In this study, we focused on HDAC6 based on its ability to inhibit cancerous Hsp90 chaperone activities by disrupting Hsp90/p23 interactions. To identify novel HDAC6 inhibitors, we used a dual-luciferase reporter system in cell culture and living mice by bioluminescence imaging (BLI). On the basis of existing knowledge, a library of hydrazone compounds was generated for screening by coupling cinnamic hydroxamates with aldehydes and ketones. Potency and selectivity were determined by in vitro HDAC profiling assays, with further evaluation to inhibit Hsp90(α/β)/p23 interactions by BLI. In this manner, we identified compound 1A12 as a dose-dependent inhibitor of Hsp90(α/β)/p23 interactions, UKE-1 myeloid cell proliferation, p21(waf1) upregulation, and acetylated histone H3 levels. 1A12 was efficacious in tumor xenografts expressing Hsp90(α)/p23 reporters relative to carrier control-treated mice as determined by BLI. Small animal (18)F-FDG PET/CT imaging on the same cohort showed that 1A12 also inhibited glucose metabolism relative to control subjects. Ex vivo analyses of tumor lysates showed that 1A12 administration upregulated acetylated-H3 by approximately 3.5-fold. Taken together, our results describe the discovery and initial preclinical validation of a novel selective HDAC inhibitor.

  View details for DOI 10.1158/0008-5472.CAN-14-0197

  View details for Web of Science ID 000346363900031

  View details for PubMedID 25320008

• Noninvasive Reporter Gene Imaging of Human Oct4 (Pluripotency) Dynamics During the Differentiation of Embryonic Stem Cells in Living Subjects MOLECULAR IMAGING AND BIOLOGY Ahn, B., Parashurama, N., Patel, M., Ziv, K., Bhaumik, S., Yaghoubi, S. S., Paulmurugan, R., Gambhir, S. S. 2014; 16 (6): 865-876

  Abstract

  Human pluripotency gene networks (PGNs), controlled in part by Oct4, are central to understanding pluripotent stem cells, but current fluorescent reporter genes (RGs) preclude noninvasive assessment of Oct4 dynamics in living subjects.To assess Oc4 activity noninvasively, we engineered a mouse embryonic stem cell line which encoded both a pOct4-hrluc (humanized renilla luciferase) reporter and a pUbi-hfluc2-gfp (humanized firefly luciferase 2 fused to green fluorescent protein) reporter.In cell culture, pOct4-hRLUC activity demonstrated a peak at 48 h (day 2) and significant downregulation by 72 h (day 3) (p=0.0001). Studies in living subjects demonstrated significant downregulation in pOct4-hRLUC activity between 12 and 144 h (p = 0.001) and between 12 and 168 h (p = 0.0003). pOct4-hRLUC signal dynamics after implantation was complex, characterized by transient upregulation after initial downregulation in all experiments (n = 10, p = 0.01). As expected, cell culture differentiation of the engineered mouse embryonic stem cell line demonstrated activation of mesendodermal, mesodermal, endodermal, and ectodermal master regulators of differentiation, indicating potency to form all three germ layers.We conclude that the Oct4-hrluc RG system enables noninvasive Oct4 imaging in cell culture and in living subjects.

  View details for DOI 10.1007/s11307-014-0744-1

  View details for Web of Science ID 000345281600014

• Noninvasive reporter gene imaging of human Oct4 (pluripotency) dynamics during the differentiation of embryonic stem cells in living subjects. Molecular imaging and biology Ahn, B., Parashurama, N., Patel, M., Ziv, K., Bhaumik, S., Yaghoubi, S. S., Paulmurugan, R., Gambhir, S. S. 2014; 16 (6): 865-876

  Abstract

  Human pluripotency gene networks (PGNs), controlled in part by Oct4, are central to understanding pluripotent stem cells, but current fluorescent reporter genes (RGs) preclude noninvasive assessment of Oct4 dynamics in living subjects.To assess Oc4 activity noninvasively, we engineered a mouse embryonic stem cell line which encoded both a pOct4-hrluc (humanized renilla luciferase) reporter and a pUbi-hfluc2-gfp (humanized firefly luciferase 2 fused to green fluorescent protein) reporter.In cell culture, pOct4-hRLUC activity demonstrated a peak at 48 h (day 2) and significant downregulation by 72 h (day 3) (p=0.0001). Studies in living subjects demonstrated significant downregulation in pOct4-hRLUC activity between 12 and 144 h (p = 0.001) and between 12 and 168 h (p = 0.0003). pOct4-hRLUC signal dynamics after implantation was complex, characterized by transient upregulation after initial downregulation in all experiments (n = 10, p = 0.01). As expected, cell culture differentiation of the engineered mouse embryonic stem cell line demonstrated activation of mesendodermal, mesodermal, endodermal, and ectodermal master regulators of differentiation, indicating potency to form all three germ layers.We conclude that the Oct4-hrluc RG system enables noninvasive Oct4 imaging in cell culture and in living subjects.

  View details for DOI 10.1007/s11307-014-0744-1

  View details for PubMedID 24845530

• A Radiofluorinated Divalent Cystine Knot Peptide for Tumor PET Imaging MOLECULAR PHARMACEUTICS Jiang, L., Kimura, R. H., Ma, X., Tu, Y., Miao, Z., Shen, B., Chin, F. T., Shi, H., Gambhir, S. S., Cheng, Z. 2014; 11 (11): 3885-3892

  Abstract

  A divalent knottin containing two separate integrin binding epitopes (RGD) in the adjacent loops, 3-4A, was recently developed and reported in our previous publication. In the current study, 3-4A was radiofluorinated with a 4-nitrophenyl 2-(18)F-fluoropropinate ((18)F-NFP) group and the resulting divalent positron emission tomography (PET) probe, (18)F-FP-3-4A, was evaluated as a novel imaging probe to detect integrin αvβ3 positive tumors in living animals. Knottin 3-4A was synthesized by solid phase peptide synthesis, folded, and site-specifically conjugated with (18/19)F-NFP to produce the fluorinated peptide (18/19)F-fluoropropinate-3-4A ((18/19)F-FP-3-4A). The stability of (18)F-FP-3-4A was tested in both phosphate buffered saline (PBS) buffer and mouse serum. Cell uptake assays of the radiolabeled peptides were performed using U87MG cells. In addition, small animal PET imaging and biodistribution studies of (18)F-FP-3-4A were performed in U87MG tumor-bearing mice. The receptor targeting specificity of the radiolabeled peptide was also verified by coinjecting the probe with a blocking peptide cyclo(RGDyK). Our study showed that (18)F-FP-3-4A exhibited excellent stability in PBS buffer (pH 7.4) and mouse serum. Small animal PET imaging and biodistribution data revealed that (18)F-FP-3-4A exhibited rapid and good tumor uptake (3.76 ± 0.59% ID/g and 2.22 ± 0.62% ID/g at 0.5 and 1 h, respectively). (18)F-FP-3-4A was rapidly cleared from the normal tissues, resulting in excellent tumor-to-normal tissue contrasts. For example, liver uptake was only 0.39 ± 0.07% ID/g and the tumor to liver ratio was 5.69 at 1 h p.i. Furthermore, coinjection of cyclo(RGDyK) with (18)F-FP-3-4A significantly inhibited tumor uptake (0.41 ± 0.12 vs 1.02 ± 0.19% ID/g at 2.5 h) in U87MG xenograft models, demonstrating specific accumulation of the probe in the tumor. In summary, the divalent probe (18)F-FP-3-4A is characterized by rapid and high tumor uptake and excellent tumor-to-normal tissue ratios. (18)F-FP-3-4A is a highly promising knottin based PET probe for translating into clinical imaging of tumor angiogenesis.

  View details for DOI 10.1021/mp500018s

  View details for Web of Science ID 000344307700012

• THE NATURALLY OCCURRING STEROID, WITHAFERIN A, IN SYNERGISTIC CONCERT WITH HER2/EGFR INHIBITORS ABROGATES PROLIFERATION OF HUMAN GLIOBLASTOMA CELL CULTURES AT NANOMOLAR CONCENTRATIONS Chang, E., Abbasi, T., D'Souza, A., Gowrishankar, G., Mallick, P., Gambhir, S. S. OXFORD UNIV PRESS INC. 2014

  View details for DOI 10.1093/neuonc/nou246.3

  View details for Web of Science ID 000350452200246

• Cerenkov luminescence endoscopy: improved molecular sensitivity with ß--emitting radiotracers. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Carpenter, C. M., Ma, X., Liu, H., Sun, C., Pratx, G., Wang, J., Gambhir, S. S., Xing, L., Cheng, Z. 2014; 55 (11): 1905-1909

  Abstract

  Cerenkov luminescence endoscopy (CLE) is an optical technique that captures the Cerenkov photons emitted from highly energetic moving charged particles (β(+) or β(-)) and can be used to monitor the distribution of many clinically available radioactive probes. A main limitation of CLE is its limited sensitivity to small concentrations of radiotracer, especially when used with a light guide. We investigated the improvement in the sensitivity of CLE brought about by using a β(-) radiotracer that improved Cerenkov signal due to both higher β-particle energy and lower γ noise in the imaging optics because of the lack of positron annihilation.The signal-to-noise ratio (SNR) of (90)Y was compared with that of (18)F in both phantoms and small-animal tumor models. Sensitivity and noise characteristics were demonstrated using vials of activity both at the surface and beneath 1 cm of tissue. Rodent U87MG glioma xenograft models were imaged with radiotracers bound to arginine-glycine-aspartate (RGD) peptides to determine the SNR.γ noise from (18)F was demonstrated by both an observed blurring across the field of view and a more pronounced fall-off with distance. A decreased γ background and increased energy of the β particles resulted in a 207-fold improvement in the sensitivity of (90)Y compared with (18)F in phantoms. (90)Y-bound RGD peptide produced a higher tumor-to-background SNR than (18)F in a mouse model.The use of (90)Y for Cerenkov endoscopic imaging enabled superior results compared with an (18)F radiotracer.

  View details for DOI 10.2967/jnumed.114.139105

  View details for PubMedID 25300598

• (18)F-FPPRGD2 PET/CT: pilot phase evaluation of breast cancer patients. Radiology Iagaru, A., Mosci, C., Shen, B., Chin, F. T., Mittra, E., Telli, M. L., Gambhir, S. S. 2014; 273 (2): 549-559

  Abstract

  Purpose To present data from the first prospective pilot phase trial of breast cancer participants imaged with fluorine 18 ((18)F)-2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2), a radiopharmaceutical agent used in positron emission tomographic (PET) imaging. Materials and Methods The local institutional review board approved the HIPAA-compliant protocol. Written informed consent was obtained from each patient. Eight women (age range, 44-67 years; mean age, 54.3 years ± 8.8 [standard deviation]) with newly diagnosed or recurrent breast cancer were recruited between November 2010 and February 2011. (18)F-FPPRGD2 PET/computed tomographic (CT) and (18)F-fluorodeoxyglucose (FDG) PET/CT examinations were performed within 3 weeks of each other. Dynamic (18)F-FPPRGD2 PET and two whole-body static (18)F-FPPRGD2 PET/CT scans were obtained. During this time, vital signs and electrocardiograms were recorded at regular intervals. Blood samples were obtained before the injection of (18)F-FPPRGD2 and at 24 hours and 1 week after injection to evaluate for toxicity. A nonparametric version of multivariate analysis of variance was used to assess the safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare the maximum standardized uptake values (SUVmax). Results (18)F-FPPRGD2 was well tolerated, without noticeable changes in vital signs, on electrocardiograms, or in laboratory values. A total of 30 lesions were evaluated at (18)F-FDG PET/CT and (18)F-FPPRGD2 PET/CT. The primary breast lesions had (18)F-FPPRGD2 uptake with SUVmax of 2.4-9.4 (mean, 5.6 ± 2.8) 60 minutes after injection, compared with (18)F-FDG uptake with SUVmax of 2.8-18.6 (mean, 10.4 ± 7.2). Metastatic lesions also showed (18)F-FPPRGD2 uptake, with SUVmax of 2.4-9.7 (mean, 5.0 ± 2.3) at 60 minutes, compared with (18)F-FDG uptake with SUVmax of 2.2-14.6 (mean, 6.6 ± 4.2). Conclusion Data from this pilot phase study suggest that (18)F-FPPRGD2 is a safe PET radiopharmaceutical agent. Evaluation of (18)F-FPPRGD2 in participants with breast cancer demonstrated significant uptake in the primary lesion and in the metastases. Larger cohorts are required to confirm these preliminary findings. © RSNA, 2014.

  View details for DOI 10.1148/radiol.14140028

  View details for PubMedID 25033190

• Endometrial VEGF induces placental sFLT1 and leads to pregnancy complications JOURNAL OF CLINICAL INVESTIGATION Fan, X., Rai, A., Kambham, N., Sung, J. F., Singh, N., Petitt, M., Dhal, S., Agrawal, R., Sutton, R. E., Druzin, M. L., Gambhir, S. S., Ambati, B. K., Cross, J. C., Nayak, N. R. 2014; 124 (11): 4941-4952

  Abstract

  There is strong evidence that overproduction of soluble fms-like tyrosine kinase-1 (sFLT1) in the placenta is a major cause of vascular dysfunction in preeclampsia through sFLT1-dependent antagonism of VEGF. However, the cause of placental sFLT1 upregulation is not known. Here we demonstrated that in women with preeclampsia, sFLT1 is upregulated in placental trophoblasts, while VEGF is upregulated in adjacent maternal decidual cells. In response to VEGF, expression of sFlt1 mRNA, but not full-length Flt1 mRNA, increased in cultured murine trophoblast stem cells. We developed a method for transgene expression specifically in mouse endometrium and found that endometrial-specific VEGF overexpression induced placental sFLT1 production and elevated sFLT1 levels in maternal serum. This led to pregnancy losses, placental vascular defects, and preeclampsia-like symptoms, including hypertension, proteinuria, and glomerular endotheliosis in the mother. Knockdown of placental sFlt1 with a trophoblast-specific transgene caused placental vascular changes that were consistent with excess VEGF activity. Moreover, sFlt1 knockdown in VEGF-overexpressing animals enhanced symptoms produced by VEGF overexpression alone. These findings indicate that sFLT1 plays an essential role in maintaining vascular integrity in the placenta by sequestering excess maternal VEGF and suggest that a local increase in VEGF can trigger placental overexpression of sFLT1, potentially contributing to the development of preeclampsia and other pregnancy complications.

  View details for DOI 10.1172/JCI76864

  View details for Web of Science ID 000344203300029

  View details for PubMedCentralID PMC4347223

• F-18-FPPRGD2 PET/CT: Pilot Phase Evaluation of Breast Cancer Patients RADIOLOGY Lagaru, A., Mosci, C., Shen, B., Chin, F. T., Mittra, E., Telli, M. L., Gambhir, S. S. 2014; 273 (2): 549-559

  Abstract

  Purpose To present data from the first prospective pilot phase trial of breast cancer participants imaged with fluorine 18 ((18)F)-2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2), a radiopharmaceutical agent used in positron emission tomographic (PET) imaging. Materials and Methods The local institutional review board approved the HIPAA-compliant protocol. Written informed consent was obtained from each patient. Eight women (age range, 44-67 years; mean age, 54.3 years ± 8.8 [standard deviation]) with newly diagnosed or recurrent breast cancer were recruited between November 2010 and February 2011. (18)F-FPPRGD2 PET/computed tomographic (CT) and (18)F-fluorodeoxyglucose (FDG) PET/CT examinations were performed within 3 weeks of each other. Dynamic (18)F-FPPRGD2 PET and two whole-body static (18)F-FPPRGD2 PET/CT scans were obtained. During this time, vital signs and electrocardiograms were recorded at regular intervals. Blood samples were obtained before the injection of (18)F-FPPRGD2 and at 24 hours and 1 week after injection to evaluate for toxicity. A nonparametric version of multivariate analysis of variance was used to assess the safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare the maximum standardized uptake values (SUVmax). Results (18)F-FPPRGD2 was well tolerated, without noticeable changes in vital signs, on electrocardiograms, or in laboratory values. A total of 30 lesions were evaluated at (18)F-FDG PET/CT and (18)F-FPPRGD2 PET/CT. The primary breast lesions had (18)F-FPPRGD2 uptake with SUVmax of 2.4-9.4 (mean, 5.6 ± 2.8) 60 minutes after injection, compared with (18)F-FDG uptake with SUVmax of 2.8-18.6 (mean, 10.4 ± 7.2). Metastatic lesions also showed (18)F-FPPRGD2 uptake, with SUVmax of 2.4-9.7 (mean, 5.0 ± 2.3) at 60 minutes, compared with (18)F-FDG uptake with SUVmax of 2.2-14.6 (mean, 6.6 ± 4.2). Conclusion Data from this pilot phase study suggest that (18)F-FPPRGD2 is a safe PET radiopharmaceutical agent. Evaluation of (18)F-FPPRGD2 in participants with breast cancer demonstrated significant uptake in the primary lesion and in the metastases. Larger cohorts are required to confirm these preliminary findings. © RSNA, 2014.

  View details for DOI 10.1148/radiol.14140028

  View details for Web of Science ID 000345069800028

• Endoscopic molecular imaging of human bladder cancer using a CD47 antibody SCIENCE TRANSLATIONAL MEDICINE Pan, Y., Volkmer, J., Mach, K. E., Rouse, R. V., Liu, J., Sahoo, D., Chang, T. C., Metzner, T. J., Kang, L., van de Rijn, M., Skinner, E. C., Gambhir, S. S., Weissman, I. L., Liao, J. C. 2014; 6 (260)

  Abstract

  A combination of optical imaging technologies with cancer-specific molecular imaging agents is a potentially powerful strategy to improve cancer detection and enable image-guided surgery. Bladder cancer is primarily managed endoscopically by white light cystoscopy with suboptimal diagnostic accuracy. Emerging optical imaging technologies hold great potential for improved diagnostic accuracy but lack imaging agents for molecular specificity. Using fluorescently labeled CD47 antibody (anti-CD47) as molecular imaging agent, we demonstrated consistent identification of bladder cancer with clinical grade fluorescence imaging systems, confocal endomicroscopy, and blue light cystoscopy in fresh surgically removed human bladders. With blue light cystoscopy, the sensitivity and specificity for CD47-targeted imaging were 82.9 and 90.5%, respectively. We detected variants of bladder cancers, which are diagnostic challenges, including carcinoma in situ, residual carcinoma in tumor resection bed, recurrent carcinoma following prior intravesical immunotherapy with Bacillus Calmette-Guérin (BCG), and excluded cancer from benign but suspicious-appearing mucosa. CD47-targeted molecular imaging could improve diagnosis and resection thoroughness for bladder cancer.

  View details for DOI 10.1126/scitranslmed.3009457

  View details for Web of Science ID 000343920500006

• Transferring biomarker into molecular probe: melanin nanoparticle as a naturally active platform for multimodality imaging. Journal of the American Chemical Society Fan, Q., Cheng, K., Hu, X., Ma, X., Zhang, R., Yang, M., Lu, X., Xing, L., Huang, W., Gambhir, S. S., Cheng, Z. 2014; 136 (43): 15185-15194

  Abstract

  Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transferring an important molecular target, melanin, into a novel mul-timodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (< 10 nm) water-soluble melanin nanoparticle (MNP) was developed and showed unique photoacoustic property and natural binding ability with metal ions (for example, 64Cu2+, Fe3+). Therefore MNP can serve not only as a photoacoustic contrast agent, but also as a nanoplatform for positron emission tomography (PET) and magnetic resonance imaging (MRI). Traditional passive nanoplatforms require complicated and time-consuming processes for pre-building reporting moieties or chemical modifications using active groups to integrate different contrast properties into one entity. In comparison, utilizing functional biomarker melanin can greatly simplify the building process. We further conjugated αvβ3 integrins targeting peptide, cyclic c(RGDfC) peptide, to MNPs and this allowed targeting of these nanoparticles to allow for greater U87MG tumor accumulation than that simply possible due to the enhanced permeability and retention (EPR) effect. The multimodal properties of MNPs demonstrate the high potential of endogenous materials with multifunctions as nanoplatforms for molecular theranostics and clinical translation.

  View details for DOI 10.1021/ja505412p

  View details for PubMedID 25292385

• Endoscopic molecular imaging of human bladder cancer using a CD47 antibody. Science translational medicine Pan, Y., Volkmer, J., Mach, K. E., Rouse, R. V., Liu, J., Sahoo, D., Chang, T. C., Metzner, T. J., Kang, L., van de Rijn, M., Skinner, E. C., Gambhir, S. S., Weissman, I. L., Liao, J. C. 2014; 6 (260): 260ra148-?

  Abstract

  A combination of optical imaging technologies with cancer-specific molecular imaging agents is a potentially powerful strategy to improve cancer detection and enable image-guided surgery. Bladder cancer is primarily managed endoscopically by white light cystoscopy with suboptimal diagnostic accuracy. Emerging optical imaging technologies hold great potential for improved diagnostic accuracy but lack imaging agents for molecular specificity. Using fluorescently labeled CD47 antibody (anti-CD47) as molecular imaging agent, we demonstrated consistent identification of bladder cancer with clinical grade fluorescence imaging systems, confocal endomicroscopy, and blue light cystoscopy in fresh surgically removed human bladders. With blue light cystoscopy, the sensitivity and specificity for CD47-targeted imaging were 82.9 and 90.5%, respectively. We detected variants of bladder cancers, which are diagnostic challenges, including carcinoma in situ, residual carcinoma in tumor resection bed, recurrent carcinoma following prior intravesical immunotherapy with Bacillus Calmette-Guérin (BCG), and excluded cancer from benign but suspicious-appearing mucosa. CD47-targeted molecular imaging could improve diagnosis and resection thoroughness for bladder cancer.

  View details for DOI 10.1126/scitranslmed.3009457

  View details for PubMedID 25355698

• Molecular photoacoustic imaging and serum diagnostics rapidly detect response to angiopoietin 1 and 2 blockade in ovarian cancer Bohndiek, S. E., Sasportas, L., Machtaler, S., Jokerst, J. V., Hori, S., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2014

  View details for DOI 10.1158/1538-7445.AM2014-2047

  View details for Web of Science ID 000349906902259

• First evaluation of a time-of-flight whole-body PET/MRI scanner in oncology patients: comparison with PET/CT Iagaru, A., Jamali, M., Minamimoto, R., Mittra, E., Gold, G., Vasanwala, S., Gambhir, S. S., Zaharchuk, G. SPRINGER. 2014: S287–S288

  View details for Web of Science ID 000348841900416

• Correlation of plasma biomarker levels with early-stage tumor viability in an orthotopic ovarian cancer mouse model Hori, S. S., Lutz, A. M., Paulmurugan, R., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2014

  View details for DOI 10.1158/1538-7445.AM2014-873

  View details for Web of Science ID 000349906905331

• MicroRNA footprints of circulating tumor cells in patients with non-small cell lung cancer Nair, V. S., Giraldez, M., Luttgen, M., Keu, K., Vasanawala, M., Horng, G., Jamali, M., Kolatkar, A., Kuschner, W., Kuhn, P., Gambhir, S., Tewari, M. AMER ASSOC CANCER RESEARCH. 2014

  View details for DOI 10.1158/1538-7445.AM2014-4006

  View details for Web of Science ID 000349910201490

• Novel method of liver tumor detection and characterization using ultrasound-induced biomarker release D'Souza, A. L., Yan, X., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2014

  View details for DOI 10.1158/1538-7445.AM2014-4287

  View details for Web of Science ID 000349910202263

• Investigation of 6-[F-18]-Fluoromaltose as a Novel PET Tracer for Imaging Bacterial Infection PLOS ONE Gowrishankar, G., Namavari, M., Jouannot, E. B., Hoehne, A., Reeves, R., Hardy, J., Gambhir, S. S. 2014; 9 (9)

  Abstract

  Despite advances in the field of nuclear medicine, the imaging of bacterial infections has remained a challenge. The existing reagents suffer from poor sensitivity and specificity. In this study we investigate the potential of a novel PET (positron emission tomography) tracer that overcomes these limitations.6-[¹⁸F]-fluoromaltose was synthesized. Its behavior in vitro was evaluated in bacterial and mammalian cultures. Detailed pharmacokinetic and biodistribution profiles for the tracer were obtained from a murine model.6-[¹⁸F]-fluoromaltose is taken up by multiple strains of pathogenic bacteria. It is not taken up by mammalian cancer cell lines. 6-[¹⁸F]-fluoromaltose is retained in infected muscles in a murine model of bacterial myositis. It does not accumulate in inflamed tissue.We have shown that 6-[¹⁸F]-fluoromaltose can be used to image bacterial infection in vivo with high specificity. We believe that this class of agents will have a significant impact on the clinical management of patients.

  View details for DOI 10.1371/journal.pone.0107951

  View details for Web of Science ID 000343679800058

  View details for PubMedCentralID PMC4171493

• Cellulose Nanoparticles are a Biodegradable Photoacoustic Contrast Agent for Use in Living Mice. Photoacoustics Jokerst, J. V., Van de Sompel, D., Bohndiek, S. E., Gambhir, S. S. 2014; 2 (3): 119-127

  Abstract

  Molecular imaging with photoacoustic ultrasound is an emerging field that combines the spatial and temporal resolution of ultrasound with the contrast of optical imaging. However, there are few imaging agents that offer both high signal intensity and biodegradation into small molecules. Here we describe a cellulose-based nanoparticle with peak photoacoustic signal at 700 nm and an in vitro limit of detection of 6 pM (0.02 mg/mL). Doses down to 0.35 nM (1.2 mg/mL) were used to image mouse models of ovarian cancer. Most importantly, the nanoparticles were shown to biodegrade in the presence of cellulase both through a glucose assay and electron microscopy.

  View details for PubMedID 25225633

• Cellulose nanoparticles are a biodegradable photoacoustic contrast agent for use in living mice PHOTOACOUSTICS Jokerst, J. V., Van de Sompel, D., Bohndiek, S. E., Gambhir, S. S. 2014; 2 (3): 119–27

  View details for DOI 10.1016/j.pacs.2014.07.001

  View details for Web of Science ID 000218887500003

• Circulating Tumor Microemboli Diagnostics for Patients with Non-Small-Cell Lung Cancer JOURNAL OF THORACIC ONCOLOGY Carlsson, A., Nair, V. S., Luttgen, M. S., Keu, K. V., Horng, G., Vasanawala, M., Kolatkar, A., Jamali, M., Iagaru, A. H., Kuschner, W., Loo, B. W., Shrager, J. B., Bethel, K., Hoh, C. K., Bazhenova, L., Nieva, J., Kuhn, P., Gambhir, S. S. 2014; 9 (8): 1111-1119

  Abstract

  Circulating tumor microemboli (CTM) are potentially important cancer biomarkers, but using them for cancer detection in early-stage disease has been assay limited. We examined CTM test performance using a sensitive detection platform to identify stage I non-small-cell lung cancer (NSCLC) patients undergoing imaging evaluation.First, we prospectively enrolled patients during 18F-FDG PET-CT imaging evaluation for lung cancer that underwent routine phlebotomy where CTM and circulating tumor cells (CTCs) were identified in blood using nuclear (DAPI), cytokeratin (CK), and CD45 immune-fluorescent antibodies followed by morphologic identification. Second, CTM and CTC data were integrated with patient (age, gender, smoking, and cancer history) and imaging (tumor diameter, location in lung, and maximum standard uptake value [SUVmax]) data to develop and test multiple logistic regression models using a case-control design in a training and test cohort followed by cross-validation in the entire group.We examined 104 patients with NSCLC, and the subgroup of 80 with stage I disease, and compared them to 25 patients with benign disease. Clinical and imaging data alone were moderately discriminating for all comers (Area under the Curve [AUC] = 0.77) and by stage I disease only (AUC = 0.77). However, the presence of CTM combined with clinical and imaging data was significantly discriminating for diagnostic accuracy in all NSCLC patients (AUC = 0.88, p value = 0.001) and for stage I patients alone (AUC = 0.87, p value = 0.002).CTM may add utility for lung cancer diagnosis during imaging evaluation using a sensitive detection platform.

  View details for PubMedID 25157764

• Imaging of hepatocellular carcinoma patient-derived xenografts using (89)Zr-labeled anti-glypican-3 monoclonal antibody. Biomaterials Yang, X., Liu, H., Sun, C. K., Natarajan, A., Hu, X., Wang, X., Allegretta, M., Guttmann, R. D., Gambhir, S. S., Chua, M. S., Cheng, Z., So, S. K. 2014; 35 (25): 6964-71

  Abstract

  Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention.

  View details for DOI 10.1016/j.biomaterials.2014.04.089

  View details for PubMedID 24836949

• Imaging of hepatocellular carcinoma patient-derived xenografts using Zr-89-labeled anti-glypican-3 monoclonal antibody BIOMATERIALS Yang, X., Liu, H., Sun, C. K., Natarajan, A., Hu, X., Wang, X., Allegretta, M., Guttmann, R. D., Gambhir, S. S., Chua, M., Cheng, Z., So, S. K. 2014; 35 (25): 6964-6971

  Abstract

  Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention.

  View details for DOI 10.1016/j.biomaterials.2014.04.089

  View details for Web of Science ID 000338386800028

• A High-Affinity, High-Stability Photoacoustic Agent for Imaging Gastrin-Releasing Peptide Receptor in Prostate Cancer CLINICAL CANCER RESEARCH Levi, J., Sathirachinda, A., Gambhir, S. S. 2014; 20 (14): 3721-3729

  Abstract

  To evaluate the utility of targeted photoacoustic imaging (PAI) in providing molecular information to complement intrinsic functional and anatomical details of the vasculature within prostate lesion.We developed a PAI agent, AA3G-740, that targets gastrin-releasing peptide receptor (GRPR), found to be highly overexpressed in prostate cancer. The binding specificity of the agent was evaluated in human prostate cancer cell lines, PC3 and LNCaP, and antagonist properties determined by cell internalization and intracellular calcium mobilization studies. The imaging sensitivity was assessed for the agent itself and for the PC3 cells labeled with agent. The in vivo stability of the agent was determined in human plasma and in the blood of living mice. The in vivo binding of the agent was evaluated in PC3 prostate tumor models in mice, and was validated ex vivo by optical imaging.AA3G-740 demonstrated strong and specific binding to GRPR. The sensitivity of detection in vitro indicated suitability of the agent to image very small lesions. In mice, the agent was able to bind to GRPR even in poorly vascularized tumors leading to nearly 2-fold difference in photoacoustic signal relative to the control agent.The ability to image both vasculature and molecular profile outside the blood vessels gives molecular PAI a unique advantage over currently used imaging techniques. The imaging method presented here can find application both in diagnosis and in image-guided biopsy.

  View details for DOI 10.1158/1078-0432.CCR-13-3405

  View details for Web of Science ID 000339611500013

  View details for PubMedID 24850845

  View details for PubMedCentralID PMC4121111

• Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery. Nature nanotechnology Smith, B. R., Ghosn, E. E., Rallapalli, H., Prescher, J. A., Larson, T., Herzenberg, L. A., Gambhir, S. S. 2014; 9 (6): 481-487

  Abstract

  In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  View details for DOI 10.1038/nnano.2014.62

  View details for PubMedID 24727688

• Observed standardized uptake values in normal tissues and malignant lesions on combined 18F-NaF/18F-FDG PET/CT Minamimoto, R., Mosci, C., Jamali, M., Mittra, E., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438102304

• Combined NaF/FDG PET/CT evaluation of prostate cancer patients Iagaru, A., Mosci, C., Keu, K., Mittra, E., Hancock, S., Pachynski, R., Srinivas, S., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438102320

• 99mTc-MDP scintigraphy vs. 18F NaF PET/CT for detection of skeletal metastases Iagaru, A., Jackson, T., Sabbah, N., Guo, H., Quon, A., Mittra, E., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438103152

• 99mTc-MDP scintigraphy vs. 18F NaF PET/CT for detection of skeletal metastases Iagaru, A., Jackson, T., Sabbah, N., Guo, H., Quon, A., Mittra, E., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438104142

• 18F FPPRGD2 PET/CT evaluation of patients with suspected recurrence of glioblastoma multiforme Iagaru, A., Mosci, C., Jamali, M., Minamimoto, R., Mittra, E., Shen, B., Chin, F., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438100032

• A novel radioluminescence microscope for imaging radiotracers at the single-cell level Pratx, G., Natarajan, A., Turkcan, S., Sasportas, L., Axente, M., Gambhir, S., Xing, L. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438100043

• Tumor imaging with a radiofluorinated divalent knottin Jiang, L., Kimura, R., Ma, X., Tu, Y., Miao, Z., Shen, B., Chin, F., Shi, H., Gambhir, S., Cheng, Z. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438101248

• Detection of tumor cell apoptosis by PET: Comparison of [F-18]C-SNAT, [Tc-99m]HYNIC-Annexin V and [F-18]ML-10 Witney, T., Hoehne, A., Ilovich, O., Namavari, M., Shen, B., Chin, F., Rao, J., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438102043

• Prospective evaluation of combined NaF/FDG PET/CT and whole-body MRI in patients with breast and prostate cancer Iagaru, A., Mosci, C., Jamali, M., Loening, A., Mittra, E., Gambhir, S., Vasanawala, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438102203

• FDG uptake in normal tissues and malignant lesions from the first whole-body time-of-flight PET/MRI scanner: Comparison with PET/CT Iagaru, A., Mittra, E., Zaharchuk, G., Frost, R., Elekes, A., Anderson, J., Bobb, C., Lahrman, J., Gold, G., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438101156

• Single cell metabolomics in circulating tumor cells Sasportas, L., Turkcan, S., Pratx, G., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2014

  View details for Web of Science ID 000361438100009

• A Radiofluorinated Divalent Cystine Knot Peptide for Tumor PET Imaging. Molecular pharmaceutics Jiang, L., Kimura, R. H., Ma, X., Tu, Y., Miao, Z., Shen, B., Chin, F. T., Shi, H., Gambhir, S. S., Cheng, Z. 2014

  Abstract

  A divalent knottin containing two separate integrin binding epitopes (RGD) in the adjacent loops, 3-4A, was recently developed and reported in our previous publication. In the current study, 3-4A was radiofluorinated with a 4-nitrophenyl 2-(18)F-fluoropropinate ((18)F-NFP) group and the resulting divalent positron emission tomography (PET) probe, (18)F-FP-3-4A, was evaluated as a novel imaging probe to detect integrin αvβ3 positive tumors in living animals. Knottin 3-4A was synthesized by solid phase peptide synthesis, folded, and site-specifically conjugated with (18/19)F-NFP to produce the fluorinated peptide (18/19)F-fluoropropinate-3-4A ((18/19)F-FP-3-4A). The stability of (18)F-FP-3-4A was tested in both phosphate buffered saline (PBS) buffer and mouse serum. Cell uptake assays of the radiolabeled peptides were performed using U87MG cells. In addition, small animal PET imaging and biodistribution studies of (18)F-FP-3-4A were performed in U87MG tumor-bearing mice. The receptor targeting specificity of the radiolabeled peptide was also verified by coinjecting the probe with a blocking peptide cyclo(RGDyK). Our study showed that (18)F-FP-3-4A exhibited excellent stability in PBS buffer (pH 7.4) and mouse serum. Small animal PET imaging and biodistribution data revealed that (18)F-FP-3-4A exhibited rapid and good tumor uptake (3.76 ± 0.59% ID/g and 2.22 ± 0.62% ID/g at 0.5 and 1 h, respectively). (18)F-FP-3-4A was rapidly cleared from the normal tissues, resulting in excellent tumor-to-normal tissue contrasts. For example, liver uptake was only 0.39 ± 0.07% ID/g and the tumor to liver ratio was 5.69 at 1 h p.i. Furthermore, coinjection of cyclo(RGDyK) with (18)F-FP-3-4A significantly inhibited tumor uptake (0.41 ± 0.12 vs 1.02 ± 0.19% ID/g at 2.5 h) in U87MG xenograft models, demonstrating specific accumulation of the probe in the tumor. In summary, the divalent probe (18)F-FP-3-4A is characterized by rapid and high tumor uptake and excellent tumor-to-normal tissue ratios. (18)F-FP-3-4A is a highly promising knottin based PET probe for translating into clinical imaging of tumor angiogenesis.

  View details for DOI 10.1021/mp500018s

  View details for PubMedID 24717098

• 99mTc-labeled cystine knot peptide targeting integrin avß6 for tumor SPECT imaging. Molecular pharmaceutics Zhu, X., Li, J., Hong, Y., Kimura, R. H., Ma, X., Liu, H., Qin, C., Hu, X., Hayes, T. R., Benny, P., Gambhir, S. S., Cheng, Z. 2014; 11 (4): 1208-1217

  Abstract

  Integrin αvβ6 is overexpressed in a variety of cancers, and its expression is often associated with poor prognosis. Therefore, there is a need to develop affinity reagents for noninvasive imaging of integrin αvβ6 expression since it may provide early cancer diagnosis, more accurate prognosis, and better treatment planning. We recently engineered and validated highly stable cystine knot peptides that selectively bind integrin αvβ6 with no cross-reactivity to integrins αvβ5, α5β1, or αvβ3, also known to be overexpressed in many cancers. Here, we developed a single photon emission computed tomography (SPECT) probe for imaging integrin αvβ6 positive tumors. Cystine knot peptide, S02, was first conjugated with a single amino acid chelate (SAAC) and labeled with [(99m)Tc(H2O)3(CO)3](+). The resulting probe, (99m)Tc-SAAC-S02, was then evaluated by in vitro cell uptake studies using two αvβ6 positive cell lines (human lung adenocarcinoma cell line HCC4006 and pancreatic cancer cell line BxPC-3) and two αvβ6 negative cell lines (human lung adenocarcinoma cell line H838 and human embryonic kidney cell line 293T). Next, SPECT/CT and biodistribution studies were performed in nude mice bearing HCC4006 and H838 tumor xenografts to evaluate the in vivo performance of (99m)Tc-SAAC-S02. Significant differences in the uptake of (99m)Tc-SAAC-S02 were observed in αvβ6 positive vs negative cells (P < 0.05). Biodistribution and small animal SPECT/CT studies revealed that (99m)Tc-SAAC-S02 accumulated to moderate levels in antigen positive tumors (∼2% ID/g at 1 and 6 h postinjection, n = 3 or 4/group). Moreover, the probe demonstrated tumor-to-background tissue ratios of 6.81 ± 2.32 (tumor-to-muscle) and 1.63 ± 0.18 (tumor-to-blood) at 6 h postinjection in αvβ6 positive tumor xenografts. Co-incubation of the probe with excess amount of unlabeled S02 as a blocking agent demonstrated significantly reduced tumor uptake, which is consistent with specific binding to the target. Renal filtration was the main route of clearance. In conclusion, knottin peptides are excellent scaffolds for which to develop highly stable imaging probes for a variety of oncological targets. (99m)Tc-SAAC-S02 demonstrates promise for use as a SPECT agent to image integrin αvβ6 expression in living systems.

  View details for DOI 10.1021/mp400683q

  View details for PubMedID 24524409

• A tunable silk-alginate hydrogel scaffold for stem cell culture and transplantation. Biomaterials Ziv, K., Nuhn, H., Ben-Haim, Y., Sasportas, L. S., Kempen, P. J., Niedringhaus, T. P., Hrynyk, M., Sinclair, R., Barron, A. E., Gambhir, S. S. 2014; 35 (12): 3736-3743

  Abstract

  One of the major challenges in regenerative medicine is the ability to recreate the stem cell niche, which is defined by its signaling molecules, the creation of cytokine gradients, and the modulation of matrix stiffness. A wide range of scaffolds has been developed in order to recapitulate the stem cell niche, among them hydrogels. This paper reports the development of a new silk-alginate based hydrogel with a focus on stem cell culture. This biocomposite allows to fine tune its elasticity during cell culture, addressing the importance of mechanotransduction during stem cell differentiation. The silk-alginate scaffold promotes adherence of mouse embryonic stem cells and cell survival upon transplantation. In addition, it has tunable stiffness as function of the silk-alginate ratio and the concentration of crosslinker - a characteristic that is very hard to accomplish in current hydrogels. The hydrogel and the presented results represents key steps on the way of creating artificial stem cell niche, opening up new paths in regenerative medicine.

  View details for DOI 10.1016/j.biomaterials.2014.01.029

  View details for PubMedID 24484675

• Tc-99m-Labeled Cystine Knot Peptide Targeting Integrin alpha(v)beta(6) for Tumor SPECT Imaging MOLECULAR PHARMACEUTICS Zhu, X., Li, J., Hong, Y., Kimura, R. H., Ma, X., Liu, H., Qin, C., Hu, X., Hayes, T. R., Benny, P., Gambhir, S. S., Cheng, Z. 2014; 11 (4): 1208-1217

  Abstract

  Integrin αvβ6 is overexpressed in a variety of cancers, and its expression is often associated with poor prognosis. Therefore, there is a need to develop affinity reagents for noninvasive imaging of integrin αvβ6 expression since it may provide early cancer diagnosis, more accurate prognosis, and better treatment planning. We recently engineered and validated highly stable cystine knot peptides that selectively bind integrin αvβ6 with no cross-reactivity to integrins αvβ5, α5β1, or αvβ3, also known to be overexpressed in many cancers. Here, we developed a single photon emission computed tomography (SPECT) probe for imaging integrin αvβ6 positive tumors. Cystine knot peptide, S02, was first conjugated with a single amino acid chelate (SAAC) and labeled with [(99m)Tc(H2O)3(CO)3](+). The resulting probe, (99m)Tc-SAAC-S02, was then evaluated by in vitro cell uptake studies using two αvβ6 positive cell lines (human lung adenocarcinoma cell line HCC4006 and pancreatic cancer cell line BxPC-3) and two αvβ6 negative cell lines (human lung adenocarcinoma cell line H838 and human embryonic kidney cell line 293T). Next, SPECT/CT and biodistribution studies were performed in nude mice bearing HCC4006 and H838 tumor xenografts to evaluate the in vivo performance of (99m)Tc-SAAC-S02. Significant differences in the uptake of (99m)Tc-SAAC-S02 were observed in αvβ6 positive vs negative cells (P < 0.05). Biodistribution and small animal SPECT/CT studies revealed that (99m)Tc-SAAC-S02 accumulated to moderate levels in antigen positive tumors (∼2% ID/g at 1 and 6 h postinjection, n = 3 or 4/group). Moreover, the probe demonstrated tumor-to-background tissue ratios of 6.81 ± 2.32 (tumor-to-muscle) and 1.63 ± 0.18 (tumor-to-blood) at 6 h postinjection in αvβ6 positive tumor xenografts. Co-incubation of the probe with excess amount of unlabeled S02 as a blocking agent demonstrated significantly reduced tumor uptake, which is consistent with specific binding to the target. Renal filtration was the main route of clearance. In conclusion, knottin peptides are excellent scaffolds for which to develop highly stable imaging probes for a variety of oncological targets. (99m)Tc-SAAC-S02 demonstrates promise for use as a SPECT agent to image integrin αvβ6 expression in living systems.

  View details for DOI 10.1021/mp400683q

  View details for Web of Science ID 000334092700013

  View details for PubMedCentralID PMC3993876

• A titratable two-step transcriptional amplification strategy for targeted gene therapy based on ligand-induced intramolecular folding of a mutant human estrogen receptor. Molecular imaging and biology Chen, I. Y., Paulmurugan, R., Nielsen, C. H., Wang, D. S., Chow, V., Robbins, R. C., Gambhir, S. S. 2014; 16 (2): 224-234

  Abstract

  The efficacy and safety of cardiac gene therapy depend critically on the level and the distribution of therapeutic gene expression following vector administration. We aimed to develop a titratable two-step transcriptional amplification (tTSTA) vector strategy, which allows modulation of transcriptionally targeted gene expression in the myocardium.We constructed a tTSTA plasmid vector (pcTnT-tTSTA-fluc), which uses the cardiac troponin T (cTnT) promoter to drive the expression of the recombinant transcriptional activator GAL4-mER(LBD)-VP2, whose ability to transactivate the downstream firefly luciferase reporter gene (fluc) depends on the binding of its mutant estrogen receptor (ER(G521T)) ligand binding domain (LBD) to an ER ligand such as raloxifene. Mice underwent either intramyocardial or hydrodynamic tail vein (HTV) injection of pcTnT-tTSTA-fluc, followed by differential modulation of fluc expression with varying doses of intraperitoneal raloxifene prior to bioluminescence imaging to assess the kinetics of myocardial or hepatic fluc expression.Intramyocardial injection of pcTnT-tTSTA-fluc followed by titration with intraperitoneal raloxifene led to up to tenfold induction of myocardial fluc expression. HTV injection of pcTnT-tTSTA-fluc led to negligible long-term hepatic fluc expression, regardless of the raloxifene dose given.The tTSTA vector strategy can effectively modulate transgene expression in a tissue-specific manner. Further refinement of this strategy should help maximize the benefit-to-risk ratio of cardiac gene therapy.

  View details for DOI 10.1007/s11307-013-0673-4

  View details for PubMedID 23955099

  View details for PubMedCentralID PMC4154804

• Construction of hybrid nanostructures as multimodal contrast agents for cancer imaging Cheng, K., Jokerst, J. V., Liu, H., Kothapalli, R., Jiang, H., Yang, M., Su, X., Ming, S., Hu, X., Li, J., Liu, Y., Levi, J., Gambhir, S., Cheng, Z. AMER CHEMICAL SOC. 2014

  View details for Web of Science ID 000348455204466

• Construction and validation of nano gold tripods for molecular imaging of living subjects. Journal of the American Chemical Society Cheng, K., Kothapalli, S., Liu, H., Koh, A. L., Jokerst, J. V., Jiang, H., Yang, M., Li, J., Levi, J., Wu, J. C., Gambhir, S. S., Cheng, Z. 2014; 136 (9): 3560-3571

  Abstract

  Anisotropic colloidal hybrid nanoparticles exhibit superior optical and physical properties compared to their counterparts with regular architectures. We herein developed a controlled, stepwise strategy to build novel, anisotropic, branched, gold nanoarchitectures (Au-tripods) with predetermined composition and morphology for bioimaging. The resultant Au-tripods with size less than 20 nm showed great promise as contrast agents for in vivo photoacoustic imaging (PAI). We further identified Au-tripods with two possible configurations as high-absorbance nanomaterials from various gold multipods using a numerical simulation analysis. The PAI signals were linearly correlated with their concentrations after subcutaneous injection. The in vivo biodistribution of Au-tripods favorable for molecular imaging was confirmed using small animal positron emission tomography (PET). Intravenous administration of cyclic Arg-Gly-Asp-d-Phe-Cys (RGDfC) peptide conjugated Au-tripods (RGD-Au-tripods) to U87MG tumor-bearing mice showed PAI contrasts in tumors almost 3-fold higher than for the blocking group. PAI results correlated well with the corresponding PET images. Quantitative biodistribution data revealed that 7.9% ID/g of RGD-Au-tripods had accumulated in the U87MG tumor after 24 h post-injection. A pilot mouse toxicology study confirmed that no evidence of significant acute or systemic toxicity was observed in histopathological examination. Our study suggests that Au-tripods can be reliably synthesized through stringently controlled chemical synthesis and could serve as a new generation of platform with high selectivity and sensitivity for multimodality molecular imaging.

  View details for DOI 10.1021/ja412001e

  View details for PubMedID 24495038

• Ultrasound Molecular Imaging in a Human CD276 Expression-Modulated Murine Ovarian Cancer Model. Clinical cancer research Lutz, A. M., Bachawal, S. V., Drescher, C. W., Pysz, M. A., Willmann, J. K., Gambhir, S. S. 2014; 20 (5): 1313-1322

  Abstract

  To develop a mouse ovarian cancer model that allows modulating the expression levels of human vascular targets in mouse xenograft tumors and to test whether expression of CD276 during tumor angiogenesis can be visualized by molecularly targeted ultrasound in vivo.CD276-expressing MILE SVEN 1 (MS1) mouse endothelial cells were engineered and used for coinjection with 2008 human ovarian cancer cells for subcutaneous xenograft tumor induction in 15 nude mice. Fourteen control mice were injected with 2008 cells only. After confirming their binding specificity in flow chamber cell attachment studies, anti-CD276 antibody-functionalized contrast microbubbles were used for in vivo CD276-targeted contrast-enhanced ultrasound imaging.CD276-targeted ultrasound imaging signal was significantly higher (P = 0.006) in mixed MS1/2008 tumors than in control tumors. Compared with control microbubbles, the ultrasound signal using CD276-targeted microbubbles was significantly higher (P = 0.002), and blocking with purified anti-CD276 antibody significantly decreased (P = 0.0096) the signal in mixed MS1/2008 tumors. Immunofluorescence analysis of the tumor tissue confirmed higher quantitative immunofluorescence signal in mixed MS1/2008 tumors than in control 2008 only tumors, but showed not significantly different (P = 0.54) microvessel density.Our novel small animal model allows for modulating the expression of human tumor-associated vascular endothelial imaging targets in a mouse host and these expression differences can be visualized noninvasively by ultrasound molecular imaging. The animal model can be applied to other human vascular targets and may facilitate the preclinical development of new imaging probes such as microbubbles targeted at human vascular markers not expressed in mice. Clin Cancer Res; 20(5); 1313-22. ©2014 AACR.

  View details for DOI 10.1158/1078-0432.CCR-13-1642

  View details for PubMedID 24389327

  View details for PubMedCentralID PMC3965293

• Semiconducting polymer nanoparticles as photoacoustic molecular imaging probes in living mice. Nature nanotechnology Pu, K., Shuhendler, A. J., Jokerst, J. V., Mei, J., Gambhir, S. S., Bao, Z., Rao, J. 2014; 9 (3): 233-239

  Abstract

  Photoacoustic imaging holds great promise for the visualization of physiology and pathology at the molecular level with deep tissue penetration and fine spatial resolution. To fully utilize this potential, photoacoustic molecular imaging probes have to be developed. Here, we introduce near-infrared light absorbing semiconducting polymer nanoparticles as a new class of contrast agents for photoacoustic molecular imaging. These nanoparticles can produce a stronger signal than the commonly used single-walled carbon nanotubes and gold nanorods on a per mass basis, permitting whole-body lymph-node photoacoustic mapping in living mice at a low systemic injection mass. Furthermore, the semiconducting polymer nanoparticles possess high structural flexibility, narrow photoacoustic spectral profiles and strong resistance to photodegradation and oxidation, enabling the development of the first near-infrared ratiometric photoacoustic probe for in vivo real-time imaging of reactive oxygen species-vital chemical mediators of many diseases. These results demonstrate semiconducting polymer nanoparticles to be an ideal nanoplatform for developing photoacoustic molecular probes.

  View details for DOI 10.1038/nnano.2013.302

  View details for PubMedID 24463363

  View details for PubMedCentralID PMC3947658

• Light in and sound out: emerging translational strategies for photoacoustic imaging. Cancer research Zackrisson, S., van de Ven, S. M., Gambhir, S. S. 2014; 74 (4): 979-1004

  Abstract

  Photoacoustic imaging (PAI) has the potential for real-time molecular imaging at high resolution and deep inside the tissue, using nonionizing radiation and not necessarily depending on exogenous imaging agents, making this technique very promising for a range of clinical applications. The fact that PAI systems can be made portable and compatible with existing imaging technologies favors clinical translation even more. The breadth of clinical applications in which photoacoustics could play a valuable role include: noninvasive imaging of the breast, sentinel lymph nodes, skin, thyroid, eye, prostate (transrectal), and ovaries (transvaginal); minimally invasive endoscopic imaging of gastrointestinal tract, bladder, and circulating tumor cells (in vivo flow cytometry); and intraoperative imaging for assessment of tumor margins and (lymph node) metastases. In this review, we describe the basics of PAI and its recent advances in biomedical research, followed by a discussion of strategies for clinical translation of the technique. Cancer Res; 74(4); 979-1004. ©2014 AACR.

  View details for DOI 10.1158/0008-5472.CAN-13-2387

  View details for PubMedID 24514041

  View details for PubMedCentralID PMC3944207

• Antiviral drug ganciclovir is a potent inhibitor of microglial proliferation and neuroinflammation. journal of experimental medicine Ding, Z., Mathur, V., Ho, P. P., James, M. L., Lucin, K. M., Hoehne, A., Alabsi, H., Gambhir, S. S., Steinman, L., Luo, J., Wyss-Coray, T. 2014; 211 (2): 189-198

  Abstract

  Aberrant microglial responses contribute to neuroinflammation in many neurodegenerative diseases, but no current therapies target pathogenic microglia. We discovered unexpectedly that the antiviral drug ganciclovir (GCV) inhibits the proliferation of microglia in experimental autoimmune encephalomyelitis (EAE), a mouse model for multiple sclerosis (MS), as well as in kainic acid-induced excitotoxicity. In EAE, GCV largely prevented infiltration of T lymphocytes into the central nervous system (CNS) and drastically reduced disease incidence and severity when delivered before the onset of disease. In contrast, GCV treatment had minimal effects on peripheral leukocyte distribution in EAE and did not inhibit generation of antibodies after immunization with ovalbumin. Additionally, a radiolabeled analogue of penciclovir, [(18)F]FHBG, which is similar in structure to GCV, was retained in areas of CNS inflammation in EAE, but not in naive control mice, consistent with the observed therapeutic effects. Our experiments suggest GCV may have beneficial effects in the CNS beyond its antiviral properties.

  View details for DOI 10.1084/jem.20120696

  View details for PubMedID 24493798

  View details for PubMedCentralID PMC3920559

• Imaging circulating tumor cells in freely moving awake small animals using a miniaturized intravital microscope. PloS one Sasportas, L. S., Gambhir, S. S. 2014; 9 (1)

  Abstract

  Metastasis, the cause for 90% of cancer mortality, is a complex and poorly understood process involving the invasion of circulating tumor cells (CTCs) into blood vessels. These cells have potential prognostic value as biomarkers for early metastatic risk. But their rarity and the lack of specificity and sensitivity in measuring them render their interrogation by current techniques very challenging. How and when these cells are circulating in the blood, on their way to potentially give rise to metastasis, is a question that remains largely unanswered. In order to provide an insight into this "black box" using non-invasive imaging, we developed a novel miniature intravital microscopy (mIVM) strategy capable of real-time long-term monitoring of CTCs in awake small animals. We established an experimental 4T1-GL mouse model of metastatic breast cancer, in which tumor cells express both fluorescent and bioluminescent reporter genes to enable both single cell and whole body tumor imaging. Using mIVM, we monitored blood vessels of different diameters in awake mice in an experimental model of metastasis. Using an in-house software algorithm we developed, we demonstrated in vivo CTC enumeration and computation of CTC trajectory and speed. These data represent the first reported use we know of for a miniature mountable intravital microscopy setup for in vivo imaging of CTCs in awake animals.

  View details for DOI 10.1371/journal.pone.0086759

  View details for PubMedID 24497977

  View details for PubMedCentralID PMC3908955

• Imaging of Heptocellular Carcinoma Patient-Derived Xenografts Using 89Zr-Labeled Anti-Glypican-3 Monoclonal Antibody Biomaterials Yang, X., Liu, H., Sun, C. K., Natarajan, A., Hu, X., Wang, X., Allegretta, M., Guttmann, R. D., Gambhir, S. S. 2014: 6964-6971
• Pediatric Molecular Imaging Pediatric Nuclear Medicine and Molecular Imaging Daldrup-Link, H., Gambhir, S. S. edited by Treves, T. 2014; 4: 571–596
• Investigation of 6-[¹8F]-fluoromaltose as a novel PET tracer for imaging bacterial infection. PloS one Gowrishankar, G., Namavari, M., Jouannot, E. B., Hoehne, A., Reeves, R., Hardy, J., Gambhir, S. S. 2014; 9 (9)

  Abstract

  Despite advances in the field of nuclear medicine, the imaging of bacterial infections has remained a challenge. The existing reagents suffer from poor sensitivity and specificity. In this study we investigate the potential of a novel PET (positron emission tomography) tracer that overcomes these limitations.6-[¹⁸F]-fluoromaltose was synthesized. Its behavior in vitro was evaluated in bacterial and mammalian cultures. Detailed pharmacokinetic and biodistribution profiles for the tracer were obtained from a murine model.6-[¹⁸F]-fluoromaltose is taken up by multiple strains of pathogenic bacteria. It is not taken up by mammalian cancer cell lines. 6-[¹⁸F]-fluoromaltose is retained in infected muscles in a murine model of bacterial myositis. It does not accumulate in inflamed tissue.We have shown that 6-[¹⁸F]-fluoromaltose can be used to image bacterial infection in vivo with high specificity. We believe that this class of agents will have a significant impact on the clinical management of patients.

  View details for DOI 10.1371/journal.pone.0107951

  View details for PubMedID 25243851

• Tracking cellular and immune therapies in cancer. Advances in cancer research Kurtz, D. M., Gambhir, S. S. 2014; 124: 257-296

  Abstract

  The field of tumor immunology has seen an explosion of renewed interest over the last decade. With the FDA approval of new immunotherapies for prostate cancer and melanoma, as well as several exciting new drugs in clinical trials, tumor immunology is becoming an increasingly important topic in preclinical studies and patient care. However, the current methods for assessing the immune status of a patient and tumor are limited, which has led to the development of novel molecular imaging methods for assessing tumor immunology. From cell tracking for cellular therapeutics to assessing the tumor immune microenvironment, these imaging methods have the potential to further preclinical understanding of immunotherapies and potentially translate into clinically useful tests to predict and assess therapeutic response of these exciting new agents. In this review, we first discuss the recent advances in cancer immunotherapy, followed by a detailed review of the current state of molecular imaging for tumor immunology. Finally, we discuss opportunities for further development and innovation in this rapidly growing field.

  View details for DOI 10.1016/B978-0-12-411638-2.00008-2

  View details for PubMedID 25287692

• Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery Nature Nanotechnology Smith, B. R., Ghosn, E. E., et al 2014: 481–87

  Abstract

  In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  View details for DOI 10.1038/nnano.2014.62

• Detection and quantitation of circulating tumor cell dynamics by bioluminescence imaging in an orthotopic mammary carcinoma model. PloS one Sasportas, L. S., Hori, S. S., Pratx, G., Gambhir, S. S. 2014; 9 (9): e105079

  Abstract

  Circulating tumor cells (CTCs) have been detected in the bloodstream of both early-stage and advanced cancer patients. However, very little is know about the dynamics of CTCs during cancer progression and the clinical relevance of longitudinal CTC enumeration. To address this, we developed a simple bioluminescence imaging assay to detect CTCs in mouse models of metastasis. In a 4T1 orthotopic metastatic mammary carcinoma mouse model, we demonstrated that this quantitative method offers sensitivity down to 2 CTCs in 0.1-1mL blood samples and high specificity for CTCs originating from the primary tumor, independently of their epithelial status. In this model, we simultaneously monitored blood CTC dynamics, primary tumor growth, and lung metastasis progression over the course of 24 days. Early in tumor development, we observed low numbers of CTCs in blood samples (10-15 cells/100 µL) and demonstrated that CTC dynamics correlate with viable primary tumor growth. To our knowledge, these data represent the first reported use of bioluminescence imaging to detect CTCs and quantify their dynamics in any cancer mouse model. This new assay is opening the door to the study of CTC dynamics in a variety of animal models. These studies may inform clinical decision on the appropriate timing of blood sampling and value of longitudinal CTC enumeration in cancer patients.

  View details for DOI 10.1371/journal.pone.0105079

  View details for PubMedID 25188396

  View details for PubMedCentralID PMC4154864

• Evaluation of s-1 receptor radioligand 18F-FTC-146 in rats and squirrel monkeys using PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Shen, B., Nielsen, C. H., Behera, D., Buckmaster, C. L., Mesangeau, C., Zavaleta, C., Vuppala, P. K., Jamalapuram, S., Avery, B. A., Lyons, D. M., McCurdy, C. R., Biswal, S., Gambhir, S. S., Chin, F. T. 2014; 55 (1): 147-153

  Abstract

  The noninvasive imaging of σ-1 receptors (S1Rs) could provide insight into their role in different diseases and lead to novel diagnostic/treatment strategies. The main objective of this study was to assess the S1R radiotracer (18)F-FTC-146 in rats. Preliminary squirrel monkey imaging and human serum/liver microsome studies were performed to gain information about the potential of (18)F-FTC-146 for eventual clinical translation.The distribution and stability of (18)F-FTC-146 in rats were assessed via PET/CT, autoradiography, γ counting, and high-performance liquid chromatography (HPLC). Preliminary PET/MRI of squirrel monkey brain was conducted along with HPLC assessment of (18)F-FTC-146 stability in monkey plasma and human serum.Biodistribution studies showed that (18)F-FTC-146 accumulated in S1R-rich rat organs, including the lungs, pancreas, spleen, and brain. Pretreatment with known S1R compounds, haloperidol, or BD1047, before radioligand administration, significantly attenuated (18)F-FTC-146 accumulation in all rat brain regions by approximately 85% (P < 0.001), suggesting radiotracer specificity for S1Rs. Similarly, PET/CT and autoradiography results demonstrated accumulation of (18)F-FTC-146 in rat brain regions known to contain S1Rs and that this uptake could be blocked by BD1047 pretreatment. Ex vivo analysis of (18)F-FTC-146 in the brain showed that only intact radiotracer was present at 15, 30, and 60 min, whereas rapid metabolism of residual (18)F-FTC-146 was observed in rat plasma. Preliminary monkey PET/MRI studies demonstrated specific accumulation of (18)F-FTC-146 in the brain (mainly in cortical structures, cerebellum, and vermis) that could be attenuated by pretreatment with haloperidol. HPLC of monkey plasma suggested radioligand metabolism, whereas (18)F-FTC-146 appeared to be stable in human serum. Finally, liver microsome studies revealed that (18)F-FTC-146 has a longer half-life in human microsomes, compared with rodents.Together, these results indicate that (18)F-FTC-146 is a promising tool for visualizing S1Rs in preclinical studies and that it has potential for mapping these sites in the human brain.

  View details for DOI 10.2967/jnumed.113.120261

  View details for PubMedID 24337599

• Cellulose nanoparticles: Photoacoustic contrast agents that biodegrade to simple sugars Conference on Photons Plus Ultrasound: Imaging and Sensing Jokerst, J. V., Bohndiek, S. E., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

  View details for DOI 10.1117/12.2036256

  View details for Web of Science ID 000338768500011

• Photoacoustic Imaging of Mesenchymal Stem Cells in Living Mice via Silica-Coated Gold Nanorods Conference on Photons Plus Ultrasound: Imaging and Sensing Jokerst, J. V., Thangaraj, M., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

  View details for DOI 10.1117/12.2036786

  View details for Web of Science ID 000338768500035

• Tracking Cellular and Immune Therapies in Cancer EMERGING APPLICATIONS OF MOLECULAR IMAGING TO ONCOLOGY Kurtz, D. M., Gambhir, S. S. 2014; 124: 257-296

  Abstract

  The field of tumor immunology has seen an explosion of renewed interest over the last decade. With the FDA approval of new immunotherapies for prostate cancer and melanoma, as well as several exciting new drugs in clinical trials, tumor immunology is becoming an increasingly important topic in preclinical studies and patient care. However, the current methods for assessing the immune status of a patient and tumor are limited, which has led to the development of novel molecular imaging methods for assessing tumor immunology. From cell tracking for cellular therapeutics to assessing the tumor immune microenvironment, these imaging methods have the potential to further preclinical understanding of immunotherapies and potentially translate into clinically useful tests to predict and assess therapeutic response of these exciting new agents. In this review, we first discuss the recent advances in cancer immunotherapy, followed by a detailed review of the current state of molecular imaging for tumor immunology. Finally, we discuss opportunities for further development and innovation in this rapidly growing field.

  View details for DOI 10.1016/B978-0-12-411638-2.00008-2

  View details for Web of Science ID 000344511500008

• A simple model for deep tissue attenuation correction and large organ analysis of Cerenkov luminescence imaging Medical Imaging - Physics of Medical Imaging Habte, F., Natarajan, A., Paik, D. S., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

  View details for DOI 10.1117/12.2043879

  View details for Web of Science ID 000338775800154

• Gold nanorods combine photoacoustic and Raman imaging for detection and treatment of ovarian cancer Conference on Photons Plus Ultrasound: Imaging and Sensing Jokerst, J. V., Cole, A. J., Bohndiek, S. E., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

  View details for DOI 10.1117/12.2036776

  View details for Web of Science ID 000338768500134

• Detection and quantitation of circulating tumor cell dynamics by bioluminescence imaging in an orthotopic mammary carcinoma model. PloS one Sasportas, L. S., Hori, S. S., Pratx, G., Gambhir, S. S. 2014; 9 (9)

  Abstract

  Circulating tumor cells (CTCs) have been detected in the bloodstream of both early-stage and advanced cancer patients. However, very little is know about the dynamics of CTCs during cancer progression and the clinical relevance of longitudinal CTC enumeration. To address this, we developed a simple bioluminescence imaging assay to detect CTCs in mouse models of metastasis. In a 4T1 orthotopic metastatic mammary carcinoma mouse model, we demonstrated that this quantitative method offers sensitivity down to 2 CTCs in 0.1-1mL blood samples and high specificity for CTCs originating from the primary tumor, independently of their epithelial status. In this model, we simultaneously monitored blood CTC dynamics, primary tumor growth, and lung metastasis progression over the course of 24 days. Early in tumor development, we observed low numbers of CTCs in blood samples (10-15 cells/100 µL) and demonstrated that CTC dynamics correlate with viable primary tumor growth. To our knowledge, these data represent the first reported use of bioluminescence imaging to detect CTCs and quantify their dynamics in any cancer mouse model. This new assay is opening the door to the study of CTC dynamics in a variety of animal models. These studies may inform clinical decision on the appropriate timing of blood sampling and value of longitudinal CTC enumeration in cancer patients.

  View details for DOI 10.1371/journal.pone.0105079

  View details for PubMedID 25188396

  View details for PubMedCentralID PMC4154864

• A Novel Engineered Anti-CD20 Tracer Enables Early Time PET Imaging in a Humanized Transgenic Mouse Model of B-cell Non-Hodgkins Lymphoma CLINICAL CANCER RESEARCH Natarajan, A., Hackel, B. J., Gambhir, S. S. 2013; 19 (24): 6820-6829

  Abstract

  The aim of this article was to evaluate the use of a novel engineered anti-CD20 protein based on the 10 kDa human fibronectin type 3 domain (FN3) and subsequently compare with (64)Cu-rituximab for positron emission tomography (PET) imaging of CD20.The engineered FN3(CD20) and FN3(WT) were produced in Escherichia coli cells at 2 to 5 mg/L, conjugated to DOTA, labeled with (64)Cu, and used for PET imaging of huCD20 expression in B cells. Humanized transgenic mice and subcutaneously xenografted mice each received intravenous (64)Cu-FN3(CD20) or FN3(WT) (3.7 MBq/4 μg Do-FN3 in 200 μL PBS). Control group received a blocking dose (50-fold excess) of unconjugated FN3(CD20) two hours before radiotracer injection. PET imaging was carried out at 1 to 24 hours postinjections.In vitro assay demonstrated FN3 binds CD20 with 20 nmol/L affinity on CD20-expressing cells. (64)Cu-FN3(CD20) showed clear, high-contrast visualization of huCD20-expressing B cells in the spleen of transgenic mice as early as 1 hour postinjection [38 ± 3% injected dose (ID)/g] and exhibited a spleen-to-blood ratio of 13 by 4 hours. This is higher uptake (P = 0.04) and 10-fold greater signal-to-background (P = 0.04) than the (64)Cu-rituximab antibody radiotracer. Tumor uptake (16.8 ± 1.6 vs. 5.6 ± 1.4%ID/g) and tumor:background ratios were superior for FN3CD20 relative to rituximab in xenograft studies as well.The (64)Cu-Do-FN3(CD20) radiotracer represents a novel small, high-affinity binder for imaging human CD20, which may be well suited for B-cell non-Hodgkin's lymphoma imaging in patients at early time points.

  View details for DOI 10.1158/1078-0432.CCR-13-0626

  View details for Web of Science ID 000328938700019

  View details for PubMedID 24097872

• A F-18-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Hoehne, A., Behera, D., Parsons, W. H., James, M. L., Shen, B., Borgohain, P., Bodapati, D., Prabhakar, A., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T., Du Bois, J. 2013; 135 (48): 18012-18015

  Abstract

  Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.

  View details for DOI 10.1021/ja408300e

  View details for Web of Science ID 000328100000002

  View details for PubMedID 24261833

• A (18)F-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury. Journal of the American Chemical Society Hoehne, A., Behera, D., Parsons, W. H., James, M. L., Shen, B., Borgohain, P., Bodapati, D., Prabhakar, A., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T., Bois, J. D. 2013; 135 (48): 18012-18015

  Abstract

  Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.

  View details for DOI 10.1021/ja408300e

  View details for PubMedID 24261833

• Combined 18F-fluoride and 18F-FDG PET/CT: a response based on actual data from prospective studies. European journal of nuclear medicine and molecular imaging Iagaru, A., Mosci, C., Dick, D. W., Sathekge, M., Lapa, P., de Lima, J. M., Gambhir, S. S. 2013; 40 (12): 1922-1924

  View details for DOI 10.1007/s00259-013-2556-y

  View details for PubMedID 24057457

• Single-cell photonic nanocavity probes. Nano letters Shambat, G., Kothapalli, S., Provine, J., Sarmiento, T., Harris, J., Gambhir, S. S., Vuckovic, J. 2013; 13 (11): 4999-5005

  Abstract

  In this report, we demonstrate for the first time photonic nanocavities operating inside single biological cells. Here we develop a nanobeam photonic crystal (PC) cavity as an advanced cellular nanoprobe, active in nature, and configurable to provide a multitude of actions for both intracellular sensing and control. Our semiconductor nanocavity probes emit photoluminescence (PL) from embedded quantum dots (QD) and sustain high quality resonant photonic modes inside cells. The probes are shown to be minimally cytotoxic to cells from viability studies, and the beams can be loaded in cells and tracked for days at a time, with cells undergoing regular division with the beams. We present in vitro label-free protein sensing with our probes to detect streptavidin as a path towards real-time biomarker and biomolecule detection inside single cells. The results of this work will enable new areas of research merging the strengths of photonic nanocavities with fundamental cell biology.

  View details for DOI 10.1021/nl304602d

  View details for PubMedID 23387382

• Nanooncology: The Future of Cancer Diagnosis and Therapy CA-A CANCER JOURNAL FOR CLINICIANS Thakor, A. S., Gambhir, S. S. 2013; 63 (6): 395-418

  Abstract

  In recent years, there has been an unprecedented expansion in the field of nanomedicine with the development of new nanoparticles for the diagnosis and treatment of cancer. Nanoparticles have unique biological properties given their small size and large surface area-to-volume ratio, which allows them to bind, absorb, and carry compounds such as small molecule drugs, DNA, RNA, proteins, and probes with high efficiency. Their tunable size, shape, and surface characteristics also enable them to have high stability, high carrier capacity, the ability to incorporate both hydrophilic and hydrophobic substances and compatibility with different administration routes, thereby making them highly attractive in many aspects of oncology. This review article will discuss how nanoparticles are able to function as carriers for chemotherapeutic drugs to increase their therapeutic index; how they can function as therapeutic agents in photodynamic, gene, and thermal therapy; and how nanoparticles can be used as molecular imaging agents to detect and monitor cancer progression.

  View details for DOI 10.3322/caac.21199

  View details for PubMedID 24114523

• Integrin-Targeted Molecular Imaging of Experimental Abdominal Aortic Aneurysms by 18F-labeled Arg-Gly-Asp Positron-Emission Tomography. Circulation. Cardiovascular imaging Kitagawa, T., Kosuge, H., Chang, E., James, M. L., Yamamoto, T., Shen, B., Chin, F. T., Gambhir, S. S., Dalman, R. L., McConnell, M. V. 2013; 6 (6): 950-956

  Abstract

  Background- Both inflammation and neoangiogenesis contribute to abdominal aortic aneurysm (AAA) disease. Arg-Gly-Asp-based molecular imaging has been shown to detect the integrin αvβ3. We studied a clinical dimeric (18)F-labeled Arg-Gly-Asp positron-emission tomography (PET) agent ((18)F-FPPRGD2) for molecular imaging of experimental AAAs. Methods and Results- Murine AAAs were induced in Apo-E-deficient mice by angiotensin II infusion, with monitoring of aortic diameter on ultrasound. AAA (n=10) and saline-infused control mice (n=7) were injected intravenously with (18)F-FPPRGD2, as well as an intravascular computed tomography contrast agent, then scanned using a small-animal PET/computed tomography scanner. Aortic uptake of (18)F-FPPRGD2 was quantified by percentage-injected dose per gram and target-to-=0.003; median target-to-=0.0008). Ex vivo autoradiography demonstrated high uptake of (18)F-FPPRGD2 into the AAA wall, with immunohistochemistry showing substantial cluster of differentiation (CD)-11b(+) macrophages and CD-31(+) neovessels. Target-to-=-0.29, P=0.41) but did strongly correlate with both mural macrophage density (r=0.79, P=0.007) and neovessel counts (r=0.87, P=0.001) on immunohistochemistry. Conclusions- PET imaging of experimental AAAs using (18)F-FPPRGD2 detects biologically active disease, correlating to the degree of vascular inflammation and neoangiogenesis. This may provide a clinically translatable molecular imaging approach to characterize AAA biology to predict risk beyond size alone.

  View details for DOI 10.1161/CIRCIMAGING.113.000234

  View details for PubMedID 23995363

• Preclinical Efficacy of the Anti-Hepatocyte Growth Factor Antibody Ficlatuzumab in a Mouse Brain Orthotopic Glioma Model Evaluated by Bioluminescence, PET, and MRI CLINICAL CANCER RESEARCH Mittra, E. S., Fan-Minogue, H., Lin, F. I., Karamchandani, J., Sriram, V., Han, M., Gambhir, S. S. 2013; 19 (20): 5711-5721

  Abstract

  Ficlatuzumab is a novel therapeutic agent targeting the hepatocyte growth factor (HGF)/c-MET pathway. We summarize extensive preclinical work using this agent in a mouse brain orthotopic model of glioblastoma.Sequential experiments were done using eight- to nine-week-old nude mice injected with 3 × 10(5) U87 MG (glioblastoma) cells into the brain. Evaluation of ficlatuzumab dose response for this brain tumor model and comparison of its response to ficlatuzumab and to temozolamide were conducted first. Subsequently, various small-animal imaging modalities, including bioluminescence imaging (BLI), positron emission tomography (PET), and MRI, were used with a U87 MG-Luc 2 stable cell line, with and without the use of ficlatuzumab, to evaluate the ability to noninvasively assess tumor growth and response to therapy. ANOVA was conducted to evaluate for significant differences in the response.There was a survival benefit with ficlatuzumab alone or in combination with temozolamide. BLI was more sensitive than PET in detecting tumor cells. Fluoro-D-thymidine (FLT) PET provided a better signal-to-background ratio than 2[(18)F]fluoro-2-deoxy-d-glucose (FDG) PET. In addition, both BLI and FLT PET showed significant changes over time in the control group as well as with response to therapy. MRI does not disclose any time-dependent change. Also, the MRI results showed a temporal delay in comparison to the BLI and FLT PET findings, showing similar results one drug cycle later.Targeting the HGF/c-MET pathway with the novel agent ficlatuzumab appears promising for the treatment of glioblastoma. Various clinically applicable imaging modalities including FLT, PET, and MRI provide reliable ways of assessing tumor growth and response to therapy. Given the clinical applicability of these findings, future studies on patients with glioblastoma may be appropriate.

  View details for DOI 10.1158/1078-0432.CCR-12-1015

  View details for Web of Science ID 000325797600019

  View details for PubMedID 23983258

• A scanning transmission electron microscopy approach to analyzing large volumes of tissue to detect nanoparticles. Microscopy and microanalysis Kempen, P. J., Thakor, A. S., Zavaleta, C., Gambhir, S. S., Sinclair, R. 2013; 19 (5): 1290-1297

  Abstract

  The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue, but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work, we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol-coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time-consuming analytical characterization. We utilized this technique to analyze 243,000 μm3 of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail vein accumulated in the liver, whereas those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation.

  View details for DOI 10.1017/S143192761300192X

  View details for PubMedID 23803218

• Noninvasive imaging of hypoxia-inducible factor-1a gene therapy for myocardial ischemia. Human gene therapy methods Chen, I. Y., Gheysens, O., Li, Z., Rasooly, J. A., Wang, Q., Paulmurugan, R., Rosenberg, J., Rodriguez-Porcel, M., Willmann, J. K., Wang, D. S., Contag, C. H., Robbins, R. C., Wu, J. C., Gambhir, S. S. 2013; 24 (5): 279-288

  Abstract

  Abstract Hypoxia-inducible factor-1 alpha (HIF-1α) gene therapy holds great promise for the treatment of myocardial ischemia. Both preclinical and clinical evaluations of this therapy are underway and can benefit from a vector strategy that allows noninvasive assessment of HIF-1α expression as an objective measure of gene delivery. We have developed a novel bidirectional plasmid vector (pcTnT-HIF-1α-VP2-TSTA-fluc), which employs the cardiac troponin T (cTnT) promoter in conjunction with a two-step transcriptional amplification (TSTA) system to drive the linked expression of a recombinant HIF-1α gene (HIF-1α-VP2) and the firefly luciferase gene (fluc). The firefly luciferase (FLuc) activity serves as a surrogate for HIF-1α-VP2 expression, and can be noninvasively assessed in mice using bioluminescence imaging after vector delivery. Transfection of cultured HL-1 cardiomyocytes with pcTnT-HIF-1α-VP2-TSTA-fluc led to a strong correlation between FLuc and HIF-1α-dependent vascular endothelial growth factor expression (r(2)=0.88). Intramyocardial delivery of pcTnT-HIF-1α-VP2-TSTA-fluc into infarcted mouse myocardium led to persistent HIF-1α-VP2 expression for 4 weeks, even though it improved neither CD31+ microvessel density nor echocardiographically determined left ventricular systolic function. These results lend support to recent findings of suboptimal efficacy associated with plasmid-mediated HIF-1α therapy. The imaging techniques developed herein should be useful for further optimizing HIF-1α-VP2 therapy in preclinical models of myocardial ischemia.

  View details for DOI 10.1089/hgtb.2013.028

  View details for PubMedID 23937265

• Pilot Prospective Evaluation of Early Response to Bevacizumab Treatment Using the Novel PET/CT Radiopharmaceutical 18F FPPRGD2 Iagaru, A., Mosci, C., Davidzon, G., Kumar, M., Shen, B., Chin, F., Gambhir, S. S. SPRINGER. 2013: S185

  View details for Web of Science ID 000325853400290

• Noninvasive imaging of hypoxia-inducible factor-1a gene therapy for myocardial ischemia. Human gene therapy methods Chen, I. Y., Gheysens, O., Li, Z., Rasooly, J. A., Wang, Q., Paulmurugan, R., Rosenberg, J., Rodriguez-Porcel, M., Willmann, J. K., Wang, D. S., Contag, C. H., Robbins, R. C., Wu, J. C., Gambhir, S. S. 2013; 24 (5): 279-288

  View details for DOI 10.1089/hgtb.2013.028

  View details for PubMedID 23937265

• MicroRNA-regulated non-viral vectors with improved tumor specificity in an orthotopic rat model of hepatocellular carcinoma GENE THERAPY Ronald, J. A., Katzenberg, R., Nielsen, C. H., Jae, H. J., Hofmann, L. V., Gambhir, S. S. 2013; 20 (10): 1006-1013

  Abstract

  In hepatocellular carcinoma (HCC), tumor specificity of gene therapy is of utmost importance to preserve liver function. MicroRNAs (miRNAs) are powerful negative regulators of gene expression and many are downregulated in human HCC. We identified seven miRNAs that are also downregulated in tumors in a rat hepatoma model (P<0.05) and attempted to improve tumor specificity by constructing a panel of luciferase-expressing vectors containing binding sites for these miRNAs. Attenuation of luciferase expression by the corresponding miRNAs was confirmed across various cell lines and in mouse liver. We then tested our vectors in tumor-bearing rats and identified two miRNAs, miR-26a and miR-122, that significantly decreased expression in liver compared with the control vector (6.40 and 0.26%, respectively; P<0.05). In tumor, miR-122 had a nonsignificant trend towards decreased (∼50%) expression, whereas miR-26 had no significant effect on tumor expression. To our knowledge, this is the first work using differentially expressed miRNAs to de-target transgene expression in an orthotopic hepatoma model and to identify miR-26a, in addition to miR-122, for de-targeting liver. Considering the heterogeneity of miRNA expression in human HCC, this information will be important in guiding development of more personalized vectors for the treatment of this devastating disease.Gene Therapy advance online publication, 30 May 2013; doi:10.1038/gt.2013.24.

  View details for DOI 10.1038/gt.2013.24

  View details for Web of Science ID 000325633500006

  View details for PubMedID 23719066

• A c-Myc Activation Sensor-Based High-Throughput Drug Screening Identifies an Antineoplastic Effect of Nitazoxanide. Molecular cancer therapeutics Fan-Minogue, H., Bodapati, S., Solow-Cordero, D., Fan, A., Paulmurugan, R., Massoud, T. F., Felsher, D. W., Gambhir, S. S. 2013; 12 (9): 1896-1905

  Abstract

  Deregulation of c-Myc plays a central role in the tumorigenesis of many human cancers. Yet, the development of drugs regulating c-Myc activity has been challenging. To facilitate the identification of c-Myc inhibitors, we developed a molecular imaging sensor based high throughput-screening (HTS) system. This system uses a cell-based assay to detect c-Myc activation in a HTS format, which is established from a pure clone of a stable breast cancer cell line that constitutively expresses a c-Myc activation sensor. Optimization of the assay performance in the HTS format resulted in uniform and robust signals at the baseline. Using this system, we performed a quantitative HTS against approximately 5,000 existing bioactive compounds from five different libraries. Thirty-nine potential hits were identified, including currently known c-Myc inhibitors. There are a few among the top potent hits that are not known for anti-c-Myc activity. One of these hits is nitazoxanide (NTZ), a thiazolide for treating human protozoal infections. Validation of NTZ in different cancer cell lines revealed a high potency for c-Myc inhibition with IC50 ranging between 10 - 500nM. Oral administration of NTZ in breast cancer xenograft mouse models significantly suppressed tumor growth by inhibition of c-Myc and induction of apoptosis. These findings suggest a potential of NTZ to be repurposed as a new anti-tumor agent for inhibition of c-Myc associated neoplasia. Our work also demonstrated the unique advantage of molecular imaging in accelerating discovery of drugs for c-Myc targeted cancer therapy.

  View details for DOI 10.1158/1535-7163.MCT-12-1243

  View details for PubMedID 23825064

• Target-Specific Molecular Imaging with Cystine Knot Peptides Kimura, R. H., Gambhir, S. S. SPRINGER WIEN. 2013: 608

  View details for Web of Science ID 000323212600159

• High-sensitivity, real-time, ratiometric imaging of surface-enhanced Raman scattering nanoparticles with a clinically translatable Raman endoscope device. Journal of biomedical optics Garai, E., Sensarn, S., Zavaleta, C. L., Van de Sompel, D., Loewke, N. O., Mandella, M. J., Gambhir, S. S., Contag, C. H. 2013; 18 (9): 096008-?

  Abstract

  ABSTRACT. Topical application and quantification of targeted, surface-enhanced Raman scattering (SERS) nanoparticles offer a new technique that has the potential for early detection of epithelial cancers of hollow organs. Although less toxic than intravenous delivery, the additional washing required to remove unbound nanoparticles cannot necessarily eliminate nonspecific pooling. Therefore, we developed a real-time, ratiometric imaging technique to determine the relative concentrations of at least two spectrally unique nanoparticle types, where one serves as a nontargeted control. This approach improves the specific detection of bound, targeted nanoparticles by adjusting for working distance and for any nonspecific accumulation following washing. We engineered hardware and software to acquire SERS signals and ratios in real time and display them via a graphical user interface. We report quantitative, ratiometric imaging with nanoparticles at pM and sub-pM concentrations and at varying working distances, up to 50 mm. Additionally, we discuss optimization of a Raman endoscope by evaluating the effects of lens material and fiber coating on background noise, and theoretically modeling and simulating collection efficiency at various working distances. This work will enable the development of a clinically translatable, noncontact Raman endoscope capable of rapidly scanning large, topographically complex tissue surfaces for small and otherwise hard to detect lesions.

  View details for DOI 10.1117/1.JBO.18.9.096008

  View details for PubMedID 24008818

  View details for PubMedCentralID PMC3763230

• Evaluation of Zr-89-rituximab Tracer by Cerenkov Luminescence Imaging and Correlation with PET in a Humanized Transgenic Mouse Model to Image NHL MOLECULAR IMAGING AND BIOLOGY Natarajan, A., Habte, F., Liu, H., Sathirachinda, A., Hu, X., Cheng, Z., Nagamine, C. M., Gambhir, S. S. 2013; 15 (4): 468-475

  Abstract

  PURPOSE: This research aimed to study the use of Cerenkov luminescence imaging (CLI) for non-Hodgkin's lymphoma (NHL) using (89)Zr-rituximab positron emission tomography (PET) tracer with a humanized transgenic mouse model that expresses human CD20 and the correlation of CLI with PET. PROCEDURES: Zr-rituximab (2.6 MBq) was tail vein-injected into transgenic mice that express the human CD20 on their B cells (huCD20TM). One group (n = 3) received 2 mg/kg pre-dose (blocking) of cold rituximab 2 h prior to tracer; a second group (n = 3) had no pre-dose (non-blocking). CLI was performed using a cooled charge-coupled device optical imager. We also performed PET imaging and ex vivo studies in order to confirm the in vivo CLI results. At each time point (4, 24, 48, 72, and 96 h), two groups of mice were imaged in vivo and ex vivo with CLI and PET, and at 96 h, organs were measured by gamma counter. RESULTS: huCD20 transgenic mice injected with (89)Zr-rituximab demonstrated a high-contrast CLI image compared to mice blocked with a cold dose. At various time points of 4-96 h post-radiotracer injection, the in vivo CLI signal intensity showed specific uptake in the spleen where B cells reside and, hence, the huCD20 biomarker is present at very high levels. The time-activity curve of dose decay-corrected CLI intensity and percent injected dose per gram of tissue of PET uptake in the spleen were increased over the time period (4-96 h). At 96 h, the (89)Zr-rituximab uptake ratio (non-blocking vs blocking) counted (mean ± standard deviation) for the spleen was 1.5 ± 0.6 for CLI and 1.9 ± 0.3 for PET. Furthermore, spleen uptake measurements (non-blocking and blocking of all time points) of CLI vs PET showed good correlation (R (2) = 0.85 and slope = 0.576), which also confirmed the corresponding correlations parameter value (R (2) = 0.834 and slope = 0.47) obtained for ex vivo measurements. CONCLUSIONS: CLI and PET of huCD20 transgenic mice injected with (89)Zr-rituximab demonstrated that the tracer was able to target huCD20-expressing B cells. The in vivo and ex vivo tracer uptake corresponding to the CLI radiance intensity from the spleen is in good agreement with PET. In this report, we have validated the use of CLI with PET for NHL imaging in huCD20TM.

  View details for DOI 10.1007/s11307-013-0624-0

  View details for Web of Science ID 000321972500014

  View details for PubMedID 23471750

• Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters. MRS bulletin Jokerst, J. V., Pohling, C., Gambhir, S. S. 2013; 38 (8)

  Abstract

  Molecular imaging scans cellular and molecular targets in living subjects through the introduction of imaging agents that bind to these targets and report their presence through a measurable signal. The picomolar sensitivity, signal stability, and high multiplexing capacity of Raman spectroscopy satisfies important needs within the field of molecular imaging, and several groups now utilize Raman and surface-enhanced Raman spectroscopy to image molecular targets in small animal models of human disease. This article details the role of Raman spectroscopy in molecular imaging, describes some substrates and imaging agents used in animal models, and illustrates some examples.

  View details for DOI 10.1557/mrs.2013.157

  View details for PubMedID 24293809

  View details for PubMedCentralID PMC3841987

• Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters MRS BULLETIN Jokerst, J. V., Pohling, C., Gambhir, S. S. 2013; 38 (8): 625-630

  View details for DOI 10.1557/mrs.2013.157

  View details for Web of Science ID 000322918100014

• Real-time, continuous, fluorescence sensing in a freely-moving subject with an implanted hybrid VCSEL/CMOS biosensor BIOMEDICAL OPTICS EXPRESS O'Sullivan, T. D., Heitz, R. T., Parashurama, N., Barkin, D. B., Wooley, B. A., Gambhir, S. S., Harris, J. S., Levi, O. 2013; 4 (8): 1332-1341

  Abstract

  Performance improvements in instrumentation for optical imaging have contributed greatly to molecular imaging in living subjects. In order to advance molecular imaging in freely moving, untethered subjects, we designed a miniature vertical-cavity surface-emitting laser (VCSEL)-based biosensor measuring 1cm(3) and weighing 0.7g that accurately detects both fluorophore and tumor-targeted molecular probes in small animals. We integrated a critical enabling component, a complementary metal-oxide semiconductor (CMOS) read-out integrated circuit, which digitized the fluorescence signal to achieve autofluorescence-limited sensitivity. After surgical implantation of the lightweight sensor for two weeks, we obtained continuous and dynamic fluorophore measurements while the subject was un-anesthetized and mobile. The technology demonstrated here represents a critical step in the path toward untethered optical sensing using an integrated optoelectronic implant.

  View details for DOI 10.1364/BOE.4.001332

  View details for Web of Science ID 000322618900008

  View details for PubMedCentralID PMC3756575

• Imaging Tumor Angiogenesis: The Road to Clinical Utility AMERICAN JOURNAL OF ROENTGENOLOGY Iagaru, A., Gambhir, S. S. 2013; 201 (2): W183-W191

  Abstract

  OBJECTIVE. Tumor growth and progression require the formation of new blood vessels from preexisting vasculature, a process called angiogenesis. The ability to noninvasively visualize angiogenesis may provide new opportunities to more appropriately select patients for antiangiogenesis treatment and to monitor treatment efficacy. CONCLUSION. The superior molecular sensitivity of PET and the lack of radiation from MRI and contrast-enhanced ultrasound put these techniques at the forefront of clinical translation.

  View details for DOI 10.2214/AJR.12.8568

  View details for Web of Science ID 000322225400003

  View details for PubMedID 23883233

• Activatable oligomerizable imaging agents for photoacoustic imaging of furin-like activity in living subjects. Journal of the American Chemical Society Dragulescu-Andrasi, A., Kothapalli, S., Tikhomirov, G. A., Rao, J., Gambhir, S. S. 2013; 135 (30): 11015-11022

  Abstract

  Photoacoustic (PA) imaging is continuing to be applied for physiological imaging and more recently for molecular imaging of living subjects. Owing to its high spatial resolution in deep tissues, PA imaging holds great potential for biomedical applications and molecular diagnostics. There is however a lack of probes for targeted PA imaging, especially in the area of enzyme-activatable probes. Here we introduce a molecular probe, which upon proteolytic processing is retained at the site of enzyme activity and provides PA contrast. The probe oligomerizes via a condensation reaction and accumulates in cells and tumors that express the protease. We demonstrate that this probe reports furin and furin-like activity in cells and tumor models by generating a significantly higher PA signal relative to furin-deficient and nontarget controls. This probe could report enzyme activity in living subjects at depths significantly greater than fluorescence imaging probes and has potential for molecular imaging in deep tumors.

  View details for DOI 10.1021/ja4010078

  View details for PubMedID 23859847

• A small animal Raman instrument for rapid, wide-area, spectroscopic imaging PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Bohndiek, S. E., Wagadarikar, A., Zavaleta, C. L., Van de Sompel, D., Garai, E., Jokerst, J. V., Yazdanfar, S., Gambhir, S. S. 2013; 110 (30): 12408-12413

  Abstract

  Raman spectroscopy, amplified by surface enhanced Raman scattering (SERS) nanoparticles, is a molecular imaging modality with ultra-high sensitivity and the unique ability to multiplex readouts from different molecular targets using a single wavelength of excitation. This approach holds exciting prospects for a range of applications in medicine, including identification and characterization of malignancy during endoscopy and intraoperative image guidance of surgical resection. The development of Raman molecular imaging with SERS nanoparticles is presently limited by long acquisition times, poor spatial resolution, small field of view, and difficulty in animal handling with existing Raman spectroscopy instruments. Our goal is to overcome these limitations by designing a bespoke instrument for Raman molecular imaging in small animals. Here, we present a unique and dedicated small-animal Raman imaging instrument that enables rapid, high-spatial resolution, spectroscopic imaging over a wide field of view (> 6 cm(2)), with simplified animal handling. Imaging of SERS nanoparticles in small animals demonstrated that this small animal Raman imaging system can detect multiplexed SERS signals in both superficial and deep tissue locations at least an order of magnitude faster than existing systems without compromising sensitivity.

  View details for DOI 10.1073/pnas.1301379110

  View details for Web of Science ID 000322112300062

  View details for PubMedID 23821752

• An Observational Study of Circulating Tumor Cells and F-18-FDG PET Uptake in Patients with Treatment-Naive Non-Small Cell Lung Cancer PLOS ONE Nair, V. S., Keu, K. V., Luttgen, M. S., Kolatkar, A., Vasanawala, M., Kuschner, W., Bethel, K., Iagaru, A. H., Hoh, C., Shrager, J. B., Loo, B. W., Bazhenova, L., Nieva, J., Gambhir, S. S., Kuhn, P. 2013; 8 (7)

  Abstract

  We investigated the relationship of circulating tumor cells (CTCs) in non-small cell lung cancer (NSCLC) with tumor glucose metabolism as defined by (18)F-fluorodeoxyglucose (FDG) uptake since both have been associated with patient prognosis.We performed a retrospective screen of patients at four medical centers who underwent FDG PET-CT imaging and phlebotomy prior to a therapeutic intervention for NSCLC. We used an Epithelial Cell Adhesion Molecule (EpCAM) independent fluid biopsy based on cell morphology for CTC detection and enumeration (defined here as High Definition CTCs or "HD-CTCs"). We then correlated HD-CTCs with quantitative FDG uptake image data calibrated across centers in a cross-sectional analysis.We assessed seventy-one NSCLC patients whose median tumor size was 2.8 cm (interquartile range, IQR, 2.0-3.6) and median maximum standardized uptake value (SUVmax) was 7.2 (IQR 3.7-15.5). More than 2 HD-CTCs were detected in 63% of patients, whether across all stages (45 of 71) or in stage I disease (27 of 43). HD-CTCs were weakly correlated with partial volume corrected tumor SUVmax (r = 0.27, p-value = 0.03) and not correlated with tumor diameter (r = 0.07; p-value = 0.60). For a given partial volume corrected SUVmax or tumor diameter there was a wide range of detected HD-CTCs in circulation for both early and late stage disease.CTCs are detected frequently in early-stage NSCLC using a non-EpCAM mediated approach with a wide range noted for a given level of FDG uptake or tumor size. Integrating potentially complementary biomarkers like these with traditional patient data may eventually enhance our understanding of clinical, in vivo tumor biology in the early stages of this deadly disease.

  View details for DOI 10.1371/journal.pone.0067733

  View details for Web of Science ID 000321425300025

  View details for PubMedID 23861795

  View details for PubMedCentralID PMC3702496

• Pilot prospective evaluation of 99mTc-MDP scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and whole-body MRI for detection of skeletal metastases. Clinical nuclear medicine Iagaru, A., Young, P., Mittra, E., Dick, D. W., Herfkens, R., Gambhir, S. S. 2013; 38 (7): e290-6

  Abstract

  The aim of this study was to compare Tc-MDP bone scanning, F NaF PET/CT, F FDG PET/CT, and whole-body MRI (WBMRI) for detection of known osseous metastases.This prospective pilot trial (September 2007-April 2009) enrolled 10 participants (5 men, 5 women, 47-81 years old) diagnosed with cancer and known osseous metastases. F NaF PET/CT, F FDG PET/CT, and WBMRI were performed within 1 month for each participant.The image quality and evaluation of extent of disease were superior by F NaF PET/CT compared to Tc-MDP scintigraphy in all patients with skeletal lesions and compared to F FDG PET/CT in 3 of the patients with skeletal metastases. F NaF PET/CT showed osseous metastases where F FDG PET/CT was negative in another 3 participants. Extraskeletal metastases were identified by F FDG PET/CT in 6 participants. WBMRI with the combination of iterative decomposition of water and fat with echo asymmetry and least-squares estimation, short tau inversion recovery, and diffusion-weighted imaging pulse sequences showed fewer lesions than F NaF PET/CT in 5 patients, same number of lesions in 2 patients, and more lesions in 1 patient. WBMRI showed fewer lesions than F FDG in 3 patients and same lesions in 6 patients.Our pilot phase prospective trial demonstrated superior image quality and evaluation of skeletal disease extent with F NaF PET/CT compared to Tc-MDP scintigraphy and F FDG PET/CT, as well as the feasibility of multisequence WBMRI. In addition, F FDG PET/CT provided valuable soft-tissue information that can change disease management. Further evaluation of these findings using the recently introduced PET/MRI scanners is warranted.

  View details for DOI 10.1097/RLU.0b013e3182815f64

  View details for PubMedID 23455520

• F-18-Fluorobenzoate-Labeled Cystine Knot Peptides for PET Imaging of Integrin alpha(v)beta(6) JOURNAL OF NUCLEAR MEDICINE Hackel, B. J., Kimura, R. H., Miao, Z., Liu, H., Sathirachinda, A., Cheng, Z., Chin, F. T., Gambhir, S. S. 2013; 54 (7): 1101-1105

  Abstract

  Integrin αvβ6 is a cell surface receptor minimally expressed by healthy tissue but elevated in lung, colon, skin, ovarian, cervical, and pancreatic cancers. A molecular PET agent for integrin αvβ6 could provide significant clinical utility by facilitating both cancer staging and treatment monitoring to more rapidly identify an effective therapeutic approach. METHODS: Here, we evaluated 2 cystine knot peptides, R01 and S02, previously engineered with a 3-6 nM affinity for integrin αvβ6, for (18)F radiolabeling and PET imaging of BxPC3 pancreatic adenocarcinoma xenografts in mice. Cystine knot peptides were labeled with N-succinimidyl-4-(18)F-fluorobenzoate and evaluated for binding affinity and serum stability. Peptides conjugated with (18)F-fluorobenzoate (2-3 MBq) were injected via the tail vein into nude mice xenografted with BxPC3 (integrin αvβ6-positive) or 293 (integrin αvβ6-negative) tumors. Small-animal PET scans were acquired at 0.5, 1, and 2 h after injection. Ex vivo γ-counting of dissected tissues was performed at 0.5 and 2 h. RESULTS: (18)F-fluorobenzoate peptides were produced in 93% ((18)F-fluorobenzoate-R01) and 99% ((18)F-fluorobenzoate-S02) purity. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 had affinities of 1.1 ± 0.2 and 0.7 ± 0.4 nM, respectively, and were 87% and 94%, respectively, stable in human serum at 37°C for 2 h. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 exhibited 2.3 ± 0.6 and 1.3 ± 0.4 percentage injected dose per gram (%ID/g), respectively, in BxPC3 xenografted tumors at 0.5 h (n = 4-5). Target specificity was confirmed by low tumor uptake in integrin αvβ6-negative 293 tumors (1.4 ± 0.6 and 0.5 ± 0.2 %ID/g, respectively, for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; both P < 0.05; n = 3-4) and low muscle uptake (3.1 ± 1.0 and 2.7 ± 0.4 tumor to muscle for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02, respectively). Small-animal PET data were corroborated by ex vivo γ-counting of dissected tissues, which demonstrated low uptake in nontarget tissues with only modest kidney uptake (9.2 ± 3.3 and 1.9 ± 1.2 %ID/g, respectively, at 2 h for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; n = 8). Uptake in healthy pancreas was low (0.3% ± 0.1% for (18)F-fluorobenzoate-R01 and 0.03% ± 0.01% for (18)F-fluorobenzoate-S02; n = 8). CONCLUSION: These cystine knot peptide tracers, in particular (18)F-fluorobenzoate-R01, show translational promise for molecular imaging of integrin αvβ6 overexpression in pancreatic and other cancers.

  View details for DOI 10.2967/jnumed.112.110759

  View details for Web of Science ID 000321113500019

• Pilot prospective evaluation of 99mTc-MDP scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and whole-body MRI for detection of skeletal metastases. Clinical nuclear medicine Iagaru, A., Young, P., Mittra, E., Dick, D. W., Herfkens, R., Gambhir, S. S. 2013; 38 (7): e290-6

  View details for DOI 10.1097/RLU.0b013e3182815f64

  View details for PubMedID 23455520

• 18F-fluorobenzoate-labeled cystine knot peptides for PET imaging of integrin avß6. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Hackel, B. J., Kimura, R. H., Miao, Z., Liu, H., Sathirachinda, A., Cheng, Z., Chin, F. T., Gambhir, S. S. 2013; 54 (7): 1101-1105

  Abstract

  Integrin αvβ6 is a cell surface receptor minimally expressed by healthy tissue but elevated in lung, colon, skin, ovarian, cervical, and pancreatic cancers. A molecular PET agent for integrin αvβ6 could provide significant clinical utility by facilitating both cancer staging and treatment monitoring to more rapidly identify an effective therapeutic approach. METHODS: Here, we evaluated 2 cystine knot peptides, R01 and S02, previously engineered with a 3-6 nM affinity for integrin αvβ6, for (18)F radiolabeling and PET imaging of BxPC3 pancreatic adenocarcinoma xenografts in mice. Cystine knot peptides were labeled with N-succinimidyl-4-(18)F-fluorobenzoate and evaluated for binding affinity and serum stability. Peptides conjugated with (18)F-fluorobenzoate (2-3 MBq) were injected via the tail vein into nude mice xenografted with BxPC3 (integrin αvβ6-positive) or 293 (integrin αvβ6-negative) tumors. Small-animal PET scans were acquired at 0.5, 1, and 2 h after injection. Ex vivo γ-counting of dissected tissues was performed at 0.5 and 2 h. RESULTS: (18)F-fluorobenzoate peptides were produced in 93% ((18)F-fluorobenzoate-R01) and 99% ((18)F-fluorobenzoate-S02) purity. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 had affinities of 1.1 ± 0.2 and 0.7 ± 0.4 nM, respectively, and were 87% and 94%, respectively, stable in human serum at 37°C for 2 h. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 exhibited 2.3 ± 0.6 and 1.3 ± 0.4 percentage injected dose per gram (%ID/g), respectively, in BxPC3 xenografted tumors at 0.5 h (n = 4-5). Target specificity was confirmed by low tumor uptake in integrin αvβ6-negative 293 tumors (1.4 ± 0.6 and 0.5 ± 0.2 %ID/g, respectively, for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; both P < 0.05; n = 3-4) and low muscle uptake (3.1 ± 1.0 and 2.7 ± 0.4 tumor to muscle for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02, respectively). Small-animal PET data were corroborated by ex vivo γ-counting of dissected tissues, which demonstrated low uptake in nontarget tissues with only modest kidney uptake (9.2 ± 3.3 and 1.9 ± 1.2 %ID/g, respectively, at 2 h for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; n = 8). Uptake in healthy pancreas was low (0.3% ± 0.1% for (18)F-fluorobenzoate-R01 and 0.03% ± 0.01% for (18)F-fluorobenzoate-S02; n = 8). CONCLUSION: These cystine knot peptide tracers, in particular (18)F-fluorobenzoate-R01, show translational promise for molecular imaging of integrin αvβ6 overexpression in pancreatic and other cancers.

  View details for DOI 10.2967/jnumed.112.110759

  View details for PubMedID 23670900

• Noninvasive Monitoring of Oxidative Stress in Transplanted Mesenchymal Stromal Cells JACC-CARDIOVASCULAR IMAGING Psaltis, P. J., Peterson, K. M., Xu, R., Franchi, F., Witt, T., Chen, I. Y., Lerman, A., Simari, R. D., Gambhir, S. S., Rodriguez-Porcel, M. 2013; 6 (7): 795-802

  Abstract

  OBJECTIVES: The goal of this study was to validate a pathway-specific reporter gene that could be used to noninvasively image the oxidative status of progenitor cells. BACKGROUND: In cell therapy studies, reporter gene imaging plays a valuable role in the assessment of cell fate in living subjects. After myocardial injury, noxious stimuli in the host tissue confer oxidative stress to transplanted cells that may influence their survival and reparative function. METHODS: Rat mesenchymal stromal cells (MSCs) were studied for phenotypic evidence of increased oxidative stress under in vitro stress. On the basis of their up-regulation of the pro-oxidant enzyme p67(phox) subunit of nicotinamide adenine dinucleotide phosphate (NAD[P]H oxidase p67(phox)), an oxidative stress sensor was constructed, comprising the firefly luciferase (Fluc) reporter gene driven by the NAD(P)H p67(phox) promoter. MSCs cotransfected with NAD(P)H p67(phox)-Fluc and a cell viability reporter gene (cytomegalovirus-Renilla luciferase) were studied under in vitro and in vivo pro-oxidant conditions. RESULTS: After in vitro validation of the sensor during low-serum culture, transfected MSCs were transplanted into a rat model of myocardial ischemia/reperfusion (IR) and monitored by using bioluminescence imaging. Compared with sham controls (no IR), cardiac Fluc intensity was significantly higher in IR rats (3.5-fold at 6 h, 2.6-fold at 24 h, 5.4-fold at 48 h; p < 0.01), indicating increased cellular oxidative stress. This finding was corroborated by ex vivo luminometry after correcting for Renilla luciferase activity as a measure of viable MSC number (Fluc:Renilla luciferase ratio 0.011 ± 0.003 for sham vs. 0.026 ± 0.004 for IR at 48 h; p < 0.05). Furthermore, in IR animals that received MSCs preconditioned with an antioxidant agent (tempol), Fluc signal was strongly attenuated, substantiating the specificity of the oxidative stress sensor. CONCLUSIONS: Pathway-specific reporter gene imaging allows assessment of changes in the oxidative status of MSCs after delivery to ischemic myocardium, providing a template to monitor key biological interactions between transplanted cells and their host environment in living subjects.

  View details for DOI 10.1016/j.jcmg.2012.11.018

  View details for Web of Science ID 000321677300006

  View details for PubMedID 23643284

• A Raman-based endoscopic strategy for multiplexed molecular imaging. Proceedings of the National Academy of Sciences of the United States of America Zavaleta, C. L., Garai, E., Liu, J. T., Sensarn, S., Mandella, M. J., Van de Sompel, D., Friedland, S., Van Dam, J., Contag, C. H., Gambhir, S. S. 2013; 110 (25): E2288-97

  Abstract

  Endoscopic imaging is an invaluable diagnostic tool allowing minimally invasive access to tissues deep within the body. It has played a key role in screening colon cancer and is credited with preventing deaths through the detection and removal of precancerous polyps. However, conventional white-light endoscopy offers physicians structural information without the biochemical information that would be advantageous for early detection and is essential for molecular typing. To address this unmet need, we have developed a unique accessory, noncontact, fiber optic-based Raman spectroscopy device that has the potential to provide real-time, multiplexed functional information during routine endoscopy. This device is ideally suited for detection of functionalized surface-enhanced Raman scattering (SERS) nanoparticles as molecular imaging contrast agents. This device was designed for insertion through a clinical endoscope and has the potential to detect and quantify the presence of a multiplexed panel of tumor-targeting SERS nanoparticles. Characterization of the Raman instrument was performed with SERS particles on excised human tissue samples, and it has shown unsurpassed sensitivity and multiplexing capabilities, detecting 326-fM concentrations of SERS nanoparticles and unmixing 10 variations of colocalized SERS nanoparticles. Another unique feature of our noncontact Raman endoscope is that it has been designed for efficient use over a wide range of working distances from 1 to 10 mm. This is necessary to accommodate for imperfect centering during endoscopy and the nonuniform surface topology of human tissue. Using this endoscope as a key part of a multiplexed detection approach could allow endoscopists to distinguish between normal and precancerous tissues rapidly and to identify flat lesions that are otherwise missed.

  View details for DOI 10.1073/pnas.1211309110

  View details for PubMedID 23703909

  View details for PubMedCentralID PMC3690865

• Molecular Imaging of Inflammation in Inflammatory Bowel Disease with a Clinically Translatable Dual-Selectin-targeted US Contrast Agent: Comparison with FDG PET/CT in a Mouse Model. Radiology Wang, H., Machtaler, S., Bettinger, T., Lutz, A. M., Luong, R., Bussat, P., Gambhir, S. S., Tranquart, F., Tian, L., Willmann, J. K. 2013; 267 (3): 818-829

  Abstract

  Purpose: To develop and test a molecular imaging approach that uses ultrasonography (US) and a clinically translatable dual-targeted (P- and E-selectin) contrast agent (MBSelectin) in the quantification of inflammation at the molecular level and to quantitatively correlate selectin-targeted US with fluorodeoxyglucose (FDG) combined positron emission tomography (PET) and computed tomography (CT) in terms of visualization and quantification of different levels of inflammation in a murine acute colitis model. Materials and Methods: Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care at Stanford University. MBSelectin was developed by covalently binding an analog of the naturally occurring binding ligand P-selectin glycoprotein ligand 1 fused to a human fragment crystallizable(or Fc) domain onto the lipid shell of perfluorobutane and nitrogen-containing MBs. Binding specificity of MBSelectin was assessed in vitro with a flow chamber assay and in vivo with a chemically induced acute colitis murine model. US signal was quantitatively correlated with FDG uptake at PET/CT and histologic grade. Statistical analysis was performed with the Student t test, analysis of variance, and Pearson correlation analysis. Results: MBSelectin showed strong attachment to both human and mouse P- and E-selectin compared with MBControl in vitro (P ≤ .002). In vivo, US signal was significantly increased (P < .001) in mice with acute colitis (173.8 arbitrary units [au] ± 134.8 [standard deviation]) compared with control mice (5.0 au ± 4.5). US imaging signal strongly correlated with FDG uptake on PET/CT images (ρ = 0.89, P < .001). Ex vivo analysis enabled confirmation of inflammation in mice with acute colitis and high expression levels of P- and E-selectin in mucosal capillaries (P = .014). Conclusion: US with MBSelectin specifically enables detection and quantification of inflammation in a murine acute colitis model, leveraging the natural pathway of leukocyte recruitment in inflammatory tissue. US imaging with MBSelectin correlates well with FDG uptake at PET/CT imaging. © RSNA, 2013 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122509/-/DC1.

  View details for DOI 10.1148/radiol.13122509

  View details for PubMedID 23371306

• A comparison of noise models in a hybrid reference spectrum and principal components analysis algorithm for Raman spectroscopy JOURNAL OF RAMAN SPECTROSCOPY Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. 2013; 44 (6): 841-856

  View details for DOI 10.1002/jrs.4258

  View details for Web of Science ID 000319935700009

• Development and validation of an immuno-PET tracer for patient stratification and therapy monitoring of antibody-drug conjugate therapy Ilovich, O., Natarajan, A., Sathirachinda, A., Kimura, R., Srinivasan, A., Gebauer, M., Kruip, J., Carrez, C., Sassoon, I., Blanc, V., Sarkar, S. K., Gambhir, S. AMER SOC CLINICAL ONCOLOGY. 2013

  View details for Web of Science ID 000335419600416

• Advanced Characterization Techniques for Nanoparticles for Cancer Research: Applications of SEM and NanoSIMS for Locating Au Nanoparticles in Cells. Materials Research Society symposia proceedings. Materials Research Society Kempen, P. J., Hitzman, C., Sasportas, L. S., Gambhir, S. S., Sinclair, R. 2013; 1569: 157-163

  Abstract

  The ability of nano secondary ion mass spectrometry (NanoSIMS) to locate and analyze Raman active gold core nanoparticles (R-AuNPs) in a biological system is compared with the standard analysis using the scanning electron microscope (SEM). The same cell with R-AuNPs on and inside the macrophage was analyzed with both techniques to directly compare them. SEM analysis showed a large number of nanoparticles within the cell. Subsequent NanoSIMS analysis showed fewer R-AuNPs with lower spatial resolution. SEM was determined to be superior to NanoSIMS for the analysis of inorganic nanoparticles in complex biological systems.

  View details for PubMedID 25364091

• [F-18]CAIP a smart PET tracer for imaging caspase-3 induced Apoptosis Shen Bin, B., Jeon, J., Palner, M., Tong Ling, L., Felsher, D., Gambhir, S. S., Chin, F. T., Rao Jianghong, J. H. WILEY-BLACKWELL. 2013: S6–S6

  View details for Web of Science ID 000318694100007

• Biodistribution and kinetics of 18F FPPRGD2 in cancer patients Davidzon, G., Mosci, C., Mittra, E., Shen, B., Chin, F., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2013

  View details for Web of Science ID 000209478700012

• Evaluation of the antitumor effects of rilotumumab by PET imaging in a U-87 MG mouse xenograft model NUCLEAR MEDICINE AND BIOLOGY Rex, K., Lewis, X. Z., Sundaresan, G., Glaus, C., Silva, M. D., Radinsky, R., Burgess, T. L., Gambhir, S. S., Coxon, A. 2013; 40 (4): 458-463

  Abstract

  Dysregulation of the hepatocyte growth factor (HGF)/MET pathway has been implicated in various cancers. Rilotumumab is an investigational, fully human monoclonal antibody that binds and neutralizes HGF. The purpose of this study was to evaluate the efficacy of rilotumumab in a U-87 MG mouse xenograft tumor model using (18)F-FDG and (18)F-FLT PET.U-87 MG tumor-bearing nude mice received rilotumumab or control IgG2. In the dose response study, increasing doses of rilotumumab (10, 30, 100, 300, or 500 μg) were administered, and mice were evaluated with (18)F-FDG PET at baseline and 7 days post-treatment. In the time course study, 300 μg of rilotumumab twice per week was used for the treatment, and mice were evaluated over 7 days using (18)F-FDG and (18)F-FLT PET.In the dose response study, rilotumumab at doses of 300 and 500 μg was similarly effective against tumor growth. Treatment with 300 and 500 μg rilotumumab inhibited (18)F-FDG accumulation with significant decreases of -37% and -40% in the percent injected dose per gram of tissue (%ID/g), respectively. In the time course study, treatment with 300 μg rilotumumab inhibited (18)F-FDG and (18)F-FLT accumulation with a maximum %ID/g of -41% and -64%, respectively. No apparent differences between the use of either tracer to evaluate rilotumumab efficacy were observed.Rilotumumab inhibited (18)F-FDG and (18)F-FLT accumulation as early as 2 and 4 days after treatment, respectively, in a mouse tumor model. Further studies to evaluate (18)F-FDG PET imaging as an early tumor response marker for rilotumumab are warranted. Rilotumumab is currently being tested in patients with MET-positive, advanced gastric and gastroesophageal cancer.

  View details for DOI 10.1016/j.nucmedbio.2013.01.004

  View details for Web of Science ID 000325842800005

• Evaluation of the antitumor effects of rilotumumab by PET imaging in a U-87 MG mouse xenograft model. Nuclear medicine and biology Rex, K., Lewis, X. Z., Gobalakrishnan, S., Glaus, C., Silva, M. D., Radinsky, R., Burgess, T. L., Gambhir, S. S., Coxon, A. 2013; 40 (4): 458-463

  Abstract

  Dysregulation of the hepatocyte growth factor (HGF)/MET pathway has been implicated in various cancers. Rilotumumab is an investigational, fully human monoclonal antibody that binds and neutralizes HGF. The purpose of this study was to evaluate the efficacy of rilotumumab in a U-87 MG mouse xenograft tumor model using (18)F-FDG and (18)F-FLT PET.U-87 MG tumor-bearing nude mice received rilotumumab or control IgG2. In the dose response study, increasing doses of rilotumumab (10, 30, 100, 300, or 500 μg) were administered, and mice were evaluated with (18)F-FDG PET at baseline and 7 days post-treatment. In the time course study, 300 μg of rilotumumab twice per week was used for the treatment, and mice were evaluated over 7 days using (18)F-FDG and (18)F-FLT PET.In the dose response study, rilotumumab at doses of 300 and 500 μg was similarly effective against tumor growth. Treatment with 300 and 500 μg rilotumumab inhibited (18)F-FDG accumulation with significant decreases of -37% and -40% in the percent injected dose per gram of tissue (%ID/g), respectively. In the time course study, treatment with 300 μg rilotumumab inhibited (18)F-FDG and (18)F-FLT accumulation with a maximum %ID/g of -41% and -64%, respectively. No apparent differences between the use of either tracer to evaluate rilotumumab efficacy were observed.Rilotumumab inhibited (18)F-FDG and (18)F-FLT accumulation as early as 2 and 4 days after treatment, respectively, in a mouse tumor model. Further studies to evaluate (18)F-FDG PET imaging as an early tumor response marker for rilotumumab are warranted. Rilotumumab is currently being tested in patients with MET-positive, advanced gastric and gastroesophageal cancer.

  View details for DOI 10.1016/j.nucmedbio.2013.01.004

  View details for PubMedID 23454250

• Developing a non-invasive, diagnostic test for stage I non-small cell lung cancer using circulating tumor cells. Luttgen, M. S., Keu, K., Nair, V. S., Horng, G., Vasanawala, M., Kolatkar, A., Carlsson, A., Sabouri, M., Loo, B. W., Shrager, J. B., Iagaru, A., Kuschner, W., Kuhn, P., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2013

  View details for DOI 10.1158/1538-7445.AM2013-3485

  View details for Web of Science ID 000331220602190

• High-resolution, serial intravital microscopic imaging of nanoparticle delivery and targeting in a small animal tumor model NANO TODAY Smith, B. R., Zavaleta, C., Rosenberg, J., Tong, R., Ramunas, J., Liu, Z., Dai, H., Gambhir, S. S. 2013; 8 (2): 126-137

  View details for DOI 10.1016/j.nantod.2013.02.004

  View details for Web of Science ID 000319236400006

• High-resolution, serial intravital microscopic imaging of nanoparticle delivery and targeting in a small animal tumor model. Nano today Smith, B. R., Zavaleta, C., Rosenberg, J., Tong, R., Ramunas, J., Liu, Z., Dai, H., Gambhir, S. S. 2013; 8 (2)

  Abstract

  Nanoparticles are under active investigation for the detection and treatment of cancer. Yet our understanding of nanoparticle delivery to tumors is limited by our ability to observe the uptake process on its own scale in living subjects. We chose to study single-walled carbon nanotubes (SWNTs) because they exhibit among the highest levels of tumor uptake across the wide variety of available nanoparticles. We target them using RGD (arginine-glycine-aspartic acid) peptide which directs them to integrins overexpressed on tumor vasculature and on the surface of some tumor cells (e.g., U87MG as used here). We employ intravital microscopy (IVM) to quantitatively examine the spatiotemporal framework of targeted SWNT uptake in a murine tumor model. IVM provided a dynamic microscale window into nanoparticle circulation, binding to tumor blood vessels, extravasation, binding to tumor cells, and tumor retention. RGD-SWNTs bound to tumor vasculature significantly more than controls (P<0.0001). RGD-SWNTs extravasated similarly compared to control RAD-SWNTs, but post-extravasation we observed as RGD-SWNTs eventually bound to individual tumor cells significantly more than RAD-SWNTs (p<0.0001) over time. RGD-SWNTs and RAD-SWNTs displayed similar signal in tumor for a week, but over time their curves significantly diverged (p<0.001) showing increasing RGD-SWNTs relative to untargeted SWNTs. We uncovered the complex spatiotemporal interplay between these competing uptake mechanisms. Specific uptake was delimited to early (1-6 hours) and late (1-4 weeks) time-points, while non-specific uptake dominated from 6 hours to 1 week. Our analysis revealed critical, quantitative insights into the dynamic, multifaceted mechanisms implicated in ligand-targeted SWNT accumulation in tumor using real-time observation.

  View details for DOI 10.1016/j.nantod.2013.02.004

  View details for PubMedID 24273594

  View details for PubMedCentralID PMC3836612

• Intracellular Aggregation of Multimodal Silica Nanoparticles for Ultrasound-Guided Stem Cell Implantation SCIENCE TRANSLATIONAL MEDICINE Jokerst, J. V., Khademi, C., Gambhir, S. S. 2013; 5 (177)

  Abstract

  The promises of cardiac stem cell therapy have yet to be fully realized, in part because of poor survival and engraftment efficacy of implanted cells. Cells die after implantation owing to ischemia, inflammation, immune response, as well as mis-injection or implantation into fibrotic tissue. Imaging tools can help implant cells in areas of the heart most receptive to stem cell therapy and monitor the efficacy of treatment by reporting the viability, location, and number of implanted stem cells. We describe a multimodal, silica-based nanoparticle that can be used for cell sorting (fluorescence), real-time guided cell implantation ultrasound, and high-resolution, long-term monitoring by magnetic resonance imaging (MRI). The nanoparticle agent increased the ultrasound and MRI contrast of labeled human mesenchymal stem cells (hMSCs) 700 and 200% versus unlabeled cells, respectively, and allowed cell imaging in animal models for 13 days after implantation. The agent had no significant impact on hMSC cell metabolic activity, proliferation, or pluripotency, and it increased the production of many paracrine factors implicated in cardiac repair. Electron microscopy and ultrasound imaging suggest that the mechanism of action is in vivo aggregation of the 300-nm silica nanoparticles into larger silica frameworks that amplify the ultrasound backscatter. The detection limit in cardiac tissue was 250,000 hMSCs via MRI and 70,000 via ultrasound. This ultrasound-guided cell delivery and multimodal optical/ultrasound/MRI intracardiac cell-tracking platform could improve cell therapy in the clinic by minimizing misdelivery or implantation into fibrotic tissue.

  View details for DOI 10.1126/scitranslmed.3005228

  View details for Web of Science ID 000316454100004

  View details for PubMedID 23515077

• Molecular Photoacoustic Imaging of Follicular Thyroid Carcinoma CLINICAL CANCER RESEARCH Levi, J., Kothapalli, S., Bohndiek, S., Yoon, J., Dragulescu-Andrasi, A., Nielsen, C., Tisma, A., Bodapati, S., Gowrishankar, G., Yan, X., Chan, C., Starcevic, D., Gambhir, S. S. 2013; 19 (6): 1494-1502

  Abstract

  To evaluate the potential of targeted photoacoustic imaging as a noninvasive method for detection of follicular thyroid carcinoma.We determined the presence and activity of two members of matrix metalloproteinase family (MMP), MMP-2 and MMP-9, suggested as biomarkers for malignant thyroid lesions, in FTC133 thyroid tumors subcutaneously implanted in nude mice. The imaging agent used to visualize tumors was MMP-activatable photoacoustic probe, Alexa750-CXeeeeXPLGLAGrrrrrXK-BHQ3. Cleavage of the MMP-activatable agent was imaged after intratumoral and intravenous injections in living mice optically, observing the increase in Alexa750 fluorescence, and photoacoustically, using a dual-wavelength imaging method.Active forms of both MMP-2 and MMP-9 enzymes were found in FTC133 tumor homogenates, with MMP-9 detected in greater amounts. The molecular imaging agent was determined to be activated by both enzymes in vitro, with MMP-9 being more efficient in this regard. Both optical and photoacoustic imaging showed significantly higher signal in tumors of mice injected with the active agent than in tumors injected with the control, nonactivatable, agent.With the combination of high spatial resolution and signal specificity, targeted photoacoustic imaging holds great promise as a noninvasive method for early diagnosis of follicular thyroid carcinomas.

  View details for DOI 10.1158/1078-0432.CCR-12-3061

  View details for Web of Science ID 000316188900021

  View details for PubMedID 23349314

  View details for PubMedCentralID PMC3602312

• Earlier Detection of Breast Cancer with Ultrasound Molecular Imaging in a Transgenic Mouse Model CANCER RESEARCH Bachawal, S. V., Jensen, K. C., Lutz, A. M., Gambhir, S. S., Tranquart, F., Tian, L., Willmann, J. K. 2013; 73 (6): 1689-1698

  Abstract

  While there is an increasing role of ultrasound for breast cancer screening in patients with dense breast, conventional anatomical ultrasound lacks sensitivity and specificity for early breast cancer detection. In this study, we assessed the potential of ultrasound molecular imaging using clinically translatable vascular endothelial growth factor receptor type 2 (VEGFR2)-targeted microbubbles (MB(VEGFR2)) to improve the diagnostic accuracy of ultrasound in earlier detection of breast cancer and ductal carcinoma in situ (DCIS) in a transgenic mouse model [FVB/N-Tg(MMTV-PyMT)634Mul]. In vivo binding specificity studies (n = 26 tumors) showed that ultrasound imaging signal was significantly higher (P < 0.001) using MB(VEGFR2) than nontargeted microbubbles and imaging signal significantly decreased (P < 0.001) by blocking antibodies. Ultrasound molecular imaging signal significantly increased (P < 0.001) when breast tissue (n = 315 glands) progressed from normal [1.65 ± 0.17 arbitrary units (a.u.)] to hyperplasia (4.21 ± 1.16), DCIS (15.95 ± 1.31), and invasive cancer (78.1 ± 6.31) and highly correlated with ex vivo VEGFR2 expression [R(2) = 0.84; 95% confidence interval (CI), 0.72-0.91; P < 0.001]. At an imaging signal threshold of 4.6 a.u., ultrasound molecular imaging differentiated benign from malignant entities with a sensitivity of 84% (95% CI, 78-88) and specificity of 89% (95% CI, 81-94). In a prospective screening trail (n = 63 glands), diagnostic performance of detecting DCIS and breast cancer was assessed and two independent readers correctly diagnosed malignant disease in more than 95% of cases and highly agreed between each other [intraclass correlation coefficient (ICC) = 0.98; 95% CI, 97-99]. These results suggest that VEGFR2-targeted ultrasound molecular imaging allows highly accurate detection of DCIS and breast cancer in transgenic mice and may be a promising approach for early breast cancer detection in women.

  View details for DOI 10.1158/0008-5472.CAN-12-3391

  View details for Web of Science ID 000316187500006

  View details for PubMedID 23328585

  View details for PubMedCentralID PMC3602408

• An Integrated Computational/Experimental Model of Lymphoma Growth PLOS COMPUTATIONAL BIOLOGY Frieboes, H. B., Smith, B. R., Chuang, Y., Ito, K., Roettgers, A. M., Gambhir, S. S., Cristini, V. 2013; 9 (3)

  Abstract

  Non-Hodgkin's lymphoma is a disseminated, highly malignant cancer, with resistance to drug treatment based on molecular- and tissue-scale characteristics that are intricately linked. A critical element of molecular resistance has been traced to the loss of functionality in proteins such as the tumor suppressor p53. We investigate the tissue-scale physiologic effects of this loss by integrating in vivo and immunohistological data with computational modeling to study the spatiotemporal physical dynamics of lymphoma growth. We compare between drug-sensitive Eμ-myc Arf-/- and drug-resistant Eμ-myc p53-/- lymphoma cell tumors grown in live mice. Initial values for the model parameters are obtained in part by extracting values from the cellular-scale from whole-tumor histological staining of the tumor-infiltrated inguinal lymph node in vivo. We compare model-predicted tumor growth with that observed from intravital microscopy and macroscopic imaging in vivo, finding that the model is able to accurately predict lymphoma growth. A critical physical mechanism underlying drug-resistant phenotypes may be that the Eμ-myc p53-/- cells seem to pack more closely within the tumor than the Eμ-myc Arf-/- cells, thus possibly exacerbating diffusion gradients of oxygen, leading to cell quiescence and hence resistance to cell-cycle specific drugs. Tighter cell packing could also maintain steeper gradients of drug and lead to insufficient toxicity. The transport phenomena within the lymphoma may thus contribute in nontrivial, complex ways to the difference in drug sensitivity between Eμ-myc Arf-/- and Eμ-myc p53-/- tumors, beyond what might be solely expected from loss of functionality at the molecular scale. We conclude that computational modeling tightly integrated with experimental data gives insight into the dynamics of Non-Hodgkin's lymphoma and provides a platform to generate confirmable predictions of tumor growth.

  View details for DOI 10.1371/journal.pcbi.1003008

  View details for Web of Science ID 000316864200070

  View details for PubMedID 23555235

  View details for PubMedCentralID PMC3610621

• BIOENGINEERING AND REGENERATIVE MEDICINE Keeping track NATURE MATERIALS Ziv, K., Gambhir, S. S. 2013; 12 (3): 180-181

  View details for Web of Science ID 000315707200009

  View details for PubMedID 23422714

• Non-Invasive Imaging of Phosphoinositide-3-Kinase-Catalytic-Subunit-Alpha (PIK3CA) Promoter Modulation in Small Animal Models PLOS ONE Gaikwad, S. M., Gunjal, L., Junutula, A. R., Astanehe, A., Gambhir, S. S., Ray, P. 2013; 8 (2)

  Abstract

  Activation of the PI3K/Akt pathway, a critical step for survival in cancer cells is often associated with decreased sensitivity to several chemotherapeutic drugs. PIK3CA gene amplification is observed in 16-24% of epithelial ovarian cancer (EOC) patients in conjunction with p53 mutations. A 900 bp long PIK3CA promoter is shown to be negatively regulated by p53 in ovarian surface epithelial cells but the consequence of chemotherapeutic drug treatments on this promoter in ovarian cancer cells is largely unknown. We aim to study the modulation of this promoter by cisplatin using an improved fusion reporter in ovarian cancer cells and tumor xenografts by non-invasive imaging approach. A PIK3CA sensor was developed using a bi-fusion reporter from a newly constructed library of bi- and tri-fusion vectors comprising of two mutant far red fluorescent proteins (mcherry/mch and tdTomato/tdt), a mutant firefly luciferase (fluc2), and a PET reporter protein (ttk). In vivo imaging of mice implanted with 293T cells transiently expressing these bi- and tri-fusion reporters along with respective controls revealed comparable activity of each reporter in the fusion background and fluc2-tdt as the most sensitive one. Repression of the PIK3CA sensor by drugs was inversely proportional to cellular p53 level in a germline (PA1) and in an EOC (A2780) cell line but not in a p53 deficient EOC (SKOV3) cell line. Bioluminescence imaging of tumor xenografts stably expressing the PIK3CA sensor in PA1 and A2780 cells exhibited attenuating activity without any change in SKOV3 tumors expressing the PIK3CA sensor after cisplatin treatment. Sequential mutation at p53 binding sites showed gradual increase in promoter activity and decreased effects of the drugs. These newly developed PIK3CA-fluc2-tdt and the mutant reporter sensors thus would be extremely useful for screening new drugs and for functional assessment of PIK3CA expression from intact cells to living subjects.

  View details for DOI 10.1371/journal.pone.0055971

  View details for Web of Science ID 000314692800061

  View details for PubMedID 23393606

  View details for PubMedCentralID PMC3564913

• Dissection of the role of the tumor microenvironment in oncogene addiction by ex vivo and in situ imaging AACR/SNMMI Joint Conference on State-of-the-Art Molecular Imaging in Cancer Biology and Therapy Tong, L., Jeon, J., Shen, B., Jianghong, R., Chin, F., Gambhir, S., Felsher, D. SOC NUCLEAR MEDICINE INC. 2013: 25–25

  View details for Web of Science ID 000314691400075

• Combined F-18-Fluoride and F-18-FDG PET/CT Scanning for Evaluation of Malignancy: Results of an International Multicenter Trial JOURNAL OF NUCLEAR MEDICINE Iagaru, A., Mittra, E., Mosci, C., Dick, D. W., Sathekge, M., Prakash, V., Iyer, V., Lapa, P., Isidoro, J., de Lima, J. M., Gambhir, S. S. 2013; 54 (2): 176-183

  Abstract

  (18)F-FDG PET/CT is used in a variety of cancers, but because of variable rates of glucose metabolism, not all cancers are reliably identified. (18)F(-) PET/CT allows for the acquisition of highly sensitive and specific images of the skeleton. We prospectively evaluated combined (18)F(-)/(18)F-FDG as a single PET/CT examination for evaluation of cancer patients and compared it with separate (18)F(-) PET/CT and (18)F-FDG PET/CT scans.One hundred fifteen participants with cancer were prospectively enrolled in an international multicenter trial evaluating (18)F(-) PET/CT, (18)F-FDG PET/CT, and combined (18)F(-)/(18)F-FDG PET/CT. The 3 PET/CT scans were performed sequentially within 4 wk of one another for each patient.(18)F(-)/(18)F-FDG PET/CT allowed for accurate interpretation of radiotracer uptake outside the skeleton, with findings similar to those of (18)F-FDG PET/CT. In 19 participants, skeletal disease was more extensive on (18)F(-) PET/CT and (18)F(-)/(18)F-FDG PET/CT than on (18)F-FDG PET/CT. In another 29 participants, (18)F(-) PET/CT and (18)F(-)/(18)F-FDG PET/CT showed osseous metastases where (18)F-FDG PET/CT was negative. The extent of skeletal lesions was similar in 18 participants on all 3 scans.This trial demonstrated that combined (18)F(-)/(18)F-FDG PET/CT shows promising results when compared with separate (18)F(-) PET/CT and (18)F-FDG PET/CT for evaluation of cancer patients. This result opens the possibility for improved patient care and reduction in health-care costs, as will be further evaluated in future trials.

  View details for DOI 10.2967/jnumed.112.108803

  View details for Web of Science ID 000314691200016

  View details for PubMedID 23243299

• Colony-stimulating factor 1 receptor (CSF1R) signaling in injured neurons facilitates protection and survival JOURNAL OF EXPERIMENTAL MEDICINE Luo, J., Elwood, F., Britschgi, M., Villeda, S., Zhang, H., Ding, Z., Zhu, L., Alabsi, H., Getachew, R., Narasimhan, R., Wabl, R., Fainberg, N., James, M. L., Wong, G., Relton, J., Gambhir, S. S., Pollard, J. W., Wyss-Coray, T. 2013; 210 (1): 157-172

  Abstract

  Colony-stimulating factor 1 (CSF1) and interleukin-34 (IL-34) are functional ligands of the CSF1 receptor (CSF1R) and thus are key regulators of the monocyte/macrophage lineage. We discovered that systemic administration of human recombinant CSF1 ameliorates memory deficits in a transgenic mouse model of Alzheimer's disease. CSF1 and IL-34 strongly reduced excitotoxin-induced neuronal cell loss and gliosis in wild-type mice when administered systemically before or up to 6 h after injury. These effects were accompanied by maintenance of cAMP responsive element-binding protein (CREB) signaling in neurons rather than in microglia. Using lineage-tracing experiments, we discovered that a small number of neurons in the hippocampus and cortex express CSF1R under physiological conditions and that kainic acid-induced excitotoxic injury results in a profound increase in neuronal receptor expression. Selective deletion of CSF1R in forebrain neurons in mice exacerbated excitotoxin-induced death and neurodegeneration. We conclude that CSF1 and IL-34 provide powerful neuroprotective and survival signals in brain injury and neurodegeneration involving CSF1R expression on neurons.

  View details for DOI 10.1084/jem.20120412

  View details for Web of Science ID 000313560900014

  View details for PubMedID 23296467

  View details for PubMedCentralID PMC3549715

• Synthesis of ligand-functionalized water-soluble [F-18]YF3 nanoparticles for PET imaging NANOSCALE Xiong, L., Shen, B., Behera, D., Gambhir, S. S., Chin, F. T., Rao, J. 2013; 5 (8): 3253-3256

  Abstract

  We report a simple, efficient synthesis of novel (18)F-labeled imaging agents based on YF3 nanoparticles. Targeting ligands and antitumor drug molecules can be introduced onto the YF3 nanoparticles in a one-pot synthesis. The (18)F-labeling reaction proceeds in aqueous solutions at room temperature with excellent radiolabeling yields (>80%) in a very short time (5-10 min). (18)F-labeled YF3 nanoparticles displayed high stability in mouse and human serum, and their application for mapping lymph nodes in live rats after local injection has also been demonstrated.

  View details for DOI 10.1039/c3nr00335c

  View details for Web of Science ID 000316959500019

  View details for PubMedID 23508229

  View details for PubMedCentralID PMC3645980

• Real-time, continuous, fluorescence sensing in a freely-moving subject with an implanted hybrid VCSEL/CMOS biosensor. Biomedical optics express O'Sullivan, T. D., Heitz, R. T., Parashurama, N., Barkin, D. B., Wooley, B. A., Gambhir, S. S., Harris, J. S., Levi, O. 2013; 4 (8): 1332-1341

  Abstract

  Performance improvements in instrumentation for optical imaging have contributed greatly to molecular imaging in living subjects. In order to advance molecular imaging in freely moving, untethered subjects, we designed a miniature vertical-cavity surface-emitting laser (VCSEL)-based biosensor measuring 1cm(3) and weighing 0.7g that accurately detects both fluorophore and tumor-targeted molecular probes in small animals. We integrated a critical enabling component, a complementary metal-oxide semiconductor (CMOS) read-out integrated circuit, which digitized the fluorescence signal to achieve autofluorescence-limited sensitivity. After surgical implantation of the lightweight sensor for two weeks, we obtained continuous and dynamic fluorophore measurements while the subject was un-anesthetized and mobile. The technology demonstrated here represents a critical step in the path toward untethered optical sensing using an integrated optoelectronic implant.

  View details for DOI 10.1364/BOE.4.001332

  View details for PubMedID 24009996

• Molecular Imaging Primer Gambhir, S. S. Apple iBookstore. 2013
• MicroRNA-Regulated Non-Viral Vectors with Improved Tumor Specifically in an Orthotopic Rat Model pf Hepatocellular Carcinoma Gene Therapy Ronald, J. A., Katzenberg, R., Nielsen, C. H., Jae, H. J., Hofmann, L. V., Gambhir, S. S. 2013: 1006-1013
• Evolution of BRET Biosensors from Live Cell to Tissue Scale Frontiers in Endocrinology De, A., Jasani, A., Arora, R., Gambhir, S. S. 2013
• Development and Validation of Non-Intergrative, Self-Limited, and Replicating Minicircles for Safe Reporter Gene Imaging of Cell-Based Therapies PLoS One Ronald, J. A., Cusso, L., Chuang, H. Y., Yan, X., Dragulescu-Andrasi, A., Gambhir, S. S. 2013: e73138
• Modification of a commercially available photoacoustic imaging system for the use of 1064nm and 532nm wavelengths to assess photoacoustic contrast agents Heinmiller, A., Homan, K., Emelianov, S., Cole, A., Gambhir, S., Needles, A., Theodoropoulos, C., Hirson, D., Oraevsky, A. A., Wang, L. V. SPIE-INT SOC OPTICAL ENGINEERING. 2013

  View details for DOI 10.1117/12.2004804

  View details for Web of Science ID 000322832800085

• Single-cell Photonic Nanocavity Probes Shambat, G., Kothapalli, R., Provine, J., Sarmiento, T., Harris, J., Gambhir, S., Vuckovic, J., IEEE IEEE. 2013

  View details for Web of Science ID 000355262503102

• Evolution of BRET Biosensors from Live Cell to Tissue-Scale In vivo Imaging. Frontiers in endocrinology De, A., Jasani, A., Arora, R., Gambhir, S. S. 2013; 4: 131-?

  Abstract

  Development of bioluminescence resonance energy transfer (BRET) based genetic sensors for sensing biological functions such as protein-protein interactions (PPIs) in vivo has a special value in measuring such dynamic events at their native environment. Since its inception in the late nineties, BRET related research has gained significant momentum in terms of adding versatility to the assay format and wider applicability where it has been suitably used. Beyond the scope of quantitative measurement of PPIs and protein dimerization, molecular imaging applications based on BRET assays have broadened its scope for screening pharmacologically important compounds by in vivo imaging as well. In this mini-review we focus on an in-depth analysis of engineered BRET systems developed and their successful application to cell-based assays as well as in vivo non-invasive imaging in live subjects.

  View details for DOI 10.3389/fendo.2013.00131

  View details for PubMedID 24065957

• Comparison of Gaussian and Poisson Noise Models in a Hybrid Reference Spectrum and Principal Component Analysis Algorithm for Raman Spectroscopy Conference on Single Molecule Spectroscopy and Superresolution Imaging VI Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2013

  View details for DOI 10.1117/12.2005455

  View details for Web of Science ID 000321741600011

• A Brain Tumor Molecular Imaging Strategy using a New Triple-Modality MRI-Photoacoustic-Raman Nanoparticle Conference on Photons Plus Ultrasound - Imaging and Sensing de la Zerda, A., Kircher, M. F., Jokerst, J. V., Zavaleta, C. L., Kempen, P. J., Mittra, E., Pitter, K., Huang, R., Campos, C., Habte, F., Sinclair, R., Brennan, C. W., Mellinghoff, I. K., Holland, E. C., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2013

  View details for DOI 10.1117/12.2001719

  View details for Web of Science ID 000322832800007

• A transgenic tri-modality reporter mouse. PloS one Yan, X., Ray, P., Paulmurugan, R., Tong, R., Gong, Y., Sathirachinda, A., Wu, J. C., Gambhir, S. S. 2013; 8 (8)

  Abstract

  Transgenic mouse with a stably integrated reporter gene(s) can be a valuable resource for obtaining uniformly labeled stem cells, tissues, and organs for various applications. We have generated a transgenic mouse model that ubiquitously expresses a tri-fusion reporter gene (fluc2-tdTomato-ttk) driven by a constitutive chicken β-actin promoter. This "Tri-Modality Reporter Mouse" system allows one to isolate most cells from this donor mouse and image them for bioluminescent (fluc2), fluorescent (tdTomato), and positron emission tomography (PET) (ttk) modalities. Transgenic colonies with different levels of tri-fusion reporter gene expression showed a linear correlation between all three-reporter proteins (R(2)=0.89 for TdTomato vs Fluc, R(2)=0.94 for Fluc vs TTK, R(2)=0.89 for TdTomato vs TTK) in vitro from tissue lysates and in vivo by optical and PET imaging. Mesenchymal stem cells (MSCs) isolated from this transgenics showed high level of reporter gene expression, which linearly correlated with the cell numbers (R(2)=0.99 for bioluminescence imaging (BLI)). Both BLI (R(2)=0.93) and micro-PET (R(2)=0.94) imaging of the subcutaneous implants of Tri-Modality Reporter Mouse derived MSCs in nude mice showed linear correlation with the cell numbers and across different imaging modalities (R(2)=0.97). Serial imaging of MSCs transplanted to mice with acute myocardial infarction (MI) by intramyocardial injection exhibited significantly higher signals in MI heart at days 2, 3, 4, and 7 (p<0.01). MSCs transplanted to the ischemic hindlimb of nude mice showed significantly higher BLI and PET signals in the first 2 weeks that dropped by 4(th) week due to poor cell survival. However, laser Doppler perfusion imaging revealed that blood circulation in the ischemic limb was significantly improved in the MSCs transplantation group compared with the control group. In summary, this mouse can be used as a source of donor cells and organs in various research areas such as stem cell research, tissue engineering research, and organ transplantation.

  View details for DOI 10.1371/journal.pone.0073580

  View details for PubMedID 23951359

  View details for PubMedCentralID PMC3739740

• Development and application of stable phantoms for the evaluation of photoacoustic imaging instruments. PloS one Bohndiek, S. E., Bodapati, S., Van de Sompel, D., Kothapalli, S., Gambhir, S. S. 2013; 8 (9)

  Abstract

  Photoacoustic imaging combines the high contrast of optical imaging with the spatial resolution and penetration depth of ultrasound. This technique holds tremendous potential for imaging in small animals and importantly, is clinically translatable. At present, there is no accepted standard physical phantom that can be used to provide routine quality control and performance evaluation of photoacoustic imaging instruments. With the growing popularity of the technique and the advent of several commercial small animal imaging systems, it is important to develop a strategy for assessment of such instruments. Here, we developed a protocol for fabrication of physical phantoms for photoacoustic imaging from polyvinyl chloride plastisol (PVCP). Using this material, we designed and constructed a range of phantoms by tuning the optical properties of the background matrix and embedding spherical absorbing targets of the same material at different depths. We created specific designs to enable: routine quality control; the testing of robustness of photoacoustic signals as a function of background; and the evaluation of the maximum imaging depth available. Furthermore, we demonstrated that we could, for the first time, evaluate two small animal photoacoustic imaging systems with distinctly different light delivery, ultrasound imaging geometries and center frequencies, using stable physical phantoms and directly compare the results from both systems.

  View details for DOI 10.1371/journal.pone.0075533

  View details for PubMedID 24086557

  View details for PubMedCentralID PMC3783368

• Stable phantoms for characterization of photoacoustic tomography (PAT) systems Conference on Design and Performance Validation of Phantoms Used in Conjunction with Optical Measurement of Tissue V Bohndiek, S. E., Van de Sompel, D., Bodapati, S., Kothapalli, S. R., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2013

  View details for DOI 10.1117/12.2005195

  View details for Web of Science ID 000322903900005

• Development and validation of non-integrative, self-limited, and replicating minicircles for safe reporter gene imaging of cell-based therapies. PloS one Ronald, J. A., Cusso, L., Chuang, H., Yan, X., Dragulescu-Andrasi, A., Gambhir, S. S. 2013; 8 (8)

  Abstract

  Reporter gene (RG) imaging of cell-based therapies provides a direct readout of therapeutic efficacy by assessing the fate of implanted cells. To permit long-term cellular imaging, RGs are traditionally required to be integrated into the cellular genome. This poses a potential safety risk and regulatory bottleneck for clinical translation as integration can lead to cellular transformation. To address this issue, we have developed non-integrative, replicating minicircles (MCs) as an alternative platform for safer monitoring of cells in living subjects. We developed both plasmids and minicircles containing the scaffold/matrix attachment regions (S/MAR) of the human interferon-beta gene, driven by the CMV promoter, and expressing the bioluminescence RG firefly luciferase. Constructs were transfected into breast cancer cells, and expanded S/MAR minicircle clones showed luciferase signal for greater than 3 months in culture and minicircles remained as episomes. Importantly, luciferase activity in clonal populations was slowly lost over time and this corresponded to a loss of episome, providing a way to reversibly label cells. To monitor cell proliferation in vivo, 1.5×10(6) cells carrying the S/MAR minicircle were implanted subcutaneously into mice (n = 5) and as tumors developed significantly more bioluminescence signal was noted at day 35 and 43 compared to day 7 post-implant (p<0.05). To our knowledge, this is the first work examining the use of episomal, self-limited, replicating minicircles to track the proliferation of cells using non-invasive imaging in living subjects. Continued development of S/MAR minicircles will provide a broadly applicable vector platform amenable with any of the numerous RG technologies available to allow therapeutic cell fate to be assessed in individual patients, and to achieve this without the need to manipulate the cell's genome so that safety concerns are minimized. This will lead to safe tools to assess treatment response at earlier time points and improve the precision of cell-based therapies.

  View details for DOI 10.1371/journal.pone.0073138

  View details for PubMedID 24015294

  View details for PubMedCentralID PMC3756008

• Human flexor tendon tissue engineering: revitalization of biostatic allograft scaffolds. Tissue engineering. Part A Woon, C. Y., Farnebo, S., Schmitt, T., Kraus, A., Megerle, K., Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 18 (23-24): 2406-2417

  Abstract

  Cadaveric tendon allografts form a readily available and underutilized source of graft material. Because of their material properties, allografts are biomechanically and biologically superior to synthetic scaffolds. However, before clinical use, allografts must undergo decellularization to reduce immunogenicity and oxidation to increase porosity, leaving a nonvital biostatic scaffold. Ex vivo seeding, or revitalization, is thought to hasten graft incorporation and stimulate intrinsic tendon healing, permitting early mobilization and return to function. In this study, we examined physical and biochemical augmentation methods, including scaffold surface scoring (physical) and rehydration of lyophilized scaffolds in serum (biochemical). Scaffolds were divided into four groups: (1) scored scaffolds, (2) lyophilized scaffolds rehydrated in fetal calf serum (FCS), (3) scaffolds both scored and rehydrated in FCS, and (4) control scaffolds. Scaffolds were reseeded with adipose-derived stem cells (ADSCs). Reseeding efficacy was quantified by a live cell and total cell assays and qualified histologically with hematoxylin and eosin, live/dead and SYTO green nucleic acid stains, TUNEL apoptosis stains, procollagen stains, and transmission electron microscopy. Scaffold-seeded cell viability at up to 2 weeks in vitro and up to 4 weeks in vivo was demonstrated with bioluminescent imaging of scaffolds seeded with luciferase-positive ADSCs. The effect of seeding on scaffold biomechanical properties was demonstrated with evaluation of ultimate tensile stress (UTS) and an elastic modulus (EM). We found that scaffold surface scoring led to an increase in live and total cell attachment and penetration (MTS assay, p<0.001 and DNA assay, p=0.003, respectively). Histology confirmed greater total cell number in both construct core and surface in scored compared with unscored constructs. Cells reseeded on scored constructs displayed reduced apoptosis, persistent procollagen production, and had a similar ultrastructural relationship to the surrounding matrix as native tenocytes on transmission electron microscopy. Rehydration of lyophilized scaffolds in serum did not improve reseeding. Seeded constructs demonstrated greater UTS and EM than unseeded constructs. Scaffolds seeded with ADSC-luc2-eGFP demonstrated persistent viability for at least 2 weeks in vitro. In conclusion, tendon surface scoring increases surface and core reseeding in vitro and may be incorporated as a final step in allograft processing before clinical implantation.

  View details for DOI 10.1089/ten.TEA.2012.0152

  View details for PubMedID 22712522

• Human Flexor Tendon Tissue Engineering: Revitalization of Biostatic Allograft Scaffolds TISSUE ENGINEERING PART A Woon, C. Y., Farnebo, S., Schmitt, T., Kraus, A., Megerle, K., Hung Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 18 (23-24): 2406-2417

  Abstract

  Cadaveric tendon allografts form a readily available and underutilized source of graft material. Because of their material properties, allografts are biomechanically and biologically superior to synthetic scaffolds. However, before clinical use, allografts must undergo decellularization to reduce immunogenicity and oxidation to increase porosity, leaving a nonvital biostatic scaffold. Ex vivo seeding, or revitalization, is thought to hasten graft incorporation and stimulate intrinsic tendon healing, permitting early mobilization and return to function. In this study, we examined physical and biochemical augmentation methods, including scaffold surface scoring (physical) and rehydration of lyophilized scaffolds in serum (biochemical). Scaffolds were divided into four groups: (1) scored scaffolds, (2) lyophilized scaffolds rehydrated in fetal calf serum (FCS), (3) scaffolds both scored and rehydrated in FCS, and (4) control scaffolds. Scaffolds were reseeded with adipose-derived stem cells (ADSCs). Reseeding efficacy was quantified by a live cell and total cell assays and qualified histologically with hematoxylin and eosin, live/dead and SYTO green nucleic acid stains, TUNEL apoptosis stains, procollagen stains, and transmission electron microscopy. Scaffold-seeded cell viability at up to 2 weeks in vitro and up to 4 weeks in vivo was demonstrated with bioluminescent imaging of scaffolds seeded with luciferase-positive ADSCs. The effect of seeding on scaffold biomechanical properties was demonstrated with evaluation of ultimate tensile stress (UTS) and an elastic modulus (EM). We found that scaffold surface scoring led to an increase in live and total cell attachment and penetration (MTS assay, p<0.001 and DNA assay, p=0.003, respectively). Histology confirmed greater total cell number in both construct core and surface in scored compared with unscored constructs. Cells reseeded on scored constructs displayed reduced apoptosis, persistent procollagen production, and had a similar ultrastructural relationship to the surrounding matrix as native tenocytes on transmission electron microscopy. Rehydration of lyophilized scaffolds in serum did not improve reseeding. Seeded constructs demonstrated greater UTS and EM than unseeded constructs. Scaffolds seeded with ADSC-luc2-eGFP demonstrated persistent viability for at least 2 weeks in vitro. In conclusion, tendon surface scoring increases surface and core reseeding in vitro and may be incorporated as a final step in allograft processing before clinical implantation.

  View details for DOI 10.1089/ten.tea.2012.0152

  View details for Web of Science ID 000311600800002

• Exogenous MC3T3 Preosteoblasts Migrate Systemically and Mitigate the Adverse Effects of Wear Particles TISSUE ENGINEERING PART A Fritton, K., Ren, P., Gibon, E., Rao, A. J., Ma, T., Biswal, S., Gambhir, S. S., Goodman, S. B. 2012; 18 (23-24): 2559-2567

  Abstract

  Understanding how relevant cell types respond to wear particles will reveal new avenues for treating osteolysis following joint replacements. In this study, we investigate the effects of ultrahigh molecular weight polyethylene (UHMWPE) particles on preosteoblast migration and function. We infused UHMWPE particles or saline into the left femur of mice and injected luciferase-expressing preosteoblasts (MC3T3 cells) into each left ventricle. Bioluminescence imaging (BLI) confirmed systemic administration of MC3T3 cells. BLI throughout the 28-day experiment showed greater MC3T3 migration to the site of particle infusion than to the site of saline infusion, with significant differences on days 0, 4, and 6 (p≤0.055). Immunostaining revealed a greater number of osteoblasts and osteoclasts in the particle-infused femora, indicating greater bone turnover. The bone mineralization of the particle-infused femora increased significantly when compared to saline-infused femora (an increase of 146.4±27.9 vs. 12.8±8.7 mg/mL, p=0.008). These results show that infused preosteoblasts can migrate to the site of wear particles. Additionally, as the migrated cells were associated with increased bone mineralization in spite of the presence of particles, increasing osteoblast recruitment is a potential strategy for combating bone loss due to increased osteoclast/macrophage number and decreased osteoblast function.

  View details for DOI 10.1089/ten.tea.2012.0086

  View details for PubMedID 22741555

• Unexpected Dissemination Patterns in Lymphoma Progression Revealed by Serial Imaging within a Murine Lymph Node CANCER RESEARCH Ito, K., Smith, B. R., Parashurama, N., Yoon, J., Song, S. Y., Miething, C., Mallick, P., Lowe, S., Gambhir, S. S. 2012; 72 (23): 6111-6118

  Abstract

  Non-Hodgkin lymphoma (NHL) is a heterogeneous and highly disseminated disease, but the mechanisms of its growth and dissemination are not well understood. Using a mouse model of this disease, we used multimodal imaging, including intravital microscopy (IVM) combined with bioluminescence, as a powerful tool to better elucidate NHL progression. We injected enhanced green fluorescent protein and luciferase-expressing Eμ-Myc/Arf(-/-) (Cdkn2a(-/-)) mouse lymphoma cells (EL-Arf(-/-)) into C57BL/6NCrl mice intravenously. Long-term observation inside a peripheral lymph node was enabled by a novel lymph node internal window chamber technique that allows chronic, sequential lymph node imaging under in vivo physiologic conditions. Interestingly, during early stages of tumor progression we found that few if any lymphoma cells homed initially to the inguinal lymph node (ILN), despite clear evidence of lymphoma cells in the bone marrow and spleen. Unexpectedly, we detected a reproducible efflux of lymphoma cells from spleen and bone marrow, concomitant with a massive and synchronous influx of lymphoma cells into the ILN, several days after injection. We confirmed a coordinated efflux/influx of tumor cells by injecting EL-Arf(-/-) lymphoma cells directly into the spleen and observing a burst of lymphoma cells, validating that the burst originated in organs remote from the lymph nodes. Our findings argue that in NHL an efflux of tumor cells from one disease site to another, distant site in which they become established occurs in discrete bursts.

  View details for DOI 10.1158/0008-5472.CAN-12-2579

  View details for Web of Science ID 000311893100005

  View details for PubMedID 23033441

  View details for PubMedCentralID PMC3664177

• Dimeric 18F-RGD PET Tracer for alpha v beta 3-Targeted Imaging of Experimental Abdominal Aortic Aneurysm Disease Kitagawa, T., Kosuge, H., Chang, E., James, M. L., Yamamoto, T., Gambhir, S. S., Dalman, R. L., McConnell, M. V. LIPPINCOTT WILLIAMS & WILKINS. 2012

  View details for Web of Science ID 000208885004051

• Continuous sensing of tumor-targeted molecular probes with a vertical cavity surface emitting laser-based biosensor JOURNAL OF BIOMEDICAL OPTICS Parashurama, N., O'Sullivan, T. D., de la Zerda, A., El Kalassi, P., Cho, S., Liu, H., Teed, R., Levy, H., Rosenberg, J., Cheng, Z., Levi, O., Harris, J. S., Gambhir, S. S. 2012; 17 (11)

  Abstract

  Molecular optical imaging is a widespread technique for interrogating molecular events in living subjects. However, current approaches preclude long-term, continuous measurements in awake, mobile subjects, a strategy crucial in several medical conditions. Consequently, we designed a novel, lightweight miniature biosensor for in vivo continuous optical sensing. The biosensor contains an enclosed vertical-cavity surface-emitting semiconductor laser and an adjacent pair of near-infrared optically filtered detectors. We employed two sensors (dual sensing) to simultaneously interrogate normal and diseased tumor sites. Having established the sensors are precise with phantom and in vivo studies, we performed dual, continuous sensing in tumor (human glioblastoma cells) bearing mice using the targeted molecular probe cRGD-Cy5.5, which targets αVβ3 cell surface integrins in both tumor neovasculature and tumor. The sensors capture the dynamic time-activity curve of the targeted molecular probe. The average tumor to background ratio after signal calibration for cRGD-Cy5.5 injection is approximately 2.43±0.95 at 1 h and 3.64±1.38 at 2 h (N=5 mice), consistent with data obtained with a cooled charge coupled device camera. We conclude that our novel, portable, precise biosensor can be used to evaluate both kinetics and steady state levels of molecular probes in various disease applications.

  View details for DOI 10.1117/1.JBO.17.11.117004

  View details for Web of Science ID 000314502700046

  View details for PubMedID 23123976

  View details for PubMedCentralID PMC3595658

• Gold Nanorods for Ovarian Cancer Detection with Photoacoustic Imaging and Resection Guidance via Raman Imaging in Living Mice ACS NANO Jokerst, J. V., Cole, A. J., Van de Sompel, D., Gambhir, S. S. 2012; 6 (11): 10366-10377

  Abstract

  Improved imaging approaches are needed for ovarian cancer screening, diagnosis, staging, and resection guidance. Here, we propose a combined photoacoustic (PA)/Raman approach using gold nanorods (GNRs) as a passively targeted molecular imaging agent. GNRs with three different aspect ratios were studied. Those with an aspect ratio of 3.5 were selected for their highest ex vivo and in vivo PA signal and used to image subcutaneous xenografts of the 2008, HEY, and SKOV3 ovarian cancer cell lines in living mice. Maximum PA signal was observed within 3 h for all three lines tested and increased signal persisted for at least two days postadministration. There was a linear relationship (R(2) = 0.95) between the PA signal and the concentration of injected molecular imaging agent with a calculated limit of detection of 0.40 nM GNRs in the 2008 cell line. The same molecular imaging agent could be used for clear visualization of the margin between tumor and normal tissue and tumor debulking via surface-enhanced Raman spectroscopy (SERS) imaging. Finally, we validated the imaging findings with biodistribution data and elemental analysis. To the best of our knowledge, this is the first report of in vivo imaging of ovarian cancer tumors with a photoacoustic and Raman imaging agent.

  View details for DOI 10.1021/nn304347g

  View details for Web of Science ID 000311521700112

  View details for PubMedID 23101432

  View details for PubMedCentralID PMC3572720

• New Positron Emission Tomography (PET) Radioligand for Imaging sigma-1 Receptors in Living Subjects JOURNAL OF MEDICINAL CHEMISTRY James, M. L., Shen, B., Zavaleta, C. L., Nielsen, C. H., Mesangeau, C., Vuppala, P. K., Chan, C., Avery, B. A., Fishback, J. A., Matsumoto, R. R., Gambhir, S. S., McCurdy, C. R., Chin, F. T. 2012; 55 (19): 8272-8282

  Abstract

  σ-1 receptor (S1R) radioligands have the potential to detect and monitor various neurological diseases. Herein we report the synthesis, radiofluorination, and evaluation of a new S1R ligand 6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ([(18)F]FTC-146, [(18)F]13). [(18)F]13 was synthesized by nucleophilic fluorination, affording a product with >99% radiochemical purity (RCP) and specific activity (SA) of 2.6 ± 1.2 Ci/μmol (n = 13) at end of synthesis (EOS). Positron emission tomography (PET) and ex vivo autoradiography studies of [(18)F]13 in mice showed high uptake of the radioligand in S1R rich regions of the brain. Pretreatment with 1 mg/kg haloperidol (2), nonradioactive 13, or BD1047 (18) reduced the binding of [(18)F]13 in the brain at 60 min by 80%, 82%, and 81%, respectively, suggesting that [(18)F]13 accumulation in mouse brain represents specific binding to S1Rs. These results indicate that [(18)F]13 is a promising candidate radiotracer for further evaluation as a tool for studying S1Rs in living subjects.

  View details for DOI 10.1021/jm300371c

  View details for Web of Science ID 000309643500008

  View details for PubMedID 22853801

• Improving Image Quality by Accounting for Changes in Water Temperature during a Photoacoustic Tomography Scan PLOS ONE Van de Sompel, D., Sasportas, L. S., Dragulescu-Andrasi, A., Bohndiek, S., Gambhir, S. S. 2012; 7 (10)

  Abstract

  The emerging field of photoacoustic tomography is rapidly evolving with many new system designs and reconstruction algorithms being published. Many systems use water as a coupling medium between the scanned object and the ultrasound transducers. Prior to a scan, the water is heated to body temperature to enable small animal imaging. During the scan, the water heating system of some systems is switched off to minimize the risk of bubble formation, which leads to a gradual decrease in water temperature and hence the speed of sound. In this work, we use a commercially available scanner that follows this procedure, and show that a failure to model intra-scan temperature decreases as small as 1.5°C leads to image artifacts that may be difficult to distinguish from true structures, particularly in complex scenes. We then improve image quality by continuously monitoring the water temperature during the scan and applying variable speed of sound corrections in the image reconstruction algorithm. While upgrading to an air bubble-free heating pump and keeping it running during the scan could also solve the changing temperature problem, we show that a software correction for the temperature changes provides a cost-effective alternative to a hardware upgrade. The efficacy of the software corrections was shown to be consistent across objects of widely varying appearances, namely physical phantoms, ex vivo tissue, and in vivo mouse imaging. To the best of our knowledge, this is the first study to demonstrate the efficacy of modeling temporal variations in the speed of sound during photoacoustic scans, as opposed to spatial variations as focused on by previous studies. Since air bubbles pose a common problem in ultrasonic and photoacoustic imaging systems, our results will be useful to future small animal imaging studies that use scanners with similarly limited heating units.

  View details for DOI 10.1371/journal.pone.0045337

  View details for Web of Science ID 000309807700008

  View details for PubMedID 23071512

  View details for PubMedCentralID PMC3469660

• Designed hydrophilic and charge mutations of the fibronectin domain: towards tailored protein biodistribution PROTEIN ENGINEERING DESIGN & SELECTION Hackel, B. J., Sathirachinda, A., Gambhir, S. S. 2012; 25 (10): 639-647

  Abstract

  Engineered proteins are attractive affinity scaffolds for molecular imaging and drug delivery. Although exquisite binding specificity and affinity can be engineered, many proteins exhibit off-target uptake, particularly in the kidneys and liver, from physiologic effects. We quantified the ability to alter renal and hepatic uptake via hydrophilic and charge mutations. As a model protein, we used the 10th type III domain of human fibronectin, which has been engineered to bind many targets and has been validated for molecular imaging. We screened rational mutants, identified by structural and phylogenetic analyses, to yield eight mutations that collectively substantially increase protein hydrophilicity. Mutation of two parental clones yielded four domains with a range of hydrophilicity. These proteins were labeled with (64)Cu, injected intravenously into nu/nu mice (n = 3-5 each) and evaluated by positron emission tomography. Renal uptake strongly correlated with hydrophilicity (Pearson's correlation coefficient = 0.97), ranging from 29 ± 11 to 100 ± 22% ID/g at 1 h. Hepatic uptake inversely correlated with hydrophilicity (Pearson's correlation coefficient = -0.92), ranging from 30 ± 7 to 3 ± 1% ID/g. Thus, renal and hepatic uptake are directly tunable through hydrophilic mutation, identifiable by structural and phylogenetic analyses. To investigate charge, we mutated acidic and basic residues in both parental clones and evaluated (64)Cu-labeled mutants in nu/nu mice (n = 5-7). Selected charge removal reduced kidney signal: 78 ± 13 to 51 ± 8%ID/g (P < 0.0001) for the hydrophilic clone and 32 ± 10 to 21 ± 3 (P = 0.0005) for the hydrophobic clone. Elucidation of hydrophilicity and charge enabled modulation of background signal thereby enhancing the utility of protein scaffolds as translatable targeting agents for molecular imaging and therapy.

  View details for DOI 10.1093/protein/gzs036

  View details for Web of Science ID 000309468100016

  View details for PubMedID 22691700

  View details for PubMedCentralID PMC3449399

• Feasibility of Limited Thoracic FDG PET/CT for the Evaluation of Solitary Pulmonary Nodules in Patients With Intermediate and High Risk of Lung Cancer Keu, K., Mittra, E., Gambhir, S. S., Iagaru, A. SPRINGER. 2012: S455

  View details for Web of Science ID 000309726602292

• Intraoperative Imaging of Tumors Using Cerenkov Luminescence Endoscopy: A Feasibility Experimental Study JOURNAL OF NUCLEAR MEDICINE Liu, H., Carpenter, C. M., Jiang, H., Pratx, G., Sun, C., Buchin, M. P., Gambhir, S. S., Xing, L., Cheng, Z. 2012; 53 (10): 1579-1584

  Abstract

  Cerenkov luminescence imaging (CLI) is an emerging new molecular imaging modality that is relatively inexpensive, easy to use, and has high throughput. CLI can image clinically available PET and SPECT probes using optical instrumentation. Cerenkov luminescence endoscopy (CLE) is one of the most intriguing applications that promise potential clinical translation. We developed a prototype customized fiberscopic Cerenkov imaging system to investigate the potential in guiding minimally invasive surgical resection.All experiments were performed in a dark chamber. Cerenkov luminescence from (18)F-FDG samples containing decaying radioactivity was transmitted through an optical fiber bundle and imaged by an intensified charge-coupled device camera. Phantoms filled with (18)F-FDG were used to assess the imaging spatial resolution. Finally, mice bearing subcutaneous C6 glioma cells were injected intravenously with (18)F-FDG to determine the feasibility of in vivo imaging. The tumor tissues were exposed, and CLI was performed on the mouse before and after surgical removal of the tumor using the fiber-based imaging system and compared with a commercial optical imaging system.The sensitivity of this particular setup was approximately 45 kBq (1.21 μCi)/300 μL. The 3 smallest sets of cylindric holes in a commercial SPECT phantom were identifiable via this system, demonstrating that the system has a resolution better than 1.2 mm. Finally, the in vivo tumor imaging study demonstrated the feasibility of using CLI to guide the resection of tumor tissues.This proof-of-concept study explored the feasibility of using fiber-based CLE for the detection of tumor tissue in vivo for guided surgery. With further improvements of the imaging sensitivity and spatial resolution of the current system, CLE may have a significant application in the clinical setting in the near future.

  View details for DOI 10.2967/jnumed.111.098541

  View details for Web of Science ID 000309432400017

  View details for PubMedID 22904353

• Exploratory Clinical Trial of (4S)-4-(3-[F-18]fluoropropyl)-L-glutamate for Imaging x(C) Transporter Using Positron Emission Tomography in Patients with Non-Small Cell Lung or Breast Cancer CLINICAL CANCER RESEARCH Baek, S., Choi, C., Ahn, S. H., Lee, J. W., Gong, G., Ryu, J., Oh, S. J., Bacher-Stier, C., Fels, L., Koglin, N., Hultsch, C., Schatz, C. A., Dinkelborg, L. M., Mittra, E. S., Gambhir, S. S., Moon, D. H. 2012; 18 (19): 5427-5437

  Abstract

  (4S)-4-(3-[(18)F]fluoropropyl)-l-glutamate (BAY 94-9392, alias [(18)F]FSPG) is a new tracer to image x(C)(-) transporter activity with positron emission tomography (PET). We aimed to explore the tumor detection rate of [(18)F]FSPG in patients relative to 2-[(18)F]fluoro-2-deoxyglucose ([(18)F]FDG). The correlation of [(18)F]FSPG uptake with immunohistochemical expression of x(C)(-) transporter and CD44, which stabilizes the xCT subunit of system x(C)(-), was also analyzed.Patients with non-small cell lung cancer (NSCLC, n = 10) or breast cancer (n = 5) who had a positive [(18)F]FDG uptake were included in this exploratory study. PET images were acquired following injection of approximately 300 MBq [(18)F]FSPG. Immunohistochemistry was done using xCT- and CD44-specific antibody.[(18)F]FSPG PET showed high uptake in the kidney and pancreas with rapid blood clearance. [(18)F]FSPG identified all 10 NSCLC and three of the five breast cancer lesions that were confirmed by pathology. [(18)F]FSPG detected 59 of 67 (88%) [(18)F]FDG lesions in NSCLC, and 30 of 73 (41%) in breast cancer. Seven lesions were additionally detected only on [(18)F]FSPG in NSCLC. The tumor-to-blood pool standardized uptake value (SUV) ratio was not significantly different from that of [(18)F]FDG in NSCLC; however, in breast cancer, it was significantly lower (P < 0.05). The maximum SUV of [(18)F]FSPG correlated significantly with the intensity of immunohistochemical staining of x(C)(-) transporter and CD44 (P < 0.01).[(18)F]FSPG seems to be a promising tracer with a relatively high cancer detection rate in patients with NSCLC. [(18)F]FSPG PET may assess x(C)(-) transporter activity in patients with cancer.

  View details for DOI 10.1158/1078-0432.CCR-12-0214

  View details for Web of Science ID 000311906600027

  View details for PubMedID 22893629

• Positron Emission Tomography of Cu-64-DOTA-Rituximab in a Transgenic Mouse Model Expressing Human CD20 for Clinical Translation to Image NHL MOLECULAR IMAGING AND BIOLOGY Natarajan, A., Gowrishankar, G., Nielsen, C. H., Wang, S., Iagaru, A., Goris, M. L., Gambhir, S. S. 2012; 14 (5): 608-616

  Abstract

  This study aims to evaluate (64)Cu-DOTA-rituximab (PETRIT) in a preclinical transgenic mouse model expressing human CD20 for potential clinical translation.(64)Cu was chelated to DOTA-rituximab. Multiple radiolabeling, quality assurance, and imaging experiments were performed. The human CD20 antigen was expressed in B cells of transgenic mice (CD20TM). The mice groups studied were: (a) control (nude mice, n = 3) that received 7.4 MBq/dose, (b) with pre-dose (CD20TM, n = 6) received 2 mg/kg pre-dose of cold rituximab prior to PETRIT of 7.4 MBq/dose, and (c) without pre-dose (CD20TM, n = 6) PETRIT alone received 7.4 MBq/dose. Small animal PET was used to image mice at various time points (0, 1, 2, 4, 24, 48, and 72 h). The OLINDA/EXM software was used to determine the human equivalent dose for individual organs.PETRIT was obtained with a specific activity of 545 ± 38.91 MBq/nmole, radiochemical purity >95%, and immunoreactivity >75%. At 24 h, spleenic uptake of PETRIT%ID/g (mean ± STD) with and without pre-dose was 1.76 ± 0.43% and 16.5 ± 0.45%, respectively (P value = 0.01). Liver uptake with and without pre-dose was 0.41 ± 0.51% and 0.52 ± 0.17% (P value = 0.86), respectively. The human equivalents of highest dose organs with and without pre-dose are osteogenic cells at 30.8 ± 0.4 μSv/MBq and the spleen at 99 ± 4 μSv/MBq, respectively.PET imaging with PETRIT in huCD20 transgenic mice provided human dosimetry data for eventual applications in non-Hodgkins lymphoma patients.

  View details for DOI 10.1007/s11307-011-0537-8

  View details for Web of Science ID 000308819300011

  View details for PubMedID 22231277

• FEASIBILITY OF AN INTRAMOLECULAR COMPLEMENTATION STRATEGY FOR SPLIT-REPORTER GENE IMAGING OF DRUGGABLE PROTEIN MISFOLDING IN BRAIN CANCER 17th Annual Scientific Meeting and Education Day of the Society-for-Neuro-Oncology (SNO) Massoud, T. F., Paulmurugan, R., Gambhir, S. S. OXFORD UNIV PRESS INC. 2012: 11–11

  View details for Web of Science ID 000310971300048

• alpha v beta 3 Integrins as a Biomarker of Disease Recurrence in Glioblastoma Multiforme: Initial Clinical Results Using 18F FPPRGD2 PET/CT 4th International Symposium on Targeted Radiotherapy and Dosimetry (ISTARD) in Conjunction with the 25th Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Iagaru, A., Mosci, C., Mittra, E. S., Shin, B., Chin, F., Gambhir, S. S. SPRINGER. 2012: S244–S245

  View details for Web of Science ID 000309726600324

• Remodeling of Endogenous Mammary Epithelium by Breast Cancer Stem Cells STEM CELLS Parashurama, N., Lobo, N. A., Ito, K., Mosley, A. R., Habte, F. G., Zabala, M., Smith, B. R., Lam, J., Weissman, I. L., Clarke, M. F., Gambhir, S. S. 2012; 30 (10): 2114-2127

  Abstract

  Poorly regulated tissue remodeling results in increased breast cancer risk, yet how breast cancer stem cells (CSC) participate in remodeling is unknown. We performed in vivo imaging of changes in fluorescent, endogenous duct architecture as a metric for remodeling. First, we quantitatively imaged physiologic remodeling of primary branches of the developing and regenerating mammary tree. To assess CSC-specific remodeling events, we isolated CSC from MMTV-Wnt1 (mouse mammary tumor virus long-term repeat enhancer driving Wnt1 oncogene) breast tumors, a well studied model in which tissue remodeling affects tumorigenesis. We confirm that CSC drive tumorigenesis, suggesting a link between CSC and remodeling. We find that normal, regenerating, and developing gland maintain a specific branching pattern. In contrast, transplantation of CSC results in changes in the branching patterns of endogenous ducts while non-CSC do not. Specifically, in the presence of CSC, we identified an increased number of branches, branch points, ducts which have greater than 40 branches (5/33 for CSC and 0/39 for non-CSC), and histological evidence of increased branching. Moreover, we demonstrate that only CSC implants invade into surrounding stroma with structures similar to developing mammary ducts (nine for CSC and one for non-CSC). Overall, we demonstrate a novel approach for imaging physiologic and pathological remodeling. Furthermore, we identify unique, CSC-specific, remodeling events. Our data suggest that CSC interact with the microenvironment differently than non-CSC, and that this could eventually be a therapeutic approach for targeting CSC.

  View details for DOI 10.1002/stem.1205

  View details for Web of Science ID 000308928300005

  View details for PubMedID 22899386

• The Impact of Partial Volume Correction in the Evaluation of Solitary Pulmonary Nodules by FDG PET/CT in a Population at Intermediate Risk of Lung Cancer 4th International Symposium on Targeted Radiotherapy and Dosimetry (ISTARD) in Conjunction with the 25th Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Keu, K., Nair, V. S., Mittra, E., Gambhir, S. S., Iagaru, A. SPRINGER. 2012: S455–S455

  View details for Web of Science ID 000309726602293

• Microfluidic Single-Cell Analysis Shows That Porcine Induced Pluripotent Stem Cell-Derived Endothelial Cells Improve Myocardial Function by Paracrine Activation CIRCULATION RESEARCH Gu, M., Nguyen, P. K., Lee, A. S., Xu, D., Hu, S., Plews, J. R., Han, L., Huber, B. C., Lee, W. H., Gong, Y., de Almeida, P. E., Lyons, J., Ikeno, F., Pacharinsak, C., Connolly, A. J., Gambhir, S. S., Robbins, R. C., Longaker, M. T., Wu, J. C. 2012; 111 (7): 882-893

  Abstract

  Induced pluripotent stem cells (iPSCs) hold great promise for the development of patient-specific therapies for cardiovascular disease. However, clinical translation will require preclinical optimization and validation of large-animal iPSC models.To successfully derive endothelial cells from porcine iPSCs and demonstrate their potential utility for the treatment of myocardial ischemia.Porcine adipose stromal cells were reprogrammed to generate porcine iPSCs (piPSCs). Immunohistochemistry, quantitative PCR, microarray hybridization, and angiogenic assays confirmed that piPSC-derived endothelial cells (piPSC-ECs) shared similar morphological and functional properties as endothelial cells isolated from the autologous pig aorta. To demonstrate their therapeutic potential, piPSC-ECs were transplanted into mice with myocardial infarction. Compared with control, animals transplanted with piPSC-ECs showed significant functional improvement measured by echocardiography (fractional shortening at week 4: 27.2±1.3% versus 22.3±1.1%; P<0.001) and MRI (ejection fraction at week 4: 45.8±1.3% versus 42.3±0.9%; P<0.05). Quantitative protein assays and microfluidic single-cell PCR profiling showed that piPSC-ECs released proangiogenic and antiapoptotic factors in the ischemic microenvironment, which promoted neovascularization and cardiomyocyte survival, respectively. Release of paracrine factors varied significantly among subpopulations of transplanted cells, suggesting that transplantation of specific cell populations may result in greater functional recovery.In summary, this is the first study to successfully differentiate piPSCs-ECs from piPSCs and demonstrate that transplantation of piPSC-ECs improved cardiac function after myocardial infarction via paracrine activation. Further development of these large animal iPSC models will yield significant insights into their therapeutic potential and accelerate the clinical translation of autologous iPSC-based therapy.

  View details for DOI 10.1161/CIRCRESAHA.112.269001

  View details for PubMedID 22821929

• Discovery and validation of small-molecule heat-shock protein 90 inhibitors through multimodality molecular imaging in living subjects PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Chan, C. T., Reeves, R. E., Geller, R., Yaghoubi, S. S., Hoehne, A., Solow-Cordero, D. E., Chiosis, G., Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2012; 109 (37): E2476-E2485

  Abstract

  Up-regulation of the folding machinery of the heat-shock protein 90 (Hsp90) chaperone protein is crucial for cancer progression. The two Hsp90 isoforms (α and β) play different roles in response to chemotherapy. To identify isoform-selective inhibitors of Hsp90(α/β)/cochaperone p23 interactions, we developed a dual-luciferase (Renilla and Firefly) reporter system for high-throughput screening (HTS) and monitoring the efficacy of Hsp90 inhibitors in cell culture and live mice. HTS of a 30,176 small-molecule chemical library in cell culture identified a compound, N-(5-methylisoxazol-3-yl)-2-[4-(thiophen-2-yl)-6-(trifluoromethyl)pyrimidin-2-ylthio]acetamide (CP9), that binds to Hsp90(α/β) and displays characteristics of Hsp90 inhibitors, i.e., degradation of Hsp90 client proteins and inhibition of cell proliferation, glucose metabolism, and thymidine kinase activity, in multiple cancer cell lines. The efficacy of CP9 in disrupting Hsp90(α/β)/p23 interactions and cell proliferation in tumor xenografts was evaluated by non-invasive, repetitive Renilla luciferase and Firefly luciferase imaging, respectively. At 38 h posttreatment (80 mg/kg × 3, i.p.), CP9 led to selective disruption of Hsp90α/p23 as compared with Hsp90β/p23 interactions. Small-animal PET/CT in the same cohort of mice showed that CP9 treatment (43 h) led to a 40% decrease in (18)F-fluorodeoxyglucose uptake in tumors relative to carrier control-treated mice. However, CP9 did not lead to significant degradation of Hsp90 client proteins in tumors. We performed a structural activity relationship study with 62 analogs of CP9 and identified A17 as the lead compound that outperformed CP9 in inhibiting Hsp90(α/β)/p23 interactions in cell culture. Our efforts demonstrated the power of coupling of HTS with multimodality molecular imaging and led to identification of Hsp90 inhibitors.

  View details for DOI 10.1073/pnas.1205459109

  View details for PubMedID 22895790

• Circulating tumour cells in early breast cancer LANCET ONCOLOGY Nair, V. S., Keu, K. V., Kuhn, P., Gambhir, S. S. 2012; 13 (9): E370-E371

  View details for Web of Science ID 000308425600024

  View details for PubMedID 22935234

• Cationic versus Neutral Microbubbles for Ultrasound-mediated Gene Delivery in Cancer RADIOLOGY Wang, D. S., Panje, C., Pysz, M. A., Paulmurugan, R., Rosenberg, J., Gambhir, S. S., Schneider, M., Willmann, J. K. 2012; 264 (3): 721-732

  Abstract

  To test whether plasmid-binding cationic microbubbles (MBs) enhance ultrasound-mediated gene delivery efficiency relative to control neutral MBs in cell culture and in vivo tumors in mice.Animal studies were approved by the institutional animal care committee. Cationic and neutral MBs were characterized in terms of size, charge, circulation time, and DNA binding. Click beetle luciferase (CBLuc) reporter plasmids were mixed with cationic or neutral MBs. The ability of cationic MBs to protect bound plasmids from nuclease degradation was tested by means of a deoxyribonuclease (DNase) protection assay. Relative efficiencies of ultrasound-mediated transfection (ultrasound parameters: 1 MHz, 1 W/cm(2), 20% duty cycle, 1 minute) of CBLuc to endothelial cells by using cationic, neutral, or no MBs were compared in cell culture. Ultrasound-mediated gene delivery to mouse hind limb tumors was performed in vivo (n = 24) with insonation (1 MHz, 2 W/cm(2), 50% duty cycle, 5 minutes) after intravenous administration of CBLuc with cationic, neutral, or no MBs. Tumor luciferase activity was assessed by means of serial in vivo bioluminescence imaging and ex vivo analysis. Results were compared by using analysis of variance.Cationic MBs (+15.8 mV; DNA binding capacity, 0.03 pg per MB) partially protected bound DNA from DNase degradation. Mean CBLuc expression of treated endothelial cells in culture was 20-fold higher with cationic than with neutral MBs (219.0 relative light units [RLUs]/µg protein ± 92.5 [standard deviation] vs 10.9 RLUs/µg protein ± 2.7, P = .001) and was significantly higher (P < .001) than that in the no MB and no ultrasound control groups. Serial in vivo bioluminescence of mouse tumors was significantly higher with cationic than with neutral MBs ([5.9 ± 2.2] to [9.3 ± 5.2] vs [2.4 ± 0.8] to [2.9 ± 1.1] × 10(4) photons/sec/cm(2)/steradian, P < .0001) and versus no MB and no ultrasound controls (P < .0001). Results of ex vivo analysis confirmed these results (ρ = 0.88, P < .0001).Plasmid-binding cationic MBs enhance ultrasound-mediated gene delivery efficiency relative to neutral MBs in both cell culture and mouse hind limb tumors.

  View details for DOI 10.1148/radiol.12112368

  View details for Web of Science ID 000308645500013

  View details for PubMedID 22723497

  View details for PubMedCentralID PMC3426857

• Tissue-engineered collateral ligament composite allografts for scapholunate ligament reconstruction: an experimental study. journal of hand surgery Endress, R., Woon, C. Y., Farnebo, S. J., Behn, A., Bronstein, J., Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 37 (8): 1529-1537

  Abstract

  In patients with chronic scapholunate (SL) dissociation or dynamic instability, ligament repair is often not possible, and surgical reconstruction is indicated. The ideal graft ligament would recreate both anatomical and biomechanical properties of the dorsal scapholunate ligament (dorsal SLIL). The finger proximal interphalangeal joint (PIP joint) collateral ligament could possibly be a substitute ligament.We harvested human PIP joint collateral ligaments and SL ligaments from 15 cadaveric limbs. We recorded ligament length, width, and thickness, and measured the biomechanical properties (ultimate load, stiffness, and displacement to failure) of native dorsal SLIL, untreated collateral ligaments, decellularized collateral ligaments, and SL repairs with bone-collateral ligament-bone composite collateral ligament grafts. As proof of concept, we then reseeded decellularized bone-collateral ligament-bone composite grafts with green fluorescent protein-labeled adipo-derived mesenchymal stem cells and evaluated them histologically.There was no difference in ultimate load, stiffness, and displacement to failure among native dorsal SLIL, untreated and decellularized collateral ligaments, and SL repairs with tissue-engineered collateral ligament grafts. With pair-matched untreated and decellularized scaffolds, there was no difference in ultimate load or stiffness. However, decellularized ligaments revealed lower displacement to failure compared with untreated ligaments. There was no difference in displacement between decellularized ligaments and native dorsal SLIL. We successfully decellularized grafts with recently described techniques, and they could be similarly reseeded.Proximal interphalangeal joint collateral ligament-based bone-collateral ligament-bone composite allografts had biomechanical properties similar to those of native dorsal SLIL. Decellularization did not adversely affect material properties.These tissue-engineered grafts may offer surgeons another option for reconstruction of chronic SL instability.

  View details for DOI 10.1016/j.jhsa.2012.05.020

  View details for PubMedID 22835583

• Tissue-engineered Collateral Ligament Composite Allografts for Scapholunate Ligament Reconstruction: An Experimental Study JOURNAL OF HAND SURGERY-AMERICAN VOLUME Endress, R., Woon, C. Y., Farnebo, S. J., Behn, A., Bronstein, J., Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 37A (8): 1529-1537

  Abstract

  In patients with chronic scapholunate (SL) dissociation or dynamic instability, ligament repair is often not possible, and surgical reconstruction is indicated. The ideal graft ligament would recreate both anatomical and biomechanical properties of the dorsal scapholunate ligament (dorsal SLIL). The finger proximal interphalangeal joint (PIP joint) collateral ligament could possibly be a substitute ligament.We harvested human PIP joint collateral ligaments and SL ligaments from 15 cadaveric limbs. We recorded ligament length, width, and thickness, and measured the biomechanical properties (ultimate load, stiffness, and displacement to failure) of native dorsal SLIL, untreated collateral ligaments, decellularized collateral ligaments, and SL repairs with bone-collateral ligament-bone composite collateral ligament grafts. As proof of concept, we then reseeded decellularized bone-collateral ligament-bone composite grafts with green fluorescent protein-labeled adipo-derived mesenchymal stem cells and evaluated them histologically.There was no difference in ultimate load, stiffness, and displacement to failure among native dorsal SLIL, untreated and decellularized collateral ligaments, and SL repairs with tissue-engineered collateral ligament grafts. With pair-matched untreated and decellularized scaffolds, there was no difference in ultimate load or stiffness. However, decellularized ligaments revealed lower displacement to failure compared with untreated ligaments. There was no difference in displacement between decellularized ligaments and native dorsal SLIL. We successfully decellularized grafts with recently described techniques, and they could be similarly reseeded.Proximal interphalangeal joint collateral ligament-based bone-collateral ligament-bone composite allografts had biomechanical properties similar to those of native dorsal SLIL. Decellularization did not adversely affect material properties.These tissue-engineered grafts may offer surgeons another option for reconstruction of chronic SL instability.

  View details for DOI 10.1016/j.jhsa.2012.05.020

  View details for Web of Science ID 000307260200001

• Impact of Screening Test Performance and Cost on Mortality Reduction and Cost-effectiveness of Multimodal Ovarian Cancer Screening CANCER PREVENTION RESEARCH Drescher, C. W., Hawley, S., Thorpe, J. D., Marticke, S., McIntosh, M., Gambhir, S. S., Urban, N. 2012; 5 (8): 1015-1024

  Abstract

  Ongoing ovarian cancer screening trials are investigating the efficacy of a two-step screening strategy using currently available blood and imaging tests [CA125 and transvaginal sonography (TVS)]. Concurrently, efforts to develop new biomarkers and imaging tests seek to improve screening performance beyond its current limits. This study estimates the mortality reduction, years of life saved, and cost-effectiveness achievable by annual multimodal screening using increasing CA125 to select women for TVS, and predicts improvements achievable by replacing currently available screening tests with hypothetical counterparts with better performance characteristics. An existing stochastic microsimulation model is refined and used to screen a virtual cohort of 1 million women from ages 45 to 85 years. Each woman is assigned a detailed disease course and screening results timeline. The preclinical behavior of CA125 and TVS is simulated using empirical data derived from clinical trials. Simulations in which the disease incidence and performance characteristics of the screening tests are independently varied are conducted to evaluate the impact of these factors on overall screening performance and costs. Our results show that when applied to women at average risk, annual screening using increasing CA125 to select women for TVS achieves modest mortality reduction (~13%) and meets currently accepted cost-effectiveness guidelines. Screening outcomes are relatively insensitive to second-line test performance and costs. Identification of a first-line test that does substantially better than CA125 and has similar costs is required for screening to reduce ovarian mortality by at least 25% and be reasonably cost-effective.

  View details for DOI 10.1158/1940-6207.CAPR-11-0468

  View details for Web of Science ID 000308223500004

  View details for PubMedID 22750949

• Fluorescent Magnetic Nanoparticles for Magnetically Enhanced Cancer Imaging and Targeting in Living Subjects ACS NANO Fu, A., Wilson, R. J., Smith, B. R., Mullenix, J., Earhart, C., Akin, D., Guccione, S., Wang, S. X., Gambhir, S. S. 2012; 6 (8): 6862-6869

  Abstract

  Early detection and targeted therapy are two major challenges in the battle against cancer. Novel imaging contrast agents and targeting approaches are greatly needed to improve the sensitivity and specificity of cancer theranostic agents. Here, we implemented a novel approach using a magnetic micromesh and biocompatible fluorescent magnetic nanoparticles (FMN) to magnetically enhance cancer targeting in living subjects. This approach enables magnetic targeting of systemically administered individual FMN, containing a single 8 nm superparamagnetic iron oxide core. Using a human glioblastoma mouse model, we show that nanoparticles can be magnetically retained in both the tumor neovasculature and surrounding tumor tissues. Magnetic accumulation of nanoparticles within the neovasculature was observable by fluorescence intravital microscopy in real time. Finally, we demonstrate that such magnetically enhanced cancer targeting augments the biological functions of molecules linked to the nanoparticle surface.

  View details for DOI 10.1021/nn301670a

  View details for Web of Science ID 000307988900039

  View details for PubMedID 22857784

  View details for PubMedCentralID PMC3601027

• Shape Matters: Intravital Microscopy Reveals Surprising Geometrical Dependence for Nanoparticles in Tumor Models of Extravasation NANO LETTERS Smith, B. R., Kempen, P., Bouley, D., Xu, A., Liu, Z., Melosh, N., Dai, H., Sinclair, R., Gambhir, S. S. 2012; 12 (7): 3369-3377

  Abstract

  Delivery is one of the most critical obstacles confronting nanoparticle use in cancer diagnosis and therapy. For most oncological applications, nanoparticles must extravasate in order to reach tumor cells and perform their designated task. However, little understanding exists regarding the effect of nanoparticle shape on extravasation. Herein we use real-time intravital microscopic imaging to meticulously examine how two different nanoparticles behave across three different murine tumor models. The study quantitatively demonstrates that high-aspect ratio single-walled carbon nanotubes (SWNTs) display extravasational behavior surprisingly different from, and counterintuitive to, spherical nanoparticles although the nanoparticles have similar surface coatings, area, and charge. This work quantitatively indicates that nanoscale extravasational competence is highly dependent on nanoparticle geometry and is heterogeneous.

  View details for DOI 10.1021/nl204175t

  View details for Web of Science ID 000306296200004

  View details for PubMedID 22650417

  View details for PubMedCentralID PMC3495189

• In vivo targeting of HER2-positive tumor using 2-helix affibody molecules AMINO ACIDS Ren, G., Webster, J. M., Liu, Z., Zhang, R., Miao, Z., Liu, H., Gambhir, S. S., Syud, F. A., Cheng, Z. 2012; 43 (1): 405-413

  Abstract

  Molecular imaging of human epidermal growth factor receptor type 2 (HER2) expression has drawn significant attention because of the unique role of the HER2 gene in diagnosis, therapy and prognosis of human breast cancer. In our previous research, a novel cyclic 2-helix small protein, MUT-DS, was discovered as an anti-HER2 Affibody analog with high affinity through rational protein design and engineering. MUT-DS was then evaluated for positron emission tomography (PET) of HER2-positive tumor by labeling with two radionuclides, 68Ga and 18F, with relatively short half-life (t1/2<2 h). In order to fully study the in vivo behavior of 2-helix small protein and demonstrate that it could be a robust platform for labeling with a variety of radionuclides for different applications, in this study, MUT-DS was further radiolabeled with 64Cu or 111In and evaluated for in vivo targeting of HER2-positive tumor in mice. Design 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated MUT-DS (DOTA-MUT-DS) was chemically synthesized using solid phase peptide synthesizer and I2 oxidation. DOTA-MUT-DS was then radiolabeled with 64Cu or 111In to prepare the HER2 imaging probe (64Cu/111In-DOTA-MUT-DS). Both biodistribution and microPET imaging of the probe were evaluated in nude mice bearing subcutaneous HER2-positive SKOV3 tumors. DOTA-MUT-DS could be successfully synthesized and radiolabeled with 64Cu or 111In. Biodistribution study showed that tumor uptake value of 64Cu or 111In-labeled DOTA-MUT-DS was 4.66±0.38 or 2.17±0.15%ID/g, respectively, in nude mice bearing SKOV3 xenografts (n=3) at 1 h post-injection (p.i.). Tumor-to-blood and tumor-to-muscle ratios for 64Cu-DOTA-MUT-DS were attained to be 3.05 and 3.48 at 1 h p.i., respectively, while for 111In-DOTA-MUT-DS, they were 2.04 and 3.19, respectively. Co-injection of the cold Affibody molecule ZHER2:342 with 64Cu-DOTA-MUT-DS specifically reduced the SKOV3 tumor uptake of the probe by 48%. 111In-DOTA-MUT-DS displayed lower liver uptake at all the time points investigated and higher tumor to blood ratios at 4 and 20 h p.i., when compared with 64Cu-DOTA-MUT-DS. This study demonstrates that the 2-helix protein based probes, 64Cu/111In DOTA-MUT-DS, are promising molecular probes for imaging HER2-positive tumor. Two-helix small protein scaffold holds great promise as a novel and robust platform for imaging and therapy applications.

  View details for DOI 10.1007/s00726-011-1096-7

  View details for Web of Science ID 000305210800041

  View details for PubMedID 21984380

• Photoacoustic Imaging of Mesenchymal Stem Cells in Living Mice via Silica-Coated Gold Nanorods ACS NANO Jokerst, J. V., Thangaraj, M., Kempen, P. J., Sinclair, R., Gambhir, S. S. 2012; 6 (7): 5920-5930

  Abstract

  Improved imaging modalities are critically needed for optimizing stem cell therapy. Techniques with real-time content to guide and quantitate cell implantation are especially important in applications such as musculoskeletal regenerative medicine. Here, we report the use of silica-coated gold nanorods as a contrast agent for photoacoustic imaging and quantitation of mesenchymal stem cells in rodent muscle tissue. The silica coating increased the uptake of gold into the cell more than 5-fold, yet no toxicity or proliferation changes were observed in cells loaded with this contrast agent. Pluripotency of the cells was retained, and secretome analysis indicated that only IL-6 was disregulated more than 2-fold from a pool of 26 cytokines. The low background of the technique allowed imaging of down to 100,000 cells in vivo. The spatial resolution is 340 μm, and the temporal resolution is 0.2 s, which is at least an order of magnitude below existing cell imaging approaches. This approach has significant advantages over traditional cell imaging techniques like positron emission tomography and magnetic resonance imaging including real time monitoring of stem cell therapy.

  View details for DOI 10.1021/nn302042y

  View details for Web of Science ID 000306673800020

  View details for PubMedID 22681633

  View details for PubMedCentralID PMC3582222

• A Hybrid Least Squares and Principal Component Analysis Algorithm for Raman Spectroscopy PLOS ONE Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. 2012; 7 (6)

  Abstract

  Raman spectroscopy is a powerful technique for detecting and quantifying analytes in chemical mixtures. A critical part of Raman spectroscopy is the use of a computer algorithm to analyze the measured Raman spectra. The most commonly used algorithm is the classical least squares method, which is popular due to its speed and ease of implementation. However, it is sensitive to inaccuracies or variations in the reference spectra of the analytes (compounds of interest) and the background. Many algorithms, primarily multivariate calibration methods, have been proposed that increase robustness to such variations. In this study, we propose a novel method that improves robustness even further by explicitly modeling variations in both the background and analyte signals. More specifically, it extends the classical least squares model by allowing the declared reference spectra to vary in accordance with the principal components obtained from training sets of spectra measured in prior characterization experiments. The amount of variation allowed is constrained by the eigenvalues of this principal component analysis. We compare the novel algorithm to the least squares method with a low-order polynomial residual model, as well as a state-of-the-art hybrid linear analysis method. The latter is a multivariate calibration method designed specifically to improve robustness to background variability in cases where training spectra of the background, as well as the mean spectrum of the analyte, are available. We demonstrate the novel algorithm's superior performance by comparing quantitative error metrics generated by each method. The experiments consider both simulated data and experimental data acquired from in vitro solutions of Raman-enhanced gold-silica nanoparticles.

  View details for DOI 10.1371/journal.pone.0038850

  View details for Web of Science ID 000305583300060

  View details for PubMedID 22723895

  View details for PubMedCentralID PMC3377733

• Development of a Novel Long-Lived ImmunoPET Tracer for Monitoring Lymphoma Therapy in a Humanized Transgenic Mouse Model. Bioconjugate chemistry Natarajan, A., Habte, F., Gambhir, S. S. 2012

  Abstract

  Positron emission tomography (PET) is an attractive imaging tool to localize and quantify tracer biodistribution. ImmunoPET with an intact mAb typically requires two to four days to achieve optimized tumor-to-normal ratios. Thus, a positron emitter with a half-life of two to four days such as zirconium-89 [(89)Zr] (t(1/2): 78.4 h) is ideal. We have developed an antibody-based, long-lived immunoPET tracer (89)Zr-Desferrioxamine-p-SCN (Df-Bz-NCS)-rituximab (Zr-iPET) to image tumor for longer durations in a humanized CD20-expressing transgenic mouse model. To optimize the radiolabeling efficiency of (89)Zr with Df-Bz-rituximab, multiple radiolabelings were performed. Radiochemical yield, purity, immunoreactivity, and stability assays were carried out to characterize the Zr-iPET for chemical and biological integrity. This tracer was used to image transgenic mice that express the human CD20 on their B cells (huCD20TM). Each huCD20TM mouse received a 7.4 MBq/dose. One group (n = 3) received a 2 mg/kg predose (blocking) of cold rituximab 2 h prior to (89)Zr-iPET; the other group (n = 3) had no predose (nonblocking). Small animal PET/CT was used to image mice at 1, 4, 24, 48, 72, and 120 h. Quality assurance of the (89)Zr-iPET demonstrated NCS-Bz-Df: antibody ratio (c/a: 1.5 ± 0.31), specific activity (0.44-1.64 TBq/mol), radiochemical yield (>70%), and purity (>98%). The Zr-iPET immunoreactivity was >80%. At 120 h, Zr-iPET uptake (% ID/g) as mean ± STD for blocking and nonblocking groups in spleen was 3.2 ± 0.1% and 83.3 ± 2.0% (p value <0.0013.). Liver uptake was 1.32 ± 0.05% and 0.61 ± 0.001% (p value <0.0128) for blocking and nonblocking, respectively. The small animal PET/CT image shows the spleen specific uptake of Zr-iPET in mice at 120 h after tracer injection. Compared to the liver, the spleen specific uptake of Zr-iPET is very high due to the expression of huCD20. We optimized the radiolabeling efficiency of (89)Zr with Df-Bz-rituximab. These radioimmunoconjugate lots were stable up to 5 days in serum in vitro. The present study showed that (89)Zr is well-suited for mAbs to image cancer over an extended period of time (up to 5 days).

  View details for DOI 10.1021/bc300039r

  View details for PubMedID 22621257

  View details for PubMedCentralID PMC3459285

• Endoscopic imaging of Cerenkov luminescence BIOMEDICAL OPTICS EXPRESS Kothapalli, S., Liu, H., Liao, J. C., Cheng, Z., Gambhir, S. S. 2012; 3 (6): 1215-1225

  Abstract

  We demonstrate feasibility of endoscopic imaging of Cerenkov light originated when charged nuclear particles, emitted from radionuclides, travel through a biological tissue of living subjects at superluminal velocity. The endoscopy imaging system consists of conventional optical fiber bundle/ clinical endoscopes, an optical imaging lens system, and a sensitive low-noise charge coupled device (CCD) camera. Our systematic studies using phantom samples show that Cerenkov light from as low as 1 µCi of radioactivity emitted from (18)F-Fluorodeoxyglucose (FDG) can be coupled and transmitted through conventional optical fibers and endoscopes. In vivo imaging experiments with tumor bearing mice, intravenously administered with (18)F-FDG, further demonstrated that Cerenkov luminescence endoscopy is a promising new tool in the field of endoscopic molecular imaging.

  View details for Web of Science ID 000304965700007

  View details for PubMedID 22741069

  View details for PubMedCentralID PMC3370963

• Transatlantic Consensus Group on active surveillance and focal therapy for prostate cancer BJU INTERNATIONAL Ahmed, H. U., Akin, O., Coleman, J. A., Crane, S., Emberton, M., Goldenberg, L., Hricak, H., Kattan, M. W., Kurhanewicz, J., Moore, C. M., Parker, C., Polascik, T. J., Scardino, P., Van As, N., Villers, A. 2012; 109 (11): 1636-1647

  Abstract

  What's known on the subject? and What does the study add? Active surveillance for prostate cancer is gaining increasing acceptance for low risk prostate cancer. Focal therapy is an emerging tissue preservation strategy that aims for treat only areas of cancer. Early phase trials have shown that side-effects can be significantly reduced using focal therapy. There is significant uncertainty in both active surveillance and focal therapy. This consensus group paper provides a road-map for clinical practice and research for both tissue-preserving strategies in the areas of patient population, tools for risk stratification and cancer localisation, treatment interventions as well as comparators and outcome measures in future comparative trials.To reach consensus on key issues for clinical practice and future research in active surveillance and focal therapy in managing localized prostate cancer.A group of expert urologists, oncologists, radiologists, pathologists and computer scientists from North America and Europe met to discuss issues in patient population, interventions, comparators and outcome measures to use in both tissue-preserving strategies of active surveillance and focal therapy. Break-out sessions were formed to provide agreement or highlight areas of disagreement on individual topics which were then collated by a writing group into statements that formed the basis of this report and agreed upon by the whole Transatlantic Consensus Group.The Transatlantic group propose that emerging diagnostic tools such as precision imaging and transperineal prostate mapping biopsy can improve prostate cancer care. These tools should be integrated into prostate cancer management and research so that better risk stratification and more effective treatment allocation can be applied. The group envisaged a process of care in which active surveillance, focal therapy, and radical treatments lie on a continuum of complementary therapies for men with a range of disease grades and burdens, rather than being applied in the mutually exclusive and competitive way they are now.The changing landscape of prostate cancer epidemiology requires the medical community to re-evaluate the entire prostate cancer diagnostic and treatment pathway in order to minimize harms resulting from over-diagnosis and over-treatment. Precise risk stratification at every point in this pathway is required alongside paradigm shifts in our thinking about what constitutes cancer in the prostate.

  View details for DOI 10.1111/j.1464-410X.2011.10633.x

  View details for Web of Science ID 000303598400015

  View details for PubMedID 22077593

• Family of Enhanced Photoacoustic Imaging Agents for High-Sensitivity and Multiplexing Studies in Living Mice ACS NANO de la Zerda, A., Bodapati, S., Teed, R., May, S. Y., Tabakman, S. M., Liu, Z., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S. 2012; 6 (6): 4694-4701

  Abstract

  Photoacoustic imaging is a unique modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a family of novel photoacoustic contrast agents that are based on the binding of small optical dyes to single-walled carbon nanotubes (SWNT-dye). We synthesized five different SWNT-dye contrast agents using different optical dyes, creating five "flavors" of SWNT-dye nanoparticles. In particular, SWNTs that were coated with either QSY(21) (SWNT-QSY) or indocyanine green (SWNT-ICG) exhibited over 100-times higher photoacoustic contrast in living animals compared to plain SWNTs, leading to subnanomolar sensitivities. We then conjugated the SWNT-dye conjugates with cyclic Arg-Gly-Asp peptides to molecularly target the α(v)β(3) integrin, which is associated with tumor angiogenesis. Intravenous administration of these tumor-targeted imaging agents to tumor-bearing mice showed significantly higher photoacoustic signal in the tumor than in mice injected with the untargeted contrast agent. Finally, we were able to spectrally separate the photoacoustic signals of SWNT-QSY and SWNT-ICG in living animals injected subcutaneously with both particles in the same location, opening the possibility for multiplexing in vivo studies.

  View details for DOI 10.1021/nn204352r

  View details for Web of Science ID 000305661300017

  View details for PubMedID 22607191

  View details for PubMedCentralID PMC3397693

• A photonic crystal cavity-optical fiber tip nanoparticle sensor for biomedical applications APPLIED PHYSICS LETTERS Shambat, G., Kothapalli, S. R., Khurana, A., Provine, J., Sarmiento, T., Cheng, K., Cheng, Z., Harris, J., Daldrup-Link, H., Gambhir, S. S., Vuckovic, J. 2012; 100 (21)

  View details for DOI 10.1063/1.4719520

  View details for Web of Science ID 000304489900085

• Effect of a CCR1 receptor antagonist on systemic trafficking of MSCs and polyethylene particle-associated bone loss BIOMATERIALS Gibon, E., Yao, Z., Rao, A. J., Zwingenberger, S., Batke, B., Valladares, R., Smith, R. L., Biswal, S., Gambhir, S. S., Goodman, S. B. 2012; 33 (14): 3632-3638

  Abstract

  Particle-associated periprosthetic osteolysis remains a major issue in joint replacement. Ongoing bone loss resulting from wear particle-induced inflammation is accompanied by continued attempts at bone repair. Previously we showed that mesenchymal stem cells (MSCs) are recruited systemically to bone exposed to continuous infusion of ultra high molecular weight polyethylene (UHMWPE) particles. The chemokine-receptor axis that mediates this process is unknown. We tested two hypotheses: (1) the CCR1 receptor mediates the systemic recruitment of MSCs to UHMWPE particles and (2) recruited MSCs are able to differentiate into functional mature osteoblasts and decrease particle-associated bone loss. Nude mice were allocated randomly to four groups. UHMWPE particles were continuously infused into the femoral shaft using a micro-pump. Genetically modified murine wild type reporter MSCs were injected systemically via the left ventricle. Non-invasive imaging was used to assay MSC migration and bone mineral density. Bioluminescence and immunohistochemistry confirmed the chemotaxis of reporter cells and their differentiation into mature osteoblasts in the presence of infused particles. Injection of a CCR1 antagonist decreased reporter cell recruitment to the UHMWPE particle infusion site and increased osteolysis. CCR1 appears to be a critical receptor for chemotaxis of MSCs in the presence of UHMWPE particles. Interference with CCR1 exacerbates particle-induced bone loss.

  View details for DOI 10.1016/j.biomaterials.2012.02.003

  View details for PubMedID 22364730

• 18F FPPRGD2 in GBM: Imaging alpha v beta 3 integrin levels as a biomarker of disease recurrence Iagaru, A., Mosci, C., Mittra, E., Shen, B., Chin, F., Fischbein, N., Gambhir, S. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680204100

• Evaluation of NaF PET/CT, FDG PET/CT, combined NaF/FDG PET/CT and CT alone for detection of bone metastases Sampath, S., Sampath, S., Lutz, A., Willmann, J., Mittra, E., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680201213

• Evaluation of the 18F-labeled L-glutamate derivative 18F-FSPG (BAY 94-9392) in brain and head and neck cancer patients Kumar, M., Mosci, C., Keu, K., Iagaru, A., Koglin, N., Fels, L., Bacher-Stier, C., Chin, F., Gambhir, S., Mittra, E. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680200262

• [18F]FPRGD2 PET/CT imaging of integrin alpha v beta 3 in renal carcinomas: Correlation with histopathology Withofs, N., Signolle, N., Nzaramba, E., Thonon, D., Leonard, M., Aerts, J., Waltregny, D., Cataldo, D., Gambhir, S., Hustinx, R. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680203206

• 18F FDG PET/CT in the management of patients with post-transplant lymphoproliferative disorder Takehana, C., Mittra, E., Quon, A., Gambhir, S., Iagaru, A. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680201186

• Evaluation of the 18F L-glutamate derivative 18F-FSPG (BAY 94-9392) in lymphoma and colon cancer patients Kumar, M., Mosci, C., Keu, K., Iagaru, A., Koglin, N., Fels, L., Bacher-Stier, C., Chin, F., Gambhir, S., Mittra, E. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680201366

• Preliminary results of [18F]FPRGD2 PET/CT imaging of integrin alpha v beta 3 levels in patients with locally advanced rectal carcinoma Withofs, N., Martinive, P., Scagnol, I., Thonon, D., Giacomelli, F., Mievis, F., Coucke, P., Cataldo, D., Gambhir, S., Hustinx, R. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680203262

• Characterization of physiological 18F-FSPG uptake in healthy volunteers: Kinetics and biodistribution Mosei, C., Kumar, M., Koglin, N., Fels, L., Bacher-Stier, C., Smolarz, K., Schwaiger, M., Gambhir, S., Mittra, E. SOC NUCLEAR MEDICINE INC. 2012

  View details for Web of Science ID 000443680201182

• Intratumoral versus Intravenous Gene Therapy Using a Transcriptionally Targeted Viral Vector in an Orthotopic Hepatocellular Carcinoma Rat Model JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Kim, Y. I., Ahn, B., Ronald, J. A., Katzenberg, R., Singh, A., Paulmurugan, R., Ray, S., Gambhir, S. S., Hofmann, L. V. 2012; 23 (5): 704-711

  Abstract

  To evaluate the feasibility of intratumoral delivery of adenoviral vector carrying a bidirectional two-step transcriptional amplification (TSTA) system to amplify transcriptional strength of cancer-specific Survivin promoter in a hepatocellular carcinoma model.MCA-RH7777 cells were implanted in rat liver, and tumor formation was confirmed with [(18)F]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET). The adenoviral vector studied had Survivin promoter driving a therapeutic gene (tumor necrosis factor-α-related apoptosis-inducing ligand [TRAIL]) and a reporter gene (firefly luciferase [FL]; Ad-pSurvivin-TSTA-TRAIL-FL). Tumor-bearing rats were administered Ad-pSurvivin-TSTA-TRAIL-FL intravenously (n = 7) or intratumorally (n = 8). For control groups, adenovirus FL under cytomegalovirus (CMV) promoter (Ad-pCMV-FL) was administered intravenously (n = 3) or intratumorally (n = 3). One day after delivery, bioluminescence imaging was performed to evaluate transduction. At 4 and 7 days after delivery, 18F-FDG-PET was performed to evaluate therapeutic efficacy.With intravenous delivery, Ad-pSurvivin-TSTA-TRAIL-FL showed no measurable liver tumor FL signal on day 1 after delivery, but showed better therapeutic efficacy than Ad-pCMV-FL on day 7 (PET tumor/liver ratio, 3.5 ± 0.58 vs 6.0 ± 0.71; P = .02). With intratumoral delivery, Ad-pSurvivin-TSTA-TRAIL-FL showed positive FL signal from all tumors and better therapeutic efficacy than Ad-pCMV-FL on day 7 (2.4 ± 0.50 vs 5.4 ± 0.78; P = .01). In addition, intratumoral delivery of Ad-pSurvivin-TSTA-TRAIL-FL demonstrated significant decrease in tumoral viability compared with intravenous delivery (2.4 ± 0.50 vs 3.5 ± 0.58; P = .03).Intratumoral delivery of a transcriptionally targeted therapeutic vector for amplifying tumor-specific effect demonstrated better transduction efficiency and therapeutic efficacy for liver cancer than systemic delivery, and may lead to improved therapeutic outcome for future clinical practice.

  View details for DOI 10.1016/j.jvir.2012.01.053

  View details for Web of Science ID 000303557000020

  View details for PubMedID 22387029

  View details for PubMedCentralID PMC4132166

• A brain tumor molecular imaging strategy using a new triple-modality MRI-photoacoustic-Raman nanoparticle NATURE MEDICINE Kircher, M. F., de la Zerda, A., Jokerst, J. V., Zavaleta, C. L., Kempen, P. J., Mittra, E., Pitter, K., Huang, R., Campos, C., Habte, F., Sinclair, R., Brennan, C. W., Mellinghoff, I. K., Holland, E. C., Gambhir, S. S. 2012; 18 (5): 829-U235

  Abstract

  The difficulty in delineating brain tumor margins is a major obstacle in the path toward better outcomes for patients with brain tumors. Current imaging methods are often limited by inadequate sensitivity, specificity and spatial resolution. Here we show that a unique triple-modality magnetic resonance imaging-photoacoustic imaging-Raman imaging nanoparticle (termed here MPR nanoparticle) can accurately help delineate the margins of brain tumors in living mice both preoperatively and intraoperatively. The MPRs were detected by all three modalities with at least a picomolar sensitivity both in vitro and in living mice. Intravenous injection of MPRs into glioblastoma-bearing mice led to MPR accumulation and retention by the tumors, with no MPR accumulation in the surrounding healthy tissue, allowing for a noninvasive tumor delineation using all three modalities through the intact skull. Raman imaging allowed for guidance of intraoperative tumor resection, and a histological correlation validated that Raman imaging was accurately delineating the brain tumor margins. This new triple-modality-nanoparticle approach has promise for enabling more accurate brain tumor imaging and resection.

  View details for DOI 10.1038/nm.2721

  View details for Web of Science ID 000303763500053

  View details for PubMedID 22504484

  View details for PubMedCentralID PMC3422133

• Deep Tissue Photoacoustic Imaging Using a Miniaturized 2-D Capacitive Micromachined Ultrasonic Transducer Array IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING Kothapalli, S., Ma, T., Vaithilingam, S., Oralkan, O., Khuri-Yakub, B. T., Gambhir, S. S. 2012; 59 (5): 1199-1204

  Abstract

  In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 μm), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 μm. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI.

  View details for DOI 10.1109/TBME.2012.2183593

  View details for Web of Science ID 000303201000001

  View details for PubMedID 22249594

• Twist1 Suppresses Senescence Programs and Thereby Accelerates and Maintains Mutant Kras-Induced Lung Tumorigenesis PLOS GENETICS Tran, P. T., Shroff, E. H., Burns, T. F., Thiyagarajan, S., Das, S. T., Zabuawala, T., Chen, J., Cho, Y., Luong, R., Tamayo, P., Salih, T., Aziz, K., Adam, S. J., Vicent, S., Nielsen, C. H., Withofs, N., Sweet-Cordero, A., Gambhir, S. S., Rudin, C. M., Felsher, D. W. 2012; 8 (5)

  Abstract

  KRAS mutant lung cancers are generally refractory to chemotherapy as well targeted agents. To date, the identification of drugs to therapeutically inhibit K-RAS have been unsuccessful, suggesting that other approaches are required. We demonstrate in both a novel transgenic mutant Kras lung cancer mouse model and in human lung tumors that the inhibition of Twist1 restores a senescence program inducing the loss of a neoplastic phenotype. The Twist1 gene encodes for a transcription factor that is essential during embryogenesis. Twist1 has been suggested to play an important role during tumor progression. However, there is no in vivo evidence that Twist1 plays a role in autochthonous tumorigenesis. Through two novel transgenic mouse models, we show that Twist1 cooperates with Kras(G12D) to markedly accelerate lung tumorigenesis by abrogating cellular senescence programs and promoting the progression from benign adenomas to adenocarcinomas. Moreover, the suppression of Twist1 to physiological levels is sufficient to cause Kras mutant lung tumors to undergo senescence and lose their neoplastic features. Finally, we analyzed more than 500 human tumors to demonstrate that TWIST1 is frequently overexpressed in primary human lung tumors. The suppression of TWIST1 in human lung cancer cells also induced cellular senescence. Hence, TWIST1 is a critical regulator of cellular senescence programs, and the suppression of TWIST1 in human tumors may be an effective example of pro-senescence therapy.

  View details for DOI 10.1371/journal.pgen.1002650

  View details for Web of Science ID 000304864000004

  View details for PubMedID 22654667

  View details for PubMedCentralID PMC3360067

• MC3T3-E1 Osteoprogenitor Cells Systemically Migrate to a Bone Defect and Enhance Bone Healing TISSUE ENGINEERING PART A Gibon, E., Batke, B., Jawad, M. U., Fritton, K., Rao, A., Yao, Z., Biswal, S., Gambhir, S. S., Goodman, S. B. 2012; 18 (9-10): 968-973

  Abstract

  Although iliac crest autologous bone graft remains the gold standard for treatment of bone defects, delayed- and nonunions, and arthrodeses, several alternative strategies have been attempted, including the use of mesenchymal stem cells. Whether cells from the osteoblast lineage demonstrate systemic recruitment to an acute bone defect or fracture, and whether these cells directly participate in bone healing is controversial. This study tests two hypotheses: (1) that exogenous murine MC3T3-E1 osteoprogenitor cells with a high propensity for osteoblast differentiation are able to systemically migrate to a bone defect and (2) that the migrated MC3T3-E1 cells enhance bone healing. Two groups of nude mice were used; a bone defect was drilled in the left femoral shaft in both groups. MC3T3-E1 were used as reporter cells and injected in the left ventricle of the heart, to avoid sequestration in the lungs. Injection of saline served as a control. We used bioluminescence and microCT to assay cell recruitment and bone mineral density (BMD). Immunohistochemical staining was used to confirm the migration of reporter cells. MC3T3-E1 cells were found to systemically migrate to the bone defect. Further, BMD at the defect was significantly increased when cells were injected. Systemic cell therapy using osteoprogenitor cells may be a potential strategy to enhance bone healing.

  View details for DOI 10.1089/ten.tea.2011.0545

  View details for PubMedID 22129134

• Glioblastoma Therapy with Cytotoxic Mesenchymal Stromal Cells Optimized by Bioluminescence Imaging of Tumor and Therapeutic Cell Response PLOS ONE Alieva, M., Bago, J. R., Aguilar, E., Soler-Botija, C., Vila, O. F., Molet, J., Gambhir, S. S., Rubio, N., Blanco, J. 2012; 7 (4)

  Abstract

  Genetically modified adipose tissue derived mesenchymal stromal cells (hAMSCs) with tumor homing capacity have been proposed for localized therapy of chemo- and radiotherapy resistant glioblastomas. We demonstrate an effective procedure to optimize glioblastoma therapy based on the use of genetically modified hAMSCs and in vivo non invasive monitoring of tumor and therapeutic cells. Glioblastoma U87 cells expressing Photinus pyralis luciferase (Pluc) were implanted in combination with hAMSCs expressing a trifunctional Renilla reniformis luciferase-red fluorescent protein-thymidine kinase reporter in the brains of SCID mice that were subsequently treated with ganciclovir (GCV). The resulting optimized therapy was effective and monitoring of tumor cells by bioluminescence imaging (BLI) showed that after 49 days GCV treatment reduced significantly the hAMSC treated tumors; by a factor of 10(4) relative to controls. Using a Pluc reporter regulated by an endothelial specific promoter and in vivo BLI to image hAMSC differentiation we gained insight on the therapeutic mechanism. Implanted hAMSCs homed to tumor vessels, where they differentiated to endothelial cells. We propose that the tumor killing efficiency of genetically modified hAMSCs results from their association with the tumor vascular system and should be useful vehicles to deliver localized therapy to glioblastoma surgical borders following tumor resection.

  View details for DOI 10.1371/journal.pone.0035148

  View details for Web of Science ID 000305347400033

  View details for PubMedID 22529983

  View details for PubMedCentralID PMC3328467

• Pilot clinical trials of FSPG (BAY 94-9392): An 18F-labeled glutamate derivative for PET imaging of system xCactivity in tumors Baek, S., Mittra, E., Cho, C., Gong, G., Oh, S., Mosci, C., Kumar, M., Chin, F. T., Fels, L. M., Stephens, A. W., Koglin, N., Mueller, A., Dinkelborg, L. M., Moon, D., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2012

  View details for Web of Science ID 000209701600355

• Correlating circulating tumor cells with F-18-FDG positron emission tomography (PET) uptake in patients with treatment naive non-small cell lung cancer: A pilot study Kuhn, P., Keu, K., Nair, V. S., Luttgen, M., Maestas, S., Bethel, K., Souder, K., Vasanawala, M., Kuschner, W., Iagaru, A. H., Hoh, C., Nieva, J., Bazhenova, L., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2012

  View details for DOI 10.1158/1538-7445.AM2012-2369

  View details for Web of Science ID 000209701505199

• Pilot clinical trials of FSPG (BAY 94-9392): An 18F-labeled glutamate derivative for PET imaging of system xC-activity in tumors Baek, S., Mittra, E., Choi, C., Gong, G., Oh, S., Mosci, C., Kumar, M., Chin, F. T., Fels, L. M., Stephens, A. W., Koglin, N., Mueller, A., Dinkelborg, L. M., Moon, D., Gambhir, S. S. AMER ASSOC CANCER RESEARCH. 2012

  View details for DOI 10.1158/1538-7445.AM2012-LB-227

  View details for Web of Science ID 000209701601440

• A novel rotational Raman imaging device for early cancer detection Garai, E., Zavaleta, C., Sensarn, S., Mandella, M., Gambhir, S. S., Contag, C. H. AMER ASSOC CANCER RESEARCH. 2012

  View details for DOI 10.1158/1538-7445.AM2012-LB-512

  View details for Web of Science ID 000209701504209

• Early detection of pancreatic cancer in transgenic mice with ultrasonic molecular imaging and VEGFR2-targeted microbubbles Pysz, M. A., Seeley, E. S., Foygel, K., Gambhir, S. S., Tian, L., Brentnall, T. A., Willmann, J. K. AMER ASSOC CANCER RESEARCH. 2012

  View details for DOI 10.1158/1538-7445.AM2012-LB-509

  View details for Web of Science ID 000209701504206

• A MOLECULAR IMAGING PRIMER: MODALITIES, IMAGING AGENTS, AND APPLICATIONS PHYSIOLOGICAL REVIEWS James, M. L., Gambhir, S. S. 2012; 92 (2): 897-965

  Abstract

  Molecular imaging is revolutionizing the way we study the inner workings of the human body, diagnose diseases, approach drug design, and assess therapies. The field as a whole is making possible the visualization of complex biochemical processes involved in normal physiology and disease states, in real time, in living cells, tissues, and intact subjects. In this review, we focus specifically on molecular imaging of intact living subjects. We provide a basic primer for those who are new to molecular imaging, and a resource for those involved in the field. We begin by describing classical molecular imaging techniques together with their key strengths and limitations, after which we introduce some of the latest emerging imaging modalities. We provide an overview of the main classes of molecular imaging agents (i.e., small molecules, peptides, aptamers, engineered proteins, and nanoparticles) and cite examples of how molecular imaging is being applied in oncology, neuroscience, cardiology, gene therapy, cell tracking, and theranostics (therapy combined with diagnostics). A step-by-step guide to answering biological and/or clinical questions using the tools of molecular imaging is also provided. We conclude by discussing the grand challenges of the field, its future directions, and enormous potential for further impacting how we approach research and medicine.

  View details for DOI 10.1152/physrev.00049.2010

  View details for Web of Science ID 000306562500009

  View details for PubMedID 22535898

• Prospective Evaluation of Tc-99m MDP Scintigraphy, F-18 NaF PET/CT, and F-18 FDG PET/CT for Detection of Skeletal Metastases MOLECULAR IMAGING AND BIOLOGY Iagaru, A., Mittra, E., Dick, D. W., Gambhir, S. S. 2012; 14 (2): 252-259

  Abstract

  Technetium (Tc) methylene diphosphonate (MDP) has been the standard method for bone scintigraphy for three decades. (18)F sodium fluoride ((18)F NaF) positron emission tomography (PET)/computed tomography (CT) has better resolution and is considered superior. The role of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F FDG) PET/CT is proven in a variety of cancers, for which it has changed the practice of oncology. There are few prospective studies comparing these three methods of detection of skeletal metastases. Thus, we were prompted to initiate this prospective pilot trial.This is a prospective study (Sep 2007-Dec 2010) of 52 patients with proven malignancy referred for evaluation of skeletal metastases. There were 37 men and 15 women, 19-84 years old (average, 55.6 ± 15.9). Technetium-99m ((99m)Tc) MDP bone scintigraphy, (18)F NaF PET/CT, and (18)F FDG PET/CT were subsequently performed within 1 month.Skeletal lesions were detected by (99m)Tc MDP bone scintigraphy in 22 of 52 patients, by (18)F NaF PET/CT in 24 of 52 patients, and by (18)F FDG PET/CT in 16 of 52 patients. The image quality and evaluation of extent of disease were superior by (18)F NaF PET/CT over (99m)Tc MDP scintigraphy in all 22 patients with skeletal lesions on both scans and over (18)F FDG PET/CT in 11 of 16 patients with skeletal metastases on (18)F FDG PET/CT. In two patients, (18)F NaF PET/CT showed skeletal metastases not seen on either of the other two scans. Extraskeletal lesions were identified by (18)F FDG PET/CT in 28 of 52 subjects.Our prospective pilot-phase trial demonstrates superior image quality and evaluation of skeletal disease extent with (18)F NaF PET/CT over (99m)Tc MDP scintigraphy and (18)F FDG PET/CT. At the same time, (18)F FDG PET detects extraskeletal disease that can significantly change disease management. As such, a combination of (18)F FDG PET/CT and (18)F NaF PET/CT may be necessary for cancer detection. Additional evaluation with larger cohorts is required to confirm these preliminary findings.

  View details for DOI 10.1007/s11307-011-0486-2

  View details for Web of Science ID 000301584100013

  View details for PubMedID 21479710

• Use of Cu-64-labeled Fibronectin Domain with EGFR-Overexpressing Tumor Xenograft: Molecular Imaging RADIOLOGY Hackel, B. J., Kimura, R. H., Gambhir, S. S. 2012; 263 (1): 179-188

  Abstract

  To assess the ability of an engineered epidermal growth factor receptor (EGFR)-binding fibronectin domain to serve as a positron emission tomographic (PET) probe for molecular imaging of EGFR in a xenograft mouse model.An EGFR-binding fibronectin domain (fibronectin abbreviated to Fn when bound) was site-specifically labeled with copper 64 ((64)Cu) (8 MBq/nmol). Copper 64-Fn binding was tested in cell cultures with varying EGFR expression. Stability in human and mouse serum was measured in vitro. Animal experiments were approved by the Stanford University Institutional Animal Care and Use Committee. Copper 64-Fn (approximately 2 MBq) was used for PET in mice (n = 5) bearing EGFR-overexpressing xenografted tumors (approximately 5-10 mm in diameter). Results of tomography were compared with those of ex vivo gamma counting of dissected tissues. Statistical analysis was performed with t tests and adjustment for multiple comparisons.Copper 64-Fn exhibited EGFR-dependent binding to multiple cell lines in culture. The tracer was stable for 24 hours in human and mouse serum at 37°C. The tracer exhibited good tumor localization (3.4% injected dose [ID]/g ± 1.0 [standard deviation] at 1 hour), retention (2.7% ID/g ± 0.6 at 24 hours), and specificity (8.6 ± 3.0 tumor-to-muscle ratio, 8.9 ± 4.7 tumor-to-blood ratio at 1 hour). Specific targeting was verified with low localization to low-expressing MDA-MB-435 tumors (0.7% ID/g ± 0.8 at 1 hour, P = .018); specificity was further demonstrated, as a nonbinding control fibronectin had low localization to EGFR-overexpressing xenografts (0.8% ID/g ± 0.2 at 1 hour, P = .013).The stability, low background, and target-specific tumor uptake and retention of the engineered fibronectin domain make it a promising EGFR molecular imaging agent. More broadly, it validates the fibronectin domain as a potential scaffold for a generation of various molecular imaging agents.

  View details for DOI 10.1148/radiol.12111504

  View details for Web of Science ID 000302642700018

  View details for PubMedID 22344401

  View details for PubMedCentralID PMC3309798

• Fiber-based system for imaging tumor margins with Cerenkov Luminescence Liu, H., Carpenter, C. M., Jiang, H., Pratx, G., Sun, C., Buchin, M. P., Gambhir, S. S., Xing, L., Cheng, Z. AMER CHEMICAL SOC. 2012

  View details for Web of Science ID 000324503202159

• Immunomodulation of Curcumin on Adoptive Therapy with T Cell Functional Imaging in Mice CANCER PREVENTION RESEARCH Chang, Y., Chuang, H., Hsu, C., Liu, R., Gambhir, S. S., Hwang, J. 2012; 5 (3): 444-452

  Abstract

  Adoptive T-cell therapy involves the ex vivo expansion and subsequent transfusion of tumor-specific T lymphocytes to eliminate tumors. Using immune modulators to block immunosuppressive factors in the tumor microenvironment has emerged as a promising strategy to enhance T-cell-mediated tumor regression. Curcumin, a major component of turmeric, has been shown to possess antitumor and immunomodulatory effects by regulating a diverse range of molecular targets. Thus, we hypothesize that these beneficial effects of curcumin may improve the therapeutic efficacy of adoptive therapy. Here, we have shown that curcumin enhances cytotoxicity of CD8(+) T cells toward tumors via alteration of the tumor microenvironment when combined with adoptive therapy. We found that T-cell accumulation and function were increased in combined treatment due to the blockade of different immunosuppressors, including TGF-β, indoleamine 2,3-dioxygenase, and regulatory T cells. Furthermore, bioluminescent imaging with a granzyme B promoter-conjugated optical reporter also reflected improved cytotoxicity of antigen-specific CD8(+) T cells in tumor-bearing mice during treatment. These findings suggest that combination of multitargeting drugs, such as curcumin, with adoptive therapy may have potential for clinical application. In addition, using a granzyme B-specific imaging reporter to assess T-cell function may also be applied for the development and therapeutic evaluation of new immunotherapy in preclinical studies.

  View details for DOI 10.1158/1940-6207.CAPR-11-0308

  View details for Web of Science ID 000300987800011

  View details for PubMedID 22135043

• Placental sFlt-1 Production Is Essential for Normal Pregnancy: Relevance to the Mechanisms of Preeclampsia. Nayak, N. R., Ambati, B. K., Dhal, S., Druzin, M. L., Gambhir, S. S., Fan, X. SAGE PUBLICATIONS INC. 2012: 86A

  View details for Web of Science ID 000329543601046

• Optical Imaging with Her2-Targeted Affibody Molecules Can Monitor Hsp90 Treatment Response in a Breast Cancer Xenograft Mouse Model CLINICAL CANCER RESEARCH van de Ven, S. M., Elias, S. G., Chan, C. T., Miao, Z., Cheng, Z., De, A., Gambhir, S. S. 2012; 18 (4): 1073-1081

  Abstract

  To determine whether optical imaging can be used for in vivo therapy response monitoring as an alternative to radionuclide techniques. For this, we evaluated the known Her2 response to 17-dimethylaminoethylamino-17-demethoxygeldanamycin hydrochloride (17-DMAG) treatment, an Hsp90 inhibitor.After in vitro 17-DMAG treatment response evaluation of MCF7 parental cells and 2 HER2-transfected clones (clone A medium, B high Her2 expression), we established human breast cancer xenografts in nude mice (only parental and clone B) for in vivo evaluation. Mice received 120 mg/kg of 17-DMAG in 4 doses at 12-hour intervals intraperitonially (n = 14) or PBS as carrier control (n = 9). Optical images were obtained both pretreatment (day 0) and posttreatment (day 3, 6, and 9), always 5 hours postinjection of 500 pmol of anti-Her2 Affibody-AlexaFluor680 via tail vein (with preinjection background subtraction). Days 3 and 9 in vivo optical imaging signal was further correlated with ex vivo Her2 levels by Western blot after sacrifice.Her2 expression decreased with 17-DMAG dose in vitro. In vivo optical imaging signal was reduced by 22.5% in clone B (P = 0.003) and by 9% in MCF7 parental tumors (P = 0.23) 3 days after 17-DMAG treatment; optical imaging signal recovered in both tumor types at days 6 to 9. In the carrier group, no signal reduction was observed. Pearson correlation of in vivo optical imaging signal with ex vivo Her2 levels ranged from 0.73 to 0.89.Optical imaging with an affibody can be used to noninvasively monitor changes in Her2 expression in vivo as a response to treatment with an Hsp90 inhibitor, with results similar to response measurements in positron emission tomography imaging studies.

  View details for DOI 10.1158/1078-0432.CCR-10-3213

  View details for Web of Science ID 000300628100017

  View details for PubMedID 22235098

  View details for PubMedCentralID PMC3288571

• First Experience with Clinical-Grade [F-18]FPP(RGD)(2): An Automated Multi-step Radiosynthesis for Clinical PET Studies MOLECULAR IMAGING AND BIOLOGY Chin, F. T., Shen, B., Liu, S., Berganos, R. A., Chang, E., Mittra, E., Chen, X., Gambhir, S. S. 2012; 14 (1): 88-95

  Abstract

  A reliable and routine process to introduce a new ¹⁸F-labeled dimeric RGD-peptide tracer ([¹⁸F]FPP(RGD₂) for noninvasive imaging of α(v)β₃ expression in tumors needed to be developed so the tracer could be evaluated for the first time in man. Clinical-grade [¹⁸F]FPP(RGD)₂ was screened in mouse prior to our first pilot study in human.[¹⁸F]FPP(RGD)₂ was synthesized by coupling 4-nitrophenyl-2-[¹⁸F]fluoropropionate ([¹⁸F]NPE) with the dimeric RGD-peptide (PEG₃-c(RGDyK)₂). Imaging studies with [¹⁸F]FPP(RGD)₂ in normal mice and a healthy human volunteer were carried out using small animal and clinical PET scanners, respectively.Through optimization of each radiosynthetic step, [¹⁸F]FPP(RGD)₂ was obtained with RCYs of 16.9 ± 2.7% (n = 8, EOB) and specific radioactivity of 114 ± 72 GBq/μmol (3.08 ± 1.95 Ci/μmol; n = 8, EOB) after 170 min of radiosynthesis. In our mouse studies, high radioactivity uptake was only observed in the kidneys and bladder with the clinical-grade tracer. Favorable [¹⁸F]FPP(RGD)₂ biodistribution in human studies, with low background signal in the head, neck, and thorax, showed the potential applications of this RGD-peptide tracer for detecting and monitoring tumor growth and metastasis.A reliable, routine, and automated radiosynthesis of clinical-grade [¹⁸F]FPP(RGD)₂ was established. PET imaging in a healthy human volunteer illustrates that [¹⁸F]FPP(RGD)₂ possesses desirable pharmacokinetic properties for clinical noninvasive imaging of α(v)β₃ expression. Further imaging studies using [¹⁸F]FPP(RGD)₂ in patient volunteers are now under active investigation.

  View details for DOI 10.1007/s11307-011-0477-3

  View details for Web of Science ID 000301583900012

  View details for PubMedID 21400112

  View details for PubMedCentralID PMC3617483

• Prospective comparison of combined F-18-FDG and F-18-NaF PET/CT vs. F-18-FDG PET/CT imaging for detection of malignancy EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Lin, F. I., Rao, J. E., Mittra, E. S., Nallapareddy, K., Chengapa, A., Dick, D. W., Gambhir, S. S., Iagaru, A. 2012; 39 (2): 262-270

  Abstract

  Typically, (18)F-FDG PET/CT and (18)F-NaF PET/CT scans are done as two separate studies on different days to allow sufficient time for the radiopharmaceutical from the first study to decay. This is inconvenient for the patients and exposes them to two doses of radiation from the CT component of the examinations. In the current study, we compared the clinical usefulness of a combined (18)F-FDG/(18)F-NaF PET/CT scan with that of a separate (18)F-FDG-only PET/CT scan.There were 62 patients enrolled in this prospective trial. All had both an (18)F-FDG-alone PET/CT scan and a combined (18)F-FDG/(18)F-NaF PET/CT scan. Of the 62 patients, 53 (85%) received simultaneous tracer injections, while 9 (15%) received (18)F-NaF subsequent to the initial (18)F-FDG dose (average delay 2.2 h). Images were independently reviewed for PET findings by two Board-Certified nuclear medicine physicians, with discrepancies resolved by a third reader. Interpreters were instructed to only report findings that were concerning for malignancy. Reading the (18)F-FDG-only scan first for half of the patients controlled for order bias.In 15 of the 62 patients (24%) neither the (18)F-FDG-only PET/CT scan nor the combined (18)F-FDG/(18)F-NaF PET/CT scan identified malignancy. In the remaining 47 patients who had PET findings of malignancy, a greater number of lesions were detected in 16 of 47 patients (34%) using the combined (18)F-FDG/(18)F-NaF PET/CT scan compared to the (18)F-FDG-only PET/CT scan. In 2 of these 47 patients (4%), the (18)F-FDG-only scan demonstrated soft tissue lesions that were not prospectively identified on the combined study. In 29 of these 47 patients (62%), the combined scan detected an equal number of lesions compared to the (18)F-FDG-only scan. Overall, 60 of all the 62 patients (97%) showed an equal or greater number of lesions on the combined scan than on the (18)F-FDG-only scan.The current study demonstrated that (18)F-FDG and (18)F-NaF can be combined in a single PET/CT scan by administering the two radiopharmaceuticals simultaneously or in sequence on the same day. In addition to patient convenience and reduced radiation exposure from the CT component, the combined (18)F-FDG/(18)F-NaF PET/CT scan appeared to increase the sensitivity for detection of osseous lesions compared to the (18)F-FDG-only PET/CT scan in the studied population.

  View details for DOI 10.1007/s00259-011-1971-1

  View details for Web of Science ID 000302286600009

  View details for PubMedID 22065013

• Proof-of-Concept Study of Monitoring Cancer Drug Therapy with Cerenkov Luminescence Imaging JOURNAL OF NUCLEAR MEDICINE Xu, Y., Chang, E., Liu, H., Jiang, H., Gambhir, S. S., Cheng, Z. 2012; 53 (2): 312-317

  Abstract

  Cerenkov luminescence imaging (CLI) has emerged as a less expensive, easier-to-use, and higher-throughput alternative to other nuclear imaging modalities such as PET. It is expected that CLI will find many applications in biomedical research such as cancer detection, probe development, drug screening, and therapy monitoring. In this study, we explored the possibility of using CLI to monitor drug efficacy by comparisons against PET. To assess the performance of both modalities in therapy monitoring, 2 murine tumor models (large cell lung cancer cell line H460 and prostate cancer cell line PC3) were given bevacizumab versus vehicle treatments. Two common radiotracers, 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) and (18)F-FDG, were used to monitor bevacizumab treatment efficacy.One group of mice (n = 6) was implanted with H460 xenografts bilaterally in the shoulder region, divided into treatment and control groups (n = 3 each), injected with (18)F-FLT, and imaged with PET immediately followed by CLI. The other group of mice (n = 6) was implanted with PC3 xenografts in the same locations, divided into treatment and control groups (n = 3 each), injected with (18)F-FDG, and imaged by the same modalities. Bevacizumab treatment was performed by 2 injections of 20 mg/kg at days 0 and 2.On (18)F-FLT scans, both CLI and PET revealed significantly decreased signals from H460 xenografts in treated mice from pretreatment to day 3. Moderately increased to unchanged signals were observed in untreated mice. On (18)F-FDG scans, both CLI and PET showed relatively unchanged signals from PC3 tumors in both treated and control groups. Quantifications of tumor signals of Cerenkov luminescence and PET images showed that the 2 modalities had excellent correlations (R(2) > 0.88 across all study groups).CLI and PET exhibit excellent correlations across different tumor xenografts and radiotracers. This is the first study, to our knowledge, demonstrating the use of CLI for monitoring cancer treatment. The findings warrant further exploration and optimization of CLI as an alternative to PET in preclinical therapeutic monitoring and drug screening.

  View details for DOI 10.2967/jnumed.111.094623

  View details for Web of Science ID 000300032800024

  View details for PubMedID 22241909

• Pharmacokinetically Stabilized Cystine Knot Peptides That Bind Alpha-v-Beta-6 Integrin with Single-Digit Nanomolar Affinities for Detection of Pancreatic Cancer CLINICAL CANCER RESEARCH Kimura, R. H., Teed, R., Hackel, B. J., Pysz, M. A., Chuang, C. Z., Sathirachinda, A., Willmann, J. K., Gambhir, S. S. 2012; 18 (3): 839-849

  Abstract

  Detection of pancreatic cancer remains a high priority and effective diagnostic tools are needed for clinical applications. Many cancer cells overexpress integrin α(v)β(6), a cell surface receptor being evaluated as a novel clinical biomarker.To validate this molecular target, several highly stable cystine knot peptides were engineered by directed evolution to bind specifically and with high affinity (3-6 nmol/L) to integrin α(v)β(6). The binders do not cross-react with related integrin α(v)β(5), integrin α(5)β(1), or tumor-angiogenesis-associated integrin, α(v)β(3).Positron emission tomography showed that these disulfide-stabilized peptides rapidly accumulate at tumors expressing integrin α(v)β(6). Clinically relevant tumor-to-muscle ratios of 7.7 ± 2.4 to 11.3 ± 3.0 were achieved within 1 hour after radiotracer injection. Minimization of off-target dosing was achieved by reformatting α(v)β(6)-binding activities across various natural and pharmacokinetically stabilized cystine knot scaffolds with different amino acid content. We show that the primary sequence of a peptide scaffold directs its pharmacokinetics. Scaffolds with high arginine or glutamic acid content suffered high renal retention of more than 75% injected dose per gram (%ID/g). Substitution of these amino acids with renally cleared amino acids, notably serine, led to significant decreases in renal accumulation of less than 20%ID/g 1 hour postinjection (P < 0.05, n = 3).We have engineered highly stable cystine knot peptides with potent and specific integrin α(v)β(6)-binding activities for cancer detection. Pharmacokinetic engineering of scaffold primary sequence led to significant decreases in off-target radiotracer accumulation. Optimization of binding affinity, specificity, stability, and pharmacokinetics will facilitate translation of cystine knots for cancer molecular imaging.

  View details for DOI 10.1158/1078-0432.CCR-11-1116

  View details for Web of Science ID 000300115000027

  View details for PubMedID 22173551

  View details for PubMedCentralID PMC3271184

• A Novel Clinically Translatable Fluorescent Nanoparticle for Targeted Molecular Imaging of Tumors in Living Subjects NANO LETTERS Gao, J., Chen, K., Luong, R., Bouley, D. M., Mao, H., Qiao, T., Gambhir, S. S., Cheng, Z. 2012; 12 (1): 281-286

  Abstract

  The use of quantum dots (QDs) in biomedical research has grown tremendously, yet successful examples of clinical applications are absent due to many clinical concerns. Here, we report on a new type of stable and biocompatible dendron-coated InP/ZnS core/shell QD as a clinically translatable nanoprobe for molecular imaging applications. The QDs (QD710-Dendron) were demonstrated to hold several significant features: near-infrared (NIR) emission, high stability in biological media, suitable size with possible renal clearance, and ability of extravasation. More importantly, a pilot mouse toxicity study confirmed that QD710-Dendron lacks significant toxicity at the doses tested. The acute tumor uptake of QD710-Dendron resulted in good contrast from the surrounding nontumorous tissues, indicating the possibility of passive targeting of the QDs. The highly specific targeting of QD710-Dendron-RGD(2) to integrin α(v)β(3)-positive tumor cells resulted in high tumor uptake and long retention of the nanoprobe at tumor sites. In summary, QD710-Dendron and RGD-modified nanoparticles demonstrate small size, high stability, biocompatibility, favorable in vivo pharmacokinetics, and successful tumor imaging properties. These features satisfy the requirements for clinical translation and should promote efforts to further investigate the possibility of using QD710-Dendron-based nanoprobes in the clinical setting in the near future.

  View details for DOI 10.1021/nl203526f

  View details for Web of Science ID 000298943100049

  View details for PubMedID 22172022

  View details for PubMedCentralID PMC3256290

• Imaging Techniques in Drug Development and Clinical Practice DRUG DELIVERY IN ONCOLOGY: FROM BASIC RESEARCH TO CANCER THERAPY, VOLS 1-3 Chang, J. C., Gambhir, S. S., Willmann, J. K., Kratz, F., Senter, P., Steinhagen, H. 2012: 189–224

  View details for Web of Science ID 000338009100010

• Photoacoustic Imaging Using a 9F MicroLinear CMUT ICE Catheter IEEE International Ultrasonics Symposium (IUS) Nikoozadeh, A., Choe, J. W., Kothapalli, S., Moini, A., Sanjani, S. S., Kamaya, A., Oralkan, O., Gambhir, S. S., Khuri-Yakub, P. T. IEEE. 2012: 24–27

  View details for DOI 10.1109/ULTSYM.2012.0007

  View details for Web of Science ID 000326960200006

• Response to Intra-Arterial Oncolytic Virotherapy with the Herpes Virus NV1020 Evaluated by [F-18]Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography HUMAN GENE THERAPY Sze, D. Y., Iagaru, A. H., Gambhir, S. S., de Haan, H. A., Reid, T. R. 2012; 23 (1): 91-97

  Abstract

  Oncolytic virotherapy poses unique challenges to the evaluation of tumor response. We hypothesized that the addition of [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to standard computed tomography (CT) evaluation would improve diagnostic and prognostic power of the measurement of tumor response to oncolytic virotherapy. A phase I/II trial was conducted to investigate treatment of hepatic metastases from colorectal carcinoma using intra-arterial administration of the oncolytic herpes virus NV1020. Both contrast-enhanced CT and FDG PET were obtained on each patient at each time point. Quantitative FDG PET and CT responses were correlated with each other and with clinical outcome metrics. A majority of patients showed initial post-viral infusion increases in tumor size (69%) or in standardized uptake value (SUV) (80%) large enough to qualify as progressive disease. Most showed subsequent decreases in tumor size (64%) or SUV (83%) enough to be reclassified as partial response or stable disease. Late PET and CT imaging results correlated well with each other and with clinical outcomes, but results from early in the treatment scheme did not correlate with each other, with later results, or with clinical outcomes. The addition of FDG PET to the evaluation of tumor response to the oncolytic virus NV1020 did not provide useful diagnostic or prognostic data. More sophisticated molecular imaging will need to be developed to monitor the effects of this novel class of antineoplastic agents.

  View details for DOI 10.1089/hum.2011.141

  View details for Web of Science ID 000299604000011

  View details for PubMedID 21895536

• Raman's "Effect" on Molecular Imaging JOURNAL OF NUCLEAR MEDICINE Zavaleta, C. L., Kircher, M. F., Gambhir, S. S. 2011; 52 (12): 1839-1844

  Abstract

  Raman spectroscopy is an optical technique that offers unsurpassed sensitivity and multiplexing capabilities to the field of molecular imaging. In the past, Raman spectroscopy had predominantly been used as an analytic tool for routine chemical analysis, but more recently, researchers have been able to harness its unique properties for imaging and spectral analysis of molecular interactions in cell populations and preclinical animal models. Additionally, researchers have already begun to translate this optical technique into a novel clinical diagnostic tool using various endoscopic strategies.

  View details for DOI 10.2967/jnumed.111.087775

  View details for Web of Science ID 000298162500016

  View details for PubMedID 21868625

• In Vitro and in Vivo Molecular Imaging of Estrogen Receptor alpha and beta Homo- and Heterodimerization: Exploration of New Modes of Receptor Regulation MOLECULAR ENDOCRINOLOGY Paulmurugan, R., Tamrazi, A., Massoud, T. F., Katzenellenbogen, J. A., Gambhir, S. S. 2011; 25 (12): 2029-2040

  Abstract

  Estrogen receptor (ER) biology reflects the actions of estrogens through the two receptors, ERα and ERβ, although little is known regarding the preference for formation of ER homo- vs. heterodimers, and how this is affected by the level of ligand occupancy and preferential ligand affinity for one of the ER subtypes. In this report, we use a split optical reporter-protein complementation system to demonstrate the physical interaction between ERα and ERβ in response to different ER ligands in cells and, for the first time, by in vivo imaging in living animals. The genetically encoded reporter vectors constructed with the ligand-binding domains of ERα and ERβ, fused to split firefly or Renilla luciferase (Fluc or hRluc) fragments, were used for this study. This molecular proteomic technique was used to detect ERα/ERα or ERβ/ERβ homodimerization, or ERα/ERβ heterodimerization induced by ER subtype-selective and nonselective ligands, and selective ER modulators (SERM), as well as in dimers in which one mutant monomer was unable to bind estradiol. The SERM-bound ERα and ERβ form the strongest dimers, and subtype-preferential homodimerization was seen with ERα-selective ligands (methyl piperidino pyrazole/propyl pyrazole triol) and the ERβ-selective ligands (diarylpropionitrile/tetrahydrochrysene/genistein). We also demonstrated that a single ligand-bound monomer can form homo- or heterodimers with an apo-monomer. Xenografts of human embryonic kidney 293T cells imaged in living mice by bioluminescence showed real-time ligand induction of ERα/ERβ heterodimerization and reversal of dimerization upon ligand withdrawal. The results from this study demonstrate the value of the split luciferase-based complementation system for studying ER-subtype interactions in cells and for evaluating them in living animals by noninvasive imaging. They also probe what combinations of ERα and ERβ dimers might be the mediators of the effects of different types of ER ligands given at different doses.

  View details for DOI 10.1210/me.2011-1145

  View details for PubMedID 22052998

• Non-invasive Bioluminescence Imaging of Myoblast-Mediated Hypoxia-Inducible Factor-1 Alpha Gene Transfer MOLECULAR IMAGING AND BIOLOGY Gheysens, O., Chen, I. Y., Rodriguez-Porcel, M., Chan, C., Rasooly, J., Vaerenberg, C., Paulmurugan, R., Willmann, J. K., Deroose, C., Wu, J., Gambhir, S. S. 2011; 13 (6): 1124-1132

  Abstract

  We tested a novel imaging strategy, in which both the survival of transplanted myoblasts and their therapeutic transgene expression, a recombinant hypoxia-inducible factor-1α (HIF-1α-VP2), can be monitored using firefly luciferase (fluc) and Renilla luciferase (hrl) bioluminescence reporter genes, respectively.The plasmid pUbi-hrl-pUbi-HIF-1α-VP2, which expresses both hrl and HIF-1α-VP2 using two ubiquitin promoters, was characterized in vitro. C2c12 myoblasts stably expressing fluc and transiently transfected with pUbi-hrl-pUbi-HIF-1α-VP2 were injected into the mouse hindlimb. Both hrl and fluc expression were monitored using bioluminescence imaging (BLI).Strong correlations existed between the expression of hRL and each of HIF-1α-VP2, VEGF, and PlGF (r(2) > 0.83, r(2) > 0.82, and r(2) > 0.97, respectively). In vivo, both transplanted cells and HIF-1α-VP2 transgene expression were successfully imaged using BLI.An objective evaluation of myoblast-mediated gene transfer in living mice can be performed by monitoring both the survival and the transgene expression of transplanted myoblasts using the techniques developed herein.

  View details for DOI 10.1007/s11307-011-0471-9

  View details for Web of Science ID 000296794400009

  View details for PubMedID 21267661

  View details for PubMedCentralID PMC4657136

• Non-Invasive Imaging of Cysteine Cathepsin Activity in Solid Tumors Using a Cu-64-Labeled Activity-Based Probe PLOS ONE Ren, G., Blum, G., Verdoes, M., Liu, H., Syed, S., Edgington, L. E., Gheysens, O., Miao, Z., Jiang, H., Gambhir, S. S., Bogyo, M., Cheng, Z. 2011; 6 (11)

  Abstract

  The papain family of cysteine cathepsins are actively involved in multiple stages of tumorigenesis. Because elevated cathepsin activity can be found in many types of human cancers, they are promising biomarkers that can be used to target radiological contrast agents for tumor detection. However, currently there are no radiological imaging agents available for these important molecular targets. We report here the development of positron emission tomography (PET) radionuclide-labeled probes that target the cysteine cathepsins by formation of an enzyme activity-dependent bond with the active site cysteine. These probes contain an acyloxymethyl ketone (AOMK) functional group that irreversibly labels the active site cysteine of papain family proteases attached to a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) tag for labeling with (64)Cu for PET imaging studies. We performed biodistribution and microPET imaging studies in nude mice bearing subcutaneous tumors expressing various levels of cysteine cathepsin activity and found that the extent of probe uptake by tumors correlated with overall protease activity as measured by biochemical methods. Furthermore, probe signals could be reduced by pre-treatment with a general cathepsin inhibitor. We also found that inclusion of a Cy5 tag on the probe increased tumor uptake relative to probes lacking this fluorogenic dye. Overall, these results demonstrate that small molecule activity-based probes carrying radio-tracers can be used to image protease activity in living subjects.

  View details for DOI 10.1371/journal.pone.0028029

  View details for Web of Science ID 000297789900039

  View details for PubMedID 22132198

  View details for PubMedCentralID PMC3221694

• Mathematical Model Identifies Blood Biomarker-Based Early Cancer Detection Strategies and Limitations SCIENCE TRANSLATIONAL MEDICINE Hori, S. S., Gambhir, S. S. 2011; 3 (109)

  Abstract

  Most clinical blood biomarkers lack the necessary sensitivity and specificity to reliably detect cancer at an early stage, when it is best treatable. It is not yet clear how early a clinical blood assay can be used to detect cancer or how biomarker-based strategies can be improved to enable earlier detection of smaller tumors. To address these issues, we developed a mathematical model describing dynamic plasma biomarker kinetics in relation to the growth of a tumor, beginning with a single cancer cell. To exemplify a realistic scenario in which biomarker is shed by both cancerous and noncancerous cells, we primed the model on ovarian tumor growth and CA125 shedding data, for which tumor growth parameters and shedding rates are readily available in published literature. We found that a tumor could grow unnoticed for more than 10.1 years and reach a volume of about π/6(25.36 mm)(3), corresponding to a spherical diameter of about 25.36 mm, before becoming detectable by current clinical blood assays. Model parameters were perturbed over log orders of magnitude to quantify ideal shedding rates and identify other blood-based strategies required for early submillimeter tumor detectability. The detection times we estimated are consistent with recently published tumor progression time lines based on clinical genomic sequencing data for several cancers. Here, we rigorously showed that shedding rates of current clinical blood biomarkers are likely 10(4)-fold too low to enable detection of a developing tumor within the first decade of tumor growth. The model presented here can be extended to virtually any solid cancer and associated biomarkers.

  View details for DOI 10.1126/scitranslmed.3003110

  View details for Web of Science ID 000297218300004

  View details for PubMedID 22089452

  View details for PubMedCentralID PMC3423335

• GLUT 5 Is Not Over-Expressed in Breast Cancer Cells and Patient Breast Cancer Tissues PLOS ONE Gowrishankar, G., Zitzmann-Kolbe, S., Junutula, A., Reeves, R., Levi, J., Srinivasan, A., Bruus-Jensen, K., Cyr, J., Dinkelborg, L., Gambhir, S. S. 2011; 6 (11)

  Abstract

  F18 2-Fluoro 2-deoxyglucose (FDG) has been the gold standard in positron emission tomography (PET) oncologic imaging since its introduction into the clinics several years ago. Seeking to complement FDG in the diagnosis of breast cancer using radio labeled fructose based analogs, we investigated the expression of the chief fructose transporter-GLUT 5 in breast cancer cells and human tissues. Our results indicate that GLUT 5 is not over-expressed in breast cancer tissues as assessed by an extensive immunohistochemistry study. RT-PCR studies showed that the GLUT 5 mRNA was present at minimal amounts in breast cancer cell lines. Further knocking down the expression of GLUT 5 in breast cancer cells using RNA interference did not affect the fructose uptake in these cell lines. Taken together these results are consistent with GLUT 5 not being essential for fructose uptake in breast cancer cells and tissues.

  View details for DOI 10.1371/journal.pone.0026902

  View details for Web of Science ID 000297154900052

  View details for PubMedID 22073218

  View details for PubMedCentralID PMC3206880

• A novel F-18-labeled two-helix scaffold protein for PET imaging of HER2-positive tumor EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Miao, Z., Ren, G., Jiang, L., Liu, H., Webster, J. M., Zhang, R., Namavari, M., Gambhir, S. S., Syud, F., Cheng, Z. 2011; 38 (11): 1977-1984

  Abstract

  Two-helix scaffold proteins (~ 5 kDa) against human epidermal growth factor receptor type 2 (HER2) have been discovered in our previous work. In this research we aimed to develop an (18)F-labeled two-helix scaffold protein for positron emission tomography (PET) imaging of HER2-positive tumors.An aminooxy-functionalized two-helix peptide (AO-MUT-DS) with high HER2 binding affinity was synthesized through conventional solid phase peptide synthesis. The purified linear peptide was cyclized by I(2) oxidation to form a disulfide bridge. The cyclic peptide was then conjugated with a radiofluorination synthon, 4-(18)F-fluorobenzyl aldehyde ((18)F-FBA), through the aminooxy functional group at the peptide N terminus (30% yield, non-decay corrected). The binding affinities of the peptides were analyzed by Biacore analysis. Cell uptake assay of the resulting PET probe, (18)F-FBO-MUT-DS, was performed at 37°C. (18)F-FBO-MUT-DS with high specific activity (20-32 MBq/nmol, 88-140 μCi/μg, end of synthesis) was injected into mice xenograft model bearing SKOV3 tumor. MicroPET and biodistribution and metabolic stability studies were then conducted.Cell uptake assays showed high and specific cell uptake (~12% applied activity at 1 h) by incubation of (18)F-FBO-MUT-DS with HER2 high-expressing SKOV3 ovarian cancer cells. The affinities (K(D)) of AO-MUT-DS and FBO-MUT-DS as tested by Biacore analysis were 2 and 1 nM, respectively. In vivo small animal PET demonstrated fast tumor targeting, high tumor accumulation, and good tumor to normal tissue contrast of (18)F-FBO-MUT-DS. Biodistribution studies further revealed that the probe had excellent tumor uptake (6.9%ID/g at 1 h post-injection) and was cleared through both liver and kidneys. Co-injection of the probe with 500 μg of HER2 Affibody protein reduced the tumor uptake (6.9 vs 1.8%ID/g, p < 0.05).F-FBO-MUT-DS displays excellent HER2 targeting ability and tumor PET imaging quality. The two-helix scaffold proteins are suitable for development of (18)F-based PET probes.

  View details for DOI 10.1007/s00259-011-1879-9

  View details for Web of Science ID 000295680200004

  View details for PubMedID 21761266

• Noninvasive cell-tracking methods NATURE REVIEWS CLINICAL ONCOLOGY Kircher, M. F., Gambhir, S. S., Grimm, J. 2011; 8 (11): 677-688

  Abstract

  Cell-based therapies, such as adoptive immunotherapy and stem-cell therapy, have received considerable attention as novel therapeutics in oncological research and clinical practice. The development of effective therapeutic strategies using tumor-targeted cells requires the ability to determine in vivo the location, distribution, and long-term viability of the therapeutic cell populations as well as their biological fate with respect to cell activation and differentiation. In conjunction with various noninvasive imaging modalities, cell-labeling methods, such as exogenous labeling or transfection with a reporter gene, allow visualization of labeled cells in vivo in real time, as well as monitoring and quantifying cell accumulation and function. Such cell-tracking methods also have an important role in basic cancer research, where they serve to elucidate novel biological mechanisms. In this Review, we describe the basic principles of cell-tracking methods, explain various approaches to cell tracking, and highlight recent examples for the application of such methods in animals and humans.

  View details for DOI 10.1038/nrclinonc.2011.141

  View details for Web of Science ID 000296812500009

  View details for PubMedID 21946842

• Endothelial Cells Derived From Human iPSCS Increase Capillary Density and Improve Perfusion in a Mouse Model of Peripheral Arterial Disease ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Rufaihah, A. J., Huang, N. F., Jame, S., Lee, J. C., Nguyen, H. N., Byers, B., De, A., Okogbaa, J., Rollins, M., Reijo-Pera, R., Gambhir, S. S., Cooke, J. P. 2011; 31 (11): E72-U44

  Abstract

  Stem cell therapy for angiogenesis and vascular regeneration has been investigated using adult or embryonic stem cells. In the present study, we investigated the potential of endothelial cells (ECs) derived from human induced pluripotent stem cells (hiPSCs) to promote the perfusion of ischemic tissue in a murine model of peripheral arterial disease.Endothelial differentiation was initiated by culturing hiPSCs for 14 days in differentiation media supplemented with BMP-4 and vascular endothelial growth factor. The hiPSC-ECs exhibited endothelial characteristics by forming capillary-like structures in matrigel and incorporating acetylated-LDL. They stained positively for EC markers such as KDR, CD31, CD144, and eNOS. In vitro exposure of hiPSC-ECs to hypoxia resulted in increased expression of various angiogenic related cytokines and growth factors. hiPSC-ECs were stably transduced with a double fusion construct encoded by the ubiquitin promoter, firefly luciferase for bioluminescence imaging and green fluorescence protein for fluorescent detection. The hiPSC-ECs (5×10(5)) were delivered by intramuscular injection into the ischemic hindlimb of SCID mice at day 0 and again on day 7 after femoral artery ligation (n=8). Bioluminescence imaging showed that hiPSC-ECs survived in the ischemic limb for at least 2 weeks. In addition, laser Doppler imaging showed that the ratio of blood perfusion was increased by hiPSC-EC treatment by comparison to the saline-treated group (0.58±0.12 versus 0.44±0.04; P=0.005). The total number of capillaries in the ischemic limb of mice receiving hiPSC-EC injections was greater than those in the saline-treated group (1284±155 versus 797±206 capillaries/mm(2)) (P<0.002).This study is a first step toward development of a regenerative strategy for peripheral arterial disease based on the use of ECs derived from hiPSCs.

  View details for DOI 10.1161/ATVBAHA.111.230938

  View details for PubMedID 21836062

• Theranostic nanomedicine. Accounts of chemical research Chen, X., Gambhir, S. S., Cheon, J. 2011; 44 (10): 841-?

  View details for DOI 10.1021/ar200231d

  View details for PubMedID 22004477

• Immobilizing Reporters for Molecular Imaging of the Extracellular Microenvironment in Living Animals ACS CHEMICAL BIOLOGY Xia, Z., Xing, Y., Jeon, J., Kim, Y., Gall, J., Dragulescu-Andrasi, A., Gambhir, S. S., Rao, J. 2011; 6 (10): 1117-1126

  Abstract

  We report here an immobilization strategy using a collagen binding protein to deliver and confine synthetic reporters to the extracellular microenvironment in vivo for noninvasively imaging the activity of targets in the microenvironment. We show that the immobilization of reporters on collagens in the local microenvironment is highly efficient and physiologically stable for repetitive, long-term imaging. By using this strategy we successfully developed an immobilized bioluminescent activatable reporter and a dual-modality reporter to map and quantitatively image the activity of extracellular matrix metalloproteinases (MMP) in tumor-bearing mice. The inhibition of MMP activity by chemical inhibitor was also demonstrated in living subjects. We further demonstrated the general applicability of this immobilization strategy by imaging MMP activity at the inflammation site in a mouse model. Our results show that the in vivo immobilization of reporters can be used as a general strategy for probing the local extracellular microenvironment.

  View details for DOI 10.1021/cb200135e

  View details for Web of Science ID 000296208100018

  View details for PubMedID 21830814

  View details for PubMedCentralID PMC3199358

• Molecular Imaging with Theranostic Nanoparticles ACCOUNTS OF CHEMICAL RESEARCH Jokerst, J. V., Gambhir, S. S. 2011; 44 (10): 1050-1060

  Abstract

  Nanoparticles (NPs) offer diagnostic and therapeutic capabilities not available with small molecules or microscale tools. As the field of molecular imaging has emerged from the blending of molecular biology with medical imaging, NP imaging is increasingly common for both therapeutic and diagnostic applications. The term theranostic describes technology with concurrent and complementary diagnostic and therapeutic capabilities. Although NPs have been FDA-approved for clinical use as transport vehicles for nearly 15 years, full translation of their theranostic potential is incomplete. However, NPs have shown remarkable success in the areas of drug delivery and magnetic resonance imaging. Emerging applications include image-guided resection, optical/photoacoustic imaging in vivo, contrast-enhanced ultrasound, and thermoablative therapy. Diagnosis with NPs in molecular imaging involves the correlation of the signal with a phenotype. The location and intensity of NP signals emanating from a living subject indicate the disease area's size, stage, and biochemical signature. Therapy with NPs uses the image for resection or delivery of a small molecule or RNA therapeutic. Ablation of the affected area is also possible via heat or radioactivity. The ideal theranostic NP includes several features: (1) it selectively and rapidly accumulates in diseased tissue; (2) it reports biochemical and morphological characteristics of the area; (3) it delivers an effective therapeutic; and (4) it is safe and biodegrades with nontoxic byproducts. Such a system contains a central imaging core surrounded by small molecule therapeutics. The system targets via ligands such as IgG and is protected from immune scavengers by a cloak of protective polymer. Although no NP has achieved all of the above criteria, many NPs possess one or more of these features. While the most clinically translatable NPs have been used in the field of magnetic resonance imaging, other types in development are quickly becoming more biocompatible through methods that modify their toxicity and biodistribution profiles. In this Account, we describe diagnostic imaging and therapeutic uses of NPs. We propose and offer examples of five primary types of nanoparticles with concurrent diagnostic and therapeutic uses.

  View details for DOI 10.1021/ar200106e

  View details for Web of Science ID 000296682400022

  View details for PubMedID 21919457

  View details for PubMedCentralID PMC3196845

• Synthesis of 2 '-Deoxy-2 '-[F-18]Fluoro-9-beta-D-Arabinofuranosylguanine: a Novel Agent for Imaging T-Cell Activation with PET MOLECULAR IMAGING AND BIOLOGY Namavari, M., Chang, Y., Kusler, B., Yaghoubi, S., Mitchell, B. S., Gambhir, S. S. 2011; 13 (5): 812-818

  Abstract

  9-(β-D-Arabinofuranosyl)guanine (AraG) is a guanosine analog that has a proven efficacy in the treatment of T-cell lymphoblastic disease. To test the possibility of using a radiofluorinated AraG as an imaging agent, we have synthesized 2'-deoxy-2'-[(18)F]fluoro-9-β-D-arabinofuranosylguanine ([(18)F]F-AraG) and investigated its uptake in T cells.We have synthesized [(18)F]F-AraG via a direct fluorination of 2-N-acetyl-6-O-((4-nitrophenyl)ethyl)-9-(3',5'-di-O-trityl-2'-O-trifyl-β-D-ribofuranosyl)guanine with [(18)F]KF/K.2.2.2 in DMSO at 85°C for 45 min. [(18)F]F-AraG uptake in both a CCRF-CEM leukemia cell line (unactivated) and activated primary thymocytes was evaluated.We have successfully prepared [(18)F]F-AraG in 7-10% radiochemical yield (decay corrected) with a specific activity of 0.8-1.3 Ci/μmol. Preliminary cell uptake experiments showed that both a CCRF-CEM leukemia cell line and activated primary thymocytes take up the [(18)F]F-AraG.For the first time to the best of our knowledge, [(18)F]F-AraG has been successfully synthesized by direct fluorination of an appropriate precursor of a guanosine nucleoside. This approach maybe also useful for the synthesis of other important positron emission tomography (PET) probes such as [(18)F]FEAU, [(18)F]FMAU, and [(18)F]FBAU w