Edward Graves

All Publications

• Radiotherapy in combination with CD47 blockade elicits a macrophage-mediated abscopal effect. Nature cancer Nishiga, Y., Drainas, A. P., Baron, M., Bhattacharya, D., Barkal, A. A., Ahrari, Y., Mancusi, R., Ross, J. B., Takahashi, N., Thomas, A., Diehn, M., Weissman, I. L., Graves, E. E., Sage, J. 2022

  Abstract

  Radiation therapy is a mainstay of cancer treatment but does not always lead to complete tumor regression. Here we combine radiotherapy with blockade of the 'don't-eat-me' cell-surface molecule CD47 in small cell lung cancer (SCLC), a highly metastatic form of lung cancer. CD47 blockade potently enhances the local antitumor effects of radiotherapy in preclinical models of SCLC. Notably, CD47 blockade also stimulates off-target 'abscopal' effects inhibiting non-irradiated SCLC tumors in mice receiving radiation. These abscopal effects are independent of T cells but require macrophages that migrate into non-irradiated tumor sites in response to inflammatory signals produced by radiation and are locally activated by CD47 blockade to phagocytose cancer cells. Similar abscopal antitumor effects were observed in other cancer models treated with radiation and CD47 blockade. The systemic activation of antitumor macrophages following radiotherapy and CD47 blockade may be particularly important in patients with cancer who suffer from metastatic disease.

  View details for DOI 10.1038/s43018-022-00456-0

  View details for PubMedID 36411318

• The role of granulocyte macrophage colony stimulating factor (GM-CSF) in radiation-induced tumor cell migration. Clinical & experimental metastasis Vilalta, M., Brune, J., Rafat, M., Soto, L., Graves, E. E. 2018

  Abstract

  Recently it has been observed in preclinical models that that radiation enhances the recruitment of circulating tumor cells to primary tumors, and results in tumor regrowth after treatment. This process may have implications for clinical radiotherapy, which improves control of a number of tumor types but which, despite continued dose escalation and aggressive fractionation, is unable to fully prevent local recurrences. By irradiating a single tumor within an animal bearing multiple lesions, we observed an increase in tumor cell migration to irradiated and unirradiated sites, suggesting a systemic component to this process. Previous work has identified the cytokine GM-CSF, produced by tumor cells following irradiation, as a key effector of this process. We evaluated the ability of systemic injections of a PEGylated form of GM-CSF to stimulate tumor cell migration. While increases in invasion and migration were observed for tumor cells in a transwell assay, we found that daily injections of PEG-GM-CSF to tumor-bearing animals did not increase migration of cells to tumors, despite the anticipated changes in circulating levels of granulocytes and monocytes produced by this treatment. Combination of PEG-GM-CSF treatment with radiation also did not increase tumor cell migration. These findings suggest that clinical use of GM-CSF to treat neutropenia in cancer patients will not have negative effects on the aggressiveness of residual cancer cells. However, further work is needed to characterize the mechanism by which GM-CSF facilitates systemic recruitment of trafficking tumor cells to tumors.

  View details for PubMedID 29536224

• Macrophages Promote Circulating Tumor Cell-Mediated Local Recurrence Following Radiation Therapy in Immunosuppressed Patients. Cancer research Rafat, M. n., Aguilera, T. A., Vilalta, M. n., Bronsart, L. L., Soto, L. A., von Eyben, R. n., Golla, M. A., Ahrari, Y. n., Melemenidis, S. n., Afghahi, A. n., Jenkins, M. J., Kurian, A. W., Horst, K. n., Giaccia, A. J., Graves, E. E. 2018

  Abstract

  Although radiation therapy (RT) decreases the incidence of locoregional recurrence in breast cancer, patients with triple-negative breast cancer (TNBC) have increased risk of local recurrence following breast-conserving therapy (BCT). The relationship between RT and local recurrence is unknown. Here we tested the hypothesis that recurrence in some instances is due to the attraction of circulating tumor cells to irradiated tissues. To evaluate the effect of absolute lymphocyte count on local recurrence after RT in TNBC patients, we analyzed radiation effects on tumor and immune cell recruitment to tissues in an orthotopic breast cancer model. Recurrent patients exhibited a prolonged low absolute lymphocyte count when compared to non-recurrent patients following RT. Recruitment of tumor cells to irradiated normal tissues was enhanced in the absence of CD8+ T cells. Macrophages (CD11b+F480+) preceded tumor cell infiltration and were recruited to tissues following RT. Tumor cell recruitment was mitigated by inhibiting macrophage infiltration using maraviroc, an FDA-approved CCR5 receptor antagonist. Our work poses the intriguing possibility that excessive macrophage infiltration in the absence of lymphocytes promotes local recurrence after RT. This combination thus defines a high-risk group of TNBC patients.

  View details for PubMedID 29880480

• 18F-EF5 PET-based Imageable Hypoxia Predicts Local Recurrence in Tumors Treated With Highly Conformal Radiation Therapy. International journal of radiation oncology, biology, physics Qian, Y. n., Von Eyben, R. n., Liu, Y. n., Chin, F. T., Miao, Z. n., Apte, S. n., Carter, J. N., Binkley, M. S., Pollom, E. L., Harris, J. P., Prionas, N. D., Kissel, M. n., Simmons, A. n., Diehn, M. n., Shultz, D. B., Brown, J. M., Maxim, P. G., Koong, A. C., Graves, E. E., Loo, B. W. 2018

  Abstract

  Tumor hypoxia contributes to radiation resistance. A noninvasive assessment of tumor hypoxia would be valuable for prognostication and possibly selection for hypoxia-targeted therapies. 18F-pentafluorinated etanidazole (18F-EF5) is a nitroimidazole derivative that has demonstrated promise as a positron emission tomography (PET) hypoxia imaging agent in preclinical and clinical studies. However, correlation of imageable hypoxia by 18F-EF5 PET with clinical outcomes after radiation therapy remains limited.Our study prospectively enrolled 28 patients undergoing radiation therapy for localized lung or other tumors to receive pretreatment 18F-EF5 PET imaging. Depending on the level of 18F-EF5 tumor uptake, patients underwent functional manipulation of tumor oxygenation with either carbogen breathing or oral dichloroacetate followed by repeated 18F-EF5 PET. The hypoxic subvolume of tumor was defined as the proportion of tumor voxels exhibiting higher 18F-EF5 uptake than the 95th percentile of 18F-EF5 uptake in the blood pool. Tumors with a hypoxic subvolume ≥ 10% on baseline 18F-EF5 PET imaging were classified as hypoxic by imaging. A Cox model was used to assess the correlation between imageable hypoxia and clinical outcomes after treatment.At baseline, imageable hypoxia was demonstrated in 43% of all patients (12 of 28), including 6 of 16 patients with early-stage non-small cell lung cancer treated with stereotactic ablative radiation therapy and 6 of 12 patients with other cancers. Carbogen breathing was significantly associated with decreased imageable hypoxia, while dichloroacetate did not result in a significant change under our protocol conditions. Tumors with imageable hypoxia had a higher incidence of local recurrence at 12 months (30%) than those without (0%) (P < .01).Noninvasive hypoxia imaging by 18F-EF5 PET identified imageable hypoxia in about 40% of tumors in our study population. Local tumor recurrence after highly conformal radiation therapy was higher in tumors with imageable hypoxia.

  View details for PubMedID 29859786

• Reprogramming the immunological microenvironment through radiation and targeting Axl NATURE COMMUNICATIONS Aguilera, T. A., Rafat, M., Castellini, L., Shehade, H., Kariolis, M. S., Hui, A. B., Stehr, H., von Eyben, R., Jiang, D., Ellies, L. G., Koong, A. C., Diehn, M., Rankin, E. B., Graves, E. E., Giaccia, A. J. 2016; 7

  Abstract

  Increasing evidence suggests that ionizing radiation therapy (RT) in combination with checkpoint immunotherapy is highly effective in treating a subset of cancers. To better understand the limited responses to this combination we analysed the genetic, microenvironmental, and immune factors in tumours derived from a transgenic breast cancer model. We identified two tumours with similar growth characteristics but different RT responses primarily due to an antitumour immune response. The combination of RT and checkpoint immunotherapy resulted in cures in the responsive but not the unresponsive tumours. Profiling the tumours revealed that the Axl receptor tyrosine kinase is overexpressed in the unresponsive tumours, and Axl knockout resulted in slower growth and increased radiosensitivity. These changes were associated with a CD8(+) T-cell response, which was improved in combination with checkpoint immunotherapy. These results suggest a novel role for Axl in suppressing antigen presentation through MHCI, and enhancing cytokine release, which promotes a suppressive myeloid microenvironment.

  View details for DOI 10.1038/ncomms13898

  View details for Web of Science ID 000390399500001

  View details for PubMedID 28008921

  View details for PubMedCentralID PMC5196438

• 18F-EF5 PET Is Predictive of Response to Fractionated Radiotherapy in Preclinical Tumor Models. PloS one Ali, R., Apte, S., Vilalta, M., Subbarayan, M., Miao, Z., Chin, F. T., Graves, E. E. 2015; 10 (10)

  Abstract

  We evaluated the relationship between pre-treatment positron emission tomography (PET) using the hypoxic tracer 18F-[2-(2-nitro-1-H-imidazol-1-yl)-N-(2,2,3,3,3- pentafluoropropyl) acetamide] (18F-EF5) and the response of preclinical tumor models to a range of fractionated radiotherapies. Subcutaneous HT29, A549 and RKO tumors grown in nude mice were imaged using 18F-EF5 positron emission tomography (PET) in order to characterize the extent and heterogeneity of hypoxia in these systems. Based on these results, 80 A549 tumors were subsequently grown and imaged using 18F-EF5 PET, and then treated with one, two, or four fraction radiation treatments to a total dose of 10-40 Gy. Response was monitored by serial caliper measurements of tumor volume. Longitudinal post-treatment 18F-EF5 PET imaging was performed on a subset of tumors. Terminal histologic analysis was performed to validate 18F-EF5 PET measures of hypoxia. EF5-positive tumors responded more poorly to low dose single fraction irradiation relative to EF5-negative tumors, however both groups responded similarly to larger single fraction doses. Irradiated tumors exhibited reduced 18F-EF5 uptake one month after treatment compared to control tumors. These findings indicate that pre- treatment 18F-EF5 PET can predict the response of tumors to single fraction radiation treatment. However, increasing the number of fractions delivered abrogates the difference in response between tumors with high and low EF5 uptake pre-treatment, in agreement with traditional radiobiology.

  View details for DOI 10.1371/journal.pone.0139425

  View details for PubMedID 26431331

• Recruitment of circulating breast cancer cells is stimulated by radiotherapy. Cell reports Vilalta, M., Rafat, M., Giaccia, A. J., Graves, E. E. 2014; 8 (2): 402-409

  Abstract

  Radiotherapy (RT) is a localized therapy that is highly effective in killing primary tumor cells located within the field of the radiation beam. We present evidence that irradiation of breast tumors can attract migrating breast cancer cells. Granulocyte-macrophage colony stimulating factor (GM-CSF) produced by tumor cells in response to radiation stimulates the recruitment of migrating tumor cells to irradiated tumors, suggesting a mechanism of tumor recurrence after radiation facilitated by transit of unirradiated, viable circulating tumor cells to irradiated tumors. Data supporting this hypothesis are presented through in vitro invasion assays and in vivo orthotopic models of breast cancer. Our work provides a mechanism for tumor recurrence in which RT attracts cells outside the radiation field to migrate to the site of treatment.

  View details for DOI 10.1016/j.celrep.2014.06.011

  View details for PubMedID 25017065

  View details for PubMedCentralID PMC4121080

• Hypoxia in Models of Lung Cancer: Implications for Targeted Therapeutics CLINICAL CANCER RESEARCH Graves, E. E., Vilalta, M., Cecic, I. K., Erler, J. T., Tran, P. T., Felsher, D., Sayles, L., Sweet-Cordero, A., Le, Q., Giaccia, A. J. 2010; 16 (19): 4843-4852

  Abstract

  To efficiently translate experimental methods from bench to bedside, it is imperative that laboratory models of cancer mimic human disease as closely as possible. In this study, we sought to compare patterns of hypoxia in several standard and emerging mouse models of lung cancer to establish the appropriateness of each for evaluating the role of oxygen in lung cancer progression and therapeutic response.Subcutaneous and orthotopic human A549 lung carcinomas growing in nude mice as well as spontaneous K-ras or Myc-induced lung tumors grown in situ or subcutaneously were studied using fluorodeoxyglucose and fluoroazomycin arabinoside positron emission tomography, and postmortem by immunohistochemical observation of the hypoxia marker pimonidazole. The response of these models to the hypoxia-activated cytotoxin PR-104 was also quantified by the formation of γH2AX foci in vitro and in vivo. Finally, our findings were compared with oxygen electrode measurements of human lung cancers.Minimal fluoroazomycin arabinoside and pimonidazole accumulation was seen in tumors growing within the lungs, whereas subcutaneous tumors showed substantial trapping of both hypoxia probes. These observations correlated with the response of these tumors to PR-104, and with the reduced incidence of hypoxia in human lung cancers relative to other solid tumor types.These findings suggest that in situ models of lung cancer in mice may be more reflective of the human disease, and encourage judicious selection of preclinical tumor models for the study of hypoxia imaging and antihypoxic cell therapies.

  View details for DOI 10.1158/1078-0432.CCR-10-1206

  View details for Web of Science ID 000282647900017

  View details for PubMedID 20858837

  View details for PubMedCentralID PMC2948600

• DEVELOPMENT OF A MICRO-COMPUTED TOMOGRAPHY-BASED IMAGE-GUIDED CONFORMAL RADIOTHERAPY SYSTEM FOR SMALL ANIMALS INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Zhou, H., Rodriguez, M., van den Haak, F., Nelson, G., Jogani, R., Xu, J., Zhu, X., Xian, Y., Tran, P. T., Felsher, D. W., Keall, P. J., Graves, E. E. 2010; 78 (1): 297-305

  Abstract

  To report on the physical aspects of a system in which radiotherapy functionality was added to a micro-computed tomography (microCT) scanner, to evaluate the accuracy of this instrument, and to and demonstrate the application of this technology for irradiating tumors growing within the lungs of mice.A GE eXplore RS120 microCT scanner was modified by the addition of a two-dimensional subject translation stage and a variable aperture collimator. Quality assurance protocols for these devices, including measurement of translation stage positioning accuracy, collimator aperture accuracy, and collimator alignment with the X-ray beam, were devised. Use of this system for image-guided radiotherapy was assessed by irradiation of a solid water phantom as well as of two mice bearing spontaneous MYC-induced lung tumors. Radiation damage was assessed ex vivo by immunohistochemical detection of gammaH2AX foci.The positioning error of the translation stage was found to be <0.05 mm, whereas after alignment of the collimator with the X-ray axis through adjustment of its displacement and rotation, the collimator aperture error was <0.1 mm measured at isocenter. Computed tomography image-guided treatment of a solid water phantom demonstrated target localization accuracy to within 0.1 mm. Gamma-H2AX foci were detected within irradiated lung tumors in mice, with contralateral lung tissue displaying background staining.Addition of radiotherapy functionality to a microCT scanner is an effective means of introducing image-guided radiation treatments into the preclinical setting. This approach has been shown to facilitate small-animal conformal radiotherapy while leveraging existing technology.

  View details for DOI 10.1016/j.ijrobp.2009.11.008

  View details for Web of Science ID 000281304600041

  View details for PubMedID 20395069

  View details for PubMedCentralID PMC2906632

• RT_Image: An open-source tool for investigating PET in radiation oncology TECHNOLOGY IN CANCER RESEARCH & TREATMENT Graves, E. E., Quon, A., Loo, B. W. 2007; 6 (2): 111-121

  Abstract

  Positron emission tomography (PET) has emerged as a valuable imaging modality for the diagnosis and staging of cancer. However, despite evidence that PET may be useful for defining target volumes for radiation therapy, no standardized methodology for accomplishing this task exists. To facilitate the investigation of the utility of PET imaging in radiotherapy treatment planning and accelerate its integration into clinical radiation oncology, we have developed software for exploratory analysis and segmentation of functional imaging datasets. The application, RT_Image, allows display of multiple imaging datasets and associated three-dimensional regions-of-interest (ROIs) at arbitrary view angles and fields of view. It also includes semi-automated image segmentation tools for defining metabolically active tumor volumes that may aid creation of target volumes for treatment planning. RT_Image is DICOM compliant, permitting the transfer of imaging data and DICOM-RT structure sets between the application and treatment planning software. RT_Image has been used by radiation oncologists, nuclear medicine physicians, and radiation physicists to analyze over 200 PET datasets. Novel segmentation techniques have been implemented within this programming framework for therapy planning and for evaluation of molecular imaging-derived parameters as prognostic indicators. RT_Image represents a freely-available software base on which further investigations of the utlity of PET and molecular imaging in radiation oncology may be built. The development of tools such as this is critical in order to realize the potential of molecular imaging-guided radiation therapy.

  View details for Web of Science ID 000245969900007

  View details for PubMedID 17375973

• Gold-siRNA supraclusters enhance the anti-tumor immune response of stereotactic ablative radiotherapy at primary and metastatic tumors. Nature biotechnology Jiang, Y., Cao, H., Deng, H., Guan, L., Langthasa, J., Colburg, D. R., Melemenidis, S., Cotton, R. M., Aleman, J., Wang, X. J., Graves, E. E., Kalbasi, A., Pu, K., Rao, J., Le, Q. T. 2024

  Abstract

  Strategies to enhance the anti-tumor immune response of stereotactic ablative radiotherapy (SABR) at primary tumors and abscopal sites are under intensive investigation. Here we report a metabolizable binary supracluster (BSCgal) that combines gold nanoclusters as radiosensitizing adjuvants with small interfering RNA (siRNA) targeting the immunosuppressive mediator galectin-1 (Gal-1). BSCgal comprises reversibly crosslinked cationic gold nanoclusters and siRNA complexes in a polymer matrix that biodegrades over weeks, facilitating clearance (90.3% in vivo clearance at 4 weeks) to reduce toxicity. The particle size well above the renal filtration threshold facilitates passive delivery to tumors. Using mouse models of head and neck cancer, we show that BSCgal augments the radiodynamic and immunotherapeutic effects of SABR at the primary and metastatic tumors by promoting tumor-inhibitory leukocytes, upregulating cytotoxic granzyme B and reducing immunosuppressive cell populations. It outperforms SABR plus Gal-1 antagonists, chemoradiation drug cisplatin or PD-1 inhibitor. This work presents a translatable strategy to converge focal radiosensitization with targeted immune checkpoint silencing for personalized radioimmunotherapy.

  View details for DOI 10.1038/s41587-024-02448-0

  View details for PubMedID 39448881

  View details for PubMedCentralID 6053911

• Dosimetric calibration of anatomy-specific ultra-high dose rate electron irradiation platform for preclinical FLASH radiobiology experiments. Medical physics Wang, J., Melemenidis, S., Manjappa, R., Viswanathan, V., Ashraf, R. M., Levy, K., Skinner, L. B., Soto, L. A., Chow, S., Lau, B., Ko, R. B., Graves, E. E., Yu, A. S., Bush, K. K., Surucu, M., Rankin, E. B., Loo, B. W., Schüler, E., Maxim, P. G. 2024

  Abstract

  FLASH radiation therapy (RT) offers a promising avenue for the broadening of the therapeutic index. However, to leverage the full potential of FLASH in the clinical setting, an improved understanding of the biological principles involved is critical. This requires the availability of specialized equipment optimized for the delivery of conventional (CONV) and ultra-high dose rate (UHDR) irradiation for preclinical studies. One method to conduct such preclinical radiobiological research involves adapting a clinical linear accelerator configured to deliver both CONV and UHDR irradiation.We characterized the dosimetric properties of a clinical linear accelerator configured to deliver ultra-high dose rate irradiation to two anatomic sites in mice and for cell-culture FLASH radiobiology experiments.Delivered doses of UHDR electron beams were controlled by a microcontroller and relay interfaced with the respiratory gating system. We also produced beam collimators with indexed stereotactic mouse positioning devices to provide anatomically specific preclinical treatments. Treatment delivery was monitored directly with an ionization chamber, and charge measurements were correlated with radiochromic film measurements at the entry surface of the mice. The setup for conventional dose rate irradiation utilized the same collimation system but at increased source-to-surface distance. Monte Carlo simulations and film dosimetry were used to characterize beam properties and dose distributions.The mean electron beam energies before the flattening filter were 18.8 MeV (UHDR) and 17.7 MeV (CONV), with corresponding values at the mouse surface of 17.2 and 16.2 MeV. The charges measured with an external ion chamber were linearly correlated with the mouse entrance dose. The use of relay gating for pulse control initially led to a delivery failure rate of 20% (± 1 pulse); adjustments to account for the linac latency improved this rate to < 1/20. Beam field sizes for two anatomically specific mouse collimators (4 × 4 cm2 for whole-abdomen and 1.5 × 1.5 cm2 for unilateral lung irradiation) were accurate within < 5% and had low radiation leakage (< 4%). Normalizing the dose at the center of the mouse (∼0.75 cm depth) produced UHDR and CONV doses to the irradiated volumes with > 95% agreement.We successfully configured a clinical linear accelerator for increased output and developed a robust preclinical platform for anatomically specific irradiation, with highly accurate and precise temporal and spatial dose delivery, for both CONV and UHDR irradiation applications.

  View details for DOI 10.1002/mp.17432

  View details for PubMedID 39331834

• Multi-Institutional Audit of FLASH and Conventional Dosimetry with a 3D-Printed Anatomically Realistic Mouse Phantom. International journal of radiation oncology, biology, physics Ashraf, M. R., Melemenidis, S., Liu, K., Grilj, V., Jansen, J., Velasquez, B., Connell, L., Schulz, J. B., Bailat, C., Libed, A., Manjappa, R., Dutt, S., Soto, L., Lau, B., Garza, A., Larsen, W., Skinner, L., Yu, A. S., Surucu, M., Graves, E. E., Maxim, P. G., Kry, S. F., Vozenin, M. C., Schüler, E., Loo, B. W. 2024

  Abstract

  We conducted a multi-institutional dosimetric audit between FLASH and conventional dose rate (CONV) electron irradiations by using an anatomically realistic 3D-printed mouse phantom.A CT scan of a live mouse was used to create a 3D model of bony anatomy, lungs, and soft tissue. A dual-nozzle 3D printer was used to print the mouse phantom using acrylonitrile butadiene styrene (∼1.02 g/cm3) and polylactic acid (∼1.24 g/cm3) simultaneously to simulate soft tissue and bone densities, respectively. The lungs were printed separately using lightweight polylactic acid (∼0.64 g/cm3). Hounsfield units (HU), densities and print-to-print stability of the phantoms were assessed. Three institutions were each provided a phantom, and each institution performed two replicates of irradiations at selected anatomic regions. The average dose difference between FLASH and CONV dose distributions and deviation from the prescribed dose were measured with radiochromic film.Compared to the reference CT scan, CT scans of the phantom demonstrated mass density differences of 0.10 g/cm3 for bone, 0.12 g/cm3 for lung, and 0.03 g/cm3 for soft tissue regions. Differences in HU between phantoms were <10 HU for soft tissue and bone, with lung showing the most variation (54 HU), but with minimal impact on dose distribution (<0.5%). Mean differences between FLASH and CONV decreased from the first to the second replicate (4.3% to 1.2%), while differences from the prescribed dose decreased for both CONV (3.6% to 2.5%) and FLASH (6.4% to 2.7%). Total dose accuracy suggests consistent pulse dose and pulse number, though these were not specifically assessed. Positioning variability was observed, likely due to the absence of robust positioning aids or image guidance.This study marks the first dosimetric audit for FLASH using a non-homogeneous phantom, challenging conventional calibration practices reliant on homogeneous phantoms. The comparison protocol offers a framework for credentialing multi-institutional studies in FLASH preclinical research to enhance reproducibility of biological findings.

  View details for DOI 10.1016/j.ijrobp.2024.03.017

  View details for PubMedID 38493902

• Exploring deep learning for estimating the isoeffective dose of FLASH irradiation from mouse intestinal histology images. International journal of radiation oncology, biology, physics Fu, J., Yang, Z., Melemenidis, S., Viswanathan, V., Dutt, S., Manjappa, R., Lau, B., Soto, L. A., Ashraf, R., Skinner, L., Yu, S. J., Surucu, M., Casey, K. M., Rankin, E. B., Graves, E., Lu, W., Loo, B. W., Gu, X. 2024

  Abstract

  Ultra-high dose rate (FLASH) irradiation has been reported to reduce normal tissue damage compared with conventional dose rate (CONV) irradiation without compromising tumor control. This proof-of-concept study aims to develop a deep learning (DL) approach to quantify the FLASH isoeffective dose (dose of CONV that would be required to produce the same effect as the given physical FLASH dose) with post-irradiation mouse intestinal histological images.84 healthy C57BL/6J female mice underwent 16 MeV electron CONV (0.12Gy/s; n=41) or FLASH (200Gy/s; n=43) single fraction whole abdominal irradiation. Physical dose ranged from 12 to 16Gy for FLASH and 11 to 15Gy for CONV in 1Gy increments. 4 days after irradiation, 9 jejunum cross-sections from each mouse were H&E stained and digitized for histological analysis. CONV dataset was randomly split into training (n=33) and testing (n=8) datasets. ResNet101-based DL models were retrained using the CONV training dataset to estimate the dose based on histological features. The classical manual crypt counting (CC) approach was implemented for model comparison. Cross-section-wise mean squared error (CS-MSE) was computed to evaluate the dose estimation accuracy of both approaches. The validated DL model was applied to the FLASH dataset to map the physical FLASH dose into the isoeffective dose.The DL model achieved a CS-MSE of 0.20Gy2 on the CONV testing dataset compared with 0.40Gy2 of the CC approach. Isoeffective doses estimated by the DL model for FLASH doses of 12, 13, 14, 15, and 16 Gy were 12.19±0.46, 12.54±0.37, 12.69±0.26, 12.84±0.26, and 13.03±0.28 Gy, respectively.Our proposed DL model achieved accurate CONV dose estimation. The DL model results indicate that in the physical dose range of 13 to 16 Gy, the biological dose response of small intestinal tissue to FLASH irradiation is represented by a lower isoeffective dose compared to the physical dose. Our DL approach can be a tool for studying isoeffective doses of other radiation dose modifying interventions.

  View details for DOI 10.1016/j.ijrobp.2023.12.032

  View details for PubMedID 38171387

• Improving radiotherapy in immunosuppressive microenvironments by targeting complement receptor C5aR1. The Journal of clinical investigation Beach, C., MacLean, D., Majorova, D., Melemenidis, S., Nambiar, D. K., Kim, R. K., Valbuena, G. N., Guglietta, S., Krieg, C., Darvish-Damavandi, M., Suwa, T., Easton, A., Hillson, L. V., McCulloch, A. K., McMahon, R. K., Pennel, K., Edwards, J., O'Cathail, S. M., Roxburgh, C. S., Domingo, E., Moon, E. J., Jiang, D., Jiang, Y., Zhang, Q., Koong, A. C., Woodruff, T. M., Graves, E. E., Maughan, T., Buczacki, S. J., Stucki, M., Le, Q. T., Leedham, S. J., Giaccia, A. J., Olcina, M. M. 2023

  Abstract

  An immunosuppressive microenvironment causes poor tumour T-cell infiltration and is associated with reduced patient overall survival in colorectal cancer. How to improve treatment responses in these tumours is still a challenge. Using an integrated screening approach to identify cancer-specific vulnerabilities, we identified complement receptor C5aR1 as a druggable target which when inhibited improved radiotherapy even in tumours displaying immunosuppressive features and poor CD8+ T-cell infiltration. While C5aR1 is well-known for its role in the immune compartment, we found that C5aR1 is also robustly expressed on malignant epithelial cells, highlighting potential tumour-cell specific functions. C5aR1 targeting resulted in increased NF-kB-dependent apoptosis specifically in tumours and not normal tissues; indicating that in malignant cells, C5aR1 primarily regulated cell fate. Collectively, these data revealed that increased complement gene expression is part of the stress response mounted by irradiated tumours and that targeting C5aR1 could improve radiotherapy even in tumours displaying immunosuppressive features.

  View details for DOI 10.1172/JCI168277

  View details for PubMedID 37824211

• Rapid recruitment and IFN-I-mediated activation of monocytes dictate focal radiotherapy efficacy. Science immunology Tadepalli, S., Clements, D. R., Saravanan, S., Arroyo Hornero, R., Lüdtke, A., Blackmore, B., Paulo, J. A., Gottfried-Blackmore, A., Seong, D., Park, S., Chan, L., Kopecky, B. J., Liu, Z., Ginhoux, F., Lavine, K. J., Murphy, J. P., Mack, M., Graves, E. E., Idoyaga, J. 2023; 8 (84): eadd7446

  Abstract

  The recruitment of monocytes and their differentiation into immunosuppressive cells is associated with the low efficacy of preclinical nonconformal radiotherapy (RT) for tumors. However, nonconformal RT (non-CRT) does not mimic clinical practice, and little is known about the role of monocytes after RT modes used in patients, such as conformal RT (CRT). Here, we investigated the acute immune response induced by after CRT. Contrary to non-CRT approaches, we found that CRT induces a rapid and robust recruitment of monocytes to the tumor that minimally differentiate into tumor-associated macrophages or dendritic cells but instead up-regulate major histocompatibility complex II and costimulatory molecules. We found that these large numbers of infiltrating monocytes are responsible for activating effector polyfunctional CD8+ tumor-infiltrating lymphocytes that reduce tumor burden. Mechanistically, we show that monocyte-derived type I interferon is pivotal in promoting monocyte accumulation and immunostimulatory function in a positive feedback loop. We also demonstrate that monocyte accumulation in the tumor microenvironment is hindered when RT inadvertently affects healthy tissues, as occurs in non-CRT. Our results unravel the immunostimulatory function of monocytes during clinically relevant modes of RT and demonstrate that limiting the exposure of healthy tissues to radiation has a positive therapeutic effect on the overall antitumor immune response.

  View details for DOI 10.1126/sciimmunol.add7446

  View details for PubMedID 37294749

• Clinical LINAC-based electron FLASH: Pathway for practical translation to FLASH clinical trials: LINAC electron FLASH. International journal of radiation oncology, biology, physics No, H. J., Wu, Y. F., Dworkin, M. L., Manjappa, R., Skinner, L., Ashraf, M. R., Lau, B., Melemenidis, S., Viswanathan, V., Yu, A. S., Surucu, M., Schüler, E., Graves, E. E., Maxim, P. G., Loo, B. W. 2023

  Abstract

  Ultra-high dose rate (UHDR) radiotherapy (RT) has produced the FLASH effect in preclinical models: reduced toxicity with comparable tumor control compared to conventional dose rate RT. Early clinical trials focused on UHDR RT feasibility using specialized devices. We explore the technical feasibility of practical electron UHDR RT on a standard clinical linear accelerator (LINAC).We tuned the program board of a decommissioned electron energy for UHDR electron delivery on a clinical LINAC, without hardware modification. Pulse delivery was controlled using the respiratory gating interface. A short SSD electron set-up with a standard scattering foil was configured and tested on an anthropomorphic phantom using circular blocks with 3-20 cm field sizes. Dosimetry was evaluated using radiochromic film and an ion chamber profiler.UHDR open field mean dose rates at 100, 80, 70, and 59 cm SSD were 36.82, 59.52, 82.01, and 112.83 Gy/s, respectively. At 80 cm SSD, mean dose rate was ∼60 Gy/s for all collimated field sizes, with an R80 depth of 6.1 cm corresponding to an energy of 17.5 MeV. Heterogeneity was <5.0% with asymmetry of 2.2 to 6.2%. The short SSD set-up was feasible under realistic treatment conditions simulating broad clinical indications on an anthropomorphic phantom.Short SSD and tuning for high electron beam current on a standard clinical LINAC can deliver flat, homogenous UHDR electrons over a broad, clinically relevant range of field sizes and depths with practical working distances, in a configuration easily reversible to standard clinical use.

  View details for DOI 10.1016/j.ijrobp.2023.04.011

  View details for PubMedID 37105403

• Technical Note: Non-Invasive monitoring of normal tissue radiation damage using spectral quantitative ultrasound spectroscopy. Medical physics Rafat, M., Kaffas, A. E., Swarnakar, A., Shostak, A., Graves, E. E. 2022

  Abstract

  BACKGROUND: While radiation therapy (RT) is a critical component of breast cancer therapy and is known to decrease overall local recurrence rates, recent studies have shown that normal tissue radiation damage may increase recurrence risk. Fibrosis is a well-known consequence of RT, but the specific sequence of molecular and mechanical changes induced by RT remains poorly understood.PURPOSE: To improve cancer therapy outcomes, there is a need to understand the role of the irradiated tissue microenvironment in tumor recurrence. This study seeks to evaluate the use of spectral quantitative ultrasound (spectral QUS) for real time determination of the normal tissue characteristic radiation response and to correlate these results to molecular features in irradiated tissues.METHODS: Murine mammary fat pads (MFPs) were irradiated to 20 Gy, and spectral QUS was used to analyze tissue physical properties pre-irradiation as well as at 1, 5, and 10 days post-irradiation. Tissues were processed for scanning electron microscopy imaging as well as histological and immunohistochemical staining to evaluate morphology and structure.RESULTS: Tissue morphological and structural changes were observed non-invasively following radiation using mid-band fit (MBF), spectral slope (SS), and spectral intercept (SI) measurements obtained from spectral QUS. Statistically significant shifts in MBF and SI indicate structural tissue changes in real time, which matched histological observations. Radiation damage was indicated by increased adipose tissue density and extracellular matrix (ECM) deposition.CONCLUSIONS: Our findings demonstrate the potential of using spectral QUS to non-invasively evaluate normal tissue changes resulting from radiation damage. This supports further pre-clinical studies to determine how the tissue microenvironment and physical properties change in response to therapy, which may be important for improving treatment strategies. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/mp.16184

  View details for PubMedID 36564922

• Design and validation of a dosimetric comparison scheme tailored for ultra-high dose-rate electron beams to support multicenter FLASH preclinical studies. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology Gonçalves Jorge, P., Melemenidis, S., Grilj, V., Buchillier, T., Manjappa, R., Viswanathan, V., Gondré, M., Vozenin, M. C., Germond, J. F., Bochud, F., Moeckli, R., Limoli, C., Skinner, L., Joshua No, H., Fred Wu, Y., Surucu, M., Yu, A. S., Lau, B., Wang, J., Schüler, E., Bush, K., Graves, E. E., Maxim, P. G., Loo, B. W., Bailat, C. 2022

  Abstract

  We describe a multicenter cross validation of ultra-high dose rate (UHDR) (>= 40 Gy/s) irradiation in order to bring a dosimetric consensus in absorbed dose to water. UHDR refers to dose rates over 100-1000 times those of conventional clinical beams. UHDR irradiations have been a topic of intense investigation as they have been reported to induce the FLASH effect in which normal tissues exhibit reduced toxicity relative to conventional dose rates. The need to establish optimal beam parameters capable of achieving the in vivo FLASH effect has become paramount. It is therefore necessary to validate and replicate dosimetry across multiple sites conducting UHDR studies with distinct beam configurations and experimental set-ups.Using a custom cuboid phantom with a cylindrical cavity (5 mm diameter by 10.4 mm length) designed to contain three type of dosimeters (thermoluminescent dosimeters (TLDs), alanine pellets, and Gafchromic films), irradiations were conducted at expected doses of 7.5 to 16 Gy delivered at UHDR or conventional dose rates using various electron beams at the Radiation Oncology Departments of the CHUV in Lausanne, Switzerland and Stanford University, CA.Data obtained between replicate experiments for all dosimeters were in excellent agreement (+/- 3 %). In general, films and TLDs were in closer agreement with each other, while alanine provided the closest match between the expected and measured dose, with certain caveats related to absolute reference dose.In conclusion, successful cross-validation of different electron beams operating under different energies and configurations lays the foundation for establishing dosimetric consensus for UHDR irradiation studies, and, if widely implemented, decrease uncertainty between different sites investigating the mechanistic basis of the FLASH effect.

  View details for DOI 10.1016/j.radonc.2022.08.023

  View details for PubMedID 36030934

• Real-time optical oximetry during FLASH radiotherapy using a phosphorescent nanoprobe. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology Ha, B., Liang, K., Liu, C., Melemenidis, S., Manjappa, R., Viswanathan, V., Das, N., Ashraf, R., Lau, B., Soto, L., Graves, E. E., Rao, J., Loo, B. W., Pratx, G. 2022

  Abstract

  The rapid depletion of oxygen during irradiation at ultra-high dose rate calls for tissue oximeters capable of high temporal resolution. This study demonstrates a water-soluble phosphorescent nanoprobe and fiber-coupled instrument, which together are used to measure the kinetics of oxygen depletion at 200 Hz during irradiation of in vitro solutions.

  View details for DOI 10.1016/j.radonc.2022.08.011

  View details for PubMedID 35964762

• Radiotherapy alters expression of molecular targets in prostate cancer in a fractionation- and time-dependent manner. Scientific reports Eke, I., Aryankalayil, M. J., Bylicky, M. A., Makinde, A. Y., Liotta, L., Calvert, V., Petricoin, E. F., Graves, E. E., Coleman, C. N. 2022; 12 (1): 3500

  Abstract

  The efficacy of molecular targeted therapy depends on expression and enzymatic activity of the target molecules. As radiotherapy modulates gene expression and protein phosphorylation dependent on dose and fractionation, we analyzed the long-term effects of irradiation on the post-radiation efficacy of molecular targeted drugs. We irradiated prostate cancer cells either with a single dose (SD) of 10Gy x-ray or a multifractionated (MF) regimen with 10 fractions of 1Gy. Whole genome arrays and reverse phase protein microarrays were used to determine gene expression and protein phosphorylation. Additionally, we evaluated radiation-induced pathway activation with the Ingenuity Pathway Analysis software. To measure cell survival and sensitivity to clinically used molecular targeted drugs, we performed colony formation assays. We found increased activation of several pathways regulating important cell functions such as cell migration and cell survival at 24h after MF irradiation or at 2months after SD irradiation. Further, cells which survived a SD of 10Gy showed a long-term upregulation and increased activity of multiple molecular targets including AKT, IGF-1R, VEGFR2, or MET, while HDAC expression was decreased. In line with this, 10Gy SD cells were more sensitive to target inhibition with Capivasertib or Ipatasertib (AKTi), BMS-754807 (IGF-1Ri), or Foretinib (VEGFR2/METi), but less sensitive to Panobinostat or Vorinostat (HDACi). In summary, understanding the molecular short- and long-term changes after irradiation can aid in optimizing the efficacy of multimodal radiation oncology in combination with post-irradiation molecularly-targeted drug treatment and improving the outcome of prostate cancer patients.

  View details for DOI 10.1038/s41598-022-07394-y

  View details for PubMedID 35241721

• TRACKING INNATE IMMUNE ACTIVATION IN A MOUSE MODEL OF PARKINSON'S DISEASE USING TREM1 AND TSPO PET TRACERS. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Lucot, K. L., Stevens, M. Y., Bonham, T. A., Azevedo, E. C., Chaney, A. M., Webber, E. D., Jain, P., Klockow, J. L., Jackson, I. M., Carlson, M. L., Graves, E. E., Montine, T. J., James, M. L. 2022

  Abstract

  Parkinson's disease (PD) is associated with aberrant innate immune responses, including microglial activation and infiltration of peripheral myeloid cells into the central nervous system (CNS). Methods to investigate innate immune activation in PD are limited and have not yet elucidated key interactions between neuroinflammation and peripheral inflammation. Translocator protein 18 kDa (TSPO)-positron emission tomography (PET) is a widely evaluated imaging approach for studying activated microglia and peripheral myeloid lineage cells in vivo, however it is yet to be fully explored in PD. Herein we investigate the utility of TSPO-PET, in addition to PET imaging of triggering receptor expressed on myeloid cells 1 (TREM1) - a novel biomarker of proinflammatory myeloid cells - for detecting innate immune responses in the 6-hydroxydopamine (6-OHDA) mouse model of dopaminergic neuron degeneration. Methods: C57/BL6J and TREM1-knockout mice were stereotaxically injected with 6-OHDA in the left striatum; control mice were saline-injected. At day 7 or 14 post-surgery, mice were administered 18F-GE-180, 64Cu-TREM1-mAb or 64Cu-Isotype control-mAb and imaged by PET/CT. Ex vivo autoradiography (ARG) was performed to obtain high resolution images of tracer binding within the brain. Immunohistochemistry was conducted to verify myeloid cell activation and dopaminergic cell death and quantitative PCR and flow cytometry were completed to assess levels of target in the brain. Results: PET/CT images of both tracers showed elevated signal within the striatum of 6-OHDA-injected mice compared to those injected with saline. ARG afforded higher resolution brain images and revealed significant TSPO and TREM1 tracer binding within the ipsilateral striatum of 6-OHDA- compared to saline-injected mice at both 7- and 14-days post-toxin. Interestingly, 18F-GE-180 enabled detection of inflammation in the brain and peripheral tissues (blood and spleen) of 6-OHDA mice, whereas 64Cu-TREM1-mAb appeared to be more sensitive and specific for detecting neuroinflammation, in particular infiltrating myeloid cells, in these mice, as demonstrated by flow cytometry findings and higher tracer binding signal-to-background ratios in brain. Conclusion: TSPO- and TREM1-PET tracers are promising tools for investigating different cell types involved in innate immune activation in the context of dopaminergic neurodegeneration, thus warranting further investigation in other PD rodent models and human postmortem tissue to assess their clinical potential.

  View details for DOI 10.2967/jnumed.121.263039

  View details for PubMedID 35177426

• C3aR Signaling Inhibits NK-cell Infiltration into the Tumor Microenvironment in Mouse Models. Cancer immunology research Nandagopal, S., Li, C. G., Xu, Y., Sodji, Q. H., Graves, E. E., Giaccia, A. J. 2021

  Abstract

  Many solid tumors have low levels of cytotoxic CD56dim NK cells, suggesting that CD56dim NK-cell exclusion from the tumor microenvironment (TME) contributes to the decreased response rate of immunotherapy. Complement component 3a (C3a) is known for its tumor-promoting and immunosuppressive roles in solid tumors. Previous reports have implicated the involvement of the C3a receptor (C3aR) in immune cell trafficking into the TME. C3aR is predominantly expressed on the surface of activated cytotoxic NK cells, but a specific role for C3aR in NK-cell biology has not been investigated. Because solid tumors generate elevated C3a and have decreased NK cell infiltration, we hypothesized that C3aR might play a role in cytotoxic NK-cell recruitment into the TME. Our results indicate that blocking C3aR signaling in NK cells increased NK-cell infiltration into the TME in mouse models and led to tumor regression. Because the critical lymphocyte trafficking integrin, LFA-1, orchestrates the migration of activated NK cells, we wanted to gain insight into the interaction between C3aR signaling and LFA-1. Our results demonstrated that direct interaction between C3aR and LFA-1, which led to a high affinity LFA-1 conformation, decreased NK-cell infiltration into the TME. We propose that approaches to enhance cytotoxic NK-cell infiltration into the TME, through either disrupting C3a and C3aR interaction or inhibiting the formation of high-affinity LFA-1, represents a new strategy to improve the efficiency of immunotherapy for cancer treatment.

  View details for DOI 10.1158/2326-6066.CIR-21-0435

  View details for PubMedID 34819308

• Long-term expression changes of immune-related genes in prostate cancer after radiotherapy. Cancer immunology, immunotherapy : CII Eke, I., Aryankalayil, M. J., Bylicky, M. A., Sandfort, V., Vanpouille-Box, C., Nandagopal, S., Graves, E. E., Giaccia, A. J., Coleman, C. N. 2021

  Abstract

  The expression of immune-related genes in cancer cells can alter the anti-tumor immune response and thereby impact patient outcomes. Radiotherapy has been shown to modulate immune-related genes dependent on the fractionation regimen. To identify long-term changes in gene expression after irradiation, PC3 (p53 deleted) and LNCaP (p53 wildtype) prostate cancer cells were irradiated with either a single dose (SD, 10Gy) or a fractionated regimen (MF) of 10 fractions (1Gy per fraction). Whole human genome arrays were used to determine gene expression at 24h and 2months after irradiation. Immune pathway activation was analyzed with Ingenuity Pathway Analysis software. Additionally, 3D colony formation assays and T-cell cytotoxicity assays were performed. LNCaP had a higher basal expression of immunogenic genes and was more efficiently killed by cytotoxic T-cells compared to PC3. In both cell lines, MF irradiation resulted in an increase in multiple immune-related genes immediately after irradiation, while at 2months, SD irradiation had a more pronounced effect on radiation-induced gene expression. Both immunogenic and immunosuppressive genes were upregulated in the long term in PC3 cells by a 10Gy SD irradiation but not in LNCaP. T-cell-mediated cytotoxicity was significantly increased in 10Gy SD PC3 cells compared to the unirradiated control and could be further enhanced by treatment with immune checkpoint inhibitors. Irradiation impacts the expression of immune-related genes in cancer cells in a fractionation-dependent manner. Understanding and targeting these changes may be a promising strategy for primary prostate cancer and recurrent tumors.

  View details for DOI 10.1007/s00262-021-03036-w

  View details for PubMedID 34435232

• The lncRNAs LINC00261 and LINC00665 are upregulated in long-term prostate cancer adaptation after radiotherapy. Molecular therapy. Nucleic acids Eke, I., Bylicky, M. A., Sandfort, V., Chopra, S., Martello, S., Graves, E. E., Coleman, C. N., Aryankalayil, M. J. 2021; 24: 175–87

  Abstract

  Long non-coding RNAs (lncRNAs) have been shown to impact important biological functions such as proliferation, survival, and genomic stability. To analyze radiation-induced lncRNA expression in human tumors, we irradiated prostate cancer cells with a single dose of 10Gy or a multifractionated radiotherapeutic regimen of 10 fractions with a dose of 1Gy (10* 1 Gy) during 5days. We found a stable upregulation of the lncRNA LINC00261 and LINC00665 at 2months after radiotherapy that was more pronounced after single-dose irradiation. Analysis of the The Cancer Genome Atlas (TCGA) and The Atlas of Non-coding RNAs in Cancer (TANRIC) databases showed that high expression of these two lncRNAs may be a potential negative prognostic marker for overall survival of prostate cancer patients. Knockdown of LINC00261 and LINC00665 in long-term survivors decreased survival after re-irradiation and affected DNA double-strand break repair. Mechanistically, both lncRNAs showed an interdependent expression and regulated expression of the DNA repair proteins CtIP (RBBP8) and XPC as well as the microRNA miR-329. Identifying long-term tumor adaptation mechanisms can lead to the discovery of new molecular targets, in effect opening up new research directions and improving multimodal radiation oncologic treatment.

  View details for DOI 10.1016/j.omtn.2021.02.024

  View details for PubMedID 33767914

• Pharmacological Regulation of Tumor Hypoxia in Model Murine Tumors and Spontaneous Canine Tumors. Cancers Benej, M., Wu, J., Kreamer, M., Kery, M., Corrales-Guerrero, S., Papandreou, I., Williams, T. M., Li, Z., Graves, E. E., Selmic, L. E., Denko, N. C. 2021; 13 (7)

  Abstract

  Hypoxia is found in many solid tumors and is associated with increased disease aggressiveness and resistance to therapy. Reducing oxygen demand by targeting mitochondrial oxidative metabolism is an emerging concept in translational cancer research aimed at reducing hypoxia. We have shown that the U.S. Food and Drug Administration (FDA)-approved drug papaverine and its novel derivative SMV-32 are potent mitochondrial complex I inhibitors.We used a dynamic in vivo luciferase reporter system, pODD-Luc, to evaluate the impact of pharmacological manipulation of mitochondrial metabolism on the levels of tumor hypoxia in transplanted mouse tumors. We also imaged canine patients with blood oxygen level-dependent (BOLD) MRI at baseline and one hour after a dose of 1 or 2 mg/kg papaverine.We showed that the pharmacological suppression of mitochondrial oxygen consumption (OCR) in tumor-bearing mice increases tumor oxygenation, while the stimulation of mitochondrial OCR decreases tumor oxygenation. In parallel experiments in a small series of spontaneous canine sarcomas treated at The Ohio State University (OSU) Veterinary Medical Center, we observed a significant increase in BOLD signals indicative of an increase in tumor oxygenation of up to 10-50 mm HgO2.In both transplanted murine tumors and spontaneous canine tumors we found that decreasing mitochondrial metabolism can decrease tumor hypoxia, potentially offering a therapeutic advantage.

  View details for DOI 10.3390/cancers13071696

  View details for PubMedID 33916656

• Pharmacological Regulation of Tumor Hypoxia in Model Murine Tumors and Spontaneous Canine Tumors CANCERS Benej, M., Wu, J., Kreamer, M., Kery, M., Corrales-Guerrero, S., Papandreou, I., Williams, T. M., Li, Z., Graves, E. E., Selmic, L. E., Denko, N. C. 2021; 13 (7)

  View details for DOI 10.3390/cancers13071696

  View details for Web of Science ID 000638373300001

• Y box binding protein 1 inhibition as a targeted therapy for ovarian cancer. Cell chemical biology Tailor, D., Resendez, A., Garcia-Marques, F. J., Pandrala, M., Going, C. C., Bermudez, A., Kumar, V., Rafat, M., Nambiar, D. K., Honkala, A., Le, Q., Sledge, G. W., Graves, E., Pitteri, S. J., Malhotra, S. V. 2021

  Abstract

  Y box binding protein 1 (YB-1) is a multifunctional protein associated with tumor progression and the emergence of treatment resistance (TR). Here, we report an azopodophyllotoxin small molecule, SU056, that potently inhibits tumor growth and progression via YB-1 inhibition. This YB-1 inhibitor inhibits cell proliferation, resistance to apoptosis in ovarian cancer (OC) cells, and arrests in the G1 phase. Inhibitor treatment leads to enrichment of proteins associated with apoptosis and RNA degradation pathways while downregulating spliceosome pathway. Invivo, SU056 independently restrains OC progression and exerts a synergistic effect with paclitaxel to further reduce disease progression with no observable liver toxicity. Moreover, invitro mechanistic studies showed delayed disease progression via inhibition of drug efflux and multidrug resistance 1, and significantly lower neurotoxicity as compared with etoposide. These data suggest that YB-1 inhibition may be an effective strategy to reduce OC progression, antagonize TR, and decrease patient mortality.

  View details for DOI 10.1016/j.chembiol.2021.02.014

  View details for PubMedID 33713600

• Effects of Focal Ionizing Radiation of the Squid Stellate Ganglion on Synaptic and Axonal Transmission in the Giant-Fiber Pathway. Cureus Gilly, W. F., Teal, P., Graves, E. E., Lo, J., Schneider, M. B., Zasio, R., Adler, J. R. 2021; 13 (2): e13110

  Abstract

  Ionizing radiation is clinically used to treat neurological problems and reduce pathological levels of neural activity in the brain, but its cellular-level mechanisms are not well understood. Although spontaneous and stimulated synaptic activity has been produced in rodents by clinically and environmentally relevant doses of radiation, the effects on basic excitability properties of neurons have seldom been reported. This study examined the effects of focused ionizing radiation on synaptic transmission and action potential generation in the squid giant-fiber system, which includes the giant synapse between a secondary interneuron and the tertiary giant motor axons. Radiation of 140-300 Gy was delivered to a stellate ganglion of a living squid over several minutes, with the contralateral stellate ganglion serving as an internal control. No qualitative changes in the efficacy of synaptic transmission were noted in conjunction with stimulation of the input to the giant synapse, although in one irradiated ganglion, the refractory period increased from about 5 ms to more than 45 seconds. Small but significant changes in the action potential recorded from the giant motor axon in response to electrical stimulation were associated with an increased maximum rate of fall and a shortened action potential duration. Other action-potential parameters, including resting potential, overshoot, the maximum rate of the rise, and the refractory period were not significantly changed. Attempts to account for the observed changes in the action potential were carried through a Hodgkin-Huxley model of the action potential. This approach suggests that an increase in the maximum voltage-gated potassium conductance of about 50% mimics the action potential shortening and increased rate of fall that was experimentally observed. We propose that such an effect could result from phosphorylation of squid potassium channels.

  View details for DOI 10.7759/cureus.13110

  View details for PubMedID 33692914

  View details for PubMedCentralID PMC7938441

• Effects of Focal Ionizing Radiation of the Squid Stellate Ganglion on Synaptic and Axonal Transmission in the Giant-Fiber Pathway CUREUS Gilly, W. F., Teal, P., Graves, E. E., Lo, J., Schneider, M., Zasio, R., Adler, J. R. 2021; 13 (2)

  View details for DOI 10.7759/cureus.13110

  View details for Web of Science ID 000616643700021

• The HIF target MAFF promotes tumor invasion and metastasis through IL11 and STAT3 signaling. Nature communications Moon, E. J., Mello, S. S., Li, C. G., Chi, J., Thakkar, K., Kirkland, J. G., Lagory, E. L., Lee, I. J., Diep, A. N., Miao, Y., Rafat, M., Vilalta, M., Castellini, L., Krieg, A. J., Graves, E. E., Attardi, L. D., Giaccia, A. J. 2021; 12 (1): 4308

  Abstract

  Hypoxia plays a critical role in tumor progression including invasion and metastasis. To determine critical genes regulated by hypoxia that promote invasion and metastasis, we screen fifty hypoxia inducible genes for their effects on invasion. In this study, we identify v-maf musculoaponeurotic fibrosarcoma oncogene homolog F (MAFF) as a potent regulator of tumor invasion without affecting cell viability. MAFF expression is elevated in metastatic breast cancer patients and is specifically correlated with hypoxic tumors. Combined ChIP- and RNA-sequencing identifies IL11 as a direct transcriptional target of the heterodimer between MAFF and BACH1, which leads to activation of STAT3 signaling. Inhibition of IL11 results in similar levels of metastatic suppression as inhibition of MAFF. This study demonstrates the oncogenic role of MAFF as an activator of the IL11/STAT3 pathways in breast cancer.

  View details for DOI 10.1038/s41467-021-24631-6

  View details for PubMedID 34262028

• FLASH irradiation enhances the therapeutic index of abdominal radiotherapy in mice Natarajan, S., Levy, K., Wang, J., Chow, S., Eggold, J., Loo, P., Manjappa, R., Lartey, F. M., Schuler, E., Skinner, L., Rafat, M., Ko, R., Kim, A., Al Rawi, D., von Eyben, R., Dorigo, O., Casey, K. M., Graves, E. E., Bush, K., Yu, A. S., Koong, A. C., Maxim, P. G., Loo, B. W., Rankin, E. B. AMER ASSOC CANCER RESEARCH. 2020

  View details for DOI 10.1158/1538-7445.AM2020-5351

  View details for Web of Science ID 000590059306341

• Reprogramming of serine metabolism during breast cancer progression Li, A., Ducker, G. S., Li, Y., Seoane, J. A., Xiao, Y., Melemenidis, S., Zhou, Y., Liu, L., Vanharanta, S., Graves, E. E., Rankin, E. B., Curtis, C., Massague, J., Rabinowitz, J. D., Thompson, C. B., Ye, J. AMER ASSOC CANCER RESEARCH. 2020

  View details for DOI 10.1158/1538-7445.AM2020-5713

  View details for Web of Science ID 000590059302016

• Visualizing innate immune activation in a mouse model of Parkinson's disease using a highly specific TREM1-PET tracer. Lucot, K., Stevens, M., Jain, P., Bonham, T., Webber, E., Klockow, J., Azevedo, E., Chaney, A., Graves, E., Montine, T., James, M. SOC NUCLEAR MEDICINE INC. 2020

  View details for Web of Science ID 000568290500016

• An activatable NIR fluorescent rosol for selectively imaging nitroreductase activity SENSORS AND ACTUATORS B-CHEMICAL Klockow, J. L., Hettie, K. S., LaGory, E. L., Moon, E., Giaccia, A. J., Graves, E. E., Chin, F. T. 2020; 306

  View details for DOI 10.1016/j.snb.2019.127446

  View details for Web of Science ID 000507459500002

• An Activatable NIR Fluorescent Rosol for Selectively Imaging Nitroreductase Activity. Sensors and actuators. B, Chemical Klockow, J. L., Hettie, K. S., LaGory, E. L., Moon, E. J., Giaccia, A. J., Graves, E. E., Chin, F. T. 2020; 306

  Abstract

  Hypoxia (pO2 ≤ ~1.5%) is an important characteristic of tumor microenvironments that directly correlates with resistance against first-line therapies and tumor proliferation/infiltration. The ability to accurately identify hypoxic tumor cells/tissue could afford tailored therapeutic regimens for personalized treatment, development of more-effective therapies, and discerning the mechanisms underlying disease progression. Fluorogenic constructs identifying aforesaid cells/tissue operate by targeting the bioreductive activity of primarily nitroreductases (NTRs), but collectively present photophysical and/or physicochemical shortcomings that could limit effectiveness. To overcome these limitations, we present the rational design, development, and evaluation of the first activatable ultracompact xanthene core-based molecular probe (NO 2 -Rosol) for selectively imaging NTR activity that affords an "OFF-ON" near-infrared (NIR) fluorescence response (> 700 nm) alongside a remarkable Stokes shift (> 150 nm) via NTR activity-facilitated modulation to its energetics whose resultant interplay discontinues an intramolecular d-PET fluorescence-quenching mechanism transpiring between directly-linked electronically-uncoupled π-systems comprising its components. DFT calculations guided selection of a suitable fluorogenic scaffold and nitroaromatic moiety candidate that when adjoined could (i) afford such photophysical response upon bioreduction by upregulated NTR activity in hypoxic tumor cells/tissue and (ii) employ a retention mechanism strategy that capitalizes on an inherent physical property of the NIR fluorogenic scaffold for achieving signal amplification. NO 2 -Rosol demonstrated 705 nm NIR fluorescence emission and 157 nm Stokes shift, selectivity for NTR over relevant bioanalytes, and a 28-/12-fold fluorescence enhancement in solution and between cells cultured under different oxic conditions, respectively. In establishing feasibility for NO 2 -Rosol to provide favorable contrast levels in solutio/vitro, we anticipate NO 2 -Rosol doing so in preclinical studies.

  View details for DOI 10.1016/j.snb.2019.127446

  View details for PubMedID 32265579

  View details for PubMedCentralID PMC7138224

• Induced tumor heterogeneity reveals factors informing radiation and immunotherapy combinations. Clinical cancer research : an official journal of the American Association for Cancer Research Aguilera, T. A., Elghonaimy, E., Shehade, H., Rafat, M., Castellini, L., Jiang, D., Kariolis, M., Koong, A., Le, Q., Ellies, L. G., Rankin, E. B., Graves, E. E., Giaccia, A. J. 2020

  Abstract

  PURPOSE: To investigate how induced tumor heterogeneity influences immune responses to radiotherapy (RT) with different proportions of mixed immune responsive and unresponsive tumor cells in a triple negative breast cancer model. It is hypothesized that studying the immune environment of mixed tumors and responses to RT could nominate immune active therapies to enhance immune responses after RT.EXPERIMENTAL DESIGN: Evaluate efficacy and immune responses generated by RT in tumors with different proportions of immunologically responsive and unresponsive tumor cells. Then study the cellular responses and transcriptomic differences between the tumors to nominate immunotherapy combinations with RT and evaluate the combination.RESULTS: The addition of the responsive cells to unresponsive tumors led to a greater than expected therapeutic response to RT with both innate and adaptive immune components. There was a distinct change in myeloid cells, greater inflammatory macrophage activity, and enhanced antigen presentation with responsive cells after RT. Since differences in matrix components, cell adhesion biology, and innate immune signaling correlated with myeloid cell response and phenotype, we hypothesized that RT combined with CD40 agonist antibody would sensitize unresponsive tumors. The combination therapy resulted improved innate and adaptive immune response. Importantly, CD40 treatment increased tumor response to RT and protected against metastatic spread in a metastatic model.CONCLUSIONS: These data combined with transcriptomics from human patients supports RT and myeloid cell targeting for immunologically cold tumors and presents opportunities to investigate the complex overlapping biologic mechanisms that limit immunotherapy and to implement RT with different immunotherapy combinations.

  View details for DOI 10.1158/1078-0432.CCR-19-4220

  View details for PubMedID 32098769

• Extracellular cGAMP is a cancer cell-produced immunotransmitter involved in radiation-induced anti-cancer immunity. Nature cancer Carozza, J. A., Böhnert, V., Nguyen, K. C., Skariah, G., Shaw, K. E., Brown, J. A., Rafat, M., von Eyben, R., Graves, E. E., Glenn, J. S., Smith, M., Li, L. 2020; 1 (2): 184-196

  Abstract

  2'3'-cyclic GMP-AMP (cGAMP) is an intracellular second messenger that is synthesized in response to cytosolic double-stranded DNA and activates the innate immune STING pathway. Our previous discovery of its extracellular hydrolase ENPP1 hinted at the existence of extracellular cGAMP. Here, we detected that cGAMP is continuously exported but then efficiently cleared by ENPP1, explaining why it has previously escaped detection. By developing potent, specific, and cell impermeable ENPP1 inhibitors, we found that cancer cells continuously export cGAMP in culture at steady state and at higher levels when treated with ionizing radiation (IR). In mouse tumors, depletion of extracellular cGAMP decreased tumor-associated immune cell infiltration and abolished the curative effect of IR. Boosting extracellular cGAMP with ENPP1 inhibitors synergized with IR to delay tumor growth. In conclusion, extracellular cGAMP is an anti-cancer immunotransmitter that could be harnessed to treat cancers with low immunogenicity.

  View details for DOI 10.1038/s43018-020-0028-4

  View details for PubMedID 33768207

  View details for PubMedCentralID PMC7990037

• Abdominal FLASH irradiation reduces radiation-induced gastrointestinal toxicity for the treatment of ovarian cancer in mice. Scientific reports Levy, K. n., Natarajan, S. n., Wang, J. n., Chow, S. n., Eggold, J. T., Loo, P. E., Manjappa, R. n., Melemenidis, S. n., Lartey, F. M., Schüler, E. n., Skinner, L. n., Rafat, M. n., Ko, R. n., Kim, A. n., H Al-Rawi, D. n., von Eyben, R. n., Dorigo, O. n., Casey, K. M., Graves, E. E., Bush, K. n., Yu, A. S., Koong, A. C., Maxim, P. G., Loo, B. W., Rankin, E. B. 2020; 10 (1): 21600

  Abstract

  Radiation therapy is the most effective cytotoxic therapy for localized tumors. However, normal tissue toxicity limits the radiation dose and the curative potential of radiation therapy when treating larger target volumes. In particular, the highly radiosensitive intestine limits the use of radiation for patients with intra-abdominal tumors. In metastatic ovarian cancer, total abdominal irradiation (TAI) was used as an effective postsurgical adjuvant therapy in the management of abdominal metastases. However, TAI fell out of favor due to high toxicity of the intestine. Here we utilized an innovative preclinical irradiation platform to compare the safety and efficacy of TAI ultra-high dose rate FLASH irradiation to conventional dose rate (CONV) irradiation in mice. We demonstrate that single high dose TAI-FLASH produced less mortality from gastrointestinal syndrome, spared gut function and epithelial integrity, and spared cell death in crypt base columnar cells compared to TAI-CONV irradiation. Importantly, TAI-FLASH and TAI-CONV irradiation had similar efficacy in reducing tumor burden while improving intestinal function in a preclinical model of ovarian cancer metastasis. These findings suggest that FLASH irradiation may be an effective strategy to enhance the therapeutic index of abdominal radiotherapy, with potential application to metastatic ovarian cancer.

  View details for DOI 10.1038/s41598-020-78017-7

  View details for PubMedID 33303827

• FLASH Irradiation Results in Reduced Severe Skin Toxicity Compared to Conventional-Dose-Rate Irradiation. Radiation research Soto, L. A., Casey, K. M., Wang, J. n., Blaney, A. n., Manjappa, R. n., Breitkreutz, D. n., Skinner, L. n., Dutt, S. n., Ko, R. B., Bush, K. n., Yu, A. S., Melemenidis, S. n., Strober, S. n., Englemann, E. n., Maxim, P. G., Graves, E. E., Loo, B. W. 2020

  Abstract

  Radiation therapy, along with surgery and chemotherapy, is one of the main treatments for cancer. While radiotherapy is highly effective in the treatment of localized tumors, its main limitation is its toxicity to normal tissue. Previous preclinical studies have reported that ultra-high dose-rate (FLASH) irradiation results in reduced toxicity to normal tissues while controlling tumor growth to a similar extent relative to conventional-dose-rate (CONV) irradiation. To our knowledge this is the first report of a dose-response study in mice comparing the effect of FLASH irradiation vs. CONV irradiation on skin toxicity. We found that FLASH irradiation results in both a lower incidence and lower severity of skin ulceration than CONV irradiation 8 weeks after single-fraction hemithoracic irradiation at high doses (30 and 40 Gy). Survival was also higher after FLASH hemithoracic irradiation (median survival >180 days at doses of 30 and 40 Gy) compared to CONV irradiation (median survival 100 and 52 days at 30 and 40 Gy, respectively). No ulceration was observed at doses 20 Gy or below in either FLASH or CONV. These results suggest a shifting of the dose-response curve for radiation-induced skin ulceration to the right for FLASH, compared to CONV irradiation, suggesting the potential for an enhanced therapeutic index for radiation therapy of cancer.

  View details for DOI 10.1667/RADE-20-00090

  View details for PubMedID 32853385

• Evaluating the Reproducibility of Mouse Anatomy under Rotation in a Custom Immobilization Device for Conformal FLASH Radiotherapy. Radiation research Ko, R. B., Soto, L. A., von Eyben, R. n., Melemenidis, S. n., Rankin, E. B., Maxim, P. G., Graves, E. E., Loo, B. W. 2020

  Abstract

  The observation of an enhanced therapeutic index for FLASH radiotherapy in mice has created interest in practical laboratory-based FLASH irradiators. To date, systems capable of 3D conformal FLASH irradiation in mice have been lacking. We are developing such a system, incorporating a high-current linear accelerator to produce a collimated X-ray beam in a stationary beamline design, rotating the mouse about a longitudinal axis to achieve conformal irradiation from multiple beam directions. The purpose of this work was to evaluate the reproducibility of mouse anatomy under rotation at speeds compatible with conformal FLASH delivery. Three short-hair mice and two hairless mice were immobilized under anesthesia in body weight-specific contoured plastic molds, and subjected to three rotational (up to 3 revolutions/s) and two non-rotational movement interventions. MicroCT images were acquired before and after each intervention. The displacements of 11 anatomic landmarks were measured on the image pairs. The displacement of the anatomical landmarks with any of the interventions was 0.5 mm or less for 92.4% of measurements, with a single measurement out of 275 (11 landmarks × 5 interventions × 5 mice) reaching 1 mm. There was no significant difference in the displacements associated with rotation compared to those associated with moving the immobilized mouse in and out of a scanner or with leaving the mouse in place for 5 min with no motion. There were no significant differences in displacements between mice with or without hair, although the analysis is limited by small numbers, or between different anatomic landmarks. These results show that anatomic reproducibility under rotation speed corresponding to FLASH irradiation times appears to be compatible with conformal/stereotactic irradiation in mice.

  View details for DOI 10.1667/RADE-20-00095

  View details for PubMedID 32857849

• 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

• Metabolic Profiling Reveals a Dependency of Human Metastatic Breast Cancer on Mitochondrial Serine and One-Carbon Unit Metabolism. Molecular cancer research : MCR Li, A. M., Ducker, G. S., Li, Y. n., Seoane, J. A., Xiao, Y. n., Melemenidis, S. n., Zhou, Y. n., Liu, L. n., Vanharanta, S. n., Graves, E. E., Rankin, E. B., Curtis, C. n., Massague, J. n., Rabinowitz, J. D., Thompson, C. B., Ye, J. n. 2020

  Abstract

  Breast cancer is the most common cancer among American women and a major cause of mortality. To identify metabolic pathways as potential targets to treat metastatic breast cancer, we performed metabolomics profiling on breast cancer cell line MDA-MB-231 and its tissue-tropic metastatic subclones. Here, we report that these subclones with increased metastatic potential display an altered metabolic profile compared to the parental population. In particular, the mitochondrial serine and one-carbon (1C) unit pathway is upregulated in metastatic subclones. Mechanistically, the mitochondrial serine and 1C unit pathway drives the faster proliferation of subclones through enhanced de novo purine biosynthesis. Inhibition of the first rate-limiting enzyme of the mitochondrial serine and 1C unit pathway, serine hydroxymethyltransferase (SHMT2), potently suppresses proliferation of metastatic subclones in culture and impairs growth of lung metastatic subclones at both primary and metastatic sites in mice. Some human breast cancers exhibit a significant association between the expression of genes in the mitochondrial serine and 1C unit pathway with disease outcome and higher expression of SHMT2 in metastatic tumor tissue compared to primary tumors. In addition to breast cancer, a few other cancer types, such as adrenocortical carcinoma (ACC) and kidney chromophobe cell carcinoma (KICH), also display increased SHMT2 expression during disease progression. Together, these results suggest that mitochondrial serine and 1C unit plays an important role in promoting cancer progression, particularly in late stage cancer. Implications: This study identifies mitochondrial serine and 1C unit metabolism as an important pathway during the progression of a subset of human breast cancers.

  View details for DOI 10.1158/1541-7786.MCR-19-0606

  View details for PubMedID 31941752

• 53BP1/RIF1 signaling promotes cell survival after multifractionated radiotherapy. Nucleic acids research Eke, I., Zong, D., Aryankalayil, M. J., Sandfort, V., Bylicky, M. A., Rath, B. H., Graves, E. E., Nussenzweig, A., Coleman, C. N. 2019

  Abstract

  Multifractionated irradiation is the mainstay of radiation treatment in cancer therapy. Yet, little is known about the cellular DNA repair processes that take place between radiation fractions, even though understanding the molecular mechanisms promoting cancer cell recovery and survival could improve patient outcome and identify new avenues for targeted intervention. To address this knowledge gap, we systematically characterized how cells respond differentially to multifractionated and single-dose radiotherapy, using a combination of genetics-based and functional approaches. We found that both cancer cells and normal fibroblasts exhibited enhanced survival after multifractionated irradiation compared with an equivalent single dose of irradiation, and this effect was entirely dependent on 53BP1-mediated NHEJ. Furthermore, we identified RIF1 as the critical effector of 53BP1. Inhibiting 53BP1 recruitment to damaged chromatin completely abolished the survival advantage after multifractionated irradiation and could not be reversed by suppressing excessive end resection. Analysis of the TCGA database revealed lower expression of 53BP1 pathway genes in prostate cancer, suggesting that multifractionated radiotherapy might be a favorable option for radio-oncologic treatment in this tumor type. We propose that elucidation of DNA repair mechanisms elicited by different irradiation dosing regimens could improve radiotherapy selection for the individual patient and maximize the efficacy of radiotherapy.

  View details for DOI 10.1093/nar/gkz1139

  View details for PubMedID 31822909

• Radiosensitization of Head and Neck Squamous Cell Carcinoma (HNSCC) by a Podophyllotoxin. ACS medicinal chemistry letters Resendez, A., Tailor, D., Graves, E., Malhotra, S. V. 2019; 10 (9): 1314–21

  Abstract

  Surgical resection and radiotherapy are an effective treatment in many head and neck squamous cell carcinomas (HNSCC), but in others, the development of radiotherapy resistance limits treatment efficacy and permits disease progression. We developed a novel multiwell radiation dosing method to increase the throughput of our investigation of the activity of a novel podophyllotoxin SU093 in acting as a radiosensitizer in the HNSCC models FaDu and SCC-25. These in vitro studies showed that combining SU093 with 5 Grays ionizing radiation acted synergistically to increase HNSCC apoptosis and decrease its proliferation via inhibition of Nuclear factor, erythroid 2 like 2 (Nrf2), a key effector of the DNA damage response induced by ionizing radiation. Combined treatment reduced in vitro migration in a simulated wounding model while also promoting cell cycle arrest at the G2/M phase. These findings validate the potential of SU093 as a synergistic radiosensitizing agent for use in combination with localized radiotherapy in treatment resistant HNSCC.

  View details for DOI 10.1021/acsmedchemlett.9b00270

  View details for PubMedID 31531203

• 2 ' 3 '-cGAMP is an immunotransmitter produced by cancer cells and regulated by ENPP1 Carozza, J., Bohnert, V., Shaw, K., Khanh Nyugen, Skariah, G., Brown, J., Rafat, M., von Eyben, R., Graves, E., Glenn, J., Smith, M., Li, L. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525061505479

• A near-infrared phosphorescent nanoprobe enables quantitative, longitudinal imaging of tumor hypoxia dynamics during radiotherapy. Cancer research Zheng, X., Cui, L., Chen, M., Soto, L. A., Graves, E. E., Rao, J. 2019

  Abstract

  Hypoxia plays a key role in tumor resistance to radiotherapy (RT). It is important to study hypoxia dynamics during RT to improve treatment planning and prognosis. Here, we describe a luminescent nanoprobe, composed of a fluorescent semiconducting polymer and palladium (Pd) complex, for quantitative longitudinal imaging of tumor hypoxia dynamics during RT. The nanoprobe was designed to provide high sensitivity and reversible response for the subtle change in hypoxia over a narrow range (0-30 mmHg O2), which spans the oxygen range where tumors have limited radiosensitivity. Following intravenous administration, the nanoprobe efficiently accumulated in and distributed across the tumor, including the hypoxic region. The ratio between emissions at 700 and 800 nm provided quantitative mapping of hypoxia across the entire tumor. The nanoprobe has been applied to image the tumor hypoxia dynamics over 7 days during fractionated RT, revealing that high fractional dose (10 Gy) was more effective in improving tumor reoxygenation than low dose (2 Gy) and the effect tended to persist longer in smaller or more radiosensitive tumors. Our results also indicated the importance of the reoxygenation efficiency of the first fraction in the prediction of the radiation treatment outcome. In summary, this work has established a new nanoprobe for highly sensitive, quantitative and longitudinal imaging of tumor hypoxia dynamics following RT, and demonstrated its value for assessing the efficacy of RT and radiation treatment planning.

  View details for DOI 10.1158/0008-5472.CAN-19-0530

  View details for PubMedID 31311808

• Papaverine and its novel derivatives radiosensitize solid tumors by inhibiting mitochondrial metabolism Benej, M., Hong, X., Vibhute, S., Scott, S., Wu, J., Graves, E., Quynh-Thu Le, Koong, A. C., Giaccia, A. J., Chen, C., Yu, B., Papandreou, I., Denko, N. C. AMER ASSOC CANCER RESEARCH. 2019

  View details for DOI 10.1158/1538-7445.AM2019-2927

  View details for Web of Science ID 000488279401375

• The irradiated tissue microenvironment and its role in breast cancer recurrence: Enhanced macrophage infiltration promotes tumor cell recruitment Hacker, B. C., Alves, S. M., Jiang, D., Koong, A. C., Giaccia, A. J., Graves, E. E., Rafat, M. AMER ASSOC CANCER RESEARCH. 2019

  View details for DOI 10.1158/1538-7445.AM2019-3931

  View details for Web of Science ID 000488279403328

• FLT-PET-CT for the Detection of Disease Recurrence After Stereotactic Ablative Radiotherapy or Hyperfractionation for Thoracic Malignancy: A Prospective Pilot Study FRONTIERS IN ONCOLOGY Hiniker, S. M., Sodji, Q., Quon, A., Gutkin, P. M., Arksey, N., Graves, E. E., Chin, F. T., Maxim, P. G., Diehn, M., Loo, B. W. 2019; 9

  View details for DOI 10.3389/fonc.2019.00467

  View details for Web of Science ID 000470114000001

• FLT-PET-CT for the Detection of Disease Recurrence After Stereotactic Ablative Radiotherapy or Hyperfractionation for Thoracic Malignancy: A Prospective Pilot Study. Frontiers in oncology Hiniker, S. M., Sodji, Q., Quon, A., Gutkin, P. M., Arksey, N., Graves, E. E., Chin, F. T., Maxim, P. G., Diehn, M., Loo, B. W. 2019; 9: 467

  Abstract

  Differentiating local recurrence from post-treatment changes on PET scans following stereotactic ablative radiotherapy (SABR) or hyperfractionation for lung tumors is challenging. We performed a prospective pilot study of 3-deoxy-3-[18F]-fluorothymidine (FLT)-PET-CT in patients with equivocal post-radiation FDG-PET-CT to assess disease recurrence. Methods: We prospectively enrolled 10 patients, 9 treated with SABR and 1 with hyperfractionated external beam radiotherapy for thoracic malignancy with subsequent equivocal follow-up FDG-PET-CT, to undergo FLT-PET-CT prior to biopsy or serial imaging. FLT-PET scans were interpreted by a radiologist with experience in reading FLT-PET-CT and blinded to the results of any subsequent biopsy or imaging. Results: Of the 10 patients enrolled, 8 were evaluable after FLT-PET-CT. Based on the FLT-PET-CT, a blinded radiologist accurately predicted disease recurrence vs. inflammatory changes in 7 patients (87.5%). The combination of higher lesion SUVmax and higher ratio of lesion SUVmax to SUVmax of mediastinal blood pool was indicative of recurrence. Qualitative assessment of increased degree of focality of the lesion also appears to be indicative of disease recurrence. Conclusion: Adjunctive FLT-PET-CT imaging can complement FDG-PET-CT scan in distinguishing post-treatment radiation changes from disease recurrence in thoracic malignancies. These findings support the investigation of FLT-PET-CT in a larger prospective study.

  View details for DOI 10.3389/fonc.2019.00467

  View details for PubMedID 31214507

  View details for PubMedCentralID PMC6555304

• [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

• INTRADETRUSOR IPSC-DERIVED HUMAN PROGENITOR SMOOTH MUSCLE CELLS IN A ROWETT NUDE RAT MODEL OF RADIATION CYSTITIS Dobberfuhl, A. D., Briggs, M. A., Wallace, S. L., Wen, Y., Zhou, Y., Graves, E. E., Diaz, E. C., Knox, S. J., Chen, B. LIPPINCOTT WILLIAMS & WILKINS. 2019: E155

  View details for Web of Science ID 000473345200333

• Increases in Serial Pretreatment F-18-FDG PET-CT Metrics Predict Survival in Early Stage Non-Small Cell Lung Cancer Treated With Stereotactic Ablative Radiation Therapy ADVANCES IN RADIATION ONCOLOGY Prionas, N. D., von Eyben, R., Yi, E., Aggarwal, S., Shaffer, J., Bazan, J., Eastham, D., Maxim, P. G., Graves, E. E., Diehn, M., Gensheimer, M. F., Loo, B. W. 2019; 4 (2): 429–37

  View details for DOI 10.1016/j.adro.2018.11.006

  View details for Web of Science ID 000516858500027

• Increases in Serial Pretreatment 18F-FDG PET-CT Metrics Predict Survival in Early Stage Non-Small Cell Lung Cancer Treated With Stereotactic Ablative Radiation Therapy. Advances in radiation oncology Prionas, N. D., von Eyben, R., Yi, E., Aggarwal, S., Shaffer, J., Bazan, J., Eastham, D., Maxim, P. G., Graves, E. E., Diehn, M., Gensheimer, M. F., Loo, B. W. 2019; 4 (2): 429–37

  Abstract

  Purpose: Quantitative changes in positron emission tomography with computed tomography imaging metrics over serial scans may be predictive biomarkers. We evaluated the relationship of pretreatment metabolic tumor growth rate (MTGR) and standardized uptake value velocity (SUVV) with disease recurrence or death in patients with early-stage non-small cell lung cancer treated with stereotactic ablative radiation therapy (SABR).Methods and Materials: Under institutional review board approval, we retrospectively identified patients who underwent positron emission tomography with computed tomography at diagnosis and staging and simulation for SABR. Two cohorts underwent SABR between November 2005 to October 2012 (discovery) and January 2012 to April 2016 (validation). MTGR and SUVV were calculated as the daily change in metabolic tumor volume and maximum standardized uptake value, respectively. Cox proportional hazard models identified predictors of local, regional, and distant recurrence and death for the combined cohort. MTGR and SUVV thresholds dichotomizing risk of death in the discovery cohort were applied to the validation cohort.Results: A total of 152 lesions were identified in 143 patients (92 lesions in 83 discovery cohort patients). In multivariable models, increasing MTGR trended toward increased hazard of distant recurrence (hazard ratio, 6.98; 95% confidence interval, 0.67-72.61; P=.10). In univariable models, SUVV trended toward risk of death (hazard ratio, 11.8, 95% confidence interval, 0.85-165.1, P=.07). MTGR greater than 0.04mL/d was prognostic of decreased survival in discovery (P=.048) and validation cohorts (P<.01).Conclusions: MTGR greater than 0.04mL/d is prognostic of death in patients with non-small cell lung cancer treated with SABR. Increasing SUVV trends, nonsignificantly, toward increased risk of recurrence and death. MTGR and SUVV may be candidate imaging biomarkers to study in trials evaluating systemic therapy with SABR for patients at high risk of out-of-field recurrence.

  View details for PubMedID 31011689

• Targeted and Selective Treatment of Pluripotent Stem Cell-derived Teratomas Using External Beam Radiation in a Small-animal Model. Journal of visualized experiments : JoVE Sallam, K., Rhee, J., Chour, T., D'addabbo, J., Lee, A. S., Graves, E., Nguyen, P. K. 2019

  Abstract

  The growing number of victims of "stem cell tourism," the unregulated transplantation of stem cells worldwide, has raised concerns about the safety of stem cell transplantation. Although the transplantation of differentiated rather than undifferentiated cells is common practice, teratomas can still arise from the presence of residual undifferentiated stem cells at the time of transplant or from spontaneous mutations in differentiated cells. Because stem cell therapies are often delivered into anatomically sensitive sites, even small tumors can be clinically devastating, resulting in blindness, paralysis, cognitive abnormalities, and cardiovascular dysfunction. Surgical access to these sites may also be limited, leaving patients with few therapeutic options. Controlling stem cell misbehavior is, therefore, critical for the clinical translation of stem cell therapy. External beam radiation offers an effective means of delivering targeted therapy to decrease the teratoma burden while minimizing injury to surrounding organs. Additionally, this method avoids genetic manipulation or viral transduction of stem cells-which are associated with additional clinical safety and efficacy concerns. Here, we describe a protocol to create pluripotent stem cell-derived teratomas in mice and to apply external beam radiation therapy to selectively ablate these tumors in vivo.

  View details for PubMedID 30829317

• Targeted and Selective Treatment of Pluripotent Stem Cell-derived Teratomas Using External Beam Radiation in a Small-animal Model JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Sallam, K., Rhee, J., Chour, T., D'addabbo, J., Lee, A. S., Graves, E., Nguyen, P. K. 2019

  View details for DOI 10.3791/58115

  View details for Web of Science ID 000462905000010

• Ambulatory and ex-vivo effect of intradetrusor ipsc-derived human progenitor smooth muscle cells in a rat model of radiation induced bladder dysfunction Dobberfuhl, A. D., Briggs, M. A., Wallace, S. L., Wen, Y., Zhou, Y., Graves, E. E., Diaz, E. C., Chen, B. WILEY. 2019: S27–S28

  View details for Web of Science ID 000462357800031

• Integrating Small Animal Irradiators withFunctional Imaging for Advanced Preclinical Radiotherapy Research. Cancers Ghita, M., Brown, K. H., Kelada, O. J., Graves, E. E., Butterworth, K. T. 2019; 11 (2)

  Abstract

  Translational research aims to provide direct support for advancing novel treatment approaches in oncology towards improving patient outcomes. Preclinical studies have a central role in this process and the ability to accurately model biological and physical aspects of the clinical scenario in radiation oncology is critical to translational success. The use of small animal irradiators with disease relevant mouse models and advanced in vivo imaging approaches offers unique possibilities to interrogate the radiotherapy response of tumors and normal tissues with high potential to translate to improvements in clinical outcomes. The present review highlights the current technology and applications of small animal irradiators, and explores how these can be combined with molecular and functional imaging in advanced preclinical radiotherapy research.

  View details for PubMedID 30717307

• Reduced cognitive deficits after FLASH irradiation of whole mouse brain are associated with less hippocampal dendritic spine loss and neuroinflammation. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology Simmons, D. A., Lartey, F. M., Schüler, E. n., Rafat, M. n., King, G. n., Kim, A. n., Ko, R. n., Semaan, S. n., Gonzalez, S. n., Jenkins, M. n., Pradhan, P. n., Shih, Z. n., Wang, J. n., von Eyben, R. n., Graves, E. E., Maxim, P. G., Longo, F. M., Loo, B. W. 2019

  Abstract

  To evaluate the impact of ultra-rapid FLASH mouse whole brain irradiation on hippocampal dendritic spines and neuroinflammation, factors associated with cognitive impairment after brain irradiation.We administered 30 Gy whole brain irradiation to C57BL6/J mice in sub-second (FLASH) vs. 240 s conventional delivery time keeping all other parameters constant, using a custom configured clinical linac. Ten weeks post-irradiation, we evaluated spatial and non-spatial object recognition using novel object location and object recognition testing. We measured dendritic spine density by tracing Golgi-stained hippocampal neurons and evaluated neuroinflammation by CD68 immunostaining, a marker of activated microglia, and expression of 10 pro-inflammatory cytokines using a multiplex immunoassay.At ten weeks post-irradiation, compared to unirradiated controls, conventional delivery time irradiation significantly impaired novel object location and recognition tasks whereas the same dose given in FLASH delivery did not. Conventional delivery time, but not FLASH, was associated with significant loss of dendritic spine density in hippocampal apical dendrites, with a similar non-significant trend in basal dendrites. Conventional delivery time was associated with significantly increased CD68-positive microglia compared to controls whereas FLASH was not. Conventional delivery time was associated with significant increases in 5 of 10 pro-inflammatory cytokines in the hippocampus (and non-significant increases in another 3), whereas FLASH was associated with smaller increases in only 3.Reduced cognitive impairment and associated neurodegeneration were observed with FLASH compared to conventional delivery time irradiation, potentially through decreased induction of neuroinflammation, suggesting a promising approach to increasing therapeutic index in radiation therapy of brain tumors.

  View details for DOI 10.1016/j.radonc.2019.06.006

  View details for PubMedID 31253467

• Irradiation or temozolomide chemotherapy enhances anti-CD47 treatment of glioblastoma. Innate immunity Gholamin, S. n., Youssef, O. A., Rafat, M. n., Esparza, R. n., Kahn, S. n., Shahin, M. n., Giaccia, A. J., Graves, E. E., Weissman, I. n., Mitra, S. n., Cheshier, S. H. 2019: 1753425919876690

  View details for DOI 10.1177/1753425919876690

  View details for PubMedID 31547758

• Theranostic nanoparticles enhance the response of glioblastomas to radiation Nanotheranostics Wu, W., Klockow, J. L., Mohanty, S., Ku, K. S., Daldrup-Link, H. E. 2019; 3(4) (299-310)

  View details for DOI 10.7150/ntno.35342

• Preclinical Evaluation of Dose-Volume Effects and Lung Toxicity Occurring in- and out-of-field. International journal of radiation oncology, biology, physics Ghita, M., Dunne, V. L., McMahon, S. J., Osman, S. O., Small, D. M., Weldon, S., Taggart, C. C., McGarry, C. K., Hounsell, A. R., Graves, E. E., Prise, K. M., Hanna, G. G., Butterworth, K. T. 2018

  Abstract

  PURPOSE: The aim of this study was to define the dose and dose-volume relationship of radiation induced pulmonary toxicities occurring in and out-of-field in mouse models of early inflammatory and late fibrotic response.MATERIALS AND METHODS: Early radiation induced inflammation and fibrosis were investigated in C3H/NeJ and C57BL/6J mice respectively. Animals were irradiated with 20 Gy delivered to the upper region of the right lung as a single fraction or as three consecutive fractions using the Small Animal Radiation Research Platform (SARRP, Xstrahl Inc., Camberley, UK). Cone Beam Computed Tomography (CBCT) was performed for image guidance prior to irradiation and to monitor late toxicity. Histological sections were examined for neutrophil and macrophage infiltration as markers of early inflammatory response, type I collagen staining as a marker of late occurring fibrosis. Correlation was evaluated with the Dose Volume Histogram (DVH) parameters calculated for individual mice and changes in the observed CBCT values.RESULTS: Mean Lung Dose (MLD) and the volume receiving over 10 Gy (V10) showed significant correlation with late responses for single and fractionated exposures in directly targeted volumes. Responses observed outside the target volume were attributed to non-targeted effects and showed no dependence on either MLD or V10.CONCLUSIONS: Quantitative assessment of normal tissue response closely correlates early and late pulmonary response with clinical parameters demonstrating this approach as a potential tool to facilitate clinical translation of preclinical studies. Out-of-field effects were observed but did not correlate with dosimetric parameters suggesting non-targeted effects may have a role in driving toxicities outside the treatment field.

  View details for PubMedID 30552964

• Papaverine and its derivatives radiosensitize solid tumors by inhibiting mitochondrial metabolism PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Benej, M., Hong, X., Vibhute, S., Scott, S., Wu, J., Graves, E., Le, Q., Koong, A. C., Giaccia, A. J., Yu, B., Chen, S., Papandreou, I., Denko, N. C. 2018; 115 (42): 10756–61

  Abstract

  Tumor hypoxia reduces the effectiveness of radiation therapy by limiting the biologically effective dose. An acute increase in tumor oxygenation before radiation treatment should therefore significantly improve the tumor cell kill after radiation. Efforts to increase oxygen delivery to the tumor have not shown positive clinical results. Here we show that targeting mitochondrial respiration results in a significant reduction of the tumor cells' demand for oxygen, leading to increased tumor oxygenation and radiation response. We identified an activity of the FDA-approved drug papaverine as an inhibitor of mitochondrial complex I. We also provide genetic evidence that papaverine's complex I inhibition is directly responsible for increased oxygenation and enhanced radiation response. Furthermore, we describe derivatives of papaverine that have the potential to become clinical radiosensitizers with potentially fewer side effects. Importantly, this radiosensitizing strategy will not sensitize well-oxygenated normal tissue, thereby increasing the therapeutic index of radiotherapy.

  View details for PubMedID 30201710

• A gold nanoparticle system for enhancement of radiotherapy and simultaneous monitoring of reactive-oxygen-species formation. Nanotechnology Choi, J., Jung, K., Graves, E. E., Pratx, G. 2018

  Abstract

  Gold nanoparticles (AuNPs) are known to sensitize cancer cells to radiation therapy (RT) by increasing the deposition of ionizing energy in their immediate vicinity. However, this process of dose enhancement is challenging to monitor because it is heterogeneous at the sub-cellular scale. Furthermore, radiation damage is primarily mediated by reactive oxygen species (ROS) that are produced following water radiolysis. Here, radiation-responsive PEGylated gold nanoparticles (RPAuNPs) were synthesized for enhanced generation and concurrent detection of ROS in cancer cells and tumors. PEGylated gold particles (20 nm diameter) were functionalized with dihydrorhodamine 123 (DHR-123), a known ROS sensor, to monitor ROS generation in their immediate vicinity. These nanoparticles were able to effectively radiosensitize cells, as measured by increased cell apoptosis following RT. Furthermore, the fluorescence of these RPAuNPs was sevenfold higher after 6 Gy RT due to local production of ROS near the surface of the nanoparticle. Finally, multispectral fluorescence imaging was used to monitor nanoparticle-induced ROS in vivo, following conformal RT, in a xenograft model of breast cancer. This theranostic nanoparticle system provides a novel approach for monitoring the nanoscale enhancement of RT by high-Z metal nanoparticles.

  View details for PubMedID 30229748

• 18F-EF5 Pet-Based Imageable Hypoxia Predicts for Local Control in Tumors Treated With Conformal Radiotherapy Qian, Y., Liu, Y., Von Eyben, R., Carter, J. N., Pollom, E. L., Harris, J. P., Prionas, N. D., Binkley, M. S., Simmons, A., Diehn, M., Chin, F. T., Shultz, D. B., Brown, J., Maxim, P. G., Koong, A. C., Graves, E. E., Loo, B. W. ELSEVIER SCIENCE INC. 2018: E17–E18

  View details for Web of Science ID 000432447200042

• The tumour microenvironment links complement system dysregulation and hypoxic signalling. The British journal of radiology Olcina, M. M., Kim, R. K., Melemenidis, S., Graves, E. E., Giaccia, A. J. 2018: 20180069

  Abstract

  The complement system is an innate immune pathway typically thought of as part of the first line of defence against "non-self" species. In the context of cancer, complement has been described to have an active role in facilitating cancer-associated processes such as increased proliferation, angiogenesis and migration. Several cellular members of the tumour microenvironment express and/or produce complement proteins locally, including tumour cells. Dysregulation of the complement system has been reported in numerous tumours and increased expression of complement activation fragments in cancer patient specimens correlates with poor patient prognosis. Importantly, genetic or pharmacological targeting of complement has been shown to reduce tumour growth in several cancer preclinical models, suggesting that complement could be an attractive therapeutic target. Hypoxia (low oxygen) is frequently found in solid tumours and has a profound biological impact on cellular and non-cellular components of the tumour microenvironment. In this review, we focus on hypoxia since this is a prevailing feature of the tumour microenvironment that, like increased complement, is typically associated with poor prognosis. Furthermore, interesting links between hypoxia and complement have been recently proposed but never collectively reviewed. Here, we explore how hypoxia alters regulation of complement proteins in different cellular components of the tumour microenvironment, as well as the downstream biological consequences of this regulation.

  View details for PubMedID 29544344

• Present developments in reaching an international consensus for a model-based approach to particle beam therapy JOURNAL OF RADIATION RESEARCH Prayongrat, A., Umegaki, K., van der Schaaf, A., Koong, A. C., Lin, S. H., Whitaker, T., McNutt, T., Matsufuji, N., Graves, E., Mizuta, M., Ogawa, K., Date, H., Moriwaki, K., Ito, Y. M., Kobashi, K., Dekura, Y., Shimizu, S., Shirato, H. 2018; 59: I72–I76

  Abstract

  Particle beam therapy (PBT), including proton and carbon ion therapy, is an emerging innovative treatment for cancer patients. Due to the high cost of and limited access to treatment, meticulous selection of patients who would benefit most from PBT, when compared with standard X-ray therapy (XRT), is necessary. Due to the cost and labor involved in randomized controlled trials, the model-based approach (MBA) is used as an alternative means of establishing scientific evidence in medicine, and it can be improved continuously. Good databases and reasonable models are crucial for the reliability of this approach. The tumor control probability and normal tissue complication probability models are good illustrations of the advantages of PBT, but pre-existing NTCP models have been derived from historical patient treatments from the XRT era. This highlights the necessity of prospectively analyzing specific treatment-related toxicities in order to develop PBT-compatible models. An international consensus has been reached at the Global Institution for Collaborative Research and Education (GI-CoRE) joint symposium, concluding that a systematically developed model is required for model accuracy and performance. Six important steps that need to be observed in these considerations include patient selection, treatment planning, beam delivery, dose verification, response assessment, and data analysis. Advanced technologies in radiotherapy and computer science can be integrated to improve the efficacy of a treatment. Model validation and appropriately defined thresholds in a cost-effectiveness centered manner, together with quality assurance in the treatment planning, have to be achieved prior to clinical implementation.

  View details for PubMedID 29529229

  View details for PubMedCentralID PMC5868183

• THE NATURAL HISTORY OF RADIATION CYSTITIS IN A RAT MODEL OF ACUTE AND CHRONIC LOWER URINARY TRACT DYSFUNCTION Dobberfuhl, A. D., Briggs, M. A., Wen, Y., Ning, S., Graves, E. E., Diaz, E. C., Chen, B. WILEY. 2018: S538

  View details for Web of Science ID 000427016100034

• Mid-radiotherapy PET/CT for prognostication and detection of early progression in patients with stage III non-small cell lung cancer RADIOTHERAPY AND ONCOLOGY Gensheimer, M. F., Hong, J. C., Chang-Halpenny, C., Zhu, H., Eclov, N. W., To, J., Murphy, J. D., Wakelee, H. A., Neal, J. W., Le, Q., Hara, W. Y., Quon, A., Maxim, P. G., Graves, E. E., Olson, M. R., Diehn, M., Loo, B. W. 2017; 125 (2): 338–43

  Abstract

  Pre- and mid-radiotherapy FDG-PET metrics have been proposed as biomarkers of recurrence and survival in patients treated for stage III non-small cell lung cancer. We evaluated these metrics in patients treated with definitive radiation therapy (RT). We also evaluated outcomes after progression on mid-radiotherapy PET/CT.Seventy-seven patients treated with RT with or without chemotherapy were included in this retrospective study. Primary tumor and involved nodes were delineated. PET metrics included metabolic tumor volume (MTV), total lesion glycolysis (TLG), and SUVmax. For mid-radiotherapy PET, both absolute value of these metrics and percentage decrease were analyzed. The influence of PET metrics on time to death, local recurrence, and regional/distant recurrence was assessed using Cox regression.91% of patients had concurrent chemotherapy. Median follow-up was 14months. None of the PET metrics were associated with overall survival. Several were positively associated with local recurrence: pre-radiotherapy MTV, and mid-radiotherapy MTV and TLG (p=0.03-0.05). Ratio of mid- to pre-treatment SUVmax was associated with regional/distant recurrence (p=0.02). 5/77 mid-radiotherapy scans showed early out-of-field progression. All of these patients died.Several PET metrics were associated with risk of recurrence. Progression on mid-radiotherapy PET/CT was a poor prognostic factor.

  View details for PubMedID 28830717

• Patterns of Vasculature in Mouse Models of Lung Cancer Are Dependent on Location MOLECULAR IMAGING AND BIOLOGY Vilalta, M., Hughes, N. P., von Eyben, R., Giaccia, A. J., Graves, E. E. 2017; 19 (2): 215-224

  View details for DOI 10.1007/s11307-016-1010-5

  View details for Web of Science ID 000396058200005

• Feasibility of external beam radiation therapy to deep-seated targets with kilovoltage x-rays. Medical physics Bazalova-Carter, M., Weil, M. D., Breitkreutz, D. Y., Wilfley, B. P., Graves, E. E. 2017; 44 (2): 597-607

  Abstract

  Radiation therapy to deep-seated targets is typically delivered with megavoltage x-ray beams generated by medical linear accelerators or (60) Co sources. Here, we used computer simulations to design and optimize a lower energy kilovoltage x-ray source generating acceptable dose distributions to a deep-seated target.The kilovoltage arc therapy (KVAT) x-ray source was designed to treat a 4-cm diameter target located at a 10-cm depth in a 40-cm diameter homogeneous cylindrical phantom. These parameters were chosen as an example of a clinical scenario for testing the performance of the kilovoltage source. A Monte Carlo (MC) model of the source was built in the EGSnrc/BEAMnrc code and source parameters, such as beam energy, tungsten anode thickness, beam filtration, number of collimator holes, collimator hole size and thickness, and source extent were varied. Dose to the phantom was calculated in the EGSnrc/DOSXYZnrc code for varying treatment parameters, such as the source-to-axis distance and the treatment arc angle. The quality of dose distributions was quantified by means of target-to-skin ratio and dose output expressed in D50 (50% isodose line) for a 30-min irradiation in the homogeneous phantom as well as a lung phantom. Additionally, a patient KVAT dose distribution to a left pararenal lesion (~1.6 cm in diameter) was calculated and compared to a 15 MV volumetric modulated arc therapy (VMAT) plan.In the design of the KVAT x-ray source, the beam energy, beam filtration, collimator hole size, source-to-isocenter distance, and treatment arc had the largest effect on the source output and the quality of dose distributions. For the 4-cm target at 10-cm depth, the optimized KVAT dose distribution generated a conformal plan with target-to-skin ratio of 5.1 and D50 in 30 min of 24.1 Gy in the homogeneous phantom. In the lung phantom, a target-to-skin ratio of 7.5 and D50 in 30 min of 25.3 Gy were achieved. High dose conformity of the 200 kV KVAT left pararenal plan was comparable to the 15 MV VMAT plan. The volume irradiated to at least 10% (<240 cGy) of the prescription dose was 2.2 × larger in the 200 kV KVAT plan than in the 15 MV VMAT plan, but considered clinically insignificant.This study demonstrated that conformal treatments of deep-seated targets were achievable with kilovoltage x-rays with dose distributions comparable to MV beams. However, due to the larger volumes irradiated to clinically tolerated low doses, KVAT x-ray source usage for deep-seated lesions will be further evaluated to determine optimal target size.

  View details for DOI 10.1002/mp.12047

  View details for PubMedID 28133751

• Dynamic CT imaging of volumetric changes in pulmonary nodules correlates with physical measurements of stiffness. Radiotherapy and oncology Lartey, F. M., Rafat, M., Negahdar, M., Malkovskiy, A. V., Dong, X., Sun, X., Li, M., Doyle, T., Rajadas, J., Graves, E. E., Loo, B. W., Maxim, P. G. 2017; 122 (2): 313-318

  Abstract

  A major challenge in CT screening for lung cancer is limited specificity when distinguishing between malignant and non-malignant pulmonary nodules (PN). Malignant nodules have different mechanical properties and tissue characteristics ('stiffness') from non-malignant nodules. This study seeks to improve CT specificity by demonstrating in rats that measurements of volumetric ratios in PNs with varying composition can be determined by respiratory-gated dynamic CT imaging and that these ratios correlate with direct physical measurements of PN stiffness.Respiratory-gated MicroCT images acquired at extreme tidal volumes of 9 rats with PNs from talc, matrigel and A549 human lung carcinoma were analyzed and their volumetric ratios (δ) derived. PN stiffness was determined by measuring the Young's modulus using atomic force microscopy (AFM) for each nodule excised immediately after MicroCT imaging.There was significant correlation (p=0.0002) between PN volumetric ratios determined by respiratory-gated CT imaging and the physical stiffness of the PNs determined from AFM measurements.We demonstrated proof of concept that PN volume changes measured non-invasively correlate with direct physical measurements of stiffness. These results may translate clinically into a means of improving the specificity of CT screening for lung cancer and/or improving individual prognostic assessments based on lung tumor stiffness.

  View details for DOI 10.1016/j.radonc.2016.11.019

  View details for PubMedID 27989402

  View details for PubMedCentralID PMC5319913

• Metabolic tumor volume predicts overall survival and local control in patients with stage III non-small cell lung cancer treated in ACRIN 6668/RTOG 0235 EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Bazan, J. G., Duan, F., Snyder, B. S., Horng, D., Graves, E. E., Siegel, B. A., Machtay, M., Loo, B. W. 2017; 44 (1): 17-24

  Abstract

  To determine whether higher pre-treatment metabolic tumor volume (tMTV-pre) is associated with worse overall survival (OS) in patients with inoperable NSCLC treated with definitive chemoradiation (CRT).This is a secondary analysis of the American College of Radiology Imaging Network (ACRIN) 6668/Radiation Therapy Oncology Group 0235 trial. Pre-treatment PET scans were performed on ACRIN-qualified scanners. Computer-aided MTV measurement was performed using RT_Image. Kaplan-Meier curves and Cox proportional hazards regression models were used to assess the association between tMTV and OS.Of the 250 patients enrolled on the study, 230 were evaluable for tMTV-pre. Patients with MTV-pre >32 mL (median value) vs. ≤32 mL had worse median OS (14.8 vs. 29.7 months, p < 0.001). As a continuous variable, higher tMTV-pre (per 10-mL increase) remained associated with worse OS (HR = 1.03, p < 0.001) after controlling for other variables. A significant interaction between radiation dose and tMTV-pre occurred for OS (p = 0.002), demonstrating that the negative prognostic impact of tMTV-pre decreased as radiotherapy dose increased. Among patients with tMTV-pre ≤32 mL, there was no difference in survival according to radiotherapy dose delivered (p = 0.694). However, median OS was inferior in patients with tMTV-pre >32 mL who received ≤60 Gy compared with those who received 61-69 Gy or ≥70 Gy (p = 0.001).Higher tMTV-pre is associated with significantly worse OS in inoperable stage III NSCLC treated with definitive CRT. Our findings suggest that for patients with large tMTV-pre, achieving a therapeutic radiation dose may help maximize OS. Prospective studies are needed to confirm this finding.

  View details for DOI 10.1007/s00259-016-3520-4

  View details for Web of Science ID 000389242200004

  View details for PubMedCentralID PMC5121029

• Detection of nociceptive-related metabolic activity in the spinal cord of low back pain patients using (18)F-FDG PET/CT. Scandinavian journal of pain Zhou, X. n., Cipriano, P. n., Kim, B. n., Dhatt, H. n., Rosenberg, J. n., Mittra, E. n., Do, B. n., Graves, E. n., Biswal, S. n. 2017; 15: 53–57

  Abstract

  Over the past couple of decades, a number of centers in the brain have been identified as important sites of nociceptive processing and are collectively known as the 'pain matrix.' Imaging tools such as functional magnetic resonance imaging (MRI) and (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) have played roles in defining these pain-relevant, physiologically active brain regions. Similarly, certain segments of the spinal cord are likely more metabolically active in the setting of pain conditions, the location of which is dependent upon location of symptoms. However, little is known about the physiologic changes in the spinal cord in the context of pain. This study aimed to determine whether uptake of (18)F-FDG in the spinal cord on positron emission tomography/computed tomography (PET/CT) of patients with low back pain (LBP) differs from that of patients without LBP.We conducted a retrospective review of (18)F-FDG PET/CT scans of 26 patients with non-central nervous system cancers, 13 of whom had reported LBP and 13 of whom were free of LBP (controls). No patients had spinal stenosis or significant (18)F-FDG contribution of degenerative changes of the spine into the spinal canal. Circular regions of interests were drawn within the spinal canal on transaxial images, excluding bony or discal elements of the spine, and the maximum standardized uptake value (SUVmax) of every slice from spinal nerves C1 to S1 was obtained. SUVmax were normalized by subtracting the SUVmax of spinal nerve L5, as minimal neural tissue is present at this level. Normalized SUVmax of LBP patients were compared to those of LBP-free patients at each vertebral level.We found the normalized SUVmax of patients with LBP to be significantly greater than those of control patients when jointly tested at spinal nerves of T7, T8, T9 and T10 (p<0.001). No significant difference was found between the two groups at other levels of the spinal cord. Within the two groups, normalized SUVmax generally decreased cephalocaudally.Patients with LBP show increased uptake of (18)F-FDG in the caudal aspect of the thoracic spinal cord, compared to patients without LBP.This paper demonstrates the potential of (18)F-FDG PET/CT as a biomarker of increased metabolic activity in the spinal cord related to LBP. As such, it could potentially aid in the treatment of LBP by localizing physiologically active spinal cord regions and guiding minimally invasive delivery of analgesics or stimulators to relevant levels of the spinal cord.

  View details for PubMedID 28850345

• External Beam Radiation Therapy for the Treatment of Human Pluripotent Stem Cell-Derived Teratomas. Stem cells (Dayton, Ohio) Lee, A. S., Tang, C. n., Hong, W. X., Park, S. n., Bazalova, M. n., Nelson, G. n., Sanchez-Freire, V. n., Bakerman, I. n., Zhang, W. n., Neofytou, E. n., Connolly, A. J., Chan, C. K., Graves, E. E., Weissman, I. L., Nguyen, P. K., Wu, J. C. 2017

  Abstract

  Human pluripotent stem cells (hPSCs), including embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), have great potential as an unlimited donor source for cell-based therapeutics. The risk of teratoma formation from residual undifferentiated cells, however, remains a critical barrier to the clinical application of these cells. Herein we describe external beam radiation therapy (EBRT) as an attractive option for the treatment of this iatrogenic growth. We present the evidence that EBRT is effective in arresting growth of hESC-derived teratomas in vivo at day 28 post-implantation by utilizing a microCT irradiator capable of targeted treatment in small animals. Within several days of irradiation, teratomas derived from injection of undifferentiated hESCs and hiPSCs demonstrated complete growth arrest lasting several months. In addition, EBRT reduced re-seeding potential of teratoma cells during serial transplantation experiments, requiring irradiated teratomas to be seeded at 1x10(3) higher doses to form new teratomas. We demonstrate that radiation induces teratoma cell apoptosis, senescence, and growth arrest, similar to established radiobiology mechanisms. Taken together, these results provide proof of concept for the use of EBRT in the treatment of existing teratomas and highlight a strategy to increase the safety of stem cell-based therapies. This article is protected by copyright. All rights reserved.

  View details for PubMedID 28600830

• Blimp1 induces transient metastatic heterogeneity in pancreatic cancer. Cancer discovery Chiou, S. H., Risca, V. I., Wang, G. X., Yang, D. n., Grüner, B. M., Kathiria, A. S., Ma, R. K., Vaka, D. n., Chu, P. n., Kozak, M. n., Castellini, L. n., Graves, E. E., Kim, G. E., Mourrain, P. n., Koong, A. C., Giaccia, A. J., Winslow, M. M. 2017

  Abstract

  Pancreatic ductal adenocarcinoma (PDAC) is one of the most metastatic and deadly cancers. Despite the clinical significance of metastatic spread, our understanding of molecular mechanisms that drive PDAC metastatic ability remains limited. Using a novel genetically engineered mouse model of human PDAC, we uncover a transient subpopulation of cancer cells with exceptionally high metastatic ability. Global gene expression profiling and functional analyses uncovered the transcription factor Blimp1 as a key driver of PDAC metastasis. The highly metastatic PDAC subpopulation is enriched for hypoxia-induced genes and hypoxia-mediated induction of Blimp1 contributes to the regulation of a subset of hypoxia-associated gene expression programs. These findings support a model in which up-regulation of Blimp1 links microenvironmental cues to a metastatic stem cell character.

  View details for PubMedID 28790031

• Patterns of Vasculature in Mouse Models of Lung Cancer Are Dependent on Location. Molecular imaging and biology Vilalta, M., Hughes, N. P., von Eyben, R., Giaccia, A. J., Graves, E. E. 2016: -?

  Abstract

  Preclinical studies of hypoxia are generally done using ectopic xenograft tumors, which behave differently from human tumors. Our previous findings have shown that subcutaneously implanted lung tumors exhibit more hypoxia than their orthotopic implanted or spontaneous K-ras-induced counterparts. We hypothesize that differences in hypoxia are due to site-specific differences in vascularity and perfusion.To compare the presence and functionality of vessels in these tumor models, we studied vascular perfusion in vivo in real time.Orthotopically implanted and spontaneous K-ras-induced lung tumors showed elevated perfusion, demonstrating vasculature functionality. Little contrast agent uptake was observed within the subcutaneously implanted tumors, indicating vascular dysfunction. These findings were corroborated at the microscopic level with Hoechst 33342 and Meca-32 staining.From these observations, we concluded that differences in hypoxia in experimental models is related to vessel perfusion. Thus, appropriate selection of preclinical lung tumor models is essential for the study of hypoxia, angiogenesis and therapies targeting these phenomena.

  View details for PubMedID 27709411

• Metabolic tumor volume predicts overall survival and local control in patients with stage III non-small cell lung cancer treated in ACRIN 6668/RTOG 0235. European journal of nuclear medicine and molecular imaging Bazan, J. G., Duan, F., Snyder, B. S., Horng, D., Graves, E. E., Siegel, B. A., Machtay, M., Loo, B. W. 2016: -?

  Abstract

  To determine whether higher pre-treatment metabolic tumor volume (tMTV-pre) is associated with worse overall survival (OS) in patients with inoperable NSCLC treated with definitive chemoradiation (CRT).This is a secondary analysis of the American College of Radiology Imaging Network (ACRIN) 6668/Radiation Therapy Oncology Group 0235 trial. Pre-treatment PET scans were performed on ACRIN-qualified scanners. Computer-aided MTV measurement was performed using RT_Image. Kaplan-Meier curves and Cox proportional hazards regression models were used to assess the association between tMTV and OS.Of the 250 patients enrolled on the study, 230 were evaluable for tMTV-pre. Patients with MTV-pre >32 mL (median value) vs. ≤32 mL had worse median OS (14.8 vs. 29.7 months, p < 0.001). As a continuous variable, higher tMTV-pre (per 10-mL increase) remained associated with worse OS (HR = 1.03, p < 0.001) after controlling for other variables. A significant interaction between radiation dose and tMTV-pre occurred for OS (p = 0.002), demonstrating that the negative prognostic impact of tMTV-pre decreased as radiotherapy dose increased. Among patients with tMTV-pre ≤32 mL, there was no difference in survival according to radiotherapy dose delivered (p = 0.694). However, median OS was inferior in patients with tMTV-pre >32 mL who received ≤60 Gy compared with those who received 61-69 Gy or ≥70 Gy (p = 0.001).Higher tMTV-pre is associated with significantly worse OS in inoperable stage III NSCLC treated with definitive CRT. Our findings suggest that for patients with large tMTV-pre, achieving a therapeutic radiation dose may help maximize OS. Prospective studies are needed to confirm this finding.

  View details for PubMedID 27645692

• Effects of radiation on metastasis and tumor cell migration. Cellular and molecular life sciences Vilalta, M., Rafat, M., Graves, E. E. 2016; 73 (16): 2999-3007

  Abstract

  It is well known that tumor cells migrate from the primary lesion to distant sites to form metastases and that these lesions limit patient outcome in a majority of cases. However, the extent to which radiation influences this process and to which migration in turn alters radiation response remains controversial. There are preclinical and clinical reports showing that focal radiotherapy can both increase the development of distant metastasis, as well as that it can induce the regression of established metastases through the abscopal effect. More recently, preclinical studies have suggested that radiation can attract migrating tumor cells and may, thereby, facilitate tumor recurrence. In this review, we summarize these phenomena and their potential mechanisms of action, and evaluate their significance for modern radiation therapy strategies.

  View details for DOI 10.1007/s00018-016-2210-5

  View details for PubMedID 27022944

• The impact of audiovisual biofeedback on 4D functional and anatomic imaging: Results of a lung cancer pilot study. Radiotherapy and oncology Yang, J., Yamamoto, T., Pollock, S., Berger, J., Diehn, M., Graves, E. E., Loo, B. W., Keall, P. J. 2016; 120 (2): 267-272

  Abstract

  The impact of audiovisual (AV) biofeedback on four dimensional (4D) positron emission tomography (PET) and 4D computed tomography (CT) image quality was investigated in a prospective clinical trial (NCT01172041).4D-PET and 4D-CT images of ten lung cancer patients were acquired with AV biofeedback (AV) and free breathing (FB). The 4D-PET images were analyzed for motion artifacts by comparing 4D to 3D PET for gross tumor volumes (GTVPET) and maximum standardized uptake values (SUVmax). The 4D-CT images were analyzed for artifacts by comparing normalized cross correlation-based scores (NCCS) and quantifying a visual assessment score (VAS). A Wilcoxon signed-ranks test was used for statistical testing.The impact of AV biofeedback varied widely. Overall, the 3D to 4D decrease of GTVPET was 1.2±1.3cm(3) with AV and 0.6±1.8cm(3) for FB. The 4D-PET increase of SUVmax was 1.3±0.9 with AV and 1.3±0.8 for FB. The 4D-CT NCCS were 0.65±0.27 with AV and 0.60±0.32 for FB (p=0.08). The 4D-CT VAS was 0.0±2.7.This study demonstrated a high patient dependence on the use of AV biofeedback to reduce motion artifacts in 4D imaging. None of the hypotheses tested were statistically significant. Future development of AV biofeedback will focus on optimizing the human-computer interface and including patient training sessions for improved comprehension and compliance.

  View details for DOI 10.1016/j.radonc.2016.05.016

  View details for PubMedID 27256597

• Quantitative and qualitative analysis of [(18)F]FDG and [(18)F]FAZA positron emission tomography of head and neck cancers and associations with HPV status and treatment outcome. European journal of nuclear medicine and molecular imaging Graves, E. E., Hicks, R. J., Binns, D., Bressel, M., Le, Q., Peters, L., Young, R. J., Rischin, D. 2016; 43 (4): 617-625

  Abstract

  While methods for imaging tumor hypoxia with positron emission tomography (PET) have been developed, optimal methods for interpreting and utilizing these datasets in the clinic remain unclear. In this study, we analyzed hypoxia PET images of head and neck cancer patients and compared imaging metrics with human papilloma virus (HPV) status and clinical outcome.Forty-one patients treated as part of a phase III trial of the hypoxic cytotoxin tirapazamine (TROG 02.02) were imaged with PET using fluorodeoxyglucose (FDG) and fluoroazomycin arabinoside (FAZA). FDG and FAZA PET images were interpreted qualitatively and quantitatively, and compared with tumor T stage, HPV status, and treatment outcome using multivariate statistics.PET signals in the tumor and lymph nodes exhibited significant intra- and inter-patient variability. The FAZA hypoxic volume demonstrated a significant correlation with tumor T stage. PET-hypoxic tumors treated with cisplatin exhibited significantly worse treatment outcomes relative to PET-oxic tumors or PET-hypoxic tumors treated with tirapazamine.Quantitative analysis of FAZA PET yielded metrics that correlated with clinical T stage and were capable of stratifying patient outcome. These results encourage further development of this technology, with particular emphasis on establishment of robust quantitative methods.

  View details for DOI 10.1007/s00259-015-3247-7

  View details for PubMedID 26577940

  View details for PubMedCentralID PMC4767583

• Quantitative and qualitative analysis of [F-18]FDG and [F-18]FAZA positron emission tomography of head and neck cancers and associations with HPV status and treatment outcome EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Graves, E. E., Hicks, R. J., Binns, D., Bressel, M., Quynh-Thu Le, Q. T., Peters, L., Young, R. J., Rischin, D. 2016; 43 (4): 617-625

  View details for DOI 10.1007/s00259-015-3247-7

  View details for Web of Science ID 000371074100003

• Outcomes of Modestly Hypofractionated Radiation for Lung Tumors: Pre- and Mid-Treatment Positron Emission Tomography-Computed Tomography Metrics as Prognostic Factors. Clinical lung cancer Harris, J. P., Chang-Halpenny, C. N., Maxim, P. G., Quon, A., Graves, E. E., Diehn, M., Loo, B. W. 2015; 16 (6): 475-485

  Abstract

  Modestly hypofractionated radiation therapy (HypoRT; 60-66 Gy in 3-Gy fractions) allows patients with locally advanced thoracic tumors and poor performance status to complete treatment within a shorter period without concurrent chemotherapy. We evaluated the outcomes and imaging prognostic factors of HypoRT.We retrospectively reviewed the data from all patients with primary and metastatic intrathoracic tumors treated with HypoRT from 2006 to 2012. We analyzed the survival and toxicity outcomes, including overall survival (OS), progression-free survival (PFS), local recurrence (LR), and distant metastasis. We also evaluated the following tumor metrics in an exploratory analysis: gross tumor volume (GTV), maximum standardized uptake value (SUVMax), and metabolic tumor volume using a threshold of ≥ 50% of the SUVMax (MTV50%) or the maximum gradient of fluorine-18 fluorodeoxyglucose uptake (MTVEdge). We assessed the association of these metrics and their changes from before to mid-RT using positron emission tomography-computed tomography (PET-CT) with OS and PFS.We identified 29 patients, all with pre-RT and 20 with mid-RT PET-CT scans. The median follow-up period was 15 months. The 2-year overall and non-small-cell lung cancer-only rate for OS, PFS, and LR, was 59% and 59%, 52% and 41%, and 27% and 32%, respectively. No grade ≥ 3 toxicities developed. The median decrease in GTV, SUVMax, and MTVEdge was 11%, 24%, and 18%, respectively. Inferior OS was associated with a larger pre-RT MTVEdge (P = .005) and pre-RT MTV50% (P = .007). Inferior PFS was associated with a larger mid-RT SUVMax (P = .003).These findings add to the growing body of data demonstrating promising outcomes and limited toxicity with HypoRT. The pre- and mid-RT PET-CT metrics could be useful for prognostic stratification in future clinical trials.

  View details for DOI 10.1016/j.cllc.2015.01.007

  View details for PubMedID 25770888

• Molecular Magnetic Resonance Imaging of Tumor Response to Therapy SCIENTIFIC REPORTS Shuhendler, A. J., Ye, D., Brewer, K. D., Bazalova-Carter, M., Lee, K., Kempen, P., Wittrup, K. D., Graves, E. E., Rutt, B., Rao, J. 2015; 5

  Abstract

  Personalized cancer medicine requires measurement of therapeutic efficacy as early as possible, which is optimally achieved by three-dimensional imaging given the heterogeneity of cancer. Magnetic resonance imaging (MRI) can obtain images of both anatomy and cellular responses, if acquired with a molecular imaging contrast agent. The poor sensitivity of MRI has limited the development of activatable molecular MR contrast agents. To overcome this limitation of molecular MRI, a novel implementation of our caspase-3-sensitive nanoaggregation MRI (C-SNAM) contrast agent is reported. C-SNAM is triggered to self-assemble into nanoparticles in apoptotic tumor cells, and effectively amplifies molecular level changes through nanoaggregation, enhancing tissue retention and spin-lattice relaxivity. At one-tenth the current clinical dose of contrast agent, and following a single imaging session, C-SNAM MRI accurately measured the response of tumors to either metronomic chemotherapy or radiation therapy, where the degree of signal enhancement is prognostic of long-term therapeutic efficacy. Importantly, C-SNAM is inert to immune activation, permitting radiation therapy monitoring.

  View details for DOI 10.1038/srep14759

  View details for Web of Science ID 000362259800001

  View details for PubMedID 26440059

  View details for PubMedCentralID PMC4594000

• F-18-EF5 PET Is Predictive of Response to Fractionated Radiotherapy in Preclinical Tumor Models PLOS ONE Ali, R., Apte, S., Vilalta, M., Subbarayan, M., Miao, Z., Chin, F. T., Graves, E. E. 2015; 10 (10)

  View details for DOI 10.1371/journal.pone.0139425

  View details for Web of Science ID 000362178700056

  View details for PubMedID 26431331

• Imaging radiation response in tumor and normal tissue. American journal of nuclear medicine and molecular imaging Rafat, M., Ali, R., Graves, E. E. 2015; 5 (4): 317-332

  Abstract

  Although X-ray computed tomography (CT) and magnetic resonance imaging (MRI) are the primary imaging modalities used in the clinic to monitor tumor response to radiation therapy, multi-modal molecular imaging may facilitate improved early and specific evaluation of this process. Fast and accurate imaging that can provide both quantitative and biological information is necessary to monitor treatment and ultimately to develop individualized treatment options for patients. A combination of molecular and anatomic information will allow for deeper insight into the mechanisms of tumor response, which will lead to more effective radiation treatments as well as improved anti-cancer drugs. Much progress has been made in nuclear medicine imaging probes and MRI techniques to achieve increased accuracy and the evaluation of relevant biomarkers of radiation response. This review will emphasize promising molecular imaging techniques that monitor various biological processes following radiotherapy, including metabolism, hypoxia, cell proliferation, and angiogenesis.

  View details for PubMedID 26269771

• Evaluation of tumor ischemia in response to an indole-based vascular disrupting agent using BLI and F-19 MRI AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Zhou, H., Hallac, R. R., Lopez, R., Denney, R., MacDonough, M. T., Li, L., Liu, L., Graves, E. E., Trawick, M., Pinney, K. G., Mason, R. P. 2015; 5 (2): 143–53

  Abstract

  Vascular disrupting agents (VDAs) have been proposed as an effective broad spectrum approach to cancer therapy, by inducing ischemia leading to hypoxia and cell death. A novel VDA (OXi8007) was recently reported to show rapid acute selective shutdown of tumor vasculature based on color-Doppler ultrasound. We have now expanded investigations to noninvasively assess perfusion and hypoxiation of orthotopic human MDA-MB-231/luc breast tumor xenografts following the administration of OXi8007 based on dynamic bioluminescence imaging (BLI) and magnetic resonance imaging (MRI). BLI showed significantly lower signal four hours after the administration of OXi8007, which was very similar to the response to combretastatin A-4P (CA4P), but the effect lasted considerably longer, with the BLI signal remaining depressed at 72 hrs. Meanwhile, control tumors exhibited minimal change. Oximetry used (19)F MRI of the reporter molecule hexafluorobenzene and FREDOM (Fluorocarbon Relaxometry using Echo Planar Imaging for Dynamic Oxygen Mapping) to assess pO2 distributions during air and oxygen breathing. pO2 decreased significantly upon the administration of OXi8007 during oxygen breathing (from 122 ± 64 to 34 ± 20 Torr), with further decrease upon switching the gas to air (pO2 = 17 ± 9 Torr). pO2 maps indicated intra-tumor heterogeneity in response to OXi8007, though ultimately all tumor regions became hypoxic. Both BLI and FREDOM showed the efficacy of OXi8007. The pO2 changes measured by FREDOM may be crucial for future study of combined therapy.

  View details for PubMedID 25973335

• The Relationship Between Serial [(18) F]PBR06 PET Imaging of Microglial Activation and Motor Function Following Stroke in Mice MOLECULAR IMAGING AND BIOLOGY Lartey, F. M., Ahn, G., Ali, R., Rosenblum, S., Miao, Z., Arksey, N., Shen, B., Colomer, M. V., Rafat, M., Liu, H., Alejandre-Alcazar, M. A., Chen, J. W., Palmer, T., Chin, F. T., Guzman, R., Loo, B. W., Graves, E. 2014; 16 (6): 821-829

  Abstract

  Using [(18) F]PBR06 positron emission tomography (PET) to characterize the time course of stroke-associated neuroinflammation (SAN) in mice, to evaluate whether brain microglia influences motor function after stroke, and to demonstrate the use of [(18) F]PBR06 PET as a therapeutic assessment tool.Stroke was induced by transient middle cerebral artery occlusion (MCAO) in Balb/c mice (control, stroke, and stroke with poststroke minocycline treatment). [18 F]PBR06 PET/CT imaging, rotarod tests, and immunohistochemistry (IHC) were performed 3, 11, and 22 days poststroke induction (PSI).The stroke group exhibited significantly increased microglial activation, and impaired motor function. Peak microglial activation was 11 days PSI. There was a strong association between microglial activation, motor function, and microglial protein expression on IHC. Minocycline significantly reduced microglial activation and improved motor function by day 22 PSI.[18 F]PBR06 PET imaging noninvasively characterizes the time course of SAN, and shows increased microglial activation is associated with decreased motor function.

  View details for DOI 10.1007/s11307-014-0745-0

  View details for Web of Science ID 000345281600009

• The relationship between serial [(18)?F]PBR06 PET imaging of microglial activation and motor function following stroke in mice. Molecular imaging and biology Lartey, F. M., Ahn, G., Ali, R., Rosenblum, S., Miao, Z., Arksey, N., Shen, B., Colomer, M. V., Rafat, M., Liu, H., Alejandre-Alcazar, M. A., Chen, J. W., Palmer, T., Chin, F. T., Guzman, R., Loo, B. W., Graves, E. 2014; 16 (6): 821-829

  Abstract

  Using [(18) F]PBR06 positron emission tomography (PET) to characterize the time course of stroke-associated neuroinflammation (SAN) in mice, to evaluate whether brain microglia influences motor function after stroke, and to demonstrate the use of [(18) F]PBR06 PET as a therapeutic assessment tool.Stroke was induced by transient middle cerebral artery occlusion (MCAO) in Balb/c mice (control, stroke, and stroke with poststroke minocycline treatment). [18 F]PBR06 PET/CT imaging, rotarod tests, and immunohistochemistry (IHC) were performed 3, 11, and 22 days poststroke induction (PSI).The stroke group exhibited significantly increased microglial activation, and impaired motor function. Peak microglial activation was 11 days PSI. There was a strong association between microglial activation, motor function, and microglial protein expression on IHC. Minocycline significantly reduced microglial activation and improved motor function by day 22 PSI.[18 F]PBR06 PET imaging noninvasively characterizes the time course of SAN, and shows increased microglial activation is associated with decreased motor function.

  View details for DOI 10.1007/s11307-014-0745-0

  View details for PubMedID 24865401

• Recruitment of Circulating Breast Cancer Cells Is Stimulated by Radiotherapy CELL REPORTS Vilalta, M., Rafat, M., Giaccia, A. J., Graves, E. E. 2014; 8 (2): 401-408

  View details for DOI 10.1016/j.celrep.2014.06.011

  View details for Web of Science ID 000341569800010

• PET Imaging of Stroke-Induced Neuroinflammation in Mice Using [F-18]PBR06 MOLECULAR IMAGING AND BIOLOGY Lartey, F. M., Ahn, G., Shen, B., Cord, K., Smith, T., Chua, J. Y., Rosenblum, S., Liu, H., James, M. L., Chernikova, S., Lee, S. W., Pisani, L. J., Tirouvanziam, R., Chen, J. W., Palmer, T. D., Chin, F. T., Guzman, R., Graves, E. E., Loo, B. W. 2014; 16 (1): 109-117

  Abstract

  The purpose of this study is to evaluate the 18 kDa translocator protein (TSPO) radioligand [(18)F]N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline ([(18)F]PBR06) as a positron emission tomography (PET) imaging biomarker of stroke-induced neuroinflammation in a rodent model.Stroke was induced by transient middle cerebral artery occlusion in Balb/c mice. Dynamic PET/CT imaging with displacement and preblocking using PK111195 was performed 3 days later. PET data were correlated with immunohistochemistry (IHC) for the activated microglial markers TSPO and CD68 and with autoradiography.[(18)F]PBR06 accumulation peaked within the first 5 min postinjection, then decreased gradually, remaining significantly higher in infarct compared to noninfarct regions. Displacement or preblocking with PK11195 eliminated the difference in [(18)F]PBR06 uptake between infarct and noninfarct regions. Autoradiography and IHC correlated well spatially with uptake on PET.[(18)F]PBR06 PET specifically images TSPO in microglial neuroinflammation in a mouse model of stroke and shows promise for imaging and monitoring microglial activation/neuroinflammation in other disease models.

  View details for DOI 10.1007/s11307-013-0664-5

  View details for PubMedID 23836504

• The potential of positron emission tomography for intratreatment dynamic lung tumor tracking: A phantom study. Medical physics Yang, J., Yamamoto, T., Mazin, S. R., Graves, E. E., Keall, P. J. 2014; 41 (2): 021718-?

  Abstract

  This study aims to evaluate the potential and feasibility of positron emission tomography for dynamic lung tumor tracking during radiation treatment. The authors propose a center of mass (CoM) tumor tracking algorithm using gated-PET images combined with a respiratory monitor and investigate the geometric accuracy of the proposed algorithm.The proposed PET dynamic lung tumor tracking algorithm estimated the target position information through the CoM of the segmented target volume on gated PET images reconstructed from accumulated coincidence events. The information was continuously updated throughout a scan based on the assumption that real-time processing was supported (actual processing time at each frame ≈10 s). External respiratory motion and list-mode PET data were acquired from a phantom programmed to move with measured respiratory traces (external respiratory motion and internal target motion) from human subjects, for which the ground truth target position was known as a function of time. The phantom was cylindrical with six hollow sphere targets (10, 13, 17, 22, 28, and 37 mm in diameter). The measured respiratory traces consisted of two sets: (1) 1D-measured motion from ten healthy volunteers and (2) 3D-measured motion from four lung cancer patients. The authors evaluated the geometric accuracy of the proposed algorithm by quantifying estimation errors (Euclidean distance) between the actual motion of targets (1D-motion and 3D-motion traces) and CoM trajectories estimated by the proposed algorithm as a function of time.The time-averaged error of 1D-motion traces over all trajectories of all targets was 1.6 mm. The error trajectories decreased with time as coincidence events were accumulated. The overall error trajectory of 1D-motion traces converged to within 2 mm in approximately 90 s. As expected, more accurate results were obtained for larger targets. For example, for the 37 mm target, the average error over all 1D-motion traces was 1.1 mm; and for the 10 mm target, the average error over all 1D-motion traces was 2.8 mm. The overall time-averaged error of 3D-motion traces was 1.6 mm, which was comparable to that of the 1D-motion traces. There were small variations in the errors between the 3D-motion traces, although the motion trajectories were very different. The accuracy of the estimates was consistent for all targets except for the smallest.The authors developed an algorithm for dynamic lung tumor tracking using list-mode PET data and a respiratory motion signal, and demonstrated proof-of-principle for PET-guided lung tumor tracking. The overall tracking error in phantom studies is less than 2 mm.

  View details for DOI 10.1118/1.4861816

  View details for PubMedID 24506609

• Modality comparison for small animal radiotherapy: a simulation study. Medical physics Bazalova, M., Nelson, G., Noll, J. M., Graves, E. E. 2014; 41 (1): 011710-?

  Abstract

  Small animal radiation therapy has advanced significantly in recent years. Whereas in the past dose was delivered using a single beam and a lead shield for sparing of healthy tissue, conformal doses can be now delivered using more complex dedicated small animal radiotherapy systems with image guidance. The goal of this paper is to investigate dose distributions for three small animal radiation treatment modalities.This paper presents a comparison of dose distributions generated by the three approaches-a single-field irradiator with a 200 kV beam and no image guidance, a small animal image-guided conformal system based on a modified microCT scanner with a 120 kV beam developed at Stanford University, and a dedicated conformal system, SARRP, using a 220 kV beam developed at Johns Hopkins University. The authors present a comparison of treatment plans for the three modalities using two cases: a mouse with a subcutaneous tumor and a mouse with a spontaneous lung tumor. A 5 Gy target dose was calculated using the EGSnrc Monte Carlo codes.All treatment modalities generated similar dose distributions for the subcutaneous tumor case, with the highest mean dose to the ipsilateral lung and bones in the single-field plan (0.4 and 0.4 Gy) compared to the microCT (0.1 and 0.2 Gy) and SARRP (0.1 and 0.3 Gy) plans. The lung case demonstrated that due to the nine-beam arrangements in the conformal plans, the mean doses to the ipsilateral lung, spinal cord, and bones were significantly lower in the microCT plan (2.0, 0.4, and 1.9 Gy) and the SARRP plan (1.5, 0.5, and 1.8 Gy) than in single-field irradiator plan (4.5, 3.8, and 3.3 Gy). Similarly, the mean doses to the contralateral lung and the heart were lowest in the microCT plan (1.5 and 2.0 Gy), followed by the SARRP plan (1.7 and 2.2 Gy), and they were highest in the single-field plan (2.5 and 2.4 Gy). For both cases, dose uniformity was greatest in the single-field irradiator plan followed by the SARRP plan due to the sensitivity of the lower energy microCT beam to target heterogeneities and image noise.The two treatment planning examples demonstrate that modern small animal radiotherapy techniques employing image guidance, variable collimation, and multiple beam angles deliver superior dose distributions to small animal tumors as compared to conventional treatments using a single-field irradiator. For deep-seated mouse tumors, however, higher-energy conformal radiotherapy could result in higher doses to critical organs compared to lower-energy conformal radiotherapy. Treatment planning optimization for small animal radiotherapy should therefore be developed to take full advantage of the novel conformal systems.

  View details for DOI 10.1118/1.4842415

  View details for PubMedID 24387502

  View details for PubMedCentralID PMC3888460

• Current status and recommendations for the future of research, teaching, and testing in the biological sciences of radiation oncology: report of the American Society for Radiation Oncology Cancer Biology/Radiation Biology Task Force, executive summary. International journal of radiation oncology, biology, physics Wallner, P. E., Anscher, M. S., Barker, C. A., Bassetti, M., Bristow, R. G., Cha, Y. I., Dicker, A. P., Formenti, S. C., Graves, E. E., Hahn, S. M., Hei, T. K., Kimmelman, A. C., Kirsch, D. G., Kozak, K. R., Lawrence, T. S., Marples, B., McBride, W. H., Mikkelsen, R. B., Park, C. C., Weidhaas, J. B., Zietman, A. L., Steinberg, M. 2014; 88 (1): 11-7

  Abstract

  In early 2011, a dialogue was initiated within the Board of Directors (BOD) of the American Society for Radiation Oncology (ASTRO) regarding the future of the basic sciences of the specialty, primarily focused on the current state and potential future direction of basic research within radiation oncology. After consideration of the complexity of the issues involved and the precise nature of the undertaking, in August 2011, the BOD empanelled a Cancer Biology/Radiation Biology Task Force (TF). The TF was charged with developing an accurate snapshot of the current state of basic (preclinical) research in radiation oncology from the perspective of relevance to the modern clinical practice of radiation oncology as well as the education of our trainees and attending physicians in the biological sciences. The TF was further charged with making suggestions as to critical areas of biological basic research investigation that might be most likely to maintain and build further the scientific foundation and vitality of radiation oncology as an independent and vibrant medical specialty. It was not within the scope of service of the TF to consider the quality of ongoing research efforts within the broader radiation oncology space, to presume to consider their future potential, or to discourage in any way the investigators committed to areas of interest other than those targeted. The TF charge specifically precluded consideration of research issues related to technology, physics, or clinical investigations. This document represents an Executive Summary of the Task Force report.

  View details for DOI 10.1016/j.ijrobp.2013.09.040

  View details for PubMedID 24246724

• Modality comparison for small animal radiotherapy: A simulation study MEDICAL PHYSICS Bazalova, M., Nelson, G., Noll, J. M., Graves, E. E. 2014; 41 (1)

  View details for DOI 10.1118/1.4842415

  View details for Web of Science ID 000329182200015

  View details for PubMedID 24387502

• Semi-automatic segmentation of subcutaneous tumours from micro-computed tomography images PHYSICS IN MEDICINE AND BIOLOGY Ali, R., Gunduz-Demir, C., Szilagyi, T., Durkee, B., Graves, E. E. 2013; 58 (22): 8007-8019

  Abstract

  This paper outlines the first attempt to segment the boundary of preclinical subcutaneous tumours, which are frequently used in cancer research, from micro-computed tomography (microCT) image data. MicroCT images provide low tissue contrast, and the tumour-to-muscle interface is hard to determine, however faint features exist which enable the boundary to be located. These are used as the basis of our semi-automatic segmentation algorithm. Local phase feature detection is used to highlight the faint boundary features, and a level set-based active contour is used to generate smooth contours that fit the sparse boundary features. The algorithm is validated against manually drawn contours and micro-positron emission tomography (microPET) images. When compared against manual expert segmentations, it was consistently able to segment at least 70% of the tumour region (n = 39) in both easy and difficult cases, and over a broad range of tumour volumes. When compared against tumour microPET data, it was able to capture over 80% of the functional microPET volume. Based on these results, we demonstrate the feasibility of subcutaneous tumour segmentation from microCT image data without the assistance of exogenous contrast agents. Our approach is a proof-of-concept that can be used as the foundation for further research, and to facilitate this, the code is open-source and available from www.setuvo.com.

  View details for DOI 10.1088/0031-9155/58/22/8007

  View details for PubMedID 24168809

• Targeted therapies and hypoxia imaging QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Ali, R., Graves, E. E. 2013; 57 (3): 283-295

  Abstract

  Hypoxia-specific cytotoxins have long exhibited considerable promise for treating hypoxic tumors, however recent negative results in large scale clinical trials have highlighted the importance of selecting patients who are most likely to respond using hypoxia imaging methods. This review looks at the available hypoxia-specific cytotoxins and describes how existing hypoxia imaging methods can be best used to predict which tumors will respond. It then surveys prior studies which combine hypoxia-selective cytotoxin treatment with hypoxia imaging, and finally concludes with a discussion of what lessons can be learnt from previous experiences in order to improve the use of these cytotoxic agents in future clinical evaluations.

  View details for PubMedID 24045624

• A Novel Aldehyde Dehydrogenase-3 Activator (Alda-89) Protects Submandibular Gland Function from Irradiation without Accelerating Tumor Growth. Clinical cancer research Xiao, N., Cao, H., Chen, C., Kong, C. S., Ali, R., Chan, C., Sirjani, D., Graves, E., Koong, A., Giaccia, A., Mochly-Rosen, D., Le, Q. 2013; 19 (16): 4455-4464

  Abstract

  To determine the effect of Alda-89 (an ALDH3 activitor) on (i) the function of irradiated (radiotherapy) submandibular gland (SMG) in mice, (ii) its toxicity profile, and (iii) its effect on the growth of head and neck cancer (HNC) in vitro and in vivo.Adult mice were infused with Alda-89 or vehicle before, during, and after radiotherapy. Saliva secretion was monitored weekly. Hematology, metabolic profile, and postmortem evaluation for toxicity were examined at the time of sacrifice. Alda-89 or vehicle was applied to HNC cell lines in vitro, and severe combined immunodeficient (SCID) mice transplanted with HNC in vivo with or without radiation; HNC growth was monitored. The ALDH3A1 and ALDH3A2 protein expression was evaluated in 89 patients with HNC and correlated to freedom from relapse (FFR) and overall survival (OS).Alda-89 infusion significantly resulted in more whole saliva production and a higher percentage of preserved acini after radiotherapy compared with vehicle control. There was no difference in the complete blood count, metabolic profile, and major organ morphology between the Alda-89 and vehicle groups. Compared with vehicle control, Alda-89 treatment neither accelerated HNC cell proliferation in vitro, nor did it affect tumor growth in vivo with or without radiotherapy. Higher expression of ALDH3A1 or ALDH3A2 was not significantly associated with worse FFR or OS in either human papillomavirus (HPV)-positive or HPV-negative group.Alda-89 preserves salivary function after radiotherapy without affecting HNC growth or causing measurable toxicity in mice. It is a promising candidate to mitigate radiotherapy-related xerostomia.

  View details for DOI 10.1158/1078-0432.CCR-13-0127

  View details for PubMedID 23812668

• A Novel Aldehyde Dehydrogenase-3 Activator (Alda-89) Protects Submandibular Gland Function from Irradiation without Accelerating Tumor Growth CLINICAL CANCER RESEARCH Xiao, N., Cao, H., Chen, C., Kong, C. S., Ali, R., Chan, C., Sirjani, D., Graves, E., Koong, A., Giaccia, A., Mochly-Rosen, D., Quynh-Thu Le, Q. T. 2013; 19 (16): 4455-4464

  Abstract

  To determine the effect of Alda-89 (an ALDH3 activitor) on (i) the function of irradiated (radiotherapy) submandibular gland (SMG) in mice, (ii) its toxicity profile, and (iii) its effect on the growth of head and neck cancer (HNC) in vitro and in vivo.Adult mice were infused with Alda-89 or vehicle before, during, and after radiotherapy. Saliva secretion was monitored weekly. Hematology, metabolic profile, and postmortem evaluation for toxicity were examined at the time of sacrifice. Alda-89 or vehicle was applied to HNC cell lines in vitro, and severe combined immunodeficient (SCID) mice transplanted with HNC in vivo with or without radiation; HNC growth was monitored. The ALDH3A1 and ALDH3A2 protein expression was evaluated in 89 patients with HNC and correlated to freedom from relapse (FFR) and overall survival (OS).Alda-89 infusion significantly resulted in more whole saliva production and a higher percentage of preserved acini after radiotherapy compared with vehicle control. There was no difference in the complete blood count, metabolic profile, and major organ morphology between the Alda-89 and vehicle groups. Compared with vehicle control, Alda-89 treatment neither accelerated HNC cell proliferation in vitro, nor did it affect tumor growth in vivo with or without radiotherapy. Higher expression of ALDH3A1 or ALDH3A2 was not significantly associated with worse FFR or OS in either human papillomavirus (HPV)-positive or HPV-negative group.Alda-89 preserves salivary function after radiotherapy without affecting HNC growth or causing measurable toxicity in mice. It is a promising candidate to mitigate radiotherapy-related xerostomia.

  View details for DOI 10.1158/1078-0432.CCR-13-0127

  View details for Web of Science ID 000323147700018

  View details for PubMedCentralID PMC3745542

• Toward a planning scheme for emission guided radiation therapy (EGRT): FDG based tumor tracking in a metastatic breast cancer patient MEDICAL PHYSICS Fan, Q., Nanduri, A., Yang, J., Yamamoto, T., Loo, B., Graves, E., Zhu, L., Mazin, S. 2013; 40 (8)

  Abstract

  Purpose: Emission guided radiation therapy (EGRT) is a new modality that uses PET emissions in real-time for direct tumor tracking during radiation delivery. Radiation beamlets are delivered along positron emission tomography (PET) lines of response (LORs) by a fast rotating ring therapy unit consisting of a linear accelerator (Linac) and PET detectors. The feasibility of tumor tracking and a primitive modulation method to compensate for attenuation have been demonstrated using a 4D digital phantom in our prior work. However, the essential capability of achieving dose modulation as in conventional intensity modulated radiation therapy (IMRT) treatments remains absent. In this work, the authors develop a planning scheme for EGRT to accomplish sophisticated intensity modulation based on an IMRT plan while preserving tumor tracking.Methods: The planning scheme utilizes a precomputed LOR response probability distribution to achieve desired IMRT planning modulation with effects of inhomogeneous attenuation and nonuniform background activity distribution accounted for. Evaluation studies are performed on a 4D digital patient with a simulated lung tumor and a clinical patient who has a moving breast cancer metastasis in the lung. The Linac dose delivery is simulated using a voxel-based Monte Carlo algorithm. The IMRT plan is optimized for a planning target volume (PTV) that encompasses the tumor motion using the MOSEK package and a Pinnacle(3)™ workstation (Philips Healthcare, Fitchburg, WI) for digital and clinical patients, respectively. To obtain the emission data for both patients, the Geant4 application for tomographic emission (GATE) package and a commercial PET scanner are used. As a comparison, 3D and helical IMRT treatments covering the same PTV based on the same IMRT plan are simulated.Results: 3D and helical IMRT treatments show similar dose distribution. In the digital patient case, compared with the 3D IMRT treatment, EGRT achieves a 15.1% relative increase in dose to 95% of the gross tumor volume (GTV) and a 31.8% increase to 50% of the GTV. In the patient case, EGRT yields a 15.2% relative increase in dose to 95% of the GTV and a 20.7% increase to 50% of the GTV. The organs at risk (OARs) doses are kept similar or lower for EGRT in both cases. Tumor tracking is observed in the presence of planning modulation in all EGRT treatments.Conclusions: As compared to conventional IMRT treatments, the proposed EGRT planning scheme allows an escalated target dose while keeping dose to the OARs within the same planning limits. With the capabilities of incorporating planning modulation and accurate tumor tracking, EGRT has the potential to greatly improve targeting in radiation therapy and enable a practical and effective implementation of 4D radiation therapy for planning and delivery.

  View details for DOI 10.1118/1.4812427

  View details for Web of Science ID 000322735900013

  View details for PubMedID 23927305

  View details for PubMedCentralID PMC3732304

• Cost-effectiveness landscape analysis of treatments addressing xerostomia in patients receiving head and neck radiation therapy. Oral surgery, oral medicine, oral pathology and oral radiology Sasportas, L. S., Hosford, D. N., Sodini, M. A., Waters, D. J., Zambricki, E. A., Barral, J. K., Graves, E. E., Brinton, T. J., Yock, P. G., Le, Q., Sirjani, D. 2013; 116 (1): e37-51

  Abstract

  Head and neck (H&N) radiation therapy (RT) can induce irreversible damage to the salivary glands thereby causing long-term xerostomia or dry mouth in 68%-85% of the patients. Not only does xerostomia significantly impair patients' quality-of-life (QOL) but it also has important medical sequelae, incurring high medical and dental costs. In this article, we review various measures to assess xerostomia and evaluate current and emerging solutions to address this condition in H&N cancer patients. These solutions typically seek to accomplish 1 of the 4 objectives: (1) to protect the salivary glands during RT, (2) to stimulate the remaining gland function, (3) to treat the symptoms of xerostomia, or (4) to regenerate the salivary glands. For each treatment, we assess its mechanisms of action, efficacy, safety, clinical utilization, and cost. We conclude that intensity-modulated radiation therapy is both the most widely used prevention approach and the most cost-effective existing solution and we highlight novel and promising techniques on the cost-effectiveness landscape.

  View details for DOI 10.1016/j.oooo.2013.02.017

  View details for PubMedID 23643579

• Cost-effectiveness landscape analysis of treatments addressing xerostomia in patients receiving head and neck radiation therapy. Oral surgery, oral medicine, oral pathology and oral radiology Sasportas, L. S., Hosford, D. N., Sodini, M. A., Waters, D. J., Zambricki, E. A., Barral, J. K., Graves, E. E., Brinton, T. J., Yock, P. G., Le, Q., Sirjani, D. 2013; 116 (1): e37-51

  Abstract

  Head and neck (H&N) radiation therapy (RT) can induce irreversible damage to the salivary glands thereby causing long-term xerostomia or dry mouth in 68%-85% of the patients. Not only does xerostomia significantly impair patients' quality-of-life (QOL) but it also has important medical sequelae, incurring high medical and dental costs. In this article, we review various measures to assess xerostomia and evaluate current and emerging solutions to address this condition in H&N cancer patients. These solutions typically seek to accomplish 1 of the 4 objectives: (1) to protect the salivary glands during RT, (2) to stimulate the remaining gland function, (3) to treat the symptoms of xerostomia, or (4) to regenerate the salivary glands. For each treatment, we assess its mechanisms of action, efficacy, safety, clinical utilization, and cost. We conclude that intensity-modulated radiation therapy is both the most widely used prevention approach and the most cost-effective existing solution and we highlight novel and promising techniques on the cost-effectiveness landscape.

  View details for DOI 10.1016/j.oooo.2013.02.017

  View details for PubMedID 23643579

• Metabolic Tumor Volume Predicts Disease Progression and Survival in Patients with Squamous Cell Carcinoma of the Anal Canal JOURNAL OF NUCLEAR MEDICINE Bazan, J. G., Koong, A. C., Kapp, D. S., Quon, A., Graves, E. E., Loo, B. W., Chang, D. T. 2013; 54 (1): 27-32

  Abstract

  PET imaging has become a useful diagnostic tool in patients with anal cancer. We evaluated the prognostic value of metabolic tumor volume (MTV) in patients with anal cancer treated with definitive chemoradiotherapy.Patients with anal cancer who underwent PET imaging for pretreatment staging or radiation therapy planning from 2003 to 2011 were included. PET parameters included MTV and maximum standardized uptake value (SUVmax). Total MTV (MTV-T) was defined as the sum of the volumes above a standardized uptake value 50% of the SUVmax within the primary tumor and involved nodes. Kaplan-Meier and Cox regression models were used to test for associations between metabolic or clinical endpoints and overall survival (OS), progression-free survival (PFS), and event-free survival (EFS). Results: Thirty-nine patients were included. Median follow-up for the cohort was 22 mo. Overall, 6 patients died and 9 patients had disease progression. The 2-y OS, PFS, and EFS for the entire cohort were 88%, 74%, and 69%, respectively. Higher MTV-T was associated with worse OS (P = 0.04), PFS (P = 0.004), and EFS (P = 0.002) on univariate analysis. Patients with an MTV greater than 26 cm(3) had worse PFS than did those with an MTV of 26 cm(3) or less (33% vs. 82%, P = 0.003). SUVmax was not prognostic for any outcome. Higher T classification (T3/T4 vs. T1/T2) was associated with worse PFS and EFS. When adjusting for T classification, MTV-T remained a significant predictor for PFS (P = 0.01) and EFS (P = 0.02).MTV-T yields prognostic information on PFS and EFS beyond that of established prognostic factors in patients with anal cancer.

  View details for DOI 10.2967/jnumed.112.109470

  View details for PubMedID 23236018

• Metabolic imaging metrics correlate with survival in early stage lung cancer treated with stereotactic ablative radiotherapy. Lung cancer Abelson, J. A., Murphy, J. D., Trakul, N., Bazan, J. G., Maxim, P. G., Graves, E. E., Quon, A., Le, Q., Diehn, M., Loo, B. W. 2012; 78 (3): 219-224

  Abstract

  To test whether (18)F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) imaging metrics correlate with outcomes in patients with stage I non-small cell lung cancer (NSCLC) treated with stereotactic ablative radiotherapy (SABR).Fifty-four patients with stage I NSCLC underwent pre-SABR PET at simulation and/or post-SABR PET within 6 months. We analyzed maximum standardized uptake value (SUV(max)) and metabolic tumor volume defined using several thresholds (MTV50%, or MTV2, 4, 7, and 10). Endpoints included primary tumor control (PTC), progression-free survival (PFS), overall survival (OS) and cancer-specific survival (CSS). We performed Kaplan-Meier, competing risk, and Cox proportional hazards survival analyses.Patients received 25-60 Gy in 1 to 5 fractions. Median follow-up time was 13.2 months. The 1-year estimated PTC, PFS, OS and CSS were 100, 83, 87 and 94%, respectively. Pre-treatment SUV(max) (p=0.014), MTV(7) (p=0.0077), and MTV(10) (p=0.0039) correlated significantly with OS. In the low-MTV(7)vs. high-MTV(7) sub-groups, 1-year estimated OS was 100 vs. 78% (p=0.0077) and CSS was 100 vs. 88% (p=0.082).In this hypothesis-generating study we identified multiple pre-treatment PET-CT metrics as potential predictors of OS and CSS in patients with NSCLC treated with SABR. These could aid risk-stratification and treatment individualization if validated prospectively.

  View details for DOI 10.1016/j.lungcan.2012.08.016

  View details for PubMedID 23009727

• Metabolic imaging metrics correlate with survival in early stage lung cancer treated with stereotactic ablative radiotherapy LUNG CANCER Abelson, J. A., Murphy, J. D., Trakul, N., Bazan, J. G., Maxim, P. G., Graves, E. E., Quon, A., Quynh-Thu Le, Q. T., Diehn, M., Loo, B. W. 2012; 78 (3): 219-224

  Abstract

  To test whether (18)F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) imaging metrics correlate with outcomes in patients with stage I non-small cell lung cancer (NSCLC) treated with stereotactic ablative radiotherapy (SABR).Fifty-four patients with stage I NSCLC underwent pre-SABR PET at simulation and/or post-SABR PET within 6 months. We analyzed maximum standardized uptake value (SUV(max)) and metabolic tumor volume defined using several thresholds (MTV50%, or MTV2, 4, 7, and 10). Endpoints included primary tumor control (PTC), progression-free survival (PFS), overall survival (OS) and cancer-specific survival (CSS). We performed Kaplan-Meier, competing risk, and Cox proportional hazards survival analyses.Patients received 25-60 Gy in 1 to 5 fractions. Median follow-up time was 13.2 months. The 1-year estimated PTC, PFS, OS and CSS were 100, 83, 87 and 94%, respectively. Pre-treatment SUV(max) (p=0.014), MTV(7) (p=0.0077), and MTV(10) (p=0.0039) correlated significantly with OS. In the low-MTV(7)vs. high-MTV(7) sub-groups, 1-year estimated OS was 100 vs. 78% (p=0.0077) and CSS was 100 vs. 88% (p=0.082).In this hypothesis-generating study we identified multiple pre-treatment PET-CT metrics as potential predictors of OS and CSS in patients with NSCLC treated with SABR. These could aid risk-stratification and treatment individualization if validated prospectively.

  View details for DOI 10.1016/j.lungcan.2012.08.016

  View details for Web of Science ID 000311881400008

• Monte Carlo model of the scanning beam digital x-ray (SBDX) source PHYSICS IN MEDICINE AND BIOLOGY Bazalova, M., Weil, M. D., Wilfley, B., Graves, E. E. 2012; 57 (22): 7381-7394

  Abstract

  The scanning-beam digital x-ray (SBDX) system has been developed for fluoroscopic imaging using an inverse x-ray imaging geometry. The SBDX system consists of a large-area x-ray source with a multihole collimator and a small detector. The goal of this study was to build a Monte Carlo (MC) model of the SBDX source as a useful tool for optimization of the SBDX imaging system in terms of its hardware components and imaging parameters. The MC model of the source was built in the EGSnrc/BEAMnrc code and validated using the DOSXYZnrc code and Gafchromic film measurements for 80, 100, and 120 kV x-ray source voltages. The MC simulated depth dose curves agreed with measurements to within 5%, and beam profiles at three selected depths generally agreed within 5%. Exposure rates and half-value layers for three voltages were also calculated from the MC simulations. Patient skin-dose per unit detector-dose was quantified as a function of patient size for all three x-ray source voltages. The skin-dose to detector-dose ratio ranged from 5-10 for a 20 cm thick patient to 1 × 10(3)-1 × 10(5) for a 50 cm patient for the 120 and 80 kV beams, respectively. Simulations of imaging dose for a prostate patient using common imaging parameters revealed that skin-dose per frame was as low as 0.2 mGy.

  View details for DOI 10.1088/0031-9155/57/22/7381

  View details for Web of Science ID 000310838700014

  View details for PubMedID 23093305

• Postchemoradiotherapy Positron Emission Tomography Predicts Pathologic Response and Survival in Patients With Esophageal Cancer 53rd Annual Meeting of the American-Society-of-Radiation-Oncology (ASTRO) Jayachandran, P., Pai, R. K., Quon, A., Graves, E., Krakow, T. E., La, T., Loo, B. W., Koong, A. C., Chang, D. T. ELSEVIER SCIENCE INC. 2012: 471–77

  Abstract

  To correlate the prechemoradiotherapy (CRT) and post-CRT metabolic tumor volume (MTV) on positron emission tomography (PET) scanning with the pathologic response and survival in patients receiving preoperative CRT for esophageal cancer.The medical records of 37 patients with histologically confirmed Stage I-IVA esophageal cancer treated with CRT with or without surgical resection were reviewed. Of the 37 patients, 21 received preoperative CRT (57%) and 16 received definitive CRT (43%). All patients had a pre-CRT and 32 had a post-CRT PET scan. The MTV was measured on the pre-CRT PET and post-CRT PET scan, respectively, using a minimum standardized uptake value (SUV) threshold x, where x = 2, 2.5, 3, or the SUV maximum × 50%. The total glycolytic activity (TGA(x)) was defined as the mean SUV × MTV(x). The MTV ratio was defined as the pre-CRT PET MTV/post-CRT MTV. The SUV ratio was defined similarly. A single pathologist scored the pathologic response using a tumor regression grade (TRG) scale.The median follow-up was 1.5 years (range, 0.4-4.9). No significant correlation was found between any parameters on the pre-CRT PET scan and the TRG or overall survival (OS). Multiple post-CRT MTV values and post-TGA values correlated with the TRG and OS; however, the MTV(2.5(Post)) and TGA(2.5(Post)) had the greatest correlation. The MTV(2) ratio correlated with OS. The maximum SUV on either the pre-CRT and post-CRT PET scans or the maximum SUV ratio did not correlate with the TRG or OS. Patients treated preoperatively had survival similar compared with those treated definitively with a good PET response (p = 0.97) and significantly better than that of patients treated definitively with a poor PET response (p < 0.0001).The maximum SUV was not a predictive or prognostic parameter. The MTV(2.5) and TGA(2.5) were useful markers for predicting the response and survival on the post-CRT PET scan. The MTV(2) ratio also correlated with survival. Post-CRT PET can potentially guide therapy after CRT.

  View details for DOI 10.1016/j.ijrobp.2011.12.029

  View details for PubMedID 22381904

• Prognostic Value of Metabolic Tumor Volume and Velocity in Predicting Head-and-Neck Cancer Outcomes INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Chu, K. P., Murphy, J. D., La, T. H., Krakow, T. E., Iagaru, A., Graves, E. E., Hsu, A., Maxim, P. G., Loo, B., Chang, D. T., Quynh-Thu Le, Q. T. 2012; 83 (5): 1521-1527

  Abstract

  We previously showed that metabolic tumor volume (MTV) on positron emission tomography-computed tomography (PET-CT) predicts for disease recurrence and death in head-and-neck cancer (HNC). We hypothesized that increases in MTV over time would correlate with tumor growth and biology, and would predict outcome. We sought to examine tumor growth over time in serial pretreatment PET-CT scans.From 2006 to 2009, 51 patients had two PET-CT scans before receiving HNC treatment. MTV was defined as the tumor volume ≥ 50% of maximum SUV (SUV(max)). MTV was calculated for the primary tumor, nodal disease, and composite (primary tumor + nodes). MTV and SUV velocity were defined as the change in MTV or SUV(max) over time, respectively. Cox regression analyses were used to examine correlations between SUV, MTV velocity, and outcome (disease progression and overall survival).The median follow-up time was 17.5 months. The median time between PET-CT scans was 3 weeks. Unexpectedly, 51% of cases demonstrated a decrease in SUV(max) (average, -0.1 cc/week) and MTV (average, -0.3 cc/week) over time. Despite the variability in MTV, primary tumor MTV velocity predicted disease progression (hazard ratio 2.94; p = 0.01) and overall survival (hazard ratio 1.85; p = 0.03).Primary tumor MTV velocity appears to be a better prognostic indicator of disease progression and survival in comparison to nodal MTV velocity. However, substantial variability was found in PET-CT biomarkers between serial scans. Caution should be used when PET-CT biomarkers are integrated into clinical protocols for HNC.

  View details for DOI 10.1016/j.ijrobp.2011.10.022

  View details for PubMedID 22270168

• Validation that Metabolic Tumor Volume Predicts Outcome in Head-and-Neck Cancer INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Tang, C., Murphy, J. D., Khong, B., La, T. H., Kong, C., Fischbein, N. J., Colevas, A. D., Iagaru, A. H., Graves, E. E., Loo, B. W., Quynh-Thu Le, Q. T. 2012; 83 (5): 1514-1520

  Abstract

  We have previously reported that metabolic tumor volume (MTV) obtained from pretreatment (18)F-fluorodeoxydeglucose positron emission tomography (FDG PET)/ computed tomography (CT) predicted outcome in patients with head-and-neck cancer (HNC). The purpose of this study was to validate these results on an independent dataset, determine whether the primary tumor or nodal MTV drives this correlation, and explore the interaction with p16(INK4a) status as a surrogate marker for human papillomavirus (HPV).The validation dataset in this study included 83 patients with squamous cell HNC who had a FDG PET/CT scan before receiving definitive radiotherapy. MTV and maximum standardized uptake value (SUV(max)) were calculated for the primary tumor, the involved nodes, and the combination of both. The primary endpoint was to validate that MTV predicted progression-free survival and overall survival. Secondary analyses included determining the prognostic utility of primary tumor vs. nodal MTV.Similarly to our prior findings, an increase in total MTV of 17 cm(3) (difference between the 75th and 25th percentiles) was associated with a 2.1-fold increase in the risk of disease progression (p = 0.0002) and a 2.0-fold increase in the risk of death (p = 0.0048). SUV(max) was not associated with either outcome. Primary tumor MTV predicted progression-free (hazard ratio [HR] = 1.94; p < 0.0001) and overall (HR = 1.57; p < 0.0001) survival, whereas nodal MTV did not. In addition, MTV predicted progression-free (HR = 4.23; p < 0.0001) and overall (HR = 3.21; p = 0.0029) survival in patients with p16(INK4a)-positive oropharyngeal cancer.This study validates our previous findings that MTV independently predicts outcomes in HNC. MTV should be considered as a potential risk-stratifying biomarker in future studies of HNC.

  View details for DOI 10.1016/j.ijrobp.2011.10.023

  View details for Web of Science ID 000306128100046

  View details for PubMedCentralID PMC3337958

• Prognostic PET F-18-FDG Uptake Imaging Features Are Associated with Major Oncogenomic Alterations in Patients with Resected Non-Small Cell Lung Cancer CANCER RESEARCH Nair, V. S., Gevaert, O., Davidzon, G., Napel, S., Graves, E. E., Hoang, C. D., Shrager, J. B., Quon, A., Rubin, D. L., Plevritis, S. K. 2012; 72 (15): 3725-3734

  Abstract

  Although 2[18F]fluoro-2-deoxy-d-glucose (FDG) uptake during positron emission tomography (PET) predicts post-surgical outcome in patients with non-small cell lung cancer (NSCLC), the biologic basis for this observation is not fully understood. Here, we analyzed 25 tumors from patients with NSCLCs to identify tumor PET-FDG uptake features associated with gene expression signatures and survival. Fourteen quantitative PET imaging features describing FDG uptake were correlated with gene expression for single genes and coexpressed gene clusters (metagenes). For each FDG uptake feature, an associated metagene signature was derived, and a prognostic model was identified in an external cohort and then tested in a validation cohort of patients with NSCLC. Four of eight single genes associated with FDG uptake (LY6E, RNF149, MCM6, and FAP) were also associated with survival. The most prognostic metagene signature was associated with a multivariate FDG uptake feature [maximum standard uptake value (SUV(max)), SUV(variance), and SUV(PCA2)], each highly associated with survival in the external [HR, 5.87; confidence interval (CI), 2.49-13.8] and validation (HR, 6.12; CI, 1.08-34.8) cohorts, respectively. Cell-cycle, proliferation, death, and self-recognition pathways were altered in this radiogenomic profile. Together, our findings suggest that leveraging tumor genomics with an expanded collection of PET-FDG imaging features may enhance our understanding of FDG uptake as an imaging biomarker beyond its association with glycolysis.

  View details for DOI 10.1158/0008-5472.CAN-11-3943

  View details for PubMedID 22710433

• Positron Emission Tomography for Predicting Pathologic Response After Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer 50th Annual Meeting of the American-Society-for-Therapeutic-Radiation-Oncology (ASTRO) Chennupati, S. K., Quon, A., Kamaya, A., Pai, R. K., La, T., Krakow, T. E., Graves, E., Koong, A. C., Chang, D. T. LIPPINCOTT WILLIAMS & WILKINS. 2012: 334–39

  Abstract

  To investigate whether before and after chemoradiotherapy (CRT) positron emission tomography (PET) predict for pathologic response after preoperative CRT in patients with locally advanced rectal adenocarcinoma.Thirty-five patients who underwent pre-CRT and post-CRT PET scans before surgery were included. All patients were staged with endoscopic ultrasound or high resolution CT. CRT was given with 50.4 Gy at 1.8 Gy per fraction and concurrent 5-fluorouracil-based chemotherapy. Surgery occurred at a median of 46 days (range, 27 to 112 d) after completing CRT. The maximum standardized uptake value (SUV(max)) and the metabolic tumor volume (MTV) using various minimum SUV thresholds (2, 2.5, 3) on the PET scans (MTV(2.0), MTV(2.5), MTV(3.0)) were determined. Post-CRT PET scans were done 3 to 5 weeks after completion of CRT. Pathologic response was assessed using the tumor regression grade (TRG) scale. Patients with complete or near-complete response (TRG=0 to 1) were considered pathologic responders. The pre-CRT and post-CRT PET scan SUV(max) and MTV values were correlated with TRG. The ΔSUV(max) and ΔMTV were correlated with TRG.No correlation was seen with SUV(max) (P=0.99), MTV(2.0) (P=0.73), MTV(2.5) (P=0.73), or MTV(3.0) (P=0.31) on the pre-CRT PET between pathologic responders versus nonresponders. No correlation was noted between SUV(max) (P=0.49), MTV(2.0) (P=0.73), MTV(2.5) (P=0.49), or MTV(3.0) (P=0.31) on the post-CRT PET scan and pathologic response. Finally, the ΔSUV(max) (P=0.32), ΔMTV(2.0) (P=0.99), ΔMTV(2.5) (P=0.31), ΔMTV(3.0) (P=0.31) did not correlate with pathologic response.Changes seen on PET have limited value in predicting for pathologic response of rectal cancer after preoperative neoadjuvant therapy.

  View details for DOI 10.1097/COC.0b013e3182118d12

  View details for PubMedID 21422989

• Validation that metabolic tumor volume predicts outcome in head-and-neck cancer. International journal of radiation oncology, biology, physics Tang, C., Murphy, J. D., Khong, B., La, T. H., Kong, C., Fischbein, N. J., Colevas, A. D., Iagaru, A. H., Graves, E. E., Loo, B. W., Le, Q. 2012; 83 (5): 1514-1520

  Abstract

  We have previously reported that metabolic tumor volume (MTV) obtained from pretreatment (18)F-fluorodeoxydeglucose positron emission tomography (FDG PET)/ computed tomography (CT) predicted outcome in patients with head-and-neck cancer (HNC). The purpose of this study was to validate these results on an independent dataset, determine whether the primary tumor or nodal MTV drives this correlation, and explore the interaction with p16(INK4a) status as a surrogate marker for human papillomavirus (HPV).The validation dataset in this study included 83 patients with squamous cell HNC who had a FDG PET/CT scan before receiving definitive radiotherapy. MTV and maximum standardized uptake value (SUV(max)) were calculated for the primary tumor, the involved nodes, and the combination of both. The primary endpoint was to validate that MTV predicted progression-free survival and overall survival. Secondary analyses included determining the prognostic utility of primary tumor vs. nodal MTV.Similarly to our prior findings, an increase in total MTV of 17 cm(3) (difference between the 75th and 25th percentiles) was associated with a 2.1-fold increase in the risk of disease progression (p = 0.0002) and a 2.0-fold increase in the risk of death (p = 0.0048). SUV(max) was not associated with either outcome. Primary tumor MTV predicted progression-free (hazard ratio [HR] = 1.94; p < 0.0001) and overall (HR = 1.57; p < 0.0001) survival, whereas nodal MTV did not. In addition, MTV predicted progression-free (HR = 4.23; p < 0.0001) and overall (HR = 3.21; p = 0.0029) survival in patients with p16(INK4a)-positive oropharyngeal cancer.This study validates our previous findings that MTV independently predicts outcomes in HNC. MTV should be considered as a potential risk-stratifying biomarker in future studies of HNC.

  View details for DOI 10.1016/j.ijrobp.2011.10.023

  View details for PubMedID 22270174

• Bioluminescence Monitoring of Metastatic Breast Cancer: Quantitative Assessment of Radiation Treatment Effects and Tracking of Tumor Cells 54th Annual Meeting and Exhibition of the American-Association-of-Physicists-in-Medicine (AAPM) Park, J., Schmidt, T., Graves, E., Bazalova, M., Lee, J., Contag, C., Suh, T. AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS. 2012: 3698–98

  Abstract

  To evaluate radiation treatment effects on mammary carcinoma cells, quantitative photon radiance were monitored to track light-emitting cancer cells and metastasis using in vivo bioluminescence imaging.Eight female BALB/c mice aged 8 weeks were orthotopically injected with 5×104/cc 4T1 tumor cells into the abdominal mammary gland. The firefly luciferase-based bioluminescence images were acquired every 2-3 days for 1 month. Bioluminescent intensity was analyzed in average surface radiance (photons/sec/cm2 /sr) taken in 3-dimensional bioluminescence tomography (BLT). After 1 week, single-radiation dose of 20 Gy was delivered by orthovoltage X-rays. Variation of detected bioluminescence signals emitted from molecular cancer cells was depicted on BLT images. To delineate tumor volumes according to bioluminescence intensity on anatomical images for radiation therapy, BLT images were registered with the micro computed tomography (CT) images using surface-constrained warping.Multispectral BLT images elaborated on early detection of cancer cells, characteristics of tumor growth, and metastasis for more accurate determination of internal bioluminescent sources. The radiation-treated mice having only primary tumor volumes showed 67% decrease in bioluminescent signals, while the mice with metastatic cancer cells suggested 88% reduction, as compared to the control group. Registration of BLT with CT images guided molecular cancer cells on anatomical coordinates.The BLT imaging was a useful tool to localize cancer cells and to quantify radiation response. Application of BLT led to more accurate definition of tumor volumes including molecular probe-based microscopic cancer cells. Monitoring of bioluminescence signals enables to diagnose real-time metastatic behavior of cancer cells and determine optimal radiation treatment strategies adapted to tumor characteristics.

  View details for Web of Science ID 000308905804428

• Prognostic and Predictive Significance of Plasma HGF and IL-8 in a Phase III Trial of Chemoradiation with or without Tirapazamine in Locoregionally Advanced Head and Neck Cancer CLINICAL CANCER RESEARCH Quynh-Thu Le, Q. T., Fisher, R., Oliner, K. S., Young, R. J., Cao, H., Kong, C., Graves, E., Hicks, R. J., McArthur, G. A., Peters, L., O'Sullivan, B., Giaccia, A., Rischin, D. 2012; 18 (6): 1798-1807

  Abstract

  Hepatocyte growth factor (HGF) is a hypoxia-induced secreted protein that binds to cMet and regulates interleukin (IL)-8 expression. We evaluated the role of circulating HGF and IL-8 as prognostic and predictive factors for efficacy of tirapazamine (TPZ), a hypoxic cell cytotoxin.Patients with stages III to IV head and neck cancer were randomized to receive radiotherapy with cisplatin (CIS) or CIS plus TPZ (TPZ/CIS). Eligibility for the substudy included plasma sample availability for HGF and IL-8 assay by ELISA and no major radiation deviations (N = 498). Analyses included adjustment for major prognostic factors. p16(INK4A) staining (human papillomavirus surrogate) was carried out on available tumors. Thirty-nine patients had hypoxia imaging with (18)F-fluoroazomycin arabinoside ((18)FAZA)-positron emission tomography.Elevated IL-8 level was associated with worse overall survival (OS) irrespective of treatment. There was an interaction between HGF and treatment arm (P = 0.053); elevated HGF was associated with worse OS in the control but not in the TPZ/CIS arm. Similar trends were observed in analyses restricted to p16(INK4A)-negative patients. Four subgroups defined by high and low HGF/IL-8 levels were examined for TPZ effect; the test for interaction with arm was P = 0.099. TPZ/CIS seemed to be beneficial for patients with high HGF and IL-8 but adverse for low HGF and high IL-8. Only HGF correlated with (18)FAZA tumor standard uptake value.IL-8 is an independent prognostic factor irrespective of treatment. There is an interaction between HGF and treatment arm. Certain subgroups based on IL-8/HGF levels seemed to do better with TPZ/CIS while others did worse, highlighting the complexity of hypoxia targeting in unselected patients.

  View details for DOI 10.1158/1078-0432.CCR-11-2094

  View details for PubMedID 22383739

• The potential for Cerenkov luminescence imaging of alpha-emitting radionuclides PHYSICS IN MEDICINE AND BIOLOGY Ackerman, N. L., Graves, E. E. 2012; 57 (3): 771-783

  Abstract

  Targeted α-emitting drugs are promising for cancer therapy, but cannot be effectively imaged by conventional techniques. Cerenkov luminescence imaging (CLI) has previously been shown capable of imaging β(+)- and β(-)-emitting radionuclides in vivo and could have the potential to image α-emitters. Cerenkov light production from α-emitters is through Compton scattering and from farther down the decay chain. This causes the Cerenkov production to vary in time and depend on sample geometry, complicating the interpretation of CLI images. We used the simulation toolkit Geant4 to predict the Cerenkov light output from five α-emitting radionuclides that have therapeutic potential: (225)Ac, (230)U, (213)Bi, (212)Bi and (212)At. We found that (225)Ac, (213)Bi and (212)Bi produced an order of magnitude more Cerenkov light than (18)F. However, the light from (225)Ac is delayed from the initial decay, possibly decreasing the correlation of the drug and light source. This indicates that CLI will not be helpful in the development of some α-emitting drugs.

  View details for DOI 10.1088/0031-9155/57/3/771

  View details for Web of Science ID 000299542000014

  View details for PubMedID 22252144

• Interim-treatment quantitative PET parameters predict progression and death among patients with hodgkin's disease RADIATION ONCOLOGY Tseng, D., Rachakonda, L. P., Su, Z., Advani, R., Horning, S., Hoppe, R. T., Quon, A., Graves, E. E., Loo, B. W., Tran, P. T. 2012; 7

  Abstract

  We hypothesized that quantitative PET parameters may have predictive value beyond that of traditional clinical factors such as the International Prognostic Score (IPS) among Hodgkin's disease (HD) patients.Thirty HD patients treated at presentation or relapse had staging and interim-treatment PET-CT scans. The majority of patients (53%) had stage III-IV disease and 67% had IPS ≥ 2. Interim-treatment scans were performed at a median of 55 days from the staging PET-CT. Chemotherapy regimens used: Stanford V (67%), ABVD (17%), VAMP (10%), or BEACOPP (7%). Hypermetabolic tumor regions were segmented semiautomatically and the metabolic tumor volume (MTV), mean standardized uptake value (SUV mean), maximum SUV (SUV max) and integrated SUV (iSUV) were recorded. We analyzed whether IPS, absolute value PET parameters or the calculated ratio of interim- to pre-treatment PET parameters were associated with progression free survival (PFS) or overall survival (OS).Median follow-up of the study group was 50 months. Six of the 30 patients progressed clinically. Absolute value PET parameters from pre-treatment scans were not significant. Absolute value SUV max from interim-treatment scans was associated with OS as determined by univariate analysis (p < 0.01). All four calculated PET parameters (interim/pre-treatment values) were associated with OS: MTV int/pre (p < 0.01), SUV mean int/pre (p < 0.05), SUV max int/pre (p = 0.01), and iSUV int/pre (p < 0.01). Absolute value SUV max from interim-treatment scans was associated with PFS (p = 0.01). Three calculated PET parameters (int/pre-treatment values) were associated with PFS: MTV int/pre (p = 0.01), SUV max int/pre (p = 0.02) and iSUV int/pre (p = 0.01). IPS was associated with PFS (p < 0.05) and OS (p < 0.01).Calculated PET metrics may provide predictive information beyond that of traditional clinical factors and may identify patients at high risk of treatment failure early for treatment intensification.

  View details for DOI 10.1186/1748-717X-7-5

  View details for PubMedID 22260710

• Metabolic Tumor Volume is an Independent Prognostic Factor in Patients Treated Definitively for Non-Small-Cell Lung Cancer CLINICAL LUNG CANCER Lee, P., Bazan, J. G., Lavori, P. W., Weerasuriya, D. K., Quon, A., Quynh-Thu Le, Q. T., Wakelee, H. A., Graves, E. E., Loo, B. W. 2012; 13 (1): 52-58

  Abstract

  Fluorine-18 flurodeoxyglucose positron emission tomography (FDG-PET) imaging has rapidly become the standard of care for staging patients with lung cancer. We evaluated the prognostic value of metabolic tumor volume (MTV), a measure of tumor burden on FDG-PET imaging, in patients with non-small-cell lung cancer (NSCLC) treated definitively.A retrospective review identified 61 patients with NSCLC who underwent FDG-PET imaging for pretreatment staging. Metabolically active tumor regions were segmented on the PET scans semiautomatically to calculate the total body MTV. We determined the relationship of overall survival (OS) and progression-free survival (PFS) with MTV in the entire cohort, and in the subgroup treated definitively.The estimated median PFS and OS for the entire cohort were 11.1 months and 18.9 months. Higher MTV was significantly associated with worse OS (P = 0.00075) and PFS (P = 0.00077). For definitively treated patients, when MTV was analyzed as a binary value above or below the median value, 2-year PFS was 60% versus 39.7% (median PFS 34.9 vs. 11.9 months) and 2-year OS was 79.7% versus 33.3% (median OS 41.9 vs. 18.9 months), respectively (log-rank P = 0.12 for PFS and P = 0.066 for OS). When MTV was analyzed as a continuous variable, multivariate Cox proportional hazards analysis demonstrated a trend to worse PFS (hazard ratio [HR] = 1.31; P = 0.12) and significantly worse OS (HR = 1.53; P = 0.018) with increasing MTV after controlling for known prognostic variables.Tumor burden as assessed by MTV yields prognostic information on survival beyond that of established prognostic factors in patients with NSCLC treated definitively.

  View details for DOI 10.1016/j.cllc.2011.05.001

  View details for PubMedID 21703935

• GPU-Enabled PET Motion Compensation Using Sparse and Low-Rank Decomposition IEEE Nuclear Science Symposium / Medical Imaging Conference Record (NSS/MIC) / 19th Room-Temperature Semiconductor X-ray and Gamma-ray Detector Workshop Cui, J., Yang, J., Graves, E., Levin, C. S. IEEE. 2012: 3367–3370

  View details for Web of Science ID 000326814203104

• Correlation between metabolic tumor volume and pathologic tumor volume in squamous cell carcinoma of the oral cavity RADIOTHERAPY AND ONCOLOGY Murphy, J. D., Chisholm, K. M., Daly, M. E., Wiegner, E. A., Truong, D., Iagaru, A., Maxim, P. G., Loo, B. W., Graves, E. E., Kaplan, M. J., Kong, C., Le, Q. 2011; 101 (3): 356-361

  Abstract

  To explore the relationship between pathologic tumor volume and volume estimated from different tumor segmentation techniques on (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in oral cavity cancer.Twenty-three patients with squamous cell carcinoma of the oral tongue had PET-CT scans before definitive surgery. Pathologic tumor volume was estimated from surgical specimens. Metabolic tumor volume (MTV) was defined from PET-CT scans as the volume of tumor above a given SUV threshold. Multiple SUV thresholds were explored including absolute SUV thresholds, relative SUV thresholds, and gradient-based techniques.Multiple MTV's were associated with pathologic tumor volume; however the correlation was poor (R(2) range 0.29-0.58). The ideal SUV threshold, defined as the SUV that generates an MTV equal to pathologic tumor volume, was independently associated with maximum SUV (p=0.0005) and tumor grade (p=0.024). MTV defined as a function of maximum SUV and tumor grade improved the prediction of pathologic tumor volume (R(2)=0.63).Common SUV thresholds fail to predict pathologic tumor volume in head and neck cancer. The optimal technique that allows for integration of PET-CT with radiation treatment planning remains to be defined. Future investigation should incorporate biomarkers such as tumor grade into definitions of MTV.

  View details for DOI 10.1016/j.radonc.2011.05.040

  View details for PubMedID 21665308

• Facilitating Multimodal Preclinical Imaging Studies in Mice by Using an Immobilization Bed COMPARATIVE MEDICINE Nelson, G. S., Perez, J., Colomer, M. V., Ali, R., Graves, E. 2011; 61 (6): 499-504

  Abstract

  We have designed an immobilization bed that accommodates mice of all ages and sizes, to improve image registration for multimodal scans and for longitudinal preclinical imaging studies. Stationary pegs were placed such that they effectively immobilized mice and reduced set-up time. (22)Na fiducial markers were placed into the pegs at unique depths to provide 3D references to facilitate image registration. Multiple users registered positron emission tomographic (PET) and CT data obtained with and without the bed to examine the effect of the bed on registration accuracy and interuser variability. The image registrations performed by different users were evaluated for their similarity by using the Entropy Correlation Coefficient as a metric. The immobilization bed significantly reduced variations in body movement and interuser variability. Average differences in quantification of tumor PET signal among users when registering images without versus with the fiduciary-marker bed fell from 9.1% to 0.8% for maximal percentage injected dose per gram (%ID/g), from 15.6% to 2.3% for mean %ID/g, and from 9.4% to 0.7% for the 90th percentile of the maximum %ID/g. The bed improves animal immobilization, greatly reduces interuser variability, and supports registration of image data acquired from different imaging sessions.

  View details for PubMedID 22330576

• Targeting GLUT1 and the Warburg Effect in Renal Cell Carcinoma by Chemical Synthetic Lethality SCIENCE TRANSLATIONAL MEDICINE Chan, D. A., Sutphin, P. D., Nguyen, P., Turcotte, S., Lai, E. W., Banh, A., Reynolds, G. E., Chi, J., Wu, J., Solow-Cordero, D. E., Bonnet, M., Flanagan, J. U., Bouley, D. M., Graves, E. E., Denny, W. A., Hay, M. P., Giaccia, A. J. 2011; 3 (94)

  Abstract

  Identifying new targeted therapies that kill tumor cells while sparing normal tissue is a major challenge of cancer research. Using a high-throughput chemical synthetic lethal screen, we sought to identify compounds that exploit the loss of the von Hippel-Lindau (VHL) tumor suppressor gene, which occurs in about 80% of renal cell carcinomas (RCCs). RCCs, like many other cancers, are dependent on aerobic glycolysis for ATP production, a phenomenon known as the Warburg effect. The dependence of RCCs on glycolysis is in part a result of induction of glucose transporter 1 (GLUT1). Here, we report the identification of a class of compounds, the 3-series, exemplified by STF-31, which selectively kills RCCs by specifically targeting glucose uptake through GLUT1 and exploiting the unique dependence of these cells on GLUT1 for survival. Treatment with these agents inhibits the growth of RCCs by binding GLUT1 directly and impeding glucose uptake in vivo without toxicity to normal tissue. Activity of STF-31 in these experimental renal tumors can be monitored by [(18)F]fluorodeoxyglucose uptake by micro-positron emission tomography imaging, and therefore, these agents may be readily tested clinically in human tumors. Our results show that the Warburg effect confers distinct characteristics on tumor cells that can be selectively targeted for therapy.

  View details for DOI 10.1126/scitranslmed.3002394

  View details for PubMedID 21813754

• Molecular Imaging of Hypoxia: Strategies for Probe Design and Application CURRENT ORGANIC SYNTHESIS Apte, S., Chin, F. T., Graves, E. E. 2011; 8 (4): 593-603

  Abstract

  Tumor hypoxia is a negative prognostic factor and its precise imaging is of great relevance to therapy planning. The present review summarizes various strategies of probe design for imaging hypoxia with a variety of techniques such as PET, SPECT and fluorescence imaging. Synthesis of some important probes that are used for preclinical and clinical imaging and their mechanism of binding in hypoxia are also discussed.

  View details for Web of Science ID 000294410500009

  View details for PubMedCentralID PMC3279754

• Molecular Imaging of Hypoxia: Strategies for Probe Design and Application. Current organic synthesis Apte, S., Chin, F. T., Graves, E. E. 2011; 8 (4): 593-603

  Abstract

  Tumor hypoxia is a negative prognostic factor and its precise imaging is of great relevance to therapy planning. The present review summarizes various strategies of probe design for imaging hypoxia with a variety of techniques such as PET, SPECT and fluorescence imaging. Synthesis of some important probes that are used for preclinical and clinical imaging and their mechanism of binding in hypoxia are also discussed.

  View details for DOI 10.2174/157017911796117179

  View details for PubMedID 22347839

  View details for PubMedCentralID PMC3279754

• The importance of tissue segmentation for dose calculations for kilovoltage radiation therapy MEDICAL PHYSICS Bazalova, M., Graves, E. E. 2011; 38 (6): 3039-3049

  Abstract

  The aim of this work was to evaluate the effect of tissue segmentation on the accuracy of Monte Carlo (MC) dose calculations for kilovoltage radiation therapy, which are commonly used in preclinical radiotherapy studies and are also being revisited as a clinical treatment modality. The feasibility of tissue segmentation routinely done on the basis of differences in tissue mass densities was studied and a new segmentation scheme based on differences in effective atomic numbers was developed.MC dose calculations in a cylindrical mouse phantom with small cylindrical inhomogeneities consisting of 34 ICRU-44 tissues were performed using the EGSnrc/BEAMnrc and DOSXYZnrc codes. The dose to tissue was calculated for five different kilovoltage beams currently used in small animal radiotherapy: a microCT 120 kV beam, two 225 kV beams filtered with either 4 mm of Al or 0.5 mm of Cu, a heavily filtered 320 kV beam, and a 192Ir beam. The mean doses to the 34 ICRU-44 tissues as a function of tissue mass density and effective atomic number and beam energy were studied. A treatment plan for an orthotopic lung tumor model was created, and the dose distribution was calculated for three tissue segmentation schemes using 4, 8, and 39 tissue bins to assess the significance of the simulation results for kilovoltage radiotherapy.In our model, incorrect assignment of adipose tissue to muscle caused dose calculation differences of 27%, 13%, and 7% for the 120 kV beam and the 225 kV beams filtered with 4 mm Al and 0.5 mm Cu, respectively. For the heavily filtered 320 kV beam and a 192Ir source, potential dose calculation differences due to tissue mis-assignment were below 4%. There was no clear relationship between the dose to tissue and its mass density for x-ray beams generated by tube potentials equal or less than 225 kV. A second order polynomial fit approximated well the absorbed dose to tissue as a function of effective atomic number for these beams. In the mouse study, the 120 kV beam dose to bone was overestimated by 100% and underestimated by 10% for the 4 and 8-tissue segmentation schemes compared to the 39-tissue segmentation scheme, respectively. Dose to adipose tissue was overestimated by 30% and underestimated by 10%, respectively. In general, organ at risk (OAR) doses were overestimated in the 4-tissue and the 8-tissue segmentation schemes compared to the 39-tissue segmentation.Tissue segmentation was shown to be a key parameter for dose calculations with kilovoltage beams used in small animal radiotherapy when an x-ray tube with a potential < or = 225 kV is used as a source. A new tissue segmentation scheme with 39 tissues based on effective number differences derived from mass density differences has been implemented.

  View details for DOI 10.1118/1.3589138

  View details for Web of Science ID 000291405200022

  View details for PubMedID 21815377

  View details for PubMedCentralID PMC3125081

• POSTRADIATION METABOLIC TUMOR VOLUME PREDICTS OUTCOME IN HEAD-AND-NECK CANCER INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Murphy, J. D., La, T. H., Chu, K., Quon, A., Fischbein, N. J., Maxim, P. G., Graves, E. E., Loo, B. W., Le, Q. 2011; 80 (2): 514-521

  Abstract

  To explore the prognostic value of metabolic tumor volume measured on postradiation (18)F-fluorodeoxyglucose positron emission tomography (PET) imaging in patients with head-and-neck cancer.Forty-seven patients with head-and-neck cancer who received pretreatment and posttreatment PET/computed tomography (CT) imaging along with definitive chemoradiotherapy were included in this study. The PET/CT parameters evaluated include the maximum standardized uptake value, metabolic tumor volume (MTV(2.0)-MTV(4.0); where MTV(2.0) refers to the volume above a standardized uptake value threshold of 2.0), and integrated tumor volume. Kaplan-Meier and Cox regression models were used to test for association between PET endpoints and disease-free survival and overall survival.Multiple postradiation PET endpoints correlated significantly with outcome; however, the most robust predictor of disease progression and death was MTV(2.0). An increase in MTV(2.0) of 21 cm(3) (difference between 75th and 25th percentiles) was associated with an increased risk of disease progression (hazard ratio [HR] = 2.5, p = 0.0001) and death (HR = 2.0, p = 0.003). In patients with nonnasopharyngeal carcinoma histology (n = 34), MTV(2.0) <18 cm(3) and MTV(2.0) ≥18 cm(3) yielded 2-year disease-free survival rates of 100% and 63%, respectively (p = 0.006) and 2-year overall survival rates of 100% and 81%, respectively (p = 0.009). There was no correlation between MTV(2.0) and disease-free survival or overall survival with nasopharyngeal carcinoma histology (n = 13). On multivariate analysis, only postradiation MTV(2.0) was predictive of disease-free survival (HR = 2.47, p = 0.0001) and overall survival (HR = 1.98, p = 0.003).Postradiation metabolic tumor volume is an adverse prognostic factor in head-and-neck cancer. Biomarkers such as MTV are important for risk stratification and will be valuable in the future with risk-adapted therapies.

  View details for DOI 10.1016/j.ijrobp.2010.01.057

  View details for Web of Science ID 000290837100028

  View details for PubMedID 20646870

  View details for PubMedCentralID PMC2962876

• Tumor Volume as a Potential Imaging-Based Risk-Stratification Factor in Trimodality Therapy for Locally Advanced Non-small Cell Lung Cancer JOURNAL OF THORACIC ONCOLOGY Kozak, M. M., Murphy, J. D., Schipper, M. L., Donington, J. S., Zhou, L., Whyte, R. I., Shrager, J. B., Hoang, C. D., Bazan, J., Maxim, P. G., Graves, E. E., Diehn, M., Hara, W. Y., Quon, A., Quynh-Thu Le, Q. T., Wakelee, H. A., Loo, B. W. 2011; 6 (5): 920-926

  Abstract

  The role of trimodality therapy for locally advanced non-small cell lung cancer (NSCLC) continues to be defined. We hypothesized that imaging parameters on pre- and postradiation positron emission tomography (PET)-computed tomography (CT) imaging are prognostic for outcome after preoperative chemoradiotherapy (CRT)/resection/consolidation chemotherapy and could help risk-stratify patients in clinical trials.We enrolled 13 patients on a prospective clinical trial of trimodality therapy for resectable locally advanced NSCLC. PET-CT was acquired for radiation planning and after 45 Gy. Gross tumor volume (GTV) and standardized uptake value were measured at pre- and post-CRT time points and correlated with nodal pathologic complete response, loco-regional and/or distant progression, and overall survival. In addition, we evaluated the performance of automatic deformable image registration (ADIR) software for volumetric response assessment.All patients responded with average total GTV reductions after 45 Gy of 43% (range: 27-64%). Pre- and post-CRT GTVs were highly correlated (R² = 0.9), and their respective median values divided the patients into the same two groups. ADIR measurements agreed closely with manually segmented post-CRT GTVs. Patients with GTV ≥ median (137 ml pre-CRT and 67 ml post-CRT) had 3-year progression-free survival (PFS) of 14% versus 75% for GTV less than median, a significant difference (p = 0.049). Pre- and post-CRT PET-standardized uptake value did not correlate significantly with pathologic complete response, PFS, or overall survival.Preoperative CRT with carboplatin/docetaxel/45 Gy resulted in excellent response rates. In this exploratory analysis, pre- and post-CRT GTV predicted PFS in trimodality therapy, consistent with our earlier studies in a broader cohort of NSCLC. ADIR seems robust enough for volumetric response assessment in clinical trials.

  View details for DOI 10.1097/JTO.0b013e31821517db

  View details for PubMedID 21774104

• PET imaging of cerebral ischemia-induced neuroinflammation in mice using F-18-PBR06 Lartey, F. M., Ahn, G., Shen, B., Cord, K., Smith, T., Chua, J. Y., Rosenblum, S., Tirouvanziam, R., Palmer, T., Guzman, R., Chin, F. T., Graves, E., Loo, B. W. WILEY-BLACKWELL. 2011: S319–S319

  View details for Web of Science ID 000295901600319

• Changes in FDG-PET/CT Parameters on Serial Pre-radiotherapy Scans Predict Disease Progression and Survival in Patients with Non-small Cell Lung Cancer Bazan, J. G., Chung, M. P., Eastham, D. V., Wakelee, H., Hara, W. Y., Maxim, P. G., Graves, E., Le, Q. T., Diehn, M., Loo, B. W. ELSEVIER SCIENCE INC. 2011: S579–S580

  View details for Web of Science ID 000296411701268

• (18)FLUORODEOXYGLUCOSE PET IS PROGNOSTIC OF PROGRESSION-FREE AND OVERALL SURVIVAL IN LOCALLY ADVANCED PANCREAS CANCER TREATED WITH STEREOTACTIC RADIOTHERAPY INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Schellenberg, D., Quon, A., Minn, A. Y., Graves, E. E., Kunz, P., Ford, J. M., Fisher, G. A., Goodman, K. A., Koong, A. C., Chang, D. T. 2010; 77 (5): 1420-1425

  Abstract

  This study analyzed the prognostic value of positron emission tomography (PET) for locally advanced pancreas cancer patients undergoing stereotactic body radiotherapy (SBRT).Fifty-five previously untreated, unresectable pancreas cancer patients received a single fraction of 25-Gy SBRT sequentially with gemcitabine-based chemotherapy. On the preradiation PET-CT, the tumor was contoured and the maximum standardized uptake value (SUVmax) and metabolic tumor burden (MTB) were calculated using an in-house software application. High-SUVmax and low-SUVmax subgroups were created by categorizing patients above or below the median SUVmax. The analysis was repeated to form high-MTB and low-MTB subgroups as well as clinically relevant subgroups with SUVmax values of <5, 5-10, or >10. Multivariate analysis analyzing SUVmax, MTB, age, chemotherapy cycles, and pretreatment carbohydrate antigen (CA)19-9 was performed.For the entire population, median survival was 12.7 months. Median survival was 9.8 vs.15.3 months for the high- and low- SUVmax subgroups (p <0.01). Similarly, median survival was 10.1 vs. 18.0 months for the high MTB and low MTB subgroups (p <0.01). When clinical SUVmax cutoffs were used, median survival was 6.4 months in those with SUVmax >10, 9.5 months with SUVmax 5.0-10.0, and 17.7 months in those with SUVmax <5 (p <0.01). On multivariate analysis, clinical SUVmax was an independent predictor for overall survival (p = 0.03) and progression-free survival (p = 0.03).PET scan parameters can predict for length of survival in locally advanced pancreas cancer patients.

  View details for DOI 10.1016/j.ijrobp.2009.06.049

  View details for Web of Science ID 000280459700020

  View details for PubMedID 20056345

• The Tumor Microenvironment in Non-Small-Cell Lung Cancer SEMINARS IN RADIATION ONCOLOGY Graves, E. E., Maity, A., Le, Q. 2010; 20 (3): 156-163

  Abstract

  The tumor microenvironment (TME) of NSCLC is heterogeneous with variable blood flow through leaky immature vessels resulting in regions of acidosis and hypoxia. Hypoxia has been documented in NSCLC directly by polarographic needle electrodes and indirectly by assessing tissue and plasma hypoxia markers. In general, elevated expression of these markers portends poorer outcomes in NSCLC. Impaired vascularity and hypoxia can lead to increased metastasis and treatment resistance. Compounds that directly target hypoxic cells such as tirapazamine have been tested in clinical trials for NSCLC with mixed results. Preclinical data, however, suggest other ways of exploiting the abnormal TME in NSCLC for therapeutic gain. The inhibition of hypoxia-inducible factor-1alpha or vascular endothelial growth factor may increase local control after radiation. Inhibitors of the epidermal growth factor receptor (EGFR)/phosphatidylinositol 3-kinase (PI3K)/Akt pathway, such as erlotinib or PI-103, may "normalize" tumor vessels, allowing for increased chemotherapy delivery or improved oxygenation and radiation response. To select patients who may respond to these therapies and to evaluate the effects of these agents, a noninvasive means of imaging the TME is critical. Presently, there are several promising modalities to image hypoxia and the tumor vasculature; these include dynamic perfusion imaging and positron emission tomography scanning with radiolabled nitroimidazoles.

  View details for DOI 10.1016/j.semradonc.2010.01.003

  View details for Web of Science ID 000279360800003

  View details for PubMedID 20685578

  View details for PubMedCentralID PMC2917385

• Investigation of the effects of treatment planning variables in small animal radiotherapy dose distributions MEDICAL PHYSICS Motomura, A. R., Bazalova, M., Zhou, H., Keall, P. J., Graves, E. E. 2010; 37 (2): 590-599

  Abstract

  Methods used for small animal radiation treatment have yet to achieve the same dose targeting as in clinical radiation therapy. Toward understanding how to better plan small animal radiation using a system recently developed for this purpose, the authors characterized dose distributions produced from conformal radiotherapy of small animals in a microCT scanner equipped with a variable-aperture collimator.Dose distributions delivered to a cylindrical solid water phantom were simulated using a Monte Carlo algorithm. Phase-space files for 120 kVp x-ray beams and collimator widths of 1-10 mm at isocenter were generated using BEAMnrc software, and dose distributions for evenly spaced beams numbered from 5 to 80 were generated in DOSXYZnrc for a variety of targets, including centered spherical targets in a range of sizes, spherical targets offset from centered by various distances, and various ellipsoidal targets. Dose distributions were analyzed using dose volume histograms. The dose delivered to a mouse bearing a spontaneous lung tumor was also simulated, and dose volume histograms were generated for the tumor, heart, left lung, right lung, and spinal cord.Results indicated that for centered, symmetric targets, the number of beams required to achieve a smooth dose volume histogram decreased with increased target size. Dose distributions for noncentered, symmetric targets did not exhibit any significant loss of conformality with increasing offset from the phantom center, indicating sufficient beam penetration through the phantom for targeting superficial targets from all angles. Even with variable collimator widths, targeting of asymmetric targets was found to have less conformality than that of spherical targets. Irradiation of a mouse lung tumor with multiple beam widths was found to effectively deliver dose to the tumor volume while minimizing dose to other critical structures.Overall, this method of generating and analyzing dose distributions provides a quantitative method for developing practical guidelines for small animal radiotherapy treatment planning. Future work should address methods to improve conformality in asymmetric targets.

  View details for DOI 10.1118/1.3276738

  View details for Web of Science ID 000274075600019

  View details for PubMedID 20229867

  View details for PubMedCentralID PMC2816985

• Prognostic Value of Metabolic Tumor Volume and Velocity in Predicting Head and Neck Cancer Outcomes 52nd Annual Meeting of the American-Society-for-Therapeutic-Radiation-Oncology (ASTRO) Chu, K. P., Murphy, J., La, T. H., Loo, B. W., Krakow, T. E., Hsu, A., Maxim, P. G., Graves, E., Chang, D., Le, Q. ELSEVIER SCIENCE INC. 2010: S460–S460

  View details for Web of Science ID 000288775701074

• Mid-treatment Metabolic Tumor Volume Predicts Progression and Death among Patients with Hodgkin's Disease 52nd Annual Meeting of the American-Society-for-Therapeutic-Radiation-Oncology (ASTRO) Tseng, D., Rachakonda, L. P., Su, Z., Advani, R., Horning, S., Rosenberg, S. A., Hoppe, R. T., Quon, A., Graves, E. E., Loo, B. W., Tran, P. T. ELSEVIER SCIENCE INC. 2010: S546–S547

  View details for Web of Science ID 000288775701265

• Pharmacologically Increased Tumor Hypoxia Can Be Measured by F-18-Fluoroazomycin Arabinoside Positron Emission Tomography and Enhances Tumor Response to Hypoxic Cytotoxin PR-104 CLINICAL CANCER RESEARCH Cairns, R. A., Bennewith, K. L., Graves, E. E., Giaccia, A. J., Chang, D. T., Denko, N. C. 2009; 15 (23): 7170-7174

  Abstract

  Solid tumors contain microenvironmental regions of hypoxia that present a barrier to traditional radiotherapy and chemotherapy, and this work describes a novel approach to circumvent hypoxia. We propose to overcome hypoxia by augmenting the effectiveness of drugs that are designed to specifically kill hypoxic tumor cells.We have constructed RKO colorectal tumor cells that express a small RNA hairpin that specifically knocks down the hypoxia-inducible factor 1a (HIF1a) transcription factor. We have used these cells in vitro to determine the effect of HIF1 on cellular sensitivity to the hypoxic cytotoxin PR-104, and its role in cellular oxygen consumption in response to the pyruvate dehydrogenase kinase inhibitor dichloroacetate (DCA). We have further used these cells in vivo in xenografted tumors to determine the role of HIF1 in regulating tumor hypoxia in response to DCA using (18)F-fluoroazomycin arabinoside positron emission tomography, and its role in regulating tumor sensitivity to the combination of DCA and PR-104.HIF1 does not affect cellular sensitivity to PR-104 in vitro. DCA transiently increases cellular oxygen consumption in vitro and increases the extent of tumor hypoxia in vivo as measured with (18)F-fluoroazomycin arabinoside positron emission tomography. Furthermore, we show that DCA-dependent alterations in hypoxia increase the antitumor activity of the next-generation hypoxic cytotoxin PR-104.DCA interferes with the HIF-dependent "adaptive response," which limits mitochondrial oxygen consumption. This approach transiently increases tumor hypoxia and represents an important method to improve antitumor efficacy of hypoxia-targeted agents, without increasing toxicity to oxygenated normal tissue.

  View details for DOI 10.1158/1078-0432.CCR-09-1676

  View details for Web of Science ID 000272363700011

  View details for PubMedID 19920111

  View details for PubMedCentralID PMC2810128

• Kilovoltage beam Monte Carlo dose calculations in submillimeter voxels for small animal radiotherapy MEDICAL PHYSICS Bazalova, M., Zhou, H., Keall, P. J., Graves, E. E. 2009; 36 (11): 4991-4999

  Abstract

  Small animal conformal radiotherapy (RT) is essential for preclinical cancer research studies and therefore various microRT systems have been recently designed. The aim of this paper is to efficiently calculate the dose delivered using our microRT system based on a microCT scanner with the Monte Carlo (MC) method and to compare the MC calculations to film measurements.Doses from 2-30 mm diameter 120 kVp photon beams deposited in a solid water phantom with 0.2 x 0.2 x 0.2 mm3 voxels are calculated using the latest versions of the EGSnrc codes BEAMNRC and DOSXYZNRC. Two dose calculation approaches are studied: a two-step approach using phase-space files and direct dose calculation with BEAMNRC simulation sources. Due to the small beam size and submillimeter voxel size resulting in long calculation times, variance reduction techniques are studied. The optimum bremsstrahlung splitting number (NBRSPL in BEAMNRC) and the optimum DOSXYZNRC photon splitting (Nsplit) number are examined for both calculation approaches and various beam sizes. The dose calculation efficiencies and the required number of histories to achieve 1% statistical uncertainty--with no particle recycling--are evaluated for 2-30 mm beams. As a final step, film dose measurements are compared to MC calculated dose distributions.The optimum NBRSPL is approximately 1 x 10(6) for both dose calculation approaches. For the dose calculations with phase-space files, Nsplit varies only slightly for 2-30 mm beams and is established to be 300. Nsplit for the DOSXYZNRC calculation with the BEAMNRC source ranges from 300 for the 30 mm beam to 4000 for the 2 mm beam. The calculation time significantly increases for small beam sizes when the BEAMNRC simulation source is used compared to the simulations with phase-space files. For the 2 and 30 mm beams, the dose calculations with phase-space files are more efficient than the dose calculations with BEAMNRC sources by factors of 54 and 1.6, respectively. The dose calculation efficiencies converge for beams with diameters larger than 30 mm.A very good agreement of MC calculated dose distributions to film measurements is found. The mean difference of percentage depth dose curves between calculated and measured data for 2, 5, 10, and 20 mm beams is 1.8%.

  View details for DOI 10.1118/1.3238465

  View details for Web of Science ID 000271217900018

  View details for PubMedID 19994508

  View details for PubMedCentralID PMC2773455

• Quantification of pre-treatment metabolic tumor growth rate in lung cancer Eastham, D., Chapman, C. H., Rao, A. K., Balasubramanian, N., Quon, A., Vasanawala, M. S., Wakelee, H., Le, Q., Colevas, D. A., Maxim, P. A., Graves, E., Loo, B. W. LIPPINCOTT WILLIAMS & WILKINS. 2009: S733–S733

  View details for Web of Science ID 000269496002262

• Mid-treatment PET predicts progression in hypofractionated accelerated radiation therapy for lung tumors Chang, C. N., Fillion, E., Chapman, C., Rao, A., Wakelee, H., Ganjoo, K., Le, Q., Maxim, P., Quon, A., Graves, E. E., Loo, B. W. LIPPINCOTT WILLIAMS & WILKINS. 2009: S939–S939

  View details for Web of Science ID 000269496002721

• METABOLIC TUMOR VOLUME PREDICTS FOR RECURRENCE AND DEATH IN HEAD-AND-NECK CANCER 50th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology (ASTRO) La, T. H., Filion, E. J., Turnbull, B. B., Chu, J. N., Lee, P., Nguyen, K., Maxim, P., Quon, A., Graves, E. E., Loo, B. W., Le, Q. ELSEVIER SCIENCE INC. 2009: 1335–41

  Abstract

  To evaluate the prognostic value of metabolic tumor volume measured on 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging and other clinical factors in patients treated for locally advanced head-and-neck cancer (HNC) at a single institution.Between March 2003 and August 2007, 85 patients received positron emission tomography (PET)/computed tomography-guided chemoradiotherapy for HNC. Metabolically active tumor regions were delineated on pretreatment PET scans semiautomatically using custom software. We evaluated the relationship of (18)F-fluorodeoxyglucose-PET maximum standardized uptake value (SUV) and total metabolic tumor volume (MTV) with disease-free survival (DFS) and overall survival (OS).Mean follow-up for surviving patients was 20.4 months. The estimated 2-year locoregional control, DFS, and OS for the group were 88.0%, 69.5%, and 78.4%, respectively. The median time to first failure was 9.8 months among the 16 patients with relapse. An increase in MTV of 17.4 mL (difference between the 75th and 25th percentiles) was significantly associated with an increased hazard of first event (recurrence or death) (1.9-fold, p < 0.001), even after controlling for Karnofsky performance status (KPS) (1.8-fold, p = 0.001), and of death (2.1-fold, p < 0.001). We did not find a significant relationship of maximum SUV, stage, or other clinical factors with DFS or OS.Metabolic tumor volume is an adverse prognostic factor for disease recurrence and death in HNC. MTV retained significance after controlling for KPS, the only other significant adverse prognostic factor found in this cohort. MTV is a direct measure of tumor burden and is a potentially valuable tool for risk stratification and guiding treatment in future studies.

  View details for DOI 10.1016/j.ijrobp.2008.10.060

  View details for Web of Science ID 000268346100006

  View details for PubMedID 19289263

  View details for PubMedCentralID PMC2752334

• Pancreatic Tumor Motion on a Single Planning 4D-CT Does Not Correlate With Intrafraction Tumor Motion During Treatment AMERICAN JOURNAL OF CLINICAL ONCOLOGY-CANCER CLINICAL TRIALS Minn, A. Y., Schellenberg, D., Maxim, P., Suh, Y., McKenna, S., Cox, B., Dieterich, S., Xing, L., Graves, E., Goodman, K. A., Chang, D., Koong, A. C. 2009; 32 (4): 364-368

  Abstract

  To quantify pancreas tumor motion on both a planning 4D-CT and during a single fraction treatment using the CyberKnife linear accelerator and Synchrony respiratory tracking software, and to investigate whether a single 4D-CT study is reliable for determining radiation treatment margins for patients with locally advanced pancreas cancer.Twenty patients underwent fiducial placement, biphasic pancreatic protocol CT scan and 4D-CT scan in the treatment position while free-breathing. Patients were then treated with a single 25 Gy fraction of stereotactic body radiotherapy. Predicted pancreas motion in the superior-inferior (SI), left-right (LR), and anterior-posterior (AP) directions was calculated from the maximum inspiration and maximum expiration 4D-CT scan. For CyberKnife treatments, mean respiratory cycle motion and maximum respiratory cycle motion was determined in the SI, LR, and AP directions.The range of centroid movement based on 4D-CT in the SI, LR, and AP directions were 0.9 to 28.8 mm, 0.1 to 13.7 mm, and 0.2 to 7.6 mm, respectively. During CyberKnife treatment, in the SI direction, the mean motion of the centroid ranged from 0.5 to 12.7 mm. In the LR direction, the mean motion range was 0.4 to 9.4 mm. In the AP direction, the mean motion range was 0.6 to 5.5 mm. The maximum range of movement (mean) during CyberKnife treatment in the SI, LR, and AP directions were 4.5 to 48.8 mm (mean 20.8 mm), 1.5 to 41.3 mm (mean 11.3 mm), and 1.6 to 68.1 mm (mean 13.4 mm), respectively. Neither the maximum or mean motion correlated with the 4D-CT movement.There is substantial respiratory associated motion of pancreatic tumors. The 4D-CT planning scans cannot accurately predict the movement of pancreatic tumors during actual treatment on CyberKnife.

  View details for DOI 10.1097/COC.0b013e31818da9e0

  View details for PubMedID 19398901

• Commissioning of a novel microCT/RT system for small animal conformal radiotherapy PHYSICS IN MEDICINE AND BIOLOGY Rodriguez, M., Zhou, H., Keall, P., Graves, E. 2009; 54 (12): 3727-3740

  Abstract

  The purpose of this work was to commission a 120 kVp photon beam produced by a micro-computed tomography (microCT) scanner for use in irradiating mice to therapeutic doses. A variable-aperture collimator has been integrated with a microCT scanner to allow the delivery of beams with pseudocircular profiles of arbitrary width between 0.1 and 6.0 cm. The dose rate at the isocenter of the system was measured using ion chamber and gafchromic EBT film as 1.56-2.13 Gy min(-1) at the water surface for field diameters between 0.2 and 6.0 cm. The dose rate decreases approximately 10% per every 5 mm depth in water for field diameters between 0.5 and 1.0 cm. The flatness, symmetry and penumbra of the beam are 3.6%, 1.0% and 0.5 mm, respectively. These parameters are sufficient to accurately conform the radiation dose delivered to target organs on mice. The irradiated field size is affected principally by the divergence of the beam. In general, the beam has appropriate dosimetric characteristics to accurately deliver the dose to organs inside the mice's bodies. Using multiple beams delivered from a variety of angular directions, targets as small as 2 mm may be irradiated while sparing surrounding tissue. This microCT/RT system is a feasible tool to irradiate mice using treatment planning and delivery methods analogous to those applied to humans.

  View details for DOI 10.1088/0031-9155/54/12/008

  View details for Web of Science ID 000266582300008

  View details for PubMedID 19478377

  View details for PubMedCentralID PMC2810127

• A bone composition model for Monte Carlo x-ray transport simulations MEDICAL PHYSICS Zhou, H., Keall, P. J., Graves, E. E. 2009; 36 (3): 1008-1018

  Abstract

  In the megavoltage energy range although the mass attenuation coefficients of different bones do not vary by more than 10%, it has been estimated that a simple tissue model containing a single-bone composition could cause errors of up to 10% in the calculated dose distribution. In the kilovoltage energy range, the variation in mass attenuation coefficients of the bones is several times greater, and the expected error from applying this type of model could be as high as several hundred percent. Based on the observation that the calcium and phosphorus compositions of bones are strongly correlated with the bone density, the authors propose an analytical formulation of bone composition for Monte Carlo computations. Elemental compositions and densities of homogeneous adult human bones from the literature were used as references, from which the calcium and phosphorus compositions were fitted as polynomial functions of bone density and assigned to model bones together with the averaged compositions of other elements. To test this model using the Monte Carlo package DOSXYZnrc, a series of discrete model bones was generated from this formula and the radiation-tissue interaction cross-section data were calculated. The total energy released per unit mass of primary photons (terma) and Monte Carlo calculations performed using this model and the single-bone model were compared, which demonstrated that at kilovoltage energies the discrepancy could be more than 100% in bony dose and 30% in soft tissue dose. Percentage terma computed with the model agrees with that calculated on the published compositions to within 2.2% for kV spectra and 1.5% for MV spectra studied. This new bone model for Monte Carlo dose calculation may be of particular importance for dosimetry of kilovoltage radiation beams as well as for dosimetry of pediatric or animal subjects whose bone composition may differ substantially from that of adult human bones.

  View details for DOI 10.1118/1.3077129

  View details for Web of Science ID 000263718100034

  View details for PubMedID 19378761

• The Role of Tumor Cell-Derived Connective Tissue Growth Factor (CTGF/CCN2) in Pancreatic Tumor Growth CANCER RESEARCH Bennewith, K. L., Huang, X., Ham, C. M., Graves, E. E., Erler, J. T., Kambham, N., Feazell, J., Yang, G. P., Koong, A., Giaccia, A. J. 2009; 69 (3): 775-784

  Abstract

  Pancreatic cancer is highly aggressive and refractory to existing therapies. Connective tissue growth factor (CTGF/CCN2) is a fibrosis-related gene that is thought to play a role in pancreatic tumor progression. However, CCN2 can be expressed in a variety of cell types, and the contribution of CCN2 derived from either tumor cells or stromal cells as it affects the growth of pancreatic tumors is unknown. Using genetic inhibition of CCN2, we have discovered that CCN2 derived from tumor cells is a critical regulator of pancreatic tumor growth. Pancreatic tumor cells derived from CCN2 shRNA-expressing clones showed dramatically reduced growth in soft agar and when implanted s.c. We also observed a role for CCN2 in the growth of pancreatic tumors implanted orthotopically, with tumor volume measurements obtained by positron emission tomography imaging. Mechanistically, CCN2 protects cells from hypoxia-mediated apoptosis, providing an in vivo selection for tumor cells that express high levels of CCN2. We found that CCN2 expression and secretion was increased in hypoxic pancreatic tumor cells in vitro, and we observed colocalization of CCN2 and hypoxia in pancreatic tumor xenografts and clinical pancreatic adenocarcinomas. Furthermore, we found increased CCN2 staining in clinical pancreatic tumor tissue relative to stromal cells surrounding the tumor, supporting our assertion that tumor cell-derived CCN2 is important for pancreatic tumor growth. Taken together, these data improve our understanding of the mechanisms responsible for pancreatic tumor growth and progression, and also indicate that CCN2 produced by tumor cells represents a viable therapeutic target for the treatment of pancreatic cancer.

  View details for DOI 10.1158/0008-5472.CAN-08-0987

  View details for Web of Science ID 000263048700010

  View details for PubMedID 19179545

  View details for PubMedCentralID PMC2747032

• AUTOMATED RADIOSYNTHESIS OF [F-18]EF-5 FOR IMAGING HYPOXIA IN HUMAN Chin, F. T., Subbarayan, M., Sorger, J., Gambhir, S. S., Graves, E. E. WILEY-BLACKWELL. 2009: S274–S274

  View details for Web of Science ID 000268724900275

• In vivo H-1 magnetic resonance spectroscopy of lactate in patients with Stage IV head and neck squamous cell carcinoma 49th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology (ASTRO) Le, Q., Koong, A., Lieskovsky, Y. Y., Narasimhan, B., Graves, E., Pinto, H., Brown, J. M., Spielman, D. ELSEVIER SCIENCE INC. 2008: 1151–57

  Abstract

  To investigate in vivo(1)H magnetic resonance spectroscopy imaging of lactate for assessing tumor hypoxia in head and neck cancers and to determine its utility in predicting the response and outcomes.Volume-localized lactate-edited (1)H magnetic resonance spectroscopy at 1.5 T was performed in vivo on involved neck nodes and control subcutaneous tissues in 36 patients with Stage IV head and neck cancer. The signal intensities (SIs) of lactate, choline, and creatine and the choline/creatine ratio were measured. The tumor partial pressure of oxygen (pO(2)) was obtained in the same lymph node before MRS. Patients were treated with either two cycles of induction chemotherapy (tirapazamine, cisplatin, 5-fluorouracil) followed by simultaneous chemoradiotherapy or the same regimen without tirapazamine. The lactate SI and the choline/creatine ratio correlated with the tumor pO(2), nodal response, and locoregional control.The lactate SI was greater for the involved nodes (median, 0.25) than for the subcutaneous tissue (median, 0.04; p = 0.07). No significant correlation was found between the lactate SI and tumor pO(2) (mean, 0.46 +/- 0.10 for hypoxic nodes [pO(2) < or =10 mm Hg, n = 15] vs. 0.36 +/- 0.07 for nonhypoxic nodes [pO(2) >10 mm Hg, n = 21], p = 0.44). A significant correlation was found between the choline/creatine ratios and tumor pO(2) (mean, 2.74 +/- 0.34 for hypoxic nodes vs. 1.78 +/- 0.31 for nonhypoxic nodes, p = 0.02). No correlation was found between the lactate SI and the complete nodal response (p = 0.52) or locoregional control rates.The lactate SI did not correlate with tumor pO(2), treatment response, or locoregional control. Additional research is needed to refine this technique.

  View details for DOI 10.1016/j.ijrobp.2007.11.030

  View details for Web of Science ID 000257299200025

  View details for PubMedID 18258377

  View details for PubMedCentralID PMC2601688

• Metabolic tumor volume predicts for recurrence and death in head and neck cancer 50th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology (ASTRO) La, T. H., Filion, E. J., Turnbull, B. B., CHU, J. N., Lee, P., Nguyen, K., Maxim, P., Loo, B. W., Graves, E. E., Le, Q. ELSEVIER SCIENCE INC. 2008: S159–S160

  View details for Web of Science ID 000258805300356

• Design and evaluation of a variable aperture collimator for conformal radiotherapy of small animals using a microCT scanner MEDICAL PHYSICS Graves, E. E., Zhou, H., Chatterjee, R., Keall, P. J., Gambhir, S. S., Contag, C. H., Boyer, A. L. 2007; 34 (11): 4359-4367

  Abstract

  Treatment of small animals with radiation has in general been limited to planar fields shaped with lead blocks, complicating spatial localization of dose and treatment of deep-seated targets. In order to advance laboratory radiotherapy toward what is accomplished in the clinic, we have constructed a variable aperture collimator for use in shaping the beam of microCT scanner. This unit can image small animal subjects at high resolution, and is capable of delivering therapeutic doses in reasonable exposure times. The proposed collimator consists of two stages, each containing six trapezoidal brass blocks that move along a frame in a manner similar to a camera iris producing a hexagonal aperture of variable size. The two stages are offset by 30 degrees and adjusted for the divergence of the x-ray beam so as to produce a dodecagonal profile at isocenter. Slotted rotating driving plates are used to apply force to pins in the collimator blocks and effect collimator motion. This device has been investigated through both simulation and measurement. The collimator aperture size varied from 0 to 8.5 cm as the driving plate angle increased from 0 to 41 degrees. The torque required to adjust the collimator varied from 0.5 to 5 N x m, increasing with increasing driving plate angle. The transmission profiles produced by the scanner at isocenter exhibited a penumbra of approximately 10% of the collimator aperture width. Misalignment between the collimator assembly and the x-ray source could be identified on the transmission images and corrected by adjustment of the collimator location. This variable aperture collimator technology is therefore a feasible and flexible solution for adjustable shaping of radiation beams for use in small animal radiotherapy as well as other applications in which beam shaping is desired.

  View details for DOI 10.1118/1.2789498

  View details for Web of Science ID 000251145900029

  View details for PubMedID 18072501

• Metabolic tumor burden predicts for disease progression and death in lung cancer 47th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology Lee, P., Weerasuriya, D. K., Lavori, P. W., Quon, A., Hara, W., Maxim, P. G., Le, Q., Wakelee, H. A., Donington, J. S., Graves, E. E., Loo, B. W. ELSEVIER SCIENCE INC. 2007: 328–33

  Abstract

  In lung cancer, stage is an important prognostic factor for disease progression and survival. However, stage may be simply a surrogate for underlying tumor burden. Our purpose was to assess the prognostic value of tumor burden measured by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging.We identified 19 patients with lung cancer who had staging PET-CT scans before any therapy, and adequate follow-up (complete to time of progression for 18, and death for 15 of 19). Metabolically active tumor regions were segmented on pretreatment PET scans semi-automatically using custom software. We determined the relationship between times to progression (TTP) and death (OS) and two PET parameters: total metabolic tumor volume (MTV), and standardized uptake value (SUV).The estimated median TTP and OS for the cohort were 9.3 months and 14.8 months. On multivariate Cox proportional hazards regression analysis, an increase in MTV of 25 ml (difference between the 75th and 25th percentiles) was associated with increased hazard of progression and of death (5.4-fold and 7.6-fold), statistically significant (p = 0.0014 and p = 0.001) after controlling for stage, treatment intent (definitive or palliative), age, Karnofsky performance status, and weight loss. We did not find a significant relationship between SUV and TTP or OS.In this study, high tumor burden assessed by PET MTV is an independent poor prognostic feature in lung cancer, promising for stratifying patients in randomized trials and ultimately for selecting risk-adapted therapies. These results will need to be validated in larger cohorts with longer follow-up, and evaluated prospectively.

  View details for DOI 10.1016/j.ijrobp.2007.04.036

  View details for PubMedID 17869659

• Oxygen sensitivity of reporter genes: Implications for preclinical imaging of tumor hypoxia MOLECULAR IMAGING Cecic, I., Chan, D. A., Sutphin, P. D., Ray, P., Gambhir, S. S., Giaccia, A. J., Gravcs, E. E. 2007; 6 (4): 219-228

  Abstract

  Reporter gene techniques have been applied toward studying the physiologic phenomena associated with tumor hypoxia, a negative prognostic indicator. The purpose of this study was to assess the potential adverse effects of hypoxic conditions on the effectiveness of four commonly used reporter genes: Renilla luciferase, monomeric red fluorescent protein, thymidine kinase, and lacZ. Tumor-forming A375 cells expressing a trifusion reporter consisting of Renilla luciferase, monomeric red fluorescent protein, and thymidine kinase were subjected to decreasing oxygen tensions and assayed for reporter expression and activity. A375 cells expressing beta-galactosidase were similarly exposed to hypoxia, with activity of the reporter monitored by cleavage of the fluorescent substrate 7-hydroxy-9H-(1,3-dichloro-9,9-dimethylacridin-2-one)-beta-galactoside (DDAOG). Generation of signal in in vivo tumor models expressing bioluminescent or beta-galactosidase reporters were also examined over the course of hypoxic stresses, either by tumor clamping or the antivascular agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA). Our findings indicate that bioluminescent and fluorescent reporter activity are decreased under hypoxia despite minimal variations in protein production, whereas beta-galactosidase reporter activity per unit protein was unchanged. These results demonstrate that combining beta-galactosidase with the DDAOG optical probe may be a robust reporter system for the in vivo study of tumor hypoxia.

  View details for DOI 10.2310/7290.2007.00017

  View details for Web of Science ID 000249349100001

  View details for PubMedID 17711777

• Small-animal PET of melanocortin 1 receptor expression using a F-18-labeled alpha-melanocyte-stimulating hormone analog JOURNAL OF NUCLEAR MEDICINE Cheng, Z., Zhang, L., Graves, E., Xiong, Z., Dandekar, M., Chen, X., Gambhir, S. S. 2007; 48 (6): 987-994

  Abstract

  (18)F-Labeled small synthetic peptides have emerged as attractive probes for imaging various molecular targets with PET. The alpha-melanocyte-stimulating hormone (alpha-MSH) receptor (melanocortin type 1 receptor [MC1R]) is overexpressed in most murine and human melanomas. It is a promising molecular target for diagnosis and therapy of melanomas. However, (18)F compounds have not been successfully developed for imaging the MC1R.In this study, an alpha-MSH analog, Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-Lys-NH(2) (NAPamide), was radiolabeled with N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB). The resulting radiopeptide was evaluated as a potential molecular probe for small-animal PET of melanoma and MC1R expression in melanoma xenografted mouse models.The binding affinity of (19)F-SFB-conjugated NAPamide, (19)F-FB-NAPamide, was determined to be 7.2 +/- 1.2 nM (mean +/- SD) using B16/F10 cells and (125)I-(Tyr(2))-[Nle(4),D-Phe(7)]-alpha-MSH [(125)I-(Tyr(2))-NDP] as a radioligand. The biodistribution of (18)F-FB-NAPamide was then investigated in C57BL/6 mice bearing subcutaneous murine B16/F10 melanoma tumors with high expression of MC1Rs and Fox Chase Scid mice bearing human A375M melanoma with a relatively low number of MC1R receptors. Biodistribution experiments showed that tumor uptake values (percentage injected dose per gram of tumor [%ID/g]) of (18)F-FB-NAPamide were 1.19 +/- 0.11 %ID/g and 0.46 +/- 0.11 %ID/g, in B16/F10 and A375M xenografted melanoma at 1 h after injection, respectively. Furthermore, the B16/F10 tumor uptake was significantly inhibited by coinjection with excess alpha-MSH peptide (P < 0.05), indicating that (18)F-FB-NAPamide specifically recognizes the MC1R in living mice. Small-animal PET of (18)F-FB-NAPamide in mice bearing B16/F10 and A375M tumors at 1 h after tail vein injection revealed good B16/F10 tumor-to-background contrast and low A375M tumor-to-background ratios.(18)F-FB-NAPamide is a promising molecular probe for alpha-MSH receptor-positive melanoma PET and warrants further study.

  View details for DOI 10.2967/jnumed.107.039602

  View details for Web of Science ID 000247054800024

  View details for PubMedID 17504880

• Imaging tumoral hypoxia: Oxygen concentrations and beyond ONCOLOGY-NEW YORK Graves, E. E., Giaccia, A. J. 2007; 21 (3): 368-376

  Abstract

  The role of hypoxia as a key determinant of outcome for human cancers has encouraged efforts to noninvasively detect and localize regions of poor oxygenation in tumors. In this review, we will summarize existing and developing techniques for imaging tumoral hypoxia. A brief review of the biology of tumor oxygenation and its effect on tumor cells will be provided initially. We will then describe existing methods for measurement of tissue oxygenation status. An overview of emerging molecular imaging techniques based on radiolabeled hypoxic markers such as misonidazole or hypoxia-related genes and proteins will then be given, and the usefulness of these approaches toward targeting hypoxia directly will be assessed. Finally, we will evaluate the clinical potential of oxygen- and molecular-specific techniques for imaging hypoxia, and discuss how these methods will individually and collectively advance oncology.

  View details for Web of Science ID 000253822400010

  View details for PubMedID 17447439

• Lactate-base H-1 magnetic spectroscopy does not predict response and outcomes in patients with stage IV head and neck squamous cell carcinoma 49th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology (ASTRO) Le, Q., Koong, A., Lieskovsky, Y., Graves, E., PINTO, H., Brown, J., Spielman, D. ELSEVIER SCIENCE INC. 2007: S200–S201

  View details for Web of Science ID 000249950200352

• Perfusion, diffusion and spectroscopy values in newly diagnosed cerebral gliomas NMR IN BIOMEDICINE Catalaa, I., Henry, R., Dillon, W. P., Graves, E. E., McKnight, T. R., Lu, Y., Vigneron, D. B., Nelson, S. J. 2006; 19 (4): 463-475

  Abstract

  To evaluate perfusion, diffusion, and spectroscopy values in enhancing and non-enhancing lesions for patients with newly diagnosed gliomas of different grades.Sixty-seven patients with newly diagnosed glioma were entered into the study 20 grade II, 26 grade III and 21 grade IV. MR data were acquired at 1.5T and included diffusion weighted images (59/67 patients), dynamic perfusion weighted images (30/67 patients) and 3D H-1 MR spectroscopy (64/67 patients). Enhancing and non-enhancing lesions were delineated by a neuroradiologist and applied to maps of relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), relative anisotropy (RA) and metabolite intensities.The median rCBV within enhancing regions of grade IV gliomas was significantly elevated relative to enhancing regions in grade III gliomas and normal brain. ADC was elevated relative to normal brain, but was not significantly different between grades or between enhancing and non-enhancing regions. The RA was higher in the non-enhancing region of grade IV gliomas relative to grade II and grade III. Levels of lactate plus lipid were significantly elevated in grade IV relative to grade II and grade III gliomas. Both enhancing and non-enhancing regions in grade IV gliomas showed significant correlations between CBV, ADC and choline levels.The data were consistent with grade IV gliomas having higher membrane turnover, increased cell density and increased vascularity within enhancing lesions. Analysis of the correlations among parameters within grade IV gliomas suggested that high vascularity (high rCBV) was correlated with increased cellularity (low ADC) and increased membrane turnover (high choline) in these lesions. The non-enhancing region of grades II and III gliomas had MR parameters consistent with increased cellularity and/or membrane turnover.

  View details for DOI 10.1002/nbm.1059

  View details for Web of Science ID 000238883100004

  View details for PubMedID 16763973

• Validation of in vivo fluorochrome concentrations measured using fluorescence molecular tomography JOURNAL OF BIOMEDICAL OPTICS Graves, E. E., Yessayan, D., Turner, G., Weissleder, R., Ntziachristos, V. 2005; 10 (4)

  Abstract

  Fluorescence molecular tomography (FMT) has emerged as a means of quantitatively imaging fluorescent molecular probes in three dimensions in living systems. To assess the accuracy of FMT in vivo, translucent plastic tubes containing a turbid solution with a known concentration of Cy 5.5 fluorescent dye are constructed and implanted subcutaneously in nude mice, simulating the presence of a tumor accumulating a fluorescent molecular reporter. Comparisons between measurements of fluorescent tubes made before and after implantation demonstrate that the accuracy of FMT reported for homogeneous phantoms extends to the in vivo situation. The sensitivity of FMT to background fluorescence is tested by imaging fluorescent tubes in mice injected with Cy 5.5-labeled Annexin V. For small tube fluorochrome concentrations, the presence of background fluorescence results in increases in the reconstructed concentration. This phenomenon is counteracted by applying a simple subtraction correction to the measured fluorescence data. The effects of varying tumor photon absorption are simulated by imaging fluorescent tubes with varying ink concentrations, and are found to be minor. These findings demonstrate the in vivo quantitative accuracy of fluorescence tomography, and encourage further development of this imaging modality as well as application of FMT in molecular imaging studies using fluorescent reporters.

  View details for DOI 10.1117/1.1993427

  View details for Web of Science ID 000232799200028

  View details for PubMedID 16178652

• Relationship of MR-derived lactate, mobile lipids, and relative blood volume for gliomas in vivo AMERICAN JOURNAL OF NEURORADIOLOGY Li, X. J., Vigneron, D. B., Cha, S. M., Graves, E. E., Crawford, F., Chang, S. M., Nelson, S. J. 2005; 26 (4): 760-769

  Abstract

  Gliomas are heterogeneous tumors with increased microvasculature, hypoxia, and necrosis. The purpose of this study was to examine the distribution and relationship of the MR-derived relative cerebral blood volume (rCBV), lactate (Lac), and mobile lipids (Lip), which have been proposed as markers for these phenomena of gliomas in vivo.Twenty-three patients with newly diagnosed gliomas were examined before surgical biopsy and/or resection (seven grade II, five grade III, and 11 grade IV), and 27 patients were studied after surgery but before radiation treatment and/or chemotherapy (11 grade II, two grade III, and 14 grade IV gliomas). Lac and Lip were estimated from Lac-edited three-dimensional MR spectroscopic images. Dynamic susceptibility-contrast MR imaging was applied to obtain perfusion-weighted images and rCBV maps.Before surgical biopsy/resection, one low-grade and 12 of 16 high-grade gliomas had significantly elevated Lac. No low-grade and 10 of 16 high-grade gliomas had significantly elevated Lip. In presurgical high-grade gliomas, volumes of elevated Lip and macronecrosis were significantly correlated. rCBV was significantly increased in regions with elevated Lac. After we excluded macronecrosis, the rCBV for regions with elevated Lip but no Lac was significantly higher than rCBV in regions with elevated Lac but no Lip. After surgical biopsy/resection, more low-grade patients showed significantly elevated Lac and Lip than before.The in vivo distribution of rCBV, Lac, and Lip, as evaluated with three-dimensional MR spectroscopic imaging, may help in the diagnosis and selection of the most appropriate therapy for patients with gliomas.

  View details for Web of Science ID 000228273400017

  View details for PubMedID 15814918

• Effect of respiratory cycle irregularities on image quality in four-dimensional computed tomography 47th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology Thorndyke, B., Xing, L., Graves, E., Loo, B. W. ELSEVIER SCIENCE INC. 2005: S506–S506

  View details for Web of Science ID 000232083301373

• Visualization of antitumor treatment by means of fluorescence molecular tomography with an annexin V-Cy5.5 conjugate PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ntziachristos, V., Schellenberger, E. A., Ripoll, J., Yessayan, D., Graves, E., Bogdanov, A., Josephson, L., Weissleder, R. 2004; 101 (33): 12294-12299

  Abstract

  In vivo imaging of treatment responses at the molecular level could have a significant impact on the speed of drug discovery and ultimately lead to personalized medicine. Strong interest has been shown in developing quantitative fluorescence-based technologies with good molecular specificity and sensitivity for noninvasive 3D imaging through tissues and whole animals. We show herein that tumor response to chemotherapy can be accurately resolved by fluorescence molecular tomography (FMT) with a phosphatidylserine-sensing fluorescent probe based on modified annexins. We observed at least a 10-fold increase of fluorochrome concentration in cyclophosphamide-sensitive tumors and a 7-fold increase of resistant tumors compared with control studies. FMT is an optical imaging technique developed to overcome limitations of commonly used planar illumination methods and demonstrates higher quantification accuracy validated by histology. It is further shown that a 3-fold variation in background absorption heterogeneity may yield 100% errors in planar imaging but only 20% error in FMT, thus confirming tomographic imaging as a preferred tool for quantitative investigations of fluorescent probes in tissues. Tomographic approaches are found essential for small-animal optical imaging and are potentially well suited for clinical drug development and monitoring.

  View details for DOI 10.1073/pnas.0401137101

  View details for Web of Science ID 000223410100070

  View details for PubMedID 15304657

• Fluorescence molecular imaging of small animal tumor models CURRENT MOLECULAR MEDICINE Graves, E. E., Weissleder, R., Ntziachristos, V. 2004; 4 (4): 419-430

  Abstract

  In vivo imaging of molecular events in small animals has great potential to impact basic science and drug development. For this reason, several imaging technologies have been adapted to small animal research, including X-ray, magnetic resonance, and radioisotope imaging. Despite this plethora of visualization techniques, fluorescence imaging is emerging as an important alternative because of its operational simplicity, safety, and cost-effectiveness. Fluorescence imaging has recently become particularly interesting because of advances in fluorescent probe technology, including targeted fluorochromes as well as fluorescent "switches" sensitive to specific biochemical events. While past biological investigations using fluorescence have focused on microscopic examination of ex vivo, in vitro, or intravital specimens, techniques for macroscopic fluorescence imaging are now emerging for in vivo molecular imaging applications. This review illuminates fluorescence imaging technologies that hold promise for small animal imaging. In particular we focus on planar illumination techniques, also known as Fluorescence Reflectance Imaging (FRI), and discuss its performance and current use. We then discuss fluorescence molecular tomography (FMT), an evolving technique for quantitative three-dimensional imaging of fluorescence in vivo. This technique offers the promise of non-invasively quantifying and visualizing specific molecular activity in living subjects in three dimensions.

  View details for Web of Science ID 000221658700008

  View details for PubMedID 15354872

• Singular-value analysis and optimization of experimental parameters in fluorescence molecular tomography JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION Graves, E. E., Culver, J. P., Ripoll, J., Weissleder, R., Ntziachristos, V. 2004; 21 (2): 231-241

  Abstract

  The advent of specific molecular markers and probes employing optical reporters has encouraged the application of in vivo diffuse tomographic imaging at greater spatial resolutions and hence data-set volumes. This study applied singular-value analysis (SVA) of the fluorescence tomographic problem to determine optimal source and detector distributions that result in data sets that are balanced between information content and size. Weight matrices describing the tomographic forward problem were constructed for a range of source and detector distributions and fields of view and were decomposed into their associated singular values. These singular-value spectra were then compared so that we could observe the effects of each parameter on imaging performance. The findings of the SVA were then confirmed by examining reconstructions of simulated and experimental data acquired with the same optode distributions as examined by SVA. It was seen that for a 20-mm target width, which is relevant to the small-animal imaging situation, the source and detector fields of view should be set at approximately 30 mm. Equal numbers of sources and detectors result in the best imaging performance in the parallel-plate geometry and should be employed when logistically feasible. These data provide guidelines for the design of small-animal diffuse optical tomographic imaging systems and demonstrate the utility of SVA as a simple and efficient means of optimizing experimental parameters in problems for which a forward model of the data collection process is available.

  View details for Web of Science ID 000188183900009

  View details for PubMedID 14763766

• A method of target definition in PET-based radiotherapy planning 46th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology Loo, B. W., Quon, A., Vasanawala, M. S., Le, Q., Graves, E. E. ELSEVIER SCIENCE INC. 2004: S602–S602

  View details for Web of Science ID 000223854700784

• Fluorescence Molecular Tomography: New detection schemes for acquiring high information content measurements 2nd IEEE International Symposium on Biomedical Imaging Ntziachristos, V., Graves, E., SCHULTZ, R. F., Ripoll, J. IEEE. 2004: 1475–1478

  View details for Web of Science ID 000227671301109

• In vivo high resolution three-dimensional imaging of antigen-specific cytotoxic T-lymphocyte trafficking to tumors CANCER RESEARCH Kircher, M. F., Allport, J. R., Graves, E. E., Love, V., Josephson, L., Lichtman, A. H., Weissleder, R. 2003; 63 (20): 6838-6846

  Abstract

  Magnetic resonance imaging (MRI) allows noninvasive and three-dimensional visualization of whole organisms over time, and, therefore, would be ideally suited to monitor cell trafficking in vivo. Until now, systemically injected cells had been difficult to visualize by MRI because of relatively inefficient labeling methods. We developed a novel, biocompatible, and physiologically inert nanoparticle (highly derivatized cross-linked iron oxide nanoparticle; CLIO-HD) for highly efficient intracellular labeling of a variety of cell types that now allows in vivo MRI tracking of systemically injected cells at near single-cell resolution. CD8+ cytotoxic T lymphocytes labeled with CLIO-HD were detectable via MRI with a detection threshold of 2 cells/voxel in vitro and approximately 3 cells/voxel in vivo in live mice. Using B16-OVA melanoma and CLIO-HD-labeled OVA-specific CD8+ T cells, we have demonstrated for the first time high resolution imaging of T-cell recruitment to intact tumors in vivo. We have revealed the extensive three-dimensional spatial heterogeneity of T-cell recruitment to target tumors and demonstrated a temporal regulation of T-cell recruitment within the tumor. Significantly, our data indicate that serial administrations of CD8+ T cells appear to home to different intratumoral locations, and may, therefore, provide a more effective treatment regimen than a single bolus administration. Together, these results demonstrate that CLIO-HD is uniquely suited for quantitative repetitive MRI of adoptively transferred cells and that this approach may be particularly useful for evaluating novel cell-based therapies in vivo.

  View details for Web of Science ID 000186213800035

  View details for PubMedID 14583481

• A submillimeter resolution fluorescence molecular imaging system for small animal imaging MEDICAL PHYSICS Graves, E. E., Ripoll, J., Weissleder, R., Ntziachristos, V. 2003; 30 (5): 901-911

  Abstract

  Most current imaging systems developed for tomographic investigations of intact tissues using diffuse photons suffer from a limited number of sources and detectors. In this paper we describe the construction and evaluation of a large dataset, low noise tomographic system for fluorescence imaging in small animals. The system consists of a parallel plate-imaging chamber and a lens coupled CCD camera, which enables conventional planar imaging as well as fluorescence tomography. The planar imaging data are used to guide the acquisition of a Fluorescence Molecular Tomography (FMT) dataset containing more than 106 measurements, and to superimpose anatomical features with tomographic results for improved visual representation. Experimental measurements exhibited good agreement with the diffusion theory models used to predict light propagation within the chamber. Tests of the instrument's capacity to quantitatively reconstruct fluorochrome distributions in three dimensions showed less than 5% errors between actual fluorochrome concentrations and FMT findings, and suggested a detection threshold of approximately 100 femptomoles for small localized objects. Experiments to assess the instrument's spatial resolution demonstrated the ability of the system to resolve objects placed at clear distances of less than 1 mm. This is a significant resolution increase over previously developed systems for animal imaging, and is primarily due to the large dataset employed and the use of inversion methods. Finally, the in vivo imaging capacity is showcased. It is expected that the large dataset collected can enable superior imaging of molecular probes in vivo and improve quantification of fluorescence signatures.

  View details for DOI 10.1118/1.1568977

  View details for Web of Science ID 000182967800022

  View details for PubMedID 12772999

• Histopathological validation of a three-dimensional magnetic resonance spectroscopy index as a predictor of tumor presence JOURNAL OF NEUROSURGERY McKnight, T. R., von dem Bussche, M. H., Vigneron, D. B., Lu, Y., Berger, M. S., McDermott, M. W., Dillon, W. P., Graves, E. E., Pirzkall, A., Nelson, S. J. 2002; 97 (4): 794-802

  Abstract

  Data obtained preoperatively from three-dimensional (3D)/proton magnetic resonance (MR) spectroscopy were compared with the results of histopathological assays of tissue biopsies obtained during surgery to verify the sensitivity and specificity of a choline-containing compound-N-acetylaspartate index (CNI) used to distinguish tumor from nontumorous tissue within T2-hyperintense and contrast-enhancing lesions of patients with untreated gliomas. The information gleaned from the biopsy correlation study was used to test the hypothesis that there is metabolically active tumor in nonenhancing regions of the T2-hyperintense lesion that can be detected using MR spectroscopy.Patients suspected of harboring a glioma underwent 3D MR spectroscopy during their preoperative MR imaging examination. Surgical navigation techniques were used to record the location of tissue biopsies collected during open resection of the tumor. A receiver operating curve analysis of the CNI and histological characteristics of specimens at each biopsy location was performed to determine the optimal threshold of the CNI required to separate tumor from nontumorous tissue. Histograms of the CNIs within enhancing and nonenhancing regions of lesions appearing on MR images were generated to determine the spatial distribution of CNIs consistent with tumor.Biopsy samples containing tumor were distinguished from those containing a mixture of normal, edematous, gliotic, and necrotic tissue with 90% sensitivity and 86% specificity by using a CNI threshold of 2.5. The CNIs of nontumorous specimens were significantly different from those of biopsy specimens containing Grade II (p < 0.03), Grade III (p < 0.005), and Grade IV (p < 0.01) tumors. On average, one third to one half of the T2-hyperintense lesion outside the contrast-enhancing lesion contained CNI greater than 2.5.

  View details for Web of Science ID 000178626400014

  View details for PubMedID 12405365

• In vivo molecular imaging for planning radiation therapy of gliomas: an application of 1H MRSI JOURNAL OF MAGNETIC RESONANCE IMAGING Nelson, S. J., Graves, E., Pirzkall, A., Li, X. J., Chan, A. A., Vigneron, D. B., McKnight, T. R. 2002; 16 (4): 464-476

  Abstract

  Gliomas are infiltrative lesions that typically have poorly defined margins on conventional magnetic resonance (MR) and computed tomography (CT) images. This presents a considerable challenge for planning radiation and other forms of focal therapy, and introduces the possibility of both under-treating macroscopic tumor, and over-treating regions of normal brain tissue. New therapy systems are able to deliver radiation more precisely and accurately to irregular three-dimensional target volumes, and have placed a premium on definition of the spatial extent of the lesion. Proton MR spectroscopic imaging (H-MRSI) has been proposed as an in vivo molecular imaging technique that assists in targeting and predicts response to radiation therapy for patients with gliomas. The evidence that supports the use of H-MRSI for planning radiation treatment is reviewed, together with the technical requirements for implementing data acquisition and analysis procedures in a clinical setting. Although there is room for improvement in the spatial resolution and chemical specificity obtained at the conventional field strength of 1.5 T, there are clear benefits to integrating H-MRSI into treatment planning and follow-up examinations. Further work is required to integrate the results of the H-MRSI examination into the treatment planning workstation, and to improve the quality of the data using more sensitive phased array coils and higher field strength magnets.

  View details for DOI 10.1002/jmri.10183

  View details for Web of Science ID 000178445700013

  View details for PubMedID 12353260

• Metabolic imaging of low-grade gliomas with three-dimensional magnetic resonance spectroscopy 43rd Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology Pirzkall, A., Nelson, S. J., McKnight, T. R., Takahashi, M. M., Li, X. J., Graves, E. E., Verhey, L. J., Wara, W. W., Larson, D. A., Sneed, P. K. ELSEVIER SCIENCE INC. 2002: 1254–64

  Abstract

  The role of radiotherapy (RT) seems established for patients with low-grade gliomas with poor prognostic factors. Three-dimensional (3D) magnetic resonance spectroscopy imaging (MRSI) has been reported to be of value in defining the extent of glioma infiltration. We performed a study examining the impact MRSI would have on the routine addition of 2-3-cm margins around MRI T2-weighted hyperintensity to generate the treatment planning clinical target volume (CTV) for low-grade gliomas.Twenty patients with supratentorial gliomas WHO Grade II (7 astrocytomas, 6 oligoastrocytomas, 7 oligodendrogliomas) underwent MRI and MRSI before surgery. The MRI was contoured manually; the regions of interest included T2 hyperintensity and, if present, regions of contrast enhancement on T1-weighted images. The 3D-MRSI peak parameters for choline and N-acetyl-aspartate, acquired voxel-by-voxel, were categorized using a choline/N-acetyl-aspartate index (CNI), a tool for quantitative assessment of tissue metabolite levels, with CNI 2 being the lowest value corresponding to tumor. CNI data were aligned to MRI and displayed as 3D contours. The relationship between the anatomic and metabolic information on tumor extent was assessed by comparing the CNI contours and other MRSI-derived metabolites to the MRI T2 volume.The limitations in the size of the region "excited" meant that MRSI could be used to evaluate only a median 68% of the T2 volume (range 38-100%), leaving the volume T2c. The CNI 2 volume (median 29 cm(3), range 10-73) was contained totally within the T2c in 55% of patients. In the remaining patients, the volume of CNI 2 extending beyond the T2c was quite small (median 2.3 cm(3), range 1.4-5.2), but was not distributed uniformly about the T2c, extending up to 22 mm beyond it. Two patients demonstrated small regions of contrast enhancement corresponding to the regions of highest CNI. Other metabolites, such as creatine and lactate, seem useful for determining less and more radioresistant areas, respectively.Metabolically active tumor, as detected by MRSI, is restricted mainly to the T2 hyperintensity in low-grade gliomas, but can extend outside it in a limited and nonuniform fashion up to 2 cm. Therefore, a CTV including T2 and areas of CNI extension beyond the T2 hyperintensity would result in a reduction in the size and a change in the shape of the standard clinical target volumes generated by adding uniform margins of 2-3 cm to the T2 hyperintensity.

  View details for Web of Science ID 000177217800021

  View details for PubMedID 12128127

• In vivo tomographic imaging of near-infrared fluorescent probes. Molecular imaging Ntziachristos, V., Bremer, C., Graves, E. E., Ripoll, J., Weissleder, R. 2002; 1 (2): 82-88

  Abstract

  Fluorescence imaging is increasingly used to probe protein function and gene expression in live animals. This technology could enhance the study of pathogenesis, drug development, and therapeutic intervention. In this article, we focus on three-dimensional fluorescence observations using fluorescence-mediated molecular tomography (FMT), a novel imaging technique that can resolve molecular function in deep tissues by reconstructing fluorescent probe distributions in vivo. We have compared FMT findings with conventional fluorescence reflectance imaging (FRI) to study protease function in nude mice with subsurface implanted tumors. This validation of FMT with FRI demonstrated the spatial congruence of fluorochrome activation as determined by the two techniques.

  View details for PubMedID 12920848

• In Vivo Tomographic Imaging of Near-Infrared Fluorescent Probes MOLECULAR IMAGING Ntziachristos, V., Bremer, C., Graves, E. E., Ripoll, J., Weissleder, R. 2002; 1 (2): 82-88

  View details for Web of Science ID 000209334600003

• In-vivo molecular investigations of live tissues using diffracting sources 5th International Conference on Medical Image Computing and Computer-Assisted Intervention Ntziachristos, V., Ripoll, J., Graves, E., Weissleder, R. SPRINGER-VERLAG BERLIN. 2002: 739–745

  View details for Web of Science ID 000189412100091

• Registration of magnetic resonance spectroscopic imaging to computed tomography for radiotherapy treatment planning MEDICAL PHYSICS Graves, E. E., Pirzkall, A., Nelson, S. J., Larson, D., Verhey, L. 2001; 28 (12): 2489-2496

  Abstract

  The incorporation of multiple imaging modalities into radiotherapy treatment planning offers the potential to improve identification of regions of pathology. This work outlines and evaluates a methodology for registration of magnetic resonance images (MRI) and spectroscopic images (MRSI) to computed tomography (CT) images, and visualization of the multimodality data on the treatment planning workstation. Volumetric magnetic resonance images were acquired during an examination prior to the initiation of radiotherapy. Registration between these images and the treatment planning computed tomography images was performed using an automated alignment routine, and was improved manually using an interactive registration tool. The parameters of the alignment were then used to transform the spectroscopic images into the same reference frame. The spectroscopy data were represented in terms of a statistical measure of abnormality, and embedded within the MRI data as overlaid contours. These images were sent via DICOM transfer to the treatment planning workstation. An analysis of the reproducibility of the

  View details for DOI 10.1118/1.1420400

  View details for Web of Science ID 000172896200013

  View details for PubMedID 11797952

• MR-spectroscopy guided target delineation for high-grade gliomas 42nd Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology (ASTRO) Pirzkall, A., McKnight, T. R., Graves, E. E., Carol, M. P., Sneed, P. K., Wara, W. W., Nelson, S. J., Verhey, L. J., Larson, D. A. ELSEVIER SCIENCE INC. 2001: 915–28

  Abstract

  Functional/metabolic information provided by MR-spectroscopy (MRSI) suggests MRI may not be a reliable indicator of active and microscopic disease in malignant brain tumors. We assessed the impact MRSI might have on the target volumes used for radiation therapy treatment planning for high-grade gliomas.Thirty-four patients (22 Grade III; 12 Grade IV astrocytomas) were evaluated; each had undergone MRI and MRSI studies before surgery. MRI data sets were contoured for T1 region of contrast enhancement (T1), region of necrosis, and T2 region of hyperintensity (T2). The three-dimensional MRSI peak parameters for choline (Cho) and N-acetylaspartate (NAA), acquired by a multivoxel technique, were categorized based on an abnormality index (AI), a quantitative assessment of tissue metabolite levels. The AI data were aligned to the MRI and displayed as three-dimensional contours. AI vs. T conjoint and disjoint volumes were compared.For both grades, although T2 estimated the region at risk of microscopic disease as being as much as 50% greater than by MRSI, metabolically active tumor still extended outside the T2 region in 88% of patients by as many as 28 mm. In addition, T1 suggested a lesser volume and different location of active disease compared to MRSI.The use of MRSI to define target volumes for RT treatment planning would increase, and change the location of, the volume receiving a boost dose as well as reduce the volume receiving a standard dose. Incorporation of MRSI into the treatment-planning process may have the potential to improve control while reducing complications.

  View details for Web of Science ID 000169615100010

  View details for PubMedID 11429219

• Serial proton MR spectroscopic imaging of recurrent malignant gliomas after gamma knife radiosurgery AMERICAN JOURNAL OF NEURORADIOLOGY Graves, E. E., Nelson, S. J., Vigneron, D. B., Verhey, L., McDermott, M., Larson, D., Chang, S., Prados, M. D., Dillon, W. P. 2001; 22 (4): 613-624

  Abstract

  The diagnosis of brain tumors after high-dose radiation therapy is frequently limited by the lack of metabolic discrimination available with conventional imaging methods. The purpose of this study was to use proton MR spectroscopy to investigate serial changes in recurrent malignant gliomas after gamma knife radiosurgery to characterize tissue response to high-dose radiation.Eighteen patients with recurrent gliomas were studied with MR imaging and 3D proton MR spectroscopic imaging at the time of radiosurgery and at regular time points thereafter. Choline (Cho) and N-acetyl aspartate levels were calculated on a voxel-by-voxel basis and compared with levels found in normal tissue and with levels observed at previous time points. The results of the spectral analysis were then compared with the radiologic findings. Statistical comparisons were precluded by the small sample sizes involved.Response within the gamma knife target was observed as a reduction of Cho levels and an increase in lactate/lipid levels, typically within 6 months of treatment. Increases in Cho correlated with poor radiologic response and suggested tumor recurrence, confirmed histologically in six cases. The development of a spectral abnormality preceded a coincident increase in contrast enhancement by 1 to 2 months in nine cases.Proton MR spectroscopic imaging provided diagnostic and monitoring information before and after radiosurgery. Evaluation of metabolic changes with proton MR spectroscopy and structural changes with MR imaging improved tissue discrimination and provided correlation with histologic findings.

  View details for Web of Science ID 000168156800006

  View details for PubMedID 11290467

• A preliminary study of the prognostic value of proton magnetic resonance spectroscopic imaging in gamma knife radiosurgery of recurrent malignant gliomas NEUROSURGERY Graves, E. E., Nelson, S. J., Vigneron, D. B., Chin, C., Verhey, L., McDermott, M., Larson, D., Sneed, P. K., Chang, S., Prados, M. D., Lamborn, K., Dillon, W. P. 2000; 46 (2): 319-326

  Abstract

  The goal of this study was to investigate the use of proton magnetic resonance spectroscopic imaging as a prognostic indicator in gamma knife radiosurgery of recurrent gliomas.Thirty-six patients with recurrent gliomas were studied with proton magnetic resonance spectroscopic imaging at the time of radiosurgery, and with conventional magnetic resonance imaging examinations at regular time intervals until the initiation of a new treatment strategy. Patients were categorized on the basis of their initial spectroscopic results, and their performance was assessed in terms of change in contrast-enhancing volume, time to further treatment, and survival.The trends in the overall population were toward more extensive increase in the percent contrast-enhancing volume, a decreased time to further treatment, and a reduced survival time for patients with more extensive initial metabolic abnormalities. Statistical analysis of the subpopulation of patients with glioblastoma multiforme found a significant increase in relative contrast-enhancing volume (P < 0.01, Wilcoxon signed-rank test), a decrease in time to further treatment (P < 0.01, log-rank test), and a reduction in survival time (P < 0.01, log-rank test) for patients with regions containing tumor-suggestive spectra outside the gamma knife target, compared with patients exhibiting spectral abnormalities restricted to the gamma knife target. Further studies are needed to establish statistical significance for patients with lower-grade lesions and to confirm the results observed in this study.The pretreatment spectroscopic results provided information that was predictive of outcome for this patient pool, both in local control (change in contrast-enhancing volume) and global outcome (time to further treatment and survival). This modality may have an important role in improving the selection, planning, and treatment process for glioma patients.

  View details for Web of Science ID 000085191800028

  View details for PubMedID 10690720

• Gamma Knife Radiosurgery for Primary Brain Tumors LINAC and Gamma Knife Radiosurgery (Germano, I.M., ed.) McDermott MW, Chang SM, Keles GE, Graves EE, Nelson SJ, Larson DA, Berger MS 2000: 189-202
• Magnetic resonance spectroscopy guided integrated boost irradiation for high grade gliomas using IMRT 13th International Conference on the Use of Computers in Radiation Therapy Pirzkall, A., Graves, E., McKnight, T., Larson, D. A., Sneed, P. K., Wara, W. M., Nelson, S. J., Verhey, L. J. SPRINGER-VERLAG BERLIN. 2000: 156–157

  View details for Web of Science ID 000088386600057

• CNN-Based Models for Color Vision and Visual Illusions IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications Zarndy A, Orz_ L, Grawes E, Werblin F 1999; 46: 229-238