Dr. Tamaresis joined the Stanford University School of Medicine in Summer 2012. He earned the Ph.D. in Applied Mathematics from the University of California, Davis and received the M.S. in Statistics from the California State University, East Bay. He has conducted research in computational biology as a postdoctoral scholar at the University of California, Merced and as a biostatistician at the University of California, San Francisco.
As a statistician, Dr. Tamaresis has developed and validated a highly accurate statistical biomarker classifier for gynecologic disease by applying multivariate techniques to a large genomic data set. His statistical consultations have produced data analyses for published research studies and analysis plans for novel research proposals in grant applications. As an applied mathematician, Dr. Tamaresis has created computational biology models and devised numerical methods for their solution. He devised a probabilistic model to study how the number of binding sites on a novel therapeutic molecule affected contact time with cancer cells to advise medical researchers about its design. For his doctoral dissertation, he created and analyzed the first mathematical system model for a mechanosensory network in vascular endothelial cells to investigate the initial stage of atherosclerotic disease.
Post-infusion CAR T-Reg cells identify patients resistant to CD19-CAR therapy
Approximately 60% of patients with large B cell lymphoma treated with chimeric antigen receptor (CAR) T cell therapies targeting CD19 experience disease progression, and neurotoxicity remains a challenge. Biomarkers associated with resistance and toxicity are limited. In this study, single-cell proteomic profiling of circulating CAR T cells in 32 patients treated with CD19-CAR identified that CD4+Helios+ CAR T cells on day 7 after infusion are associated with progressive disease and less severe neurotoxicity. Deep profiling demonstrated that this population is non-clonal and manifests hallmark features of T regulatory (TReg) cells. Validation cohort analysis upheld the link between higher CAR TReg cells with clinical progression and less severe neurotoxicity. A model combining expansion of this subset with lactate dehydrogenase levels, as a surrogate for tumor burden, was superior for predicting durable clinical response compared to models relying on each feature alone. These data credential CAR TReg cell expansion as a novel biomarker of response and toxicity after CAR T cell therapy and raise the prospect that this subset may regulate CAR T cell responses in humans.
View details for DOI 10.1038/s41591-022-01960-7
View details for Web of Science ID 000852940800007
View details for PubMedID 36097223
- A Composite Endpoint for Treatment Benefit According to Patient Preference STATISTICS IN BIOPHARMACEUTICAL RESEARCH 2022
- Mgta-145+Plerixafor Provides GCSFFree Rapid and Reliable Hematopoietic Stem Cell Mobilization for Autologous Stem Cell Transplant in Patients with Multiple Myeloma: A Phase 2 Study AMER SOC HEMATOLOGY. 2021
- Long-Term Outcomes of Patients with Large B-Cell Lymphoma Treated with Standard-of-Care Axicabtagene Ciloleucel: Results from the US Lymphoma CAR-T Cell Consortium AMER SOC HEMATOLOGY. 2021: 3826-+
- Incidence and risk factors associated with bleeding and thrombosis following chimeric antigen receptor T-cell therapy BLOOD ADVANCES 2021; 5 (21): 4465-4475
Development of immunosuppressive myeloid cells to induce tolerance in solid organ and hematopoietic cell transplant recipients.
Replacement of failed organs followed by safe withdrawal of immunosuppressive drugs have long been the goals of organ transplantation. We studied changes in the balance of T and myeloid cells in blood of HLA-matched and -mismatched patients given living donor kidney transplants (KTx) followed by total lymphoid irradiation (TLI), anti-thymocyte globulin (ATG) conditioning, and donor hematopoietic cell transplant (HCT) to induce mixed chimerism and immune tolerance. The clinical trials were based on a conditioning regimen used to establish mixed chimerism and tolerance in mice. In pre-clinical murine studies, there was a profound depletion of T cells and an increase in immunosuppressive, polymorphonuclear (pmn), myeloid derived suppressor cells (MDSCs) in the spleen and blood following transplant. Selective depletion of the pmn-MDSCs in mice abrogated mixed chimerism and tolerance. In our clinical trials, patients given an analogous tolerance conditioning regimen developed similar changes including profound depletion of T cells and a marked increase in MDSCs in blood post-transplant. Post-transplant pmn-MDSCs transiently increased expression of lectin-type, oxidized LDL receptor-1 (LOX-1), a marker of immunosuppression, and production of the T cell inhibitor, arginase-1. These post-transplant pmn-MDSCs suppressed the activation, proliferation, and inflammatory cytokine secretion of autologous, TCR microbead-stimulated, pre-transplant T cells when co-cultured in vitro. In conclusion, we elucidated changes in receptors, and function of immunosuppressive myeloid cells in patients enrolled in the tolerance protocol that were nearly identical to the that of MDSCs required for tolerance in mice. The clinical trials are registered in Clinicaltrials.gov under NCT #s 00319657 and 01165762.
View details for DOI 10.1182/bloodadvances.2020003669
View details for PubMedID 34432869
CAR T cells with dual targeting of CD19 and CD22 in adult patients with recurrent or refractory B cell malignancies: a phase 1 trial.
Despite impressive progress, more than 50% of patients treated with CD19-targeting chimeric antigen receptor T cells (CAR19) experience progressive disease. Ten of 16 patients with large B cell lymphoma (LBCL) with progressive disease after CAR19 treatment had absent or low CD19. Lower surface CD19 density pretreatment was associated with progressive disease. To prevent relapse with CD19- or CD19lo disease, we tested a bispecific CAR targeting CD19 and/or CD22 (CD19-22.BB.z-CAR) in a phase I clinical trial ( NCT03233854 ) of adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) and LBCL. The primary end points were manufacturing feasibility and safety with a secondary efficacy end point. Primary end points were met; 97% of products met protocol-specified dose and no dose-limiting toxicities occurred during dose escalation. In B-ALL (n=17), 100% of patients responded with 88% minimal residual disease-negative complete remission (CR); in LBCL (n=21), 62% of patients responded with 29% CR. Relapses were CD19-/lo in 50% (5 out of 10) of patients with B-ALL and 29% (4 out of 14) of patients with LBCL but were not associated with CD22-/lo disease. CD19/22-CAR products demonstrated reduced cytokine production when stimulated with CD22 versus CD19. Our results further implicate antigen loss as a major cause of CAR T cell resistance, highlight the challenge of engineering multi-specific CAR T cells with equivalent potency across targets and identify cytokine production as an important quality indicator for CAR T cell potency.
View details for DOI 10.1038/s41591-021-01436-0
View details for PubMedID 34312556
GD2 CAR T cells mediate clinical activity and manageable toxicity in children and young adults with DIPG and H3K27M-mutated diffuse midline gliomas.
AMER ASSOC CANCER RESEARCH. 2021
View details for Web of Science ID 000680263501014
Immune reconstitution and infectious complications following axicabtagene ciloleucel therapy for large B-cell lymphoma.
2021; 5 (1): 143-155
Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 has significantly improved outcomes in the treatment of refractory or relapsed large B-cell lymphoma (LBCL). We evaluated the long-term course of hematologic recovery, immune reconstitution, and infectious complications in 41 patients with LBCL treated with axicabtagene ciloleucel (axi-cel) at a single center. Grade 3+ cytopenias occurred in 97.6% of patients within the first 28 days postinfusion, with most resolved by 6 months. Overall, 63.4% of patients received a red blood cell transfusion, 34.1% of patients received a platelet transfusion, 36.6% of patients received IV immunoglobulin, and 51.2% of patients received growth factor (granulocyte colony-stimulating factor) injections beyond the first 28 days postinfusion. Only 40% of patients had recovered detectable CD19+ B cells by 1 year, and 50% of patients had a CD4+ T-cell count <200 cells per μL by 18 months postinfusion. Patients with durable responses to axi-cel had significantly longer durations of B-cell aplasia, and this duration correlated strongly with the recovery of CD4+ T-cell counts. There were significantly more infections within the first 28 days compared with any other period of follow-up, with the majority being mild-moderate in severity. Receipt of corticosteroids was the only factor that predicted risk of infection in a multivariate analysis (hazard ratio, 3.69; 95% confidence interval, 1.18-16.5). Opportunistic infections due to Pneumocystis jirovecii and varicella-zoster virus occurred up to 18 months postinfusion in patients who prematurely discontinued prophylaxis. These results support the use of comprehensive supportive care, including long-term monitoring and antimicrobial prophylaxis, beyond 12 months after axi-cel treatment.
View details for DOI 10.1182/bloodadvances.2020002732
View details for PubMedID 33570626
- Immune reconstitution and infectious complications following axicabtagene ciloleucel therapy for large B-cell lymphoma BLOOD ADVANCES 2021; 5 (1): 143–55
Incidence and Risk Factors Associated with Bleeding and Thrombosis Following Chimeric Antigen Receptor T Cell Therapy.
Bleeding and thrombotic events are an emerging toxicity associated with chimeric antigen receptor (CAR) therapies. To determine their incidence, we retrospectively analyzed consecutive adult patients (n=127) with large B-cell lymphoma (LBCL) or B-cell acute lymphoblastic leukemia (B-ALL) treated between 2017-2020 with axicabtagene ciloleucel (axi-cel) (N=89) or a bispecific CD19/CD22 CAR (N=38). 12 (9.4%) and 8 (6.3%) patients developed bleeding and thrombosis within first 3 months, respectively. In the axi-cel subgroup, these occurred in 11.2% and 6.7%, respectively. Bleeding occurred between days 8-30 (median 17.5), and thrombosis between days 2-91 (median 29). Bleeding sites included genitourinary (N=6), soft tissue (N=2), intracranial (N=2), gastrointestinal (N=1), pulmonary (N=1), and were associated with features of consumptive coagulopathy. On univariate analysis, patients with bleeding were older (median 72 vs. 60 yrs, P<0.01), had lower baseline platelets (86 vs. 178 K/uL, P<0.01), lower platelet nadir after CAR-T (median 17.5 vs. 48 K/uL; P<0.01), lower fibrinogen nadir (median 122 vs. 340 ug/mL; P<0.01) and elevated LDH (P=0.01). ICANS grade ≥3 was associated with increased bleeding (50% vs. 15%; P=0.01), thrombosis (50% vs. 16%; P=0.04), PT prolongation, hypofibrinogenemia and elevated D-dimer. A paucity of events limited multivariate analysis, however low pre-treatment platelets were associated with bleeding in a multivariate logistic regression model. Patients with thrombocytopenia or severe ICANS are at increased risk of bleeding complications and should be closely monitored particularly within the first month after CAR therapy. Future studies in larger cohorts should assess risk factors for systemic coagulopathies in CAR-T therapy, including their association with neurotoxicity.
View details for DOI 10.1182/bloodadvances.2021004716
View details for PubMedID 34521106
- Outcomes of Patients with Large B-cell Lymphoma Progressing after Axicabtagene Ciloleucel. Blood 2020
Analysis of Whole CDR3 TCR Repertoire after Hematopoietic Stem Cell Transplantation in Two Clinical Cohorts.
Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation
A major cause of morbidity and mortality for patients who undergo hematological stem cell transplantations (HSCT) is acute graft-versus-host disease (GVHD), a mostly T cell mediated disease. The examination of the T cell receptor (TCR) repertoire of HSCT patients and through the use of next generation nucleotide sequencing leads to the question of whether features of TCR repertoire reconstitution might reproducibly associate with GVHD.HYPOTHESIS: We hypothesized that the peripheral blood TCR repertoire of patients with steroid non-responsive, acute GVHD would be less diverse. We also hypothesized that patients with GVHD who shared HLA might also share common clones at the time of GVHD diagnosis, thereby potentially providing potential clinical indicators for treatment stratification. We further hypothesized that HSCT recipients with the same HLA mismatch might share a more similar TCR repertoire based on a potentially shared focus of alloreactive responses.METHOD: We studied two separate patient cohorts and two separate platforms to measure TCR repertoire. The first cohort of patients are from a multicenter, phase III, randomized, double-blinded clinical trial of patients who developed acute GVHD (NCT01002742). The second are samples from biobanks from two centers and the CIBMTR of patients who mismatched HSCT.CONCLUSION: There were no statistically significant differences in the TCR diversity of steroid responders and non-responders among patients with acute GVHD on the day of diagnosis. Most clones in the repertoire were unique to each patient, but a small number of clones were found to be both exclusive to, and shared, amongst GVHD non-responders. We were also able to show a strong correlation between the presence of VSS 20 and VSS29 and steroid responsiveness. Using the Bhattacharya coefficient, those patients who shared the same HLA mismatch were shown to be no more similar to one another than to those who had a completely different mismatch. Using two separate clinical cohorts and two separate platforms for analyzing the TCR repertoire, we have shown that the sampled human TCR repertoire is largely unique to each patient but showed glimmers of common clones of subsets of clones based on responsiveness to steroids in aGVHD on the day of diagnosis. These studies are informative for future strategies to assess for reproducible TCR responses in human alloreactivity and possible markers of GVHD responsiveness to therapy.
View details for DOI 10.1016/j.bbmt.2020.01.020
View details for PubMedID 32081787
Mixed chimerism and acceptance of kidney transplants after immunosuppressive drug withdrawal.
Science translational medicine
2020; 12 (528)
Preclinical studies have shown that persistent mixed chimerism is linked to acceptance of organ allografts without immunosuppressive (IS) drugs. Mixed chimerism refers to continued mixing of donor and recipient hematopoietic cells in recipient tissues after transplantation of donor cells. To determine whether persistent mixed chimerism and tolerance can be established in patients undergoing living donor kidney transplantation, we infused allograft recipients with donor T cells and hematopoietic progenitors after posttransplant lymphoid irradiation. In 24 of 29 fully human leukocyte antigen (HLA)-matched patients who had persistent mixed chimerism for at least 6 months, complete IS drug withdrawal was achieved without subsequent evidence of rejection for at least 2 years. In 10 of 22 HLA haplotype-matched patients with persistent mixed chimerism for at least 12 months, reduction of IS drugs to tacrolimus monotherapy was achieved. Withdrawal of tacrolimus during the second year resulted in loss of detectable chimerism and subsequent rejection episodes, unless tacrolimus therapy was reinstituted. Posttransplant immune reconstitution of naïve B cells and B cell precursors was more rapid than the reconstitution of naïve T cells and thymic T cell precursors. Robust chimerism was observed only among naïve T and B cells but not among memory T cells. No evidence of rejection was observed in all surveillance graft biopsies obtained from mixed chimeric patients withdrawn from IS drugs, and none developed graft-versus-host disease. In conclusion, persistent mixed chimerism established in fully HLA- or haplotype-matched patients allowed for complete or partial IS drug withdrawal without rejection.
View details for DOI 10.1126/scitranslmed.aax8863
View details for PubMedID 31996467
CD22-Directed CAR T-Cell Therapy Induces Complete Remissions in CD19-Directed CAR-Refractory Large B-Cell Lymphoma.
The prognosis for patients with large B-cell lymphoma (LBCL) progressing after treatment with chimeric antigen receptor (CAR) T-cell therapy targeting CD19 (CAR19) is poor. We report on the first three consecutive patients with autologous CAR19-refractory LBCL treated with a single infusion of autologous 1×106 CAR+ T-cells/kg targeting CD22 (CAR22) as part of a phase I dose escalation study. CAR22 therapy was relatively well tolerated, without any observed non-hematologic adverse events higher than grade 2. Following infusion, all three patients achieved complete remission, with all responses ongoing at the time of last follow up (mean 7.8 months, range 6-9.3). Circulating CAR22 cells demonstrated robust expansion (peak range 85.4-350 cells/µL), and persisted beyond three months in all patients with continued radiographic responses and corresponding decreases in circulating tumor DNA (ctDNA) beyond six months post-infusion. Further accrual at a higher dose level in this phase 1 dose-escalation study is ongoing and will explore the role of this therapy in patients who have failed prior CAR T-cell therapies. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT04088890).
View details for DOI 10.1182/blood.2020009432
View details for PubMedID 33512414
Recipient-specific T-cell repertoire reconstitution in the gut following murine hematopoietic cell transplant.
2020; 4 (17): 4232–43
Graft-versus-host disease (GVHD) is a complication of hematopoietic cell transplantation (HCT) caused by alloreactive T cells. Murine models of HCT are used to understand GVHD and T-cell reconstitution in GVHD target organs, most notably the gastrointestinal (GI) tract where the disease contributes most to patient mortality. T-cell receptor (TCR) repertoire sequencing was used to measure T-cell reconstitution from the same donor graft (C57BL/6 H-2b) in the GI tract of different recipients across a spectrum of matching, from syngeneic (C57BL/6), to minor histocompatibility (MHC) antigen mismatch BALB.B (H-2b), to major MHC mismatched B10.BR (H-2k) and BALB/c (H-2d). Although the donor T-cell pools had highly similar TCR, the TCR repertoire after HCT was very specific to recipients in each experiment independent of geography. A single invariant natural killer T clone was identifiable in every recipient group and was enriched in syngeneic recipients according to clonal count and confirmatory flow cytometry. Using a novel cluster analysis of the TCR repertoire, we could classify recipient groups based only on their CDR3 size distribution or TCR repertoire relatedness. Using a method for evaluating the contribution of common TCR motifs to relatedness, we found that reproducible sets of clones were associated with specific recipient groups within each experiment and that relatedness did not necessarily depend on the most common clones in allogeneic recipients. This finding suggests that TCR reconstitution is highly stochastic and likely does not depend on the evaluation of the most expanded TCR clones in any individual recipient but instead depends on a complex polyclonal architecture.
View details for DOI 10.1182/bloodadvances.2019000977
View details for PubMedID 32898248
Image-based scaling laws for somatic growth and pulmonary artery morphometry from infant- to adulthood.
American journal of physiology. Heart and circulatory physiology
Pulmonary artery (PA) morphometry has been extensively explored in adults, with particular focus on intra-acinar arteries. However, scaling law relationships for length and diameter of extensive pre-acinar PAs by age have not been previously reported for in vivo human data. To understand pre-acinar PA growth spanning children to adults, we performed morphometric analyses of all PAs visible in the computed tomography (CT) and magnetic resonance (MR) images from a healthy subject cohort (n=16; age: 1-51 years; body surface area, BSA: 0.49-2.01 m2). Subject-specific anatomic PA models were constructed from CT and MR images, and morphometric information - diameter, length, tortuosity, bifurcation angle, and connectivity - was extracted and sorted into diameter-defined Strahler orders. Validation of Murray's law, describing optimal scaling exponents of radii for branching vessels, was performed to determine how closely PAs conform to this classical relationship. Using regression analyses of vessel diameters and lengths against orders and patient metrics (BSA, age, height), we found that diameters increased exponentially with order and allometrically with patient metrics, and length increased allometrically with patient metrics, albeit weakly. The average tortuosity index of all vessels was 0.026 ± 0.024, average bifurcation angle was 28.2º ± 15.1º, and average Murray's law exponent was 2.92 ± 1.07. We report a set of scaling laws for vessel diameter and length, along with other morphometric information. These provide an initial understanding of healthy structural pre-acinar PA development with age, which can be used for computational modeling studies and comparison with diseased PA anatomy.
View details for DOI 10.1152/ajpheart.00123.2020
View details for PubMedID 32618514
Outcomes in large B-cell lymphoma progressing after axicabtagene ciloleucel (Axi-cel): Results from the US Lymphoma CAR-T Consortium.
AMER SOC CLINICAL ONCOLOGY. 2019
View details for Web of Science ID 000487345806279
Nonmyeloablative TLI-ATG conditioning for allogeneic transplantation: mature follow-up from a large single-center cohort.
2019; 3 (16): 2454–64
Nonmyeloablative total lymphoid irradiation and antithymocyte globulin (TLI-ATG) conditioning is protective against graft-versus-host disease (GVHD), while retaining graft-versus-tumor activity across various hematologic malignancies. We report our comprehensive experience using TLI-ATG conditioning in 612 patients with hematologic malignancies who underwent allogeneic transplantation at Stanford University from 2001 to 2016. All patients received granulocyte colony-stimulating factor-mobilized peripheral blood grafts and cyclosporine and mycophenolate mofetil for GVHD prophylaxis. The median age was 60 years (range, 21-78), with a median follow-up of 6.0 years (range, 1.0-16.4). Common diagnoses included acute myeloid leukemia (AML; n = 193), myelodysplastic syndrome (MDS; n = 94), chronic lymphocytic leukemia (CLL; n = 80), non-Hodgkin lymphoma (NHL; n = 175), and Hodgkin lymphoma (HL; n = 35). Thirty-four percent of patients had a comorbidity index ≥3, 30% had a high to very high disease risk index, and 56% received unrelated donor grafts, including 15% with HLA-mismatched donors. Ninety-eight percent underwent transplant in the outpatient setting, and 57% were never hospitalized from days 0 through 100. The 1-year rates of nonrelapse mortality (NRM), grade II-IV acute GVHD, and extensive chronic GVHD were 9%, 14%, and 22%, respectively. The 4-year estimates for overall and progression-free survival were 42% and 32% for AML, 30% and 21% for MDS, 67% and 43% for CLL, 68% and 45% for NHL, and 78% and 49% for HL. Mixed chimerism correlated with the risk of relapse. TLI-ATG conditioning was well tolerated, with low rates of GVHD and NRM. Durable remissions were observed across hematologic malignancies, with particularly favorable outcomes for heavily pretreated lymphomas. Several efforts are underway to augment donor chimerism and reduce relapse rates while maintaining the favorable safety and tolerability profile of this regimen.
View details for DOI 10.1182/bloodadvances.2019000297
View details for PubMedID 31427277
- Nonmyeloablative Allogeneic Transplantation Using TLI-ATG Conditioning for Lymphoid and Myeloid Malignancies: Mature Follow-up from a Large, Single Institution Cohort AMER SOC HEMATOLOGY. 2018
High human herpesvirus 6 viral load in pediatric allogeneic hematopoietic stem cell transplant patients is associated with detection in end organs and high mortality
2018; 22 (2)
Human Herpes Virus 6 (HHV-6) reactivation occurs in approximately half of patients following allogeneic hematopoietic stem cell transplant (HSCT). While encephalitis and delayed engraftment are well-documented complications of HHV-6 following HSCT, the extent to which HHV-6 viremia causes disease in children is controversial. We performed a retrospective review of HHV-6 reactivation and possible manifestations in pediatric allogeneic HSCT patients at a single institution. Of 89 children and young adults who underwent allogeneic HSCT over a three-and-a-half-year period, 34 patients reactivated HHV-6 early post-transplant. Unrelated donor stem cell source and lack of antiviral prophylaxis were risk factors for the development of HHV-6 viremia. Viremia correlated with the presence of acute graft-versus-host disease, but not chronic graft-versus-host disease. We identified two subgroups within the viremic patients-a high-risk viremic and tissue-positive group that reactivated HHV-6 and had suspected end-organ disease and a low-risk viremic but asymptomatic group that reactivated HHV-6 but did not exhibit symptoms or signs of end-organ disease. Peak viral load was found to be strongly associated with mortality. Prospective studies in larger numbers of patients are needed to further investigate the role of HHV-6 in causing symptomatic end-organ disease as well as the association of viral load with mortality.
View details for PubMedID 29181879
View details for PubMedCentralID PMC5820136
Local estrogen axis in the human bone microenvironment regulates estrogen receptor-positive breast cancer cells.
Breast cancer research : BCR
2017; 19 (1): 121
Approximately 70% of all breast cancers express the estrogen receptor, and are regulated by estrogen. While the ovaries are the primary source of estrogen in premenopausal women, most breast cancer is diagnosed following menopause, when systemic levels of this hormone decline. Estrogen production from androgen precursors is catalyzed by the aromatase enzyme. Although aromatase expression and local estrogen production in breast adipose tissue have been implicated in the development of primary breast cancer, the source of estrogen involved in the regulation of estrogen receptor-positive (ER+) metastatic breast cancer progression is less clear.Bone is the most common distant site of breast cancer metastasis, particularly for ER+ breast cancers. We employed a co-culture model using trabecular bone tissues obtained from total hip replacement (THR) surgery specimens to study ER+ and estrogen receptor-negative (ER-) breast cancer cells within the human bone microenvironment. Luciferase-expressing ER+ (MCF-7, T-47D, ZR-75) and ER- (SK-BR-3, MDA-MB-231, MCF-10A) breast cancer cells were cultured directly on bone tissue fragments or in bone tissue-conditioned media, and monitored over time with bioluminescence imaging (BLI). Bone tissue-conditioned media were generated in the presence vs. absence of aromatase inhibitors, and testosterone. Bone tissue fragments were analyzed for aromatase expression by immunohistochemistry.ER+ breast cancer cells were preferentially sustained in co-cultures with bone tissues and bone tissue-conditioned media relative to ER- cells. Bone fragments analyzed by immunohistochemistry revealed expression of the aromatase enzyme. Bone tissue-conditioned media generated in the presence of testosterone had increased estrogen levels and heightened capacity to stimulate ER+ breast cancer cell proliferation. Pretreatment of cultured bone tissues with aromatase inhibitors, which inhibited estrogen production, reduced the capacity of conditioned media to stimulate ER+ cell proliferation.These results suggest that a local estrogen signaling axis regulates ER+ breast cancer cell viability and proliferation within the bone metastatic niche, and that aromatase inhibitors modulate this axis. Although endocrine therapies are highly effective in the treatment of ER+ breast cancer, resistance to these treatments reduces their efficacy. Characterization of estrogen signaling networks within the bone microenvironment will identify new strategies for combating metastatic progression and endocrine resistance.
View details for PubMedID 29141657
View details for PubMedCentralID PMC5688761
Updated analysis: central venous access device infection rates in an expanded cohort of paediatric patients with severe haemophilia receiving prophylactic recombinant tissue plasminogen activator.
2016; 22 (1): 81-86
Central venous access devices (CVADs) are used in the care of paediatric haemophilic patients with difficult peripheral access, but their use is limited by complications such as infection. We previously published our experience with monthly recombinant tissue plasminogen activator (r-tPA) administration to CVADs of haemophilic patients as an intervention for infection prophylaxis, which suggested a 10-fold decrease in infection rate compared to published rates without r-tPA.This study was conducted to assess the CVAD infection rate in an expanded haemophilia cohort receiving r-tPA over an extended period.A retrospective review was performed on patients with haemophilia who received monthly r-tPA to CVADs, with data collected from January 1, 2008 to December 31, 2012. The data were merged with the previously reported data set (collected from June 1, 1998 to December 31, 2007).Over the entire observation period, there were 46 350 CVAD days among 32 patients [26 severe factor VIII (FVIII) deficiency, six severe FIX deficiency]. Eight patients received immune tolerance therapy for inhibitors and 24 patients received prophylactic factor administration. No patients were HIV positive. Three infections were observed, with an overall infection rate of 0.06 infections per 1000 CVAD days.A low CVAD infection rate, similar to that observed in our previous study (0.04 per 1000 CVAD days), was observed in this expanded haemophilia cohort treated with prophylactic r-tPA, supporting the use of monthly r-tPA as CVAD infection prophylaxis in haemophilia patients.
View details for DOI 10.1111/hae.12772
View details for PubMedID 26248602
Breast Cancer Cell Colonization of the Human Bone Marrow Adipose Tissue Niche
2015; 17 (12): 849-861
Bone is a preferred site of breast cancer metastasis, suggesting the presence of tissue-specific features that attract and promote the outgrowth of breast cancer cells. We sought to identify parameters of human bone tissue associated with breast cancer cell osteotropism and colonization in the metastatic niche.Migration and colonization patterns of MDA-MB-231-fLuc-EGFP (luciferase-enhanced green fluorescence protein) and MCF-7-fLuc-EGFP breast cancer cells were studied in co-culture with cancellous bone tissue fragments isolated from 14 hip arthroplasties. Breast cancer cell migration into tissues and toward tissue-conditioned medium was measured in Transwell migration chambers using bioluminescence imaging and analyzed as a function of secreted factors measured by multiplex immunoassay. Patterns of breast cancer cell colonization were evaluated with fluorescence microscopy and immunohistochemistry.Enhanced MDA-MB-231-fLuc-EGFP breast cancer cell migration to bone-conditioned versus control medium was observed in 12/14 specimens (P = .0014) and correlated significantly with increasing levels of the adipokines/cytokines leptin (P = .006) and IL-1β (P = .001) in univariate and multivariate regression analyses. Fluorescence microscopy and immunohistochemistry of fragments underscored the extreme adiposity of adult human bone tissues and revealed extensive breast cancer cell colonization within the marrow adipose tissue compartment.Our results show that breast cancer cells migrate to human bone tissue-conditioned medium in association with increasing levels of leptin and IL-1β, and colonize the bone marrow adipose tissue compartment of cultured fragments. Bone marrow adipose tissue and its molecular signals may be important but understudied components of the breast cancer metastatic niche.
View details for DOI 10.1016/j.neo.2015.11.005
View details for Web of Science ID 000366560300001
View details for PubMedID 26696367
View details for PubMedCentralID PMC4688564
Reading abilities in school-aged preterm children: a review and meta-analysis
DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY
2015; 57 (5): 410-419
Children born preterm (at ≤32wks) are at risk of developing deficits in reading ability. This meta-analysis aims to determine whether or not school-aged preterm children perform worse than those born at term in single-word reading (decoding) and reading comprehension.Electronic databases were searched for studies published between 2000 and 2013, which assessed decoding or reading comprehension performance in English-speaking preterm and term-born children aged between 6 years and 13 years, and born after 1990. Standardized mean differences in decoding and reading comprehension scores were calculated.Nine studies were suitable for analysis of decoding, and five for analysis of reading comprehension. Random-effects meta-analyses showed that children born preterm had significantly lower scores (reported as Cohen's d values [d] with 95% confidence intervals [CIs]) than those born at term for decoding (d=-0.42, 95% CI -0.57 to -0.27, p<0.001) and reading comprehension (d=-0.57, 95% CI -0.68 to -0.46, p<0.001). Meta-regressions showed that lower gestational age was associated with larger differences in decoding (Q=5.92, p=0.02) and reading comprehension (Q=4.69, p=0.03) between preterm and term groups. Differences between groups increased with age for reading comprehension (Q=5.10, p=0.02) and, although not significant, there was also a trend for increased group differences for decoding (Q=3.44, p=0.06).Preterm children perform worse than peers born at term on decoding and reading comprehension. These findings suggest that preterm children should receive more ongoing monitoring for reading difficulties throughout their education.
View details for DOI 10.1111/dmcn.12652
View details for Web of Science ID 000352819600010
View details for PubMedID 25516105
- A Randomized Clinical Trial of Therapeutic Hypothermia Mode during Transport for Neonatal Encephalopathy. journal of pediatrics 2015; 166 (4): 856-861 e2
A randomized clinical trial of therapeutic hypothermia mode during transport for neonatal encephalopathy.
journal of pediatrics
2015; 166 (4): 856-61 e1 2
To determine if temperature regulation is improved during neonatal transport using a servo-regulated cooling device when compared with standard practice.We performed a multicenter, randomized, nonmasked clinical trial in newborns with neonatal encephalopathy cooled during transport to 9 neonatal intensive care units in California. Newborns who met institutional criteria for therapeutic hypothermia were randomly assigned to receive cooling according to usual center practices vs device servo-regulated cooling. The primary outcome was the percentage of temperatures in target range (33°-34°C) during transport. Secondary outcomes included percentage of newborns reaching target temperature any time during transport, time to target temperature, and percentage of newborns in target range 1 hour after cooling initiation.One hundred newborns were enrolled: 49 to control arm and 51 to device arm. Baseline demographics did not differ with the exception of cord pH. For each subject, the percentage of temperatures in the target range was calculated. Infants cooled using the device had a higher percentage of temperatures in target range compared with control infants (median 73% [IQR 17-88] vs 0% [IQR 0-52], P < .001). More subjects reached target temperature during transport using the servo-regulated device (80% vs 49%, P <.001), and in a shorter time period (44 ± 31 minutes vs 63 ± 37 minutes, P = .04). Device-cooled infants reached target temperature by 1 hour with greater frequency than control infants (71% vs 20%, P < .001).Cooling using a servo-regulated device provides more predictable temperature management during neonatal transport than does usual care for outborn newborns with neonatal encephalopathy.
View details for DOI 10.1016/j.jpeds.2014.12.061
View details for PubMedID 25684087
Regional variation in antenatal corticosteroid use: a network-level quality improvement study.
2015; 135 (2): e397-404
Examination of regional care patterns in antenatal corticosteroid use (ACU) rates may be salient for the development of targeted interventions. Our objective was to assess network-level variation using California perinatal care regions as a proxy. We hypothesized that (1) significant variation in ACU exists within and between California perinatal care regions, and (2) lower performing regions exhibit greater NICU-level variability in ACU than higher performing regions.We undertook cross-sectional analysis of 33 610 very low birth weight infants cared for at 120 hospitals in 11 California perinatal care regions from 2005 to 2011. We computed risk-adjusted median ACU rates and interquartile ranges (IQR) for each perinatal care region. The degree of variation was assessed using hierarchical multivariate regression analysis with NICU as a random effect and region as a fixed effect.From 2005 to 2011, mean ACU rates across California increased from 82% to 87.9%. Regional median (IQR) ACU rates ranged from 68.4% (24.3) to 92.9% (4.8). We found significant variation in ACU rates among regions (P < .0001). Compared with Level IV NICUs, care in a lower level of care was a strongly significant predictor of lower odds of receiving antenatal corticosteroids in a multilevel model (Level III, 0.65 [0.45-0.95]; Level II, 0.39 [0.24-0.64]; P < .001). Regions with lower performance in ACU exhibited greater variability in performance.We found significant variation in ACU rates among California perinatal regions. Regional quality improvement approaches may offer a new avenue to spread best practice.
View details for DOI 10.1542/peds.2014-2177
View details for PubMedID 25601974
Molecular Classification of Endometriosis and Disease Stage Using High-Dimensional Genomic Data
2014; 155 (12): 4986-4999
Endometriosis (E), an estrogen-dependent, progesterone-resistant, inflammatory disorder, affects 10% of reproductive-age women. It is diagnosed and staged at surgery, resulting in an 11-year latency from symptom onset to diagnosis, underscoring the need for less invasive, less expensive approaches. Because the uterine lining (endometrium) in women with E has altered molecular profiles, we tested whether molecular classification of this tissue can distinguish and stage disease. We developed classifiers using genomic data from n = 148 archived endometrial samples from women with E or without E (normal controls or with other common uterine/pelvic pathologies) across the menstrual cycle and evaluated their performance on independent sample sets. Classifiers were trained separately on samples in specific hormonal milieu, using margin tree classification, and accuracies were scored on independent validation samples. Classification of samples from women with E or no E involved 2 binary decisions, each based on expression of specific genes. These first distinguished presence or absence of uterine/pelvic pathology and then no E from E, with the latter further classified according to severity (minimal/mild or moderate/severe). Best performing classifiers identified E with 90%-100% accuracy, were cycle phase-specific or independent, and used relatively few genes to determine disease and severity. Differential gene expression and pathway analyses revealed immune activation, altered steroid and thyroid hormone signaling/metabolism, and growth factor signaling in endometrium of women with E. Similar findings were observed with other disorders vs controls. Thus, classifier analysis of genomic data from endometrium can detect and stage pelvic E with high accuracy, dependent or independent of hormonal milieu. We propose that limited classifier candidate genes are of high value in developing diagnostics and identifying therapeutic targets. Discovery of endometrial molecular differences in the presence of E and other uterine/pelvic pathologies raises the broader biological question of their impact on the steroid hormone response and normal functions of this tissue.
View details for DOI 10.1210/en.2014-1490
View details for Web of Science ID 000346668000036
View details for PubMedID 25243856
View details for PubMedCentralID PMC4239429
Coculturing human endometrial epithelial cells and stromal fibroblasts alters cell-specific gene expression and cytokine production
FERTILITY AND STERILITY
2013; 100 (4): 1132-1143
To determine the effects of coculturing endometrial epithelial cells (eEC) with paired endometrial stromal fibroblasts (eSF) on cell-specific gene expression and cytokine secretion patterns.In vitro study.University research laboratory.Endometrial biopsies were obtained from premenopausal women.Polarized eEC and subject-paired eSF were cultured for 12.5 hours alone (monoculture) or combined in a two-chamber coculture system without cell-cell contact. Cells and conditioned media were analyzed for global gene expression and cytokine secretion, respectively. Purified, endometrial tissue-derived eEC and eSF isolated by fluorescent activated cell sorting (FACS) were used as noncultured controls.Cell-specific global gene expression profiling and analysis of secreted cytokines in eEC/eSF cocultures and respective monocultures.Transepithelial resistance, diffusible tracer exclusion, expression of tight junction proteins, and apical/basolateral vectorial secretion confirmed eEC structural and functional polarization. Distinct transcriptomes of eEC and eSF were consistent with their respective lineages and their endometrial origin. Coculture of eEC with eSF resulted in altered cell-specific gene expression and cytokine secretion.This coculture model provides evidence that interactions between endometrial functionally polarized epithelium and stromal fibroblasts affect cell-specific gene expression and cytokine secretion underscoring their relevance when modeling endometrium in vitro.
View details for DOI 10.1016/j.fertnstert.2013.06.007
View details for Web of Science ID 000324995200053
View details for PubMedID 23849844
View details for PubMedCentralID PMC3820417
Molecular probe technology detects bacteria without culture
Our ultimate goal is to detect the entire human microbiome, in health and in disease, in a single reaction tube, and employing only commercially available reagents. To that end, we adapted molecular inversion probes to detect bacteria using solely a massively multiplex molecular technology. This molecular probe technology does not require growth of the bacteria in culture. Rather, the molecular probe technology requires only a sequence of forty sequential bases unique to the genome of the bacterium of interest. In this communication, we report the first results of employing our molecular probes to detect bacteria in clinical samples.While the assay on Affymetrix GenFlex Tag16K arrays allows the multiplexing of the detection of the bacteria in each clinical sample, one Affymetrix GenFlex Tag16K array must be used for each clinical sample. To multiplex the clinical samples, we introduce a second, independent assay for the molecular probes employing Sequencing by Oligonucleotide Ligation and Detection. By adding one unique oligonucleotide barcode for each clinical sample, we combine the samples after processing, but before sequencing, and sequence them together.Overall, we have employed 192 molecular probes representing 40 bacteria to detect the bacteria in twenty-one vaginal swabs as assessed by the Affymetrix GenFlex Tag16K assay and fourteen of those by the Sequencing by Oligonucleotide Ligation and Detection assay. The correlations among the assays were excellent.
View details for DOI 10.1186/1471-2180-12-29
View details for PubMedID 22404909
Perivascular Human Endometrial Mesenchymal Stem Cells Express Pathways Relevant to Self-Renewal, Lineage Specification, and Functional Phenotype
BIOLOGY OF REPRODUCTION
2012; 86 (2)
Human endometrium regenerates on a cyclic basis from candidate stem/progenitors whose genetic programs are yet to be determined. A subpopulation of endometrial stromal cells, displaying key properties of mesenchymal stem cells (MSCs), has been characterized. The endometrial MSC (eMSC) is likely the precursor of the endometrial stromal fibroblast. The goal of this study was to determine the transcriptome and signaling pathways in the eMSC to understand its functional phenotype. Endometrial stromal cells from oocyte donors (n = 20) and patients undergoing benign gynecologic surgery (n = 7) were fluorescence-activated cell sorted into MCAM (CD146)(+)/PDGFRB(+) (eMSC), MCAM (CD146)(-)/PDGFRB(+) (fibroblast), and MCAM (CD146)(+)/PDGFRB(-) (endothelial) populations. The eMSC population contained clonogenic cells with a mesenchymal phenotype differentiating into adipocytes when cultured in adipogenic medium. Gene expression profiling using Affymetrix Human Gene 1.0 ST arrays revealed 762 and 1518 significantly differentially expressed genes in eMSCs vs. stromal fibroblasts and eMSCs vs. endothelial cells, respectively. By principal component and hierarchical clustering analyses, eMSCs clustered with fibroblasts and distinctly from endothelial cells. Endometrial MSCs expressed pericyte markers and were localized by immunofluorescence to the perivascular space of endometrial small vessels. Endometrial MSCs also expressed genes involved in angiogenesis/vasculogenesis, steroid hormone/hypoxia responses, inflammation, immunomodulation, cell communication, and proteolysis/inhibition, and exhibited increased Notch, TGFB, IGF, Hedgehog, and G-protein-coupled receptor signaling pathways, characteristic of adult tissue MSC self-renewal and multipotency. Overall, the data support the eMSC as a clonogenic, multipotent pericyte that displays pathways of self-renewal and lineage specification, the potential to respond to conditions during endometrial desquamation and regeneration, and a genetic program predictive of its differentiated lineage, the stromal fibroblast.
View details for DOI 10.1095/biolreprod.111.095885
View details for Web of Science ID 000301341500017
View details for PubMedID 22075475
View details for PubMedCentralID PMC3290674
A model for shear stress sensing and transmission in vascular endothelial cells
2003; 84 (6): 4087-4101
Arterial endothelial cell (EC) responsiveness to flow is essential for normal vascular function and plays a role in the development of atherosclerosis. EC flow responses may involve sensing of the mechanical stimulus at the cell surface with subsequent transmission via cytoskeleton to intracellular transduction sites. We had previously modeled flow-induced deformation of EC-surface flow sensors represented as viscoelastic materials with standard linear solid behavior (Kelvin bodies). In the present article, we extend the analysis to arbitrary networks of viscoelastic structures connected in series and/or parallel. Application of the model to a system of two Kelvin bodies in parallel reveals that flow induces an instantaneous deformation followed by creeping to the asymptotic response. The force divides equally between the two bodies when they have identical viscoelastic properties. When one body is stiffer than the other, a larger fraction of the applied force is directed to the stiffer body. We have also probed the impact of steady and oscillatory flow on simple sensor-cytoskeleton-nucleus networks. The results demonstrated that, consistent with the experimentally observed temporal chronology of EC flow responses, the flow sensor attains its peak deformation faster than intracellular structures and the nucleus deforms more rapidly than cytoskeletal elements. The results have also revealed that a 1-Hz oscillatory flow induces significantly smaller deformations than steady flow. These results may provide insight into the mechanisms behind the experimental observations that a number of EC responses induced by steady flow are not induced by oscillatory flow.
View details for Web of Science ID 000183129800052
View details for PubMedID 12770912
View details for PubMedCentralID PMC1302988