Publications by authors named "Robert M Prins"

64 Publications

Unique challenges for glioblastoma immunotherapy-discussions across neuro-oncology and non-neuro-oncology experts in cancer immunology. Meeting Report from the 2019 SNO Immuno-Oncology Think Tank.

Neuro Oncol 2021 Mar;23(3):356-375

Department of Neurological Surgery, UCSF, San Francisco, California.

Cancer immunotherapy has made remarkable advances with over 50 separate Food and Drug Administration (FDA) approvals as first- or second-line indications since 2015. These include immune checkpoint blocking antibodies, chimeric antigen receptor-transduced T cells, and bispecific T-cell-engaging antibodies. While multiple cancer types now benefit from these immunotherapies, notable exceptions thus far include brain tumors, such as glioblastoma. As such, it seems critical to gain a better understanding of unique mechanistic challenges underlying the resistance of malignant gliomas to immunotherapy, as well as to acquire insights into the development of future strategies. An Immuno-Oncology Think Tank Meeting was held during the 2019 Annual Society for Neuro-Oncology Scientific Conference. Discussants in the fields of neuro-oncology, neurosurgery, neuro-imaging, medical oncology, and cancer immunology participated in the meeting. Sessions focused on topics such as the tumor microenvironment, myeloid cells, T-cell dysfunction, cellular engineering, and translational aspects that are critical and unique challenges inherent with primary brain tumors. In this review, we summarize the discussions and the key messages from the meeting, which may potentially serve as a basis for advancing the field of immune neuro-oncology in a collaborative manner.
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http://dx.doi.org/10.1093/neuonc/noaa277DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7992879PMC
March 2021

Emerging immunotherapies for malignant glioma: from immunogenomics to cell therapy.

Neuro Oncol 2020 10;22(10):1425-1438

Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois.

As immunotherapy assumes a central role in the management of many cancers, ongoing work is directed at understanding whether immune-based treatments will be successful in patients with glioblastoma (GBM). Despite several large studies conducted in the last several years, there remain no FDA-approved immunotherapies in this patient population. Nevertheless, there are a range of exciting new approaches being applied to GBM, all of which may not only allow us to develop new treatments but also help us understand fundamental features of the immune response in the central nervous system. In this review, we summarize new developments in the application of immune checkpoint blockade, from biomarker-driven patient selection to the timing of treatment. Moreover, we summarize novel work in personalized immune-oncology by reviewing work in cancer immunogenomics-driven neoantigen vaccine studies. Finally, we discuss cell therapy efforts by reviewing the current state of chimeric antigen receptor T-cell therapy.
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http://dx.doi.org/10.1093/neuonc/noaa154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7686464PMC
October 2020

Advanced Age Increases Immunosuppression in the Brain and Decreases Immunotherapeutic Efficacy in Subjects with Glioblastoma.

Clin Cancer Res 2020 Oct 16;26(19):5232-5245. Epub 2020 Jun 16.

Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois.

Purpose: Wild-type isocitrate dehydrogenase-expressing glioblastoma (GBM) is the most common and aggressive primary brain tumor with a median age at diagnosis of ≥65 years. It accounts for approximately 90% of all GBMs and has a median overall survival (OS) of <15 months. Although immune checkpoint blockade (ICB) therapy has achieved remarkable survival benefits in a variety of aggressive malignancies, similar success has yet to be achieved for GBM among phase III clinical trials to date. Our study aimed to understand the relationship between subject age and immunotherapeutic efficacy as it relates to survival from glioma.

Experimental Design: (i) Clinical data: GBM patient datasets from The Cancer Genome Atlas, Northwestern Medicine Enterprise Data Warehouse, and clinical studies evaluating ICB were stratified by age and compared for OS. (ii) Animal models: young, middle-aged, and older adult wild-type and indoleamine 2,3 dioxygenase (IDO)-knockout syngeneic mice were intracranially engrafted with CT-2A or GL261 glioma cell lines and treated with or without CTLA-4/PD-L1 mAbs, or radiation, anti-PD-1 mAb, and/or a pharmacologic IDO enzyme inhibitor.

Results: Advanced age was associated with decreased GBM patient survival regardless of treatment with ICB. The advanced age-associated increase of brain IDO expression was linked to the suppression of immunotherapeutic efficacy and was not reversed by IDO enzyme inhibitor treatment.

Conclusions: Immunosuppression increases in the brain during advanced age and inhibits antiglioma immunity in older adults. Going forward, it will be important to fully understand the factors and mechanisms in the elderly brain that contribute to the decreased survival of older patients with GBM during treatment with ICB.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-3874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7541490PMC
October 2020

Metabolic characterization of human IDH mutant and wild type gliomas using simultaneous pH- and oxygen-sensitive molecular MRI.

Neuro Oncol 2019 09;21(9):1184-1196

UCLA Brain Tumor Imaging Laboratory, Center for Computer Vision and Imaging Biomarkers, University of California Los Angeles, Los Angeles, California.

Background: Isocitrate dehydrogenase 1 (IDH1) mutant gliomas are thought to have distinct metabolic characteristics, including a blunted response to hypoxia and lower glycolytic flux. We hypothesized that non-invasive quantification of abnormal metabolic behavior in human IDH1 mutant gliomas could be performed using a new pH- and oxygen-sensitive molecular MRI technique.

Methods: Simultaneous pH- and oxygen-sensitive MRI was obtained at 3T using amine CEST-SAGE-EPI. The pH-dependent measure of the magnetization transfer ratio asymmetry (MTRasym) at 3 ppm and oxygen-sensitive measure of R2' were quantified in 90 patients with gliomas. Additionally, stereotactic, image-guided biopsies were performed in 20 patients for a total of 52 samples. The association between imaging measurements and hypoxia-inducible factor 1 alpha (HIF1α) expression was identified using Pearson correlation analysis.

Results: IDH1 mutant gliomas exhibited significantly lower MTRasym at 3 ppm, R2', and MTRasymxR2' (P = 0.007, P = 0.003, and P = 0.001, respectively). MTRasymxR2' could identify IDH1 mutant gliomas with a high sensitivity (81.0%) and specificity (81.3%). HIF1α was positively correlated with MTRasym at 3 ppm, R2' and MTRasymxR2' in IDH1 wild type (r = 0.610, P = 0.003; r = 0.667, P = 0.008; r = 0.635, P = 0.006), but only MTRasymxR2' in IDH1 mutant gliomas (r = 0.727, P = 0.039).

Conclusions: IDH1 mutant gliomas have distinct metabolic and microenvironment characteristics compared with wild type gliomas. An imaging biomarker combining tumor acidity and hypoxia (MTRasymxR2') can differentiate IDH1 mutation status and is correlated with tumor acidity and hypoxia.
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http://dx.doi.org/10.1093/neuonc/noz078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594567PMC
September 2019

Validation of vessel size imaging (VSI) in high-grade human gliomas using magnetic resonance imaging, image-guided biopsies, and quantitative immunohistochemistry.

Sci Rep 2019 02 26;9(1):2846. Epub 2019 Feb 26.

UCLA Brain Tumor Imaging Laboratory (BTIL), Center for Computer Vision and Imaging Biomarkers, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.

To evaluate the association between a vessel size index (VSI) derived from dynamic susceptibility contrast (DSC) perfusion imaging using a custom spin-and-gradient echo echoplanar imaging (SAGE-EPI) sequence and quantitative estimates of vessel morphometry based on immunohistochemistry from image-guided biopsy samples. The current study evaluated both relative cerebral blood volume (rCBV) and VSI in eleven patients with high-grade glioma (7 WHO grade III and 4 WHO grade IV). Following 26 MRI-guided glioma biopsies in these 11 patients, we evaluated tissue morphometry, including vessel density and average radius, using an automated procedure based on the endothelial cell marker CD31 to highlight tumor vasculature. Measures of rCBV and VSI were then compared to histological measures. We demonstrate good agreement between VSI measured by MRI and histology; VSI = 13.67 μm and VSI = 12.60 μm, with slight overestimation of VSI in grade III patients compared to histology. rCBV showed a moderate but significant correlation with vessel density (r = 0.42, p = 0.03), and a correlation was also observed between VSI and VSI (r = 0.49, p = 0.01). The current study supports the hypothesis that vessel size measures using MRI accurately reflect vessel caliber within high-grade gliomas, while traditional measures of rCBV are correlated with vessel density and not vessel caliber.
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http://dx.doi.org/10.1038/s41598-018-37564-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391482PMC
February 2019

Evidence for Innate and Adaptive Immune Responses in a Cohort of Intractable Pediatric Epilepsy Surgery Patients.

Front Immunol 2019 29;10:121. Epub 2019 Jan 29.

Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.

Brain-infiltrating lymphocytes (BILs) were isolated from resected brain tissue from 10 pediatric epilepsy patients who had undergone surgery for Hemimegalencephaly (HME) ( = 1), Tuberous sclerosis complex (TSC) ( = 2), Focal cortical dysplasia (FCD) ( = 4), and Rasmussen encephalitis (RE) ( = 3). Peripheral blood mononuclear cells (PBMCs) were also isolated from blood collected at the time of the surgery. Cells were immunostained with a panel of 20 antibody markers, and analyzed by mass cytometry. To identify and quantify the immune cell types in the samples, an unbiased clustering method was applied to the entire data set. More than 85 percent of the CD45 cells isolated from resected RE brain tissue comprised T cells; by contrast NK cells and myeloid cells constituted 80-95 percent of the CD45 cells isolated from the TSC and the FCD brain specimens. Three populations of myeloid cells made up >50 percent of all of the myeloid cells in all of the samples of which a population of HLA-DR CD11b CD4 cells comprised the vast majority of myeloid cells in the BIL fractions from the FCD and TSC cases. CD45RA HLA-DR CD11b CD16 NK cells constituted the major population of NK cells in the blood from all of the cases. This subset also comprised the majority of NK cells in BILs from the resected RE and HME brain tissue, whereas NK cells defined as CD45RA HLA-DR CD11b CD16 cells comprised 86-96 percent of the NK cells isolated from the FCD and TSC brain tissue. Thirteen different subsets of CD4 and CD8 αβ T cells and γδ T cells accounted for over 80% of the CD3 T cells in all of the BIL and PBMC samples. At least 90 percent of the T cells in the RE BILs, 80 percent of the T cells in the HME BILs and 40-66 percent in the TSC and FCD BILs comprised activated antigen-experienced (CD45RO HLA-DR CD69) T cells. We conclude that even in cases where there is no evidence for an infection or an immune disorder, activated peripheral immune cells may be present in epileptogenic areas of the brain, possibly in response to seizure-driven brain inflammation.
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http://dx.doi.org/10.3389/fimmu.2019.00121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362260PMC
January 2020

Neoadjuvant anti-PD-1 immunotherapy promotes a survival benefit with intratumoral and systemic immune responses in recurrent glioblastoma.

Nat Med 2019 03 11;25(3):477-486. Epub 2019 Feb 11.

Department of Medical and Molecular Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.

Glioblastoma is the most common primary malignant brain tumor in adults and is associated with poor survival. The Ivy Foundation Early Phase Clinical Trials Consortium conducted a randomized, multi-institution clinical trial to evaluate immune responses and survival following neoadjuvant and/or adjuvant therapy with pembrolizumab in 35 patients with recurrent, surgically resectable glioblastoma. Patients who were randomized to receive neoadjuvant pembrolizumab, with continued adjuvant therapy following surgery, had significantly extended overall survival compared to patients that were randomized to receive adjuvant, post-surgical programmed cell death protein 1 (PD-1) blockade alone. Neoadjuvant PD-1 blockade was associated with upregulation of T cell- and interferon-γ-related gene expression, but downregulation of cell-cycle-related gene expression within the tumor, which was not seen in patients that received adjuvant therapy alone. Focal induction of programmed death-ligand 1 in the tumor microenvironment, enhanced clonal expansion of T cells, decreased PD-1 expression on peripheral blood T cells and a decreasing monocytic population was observed more frequently in the neoadjuvant group than in patients treated only in the adjuvant setting. These findings suggest that the neoadjuvant administration of PD-1 blockade enhances both the local and systemic antitumor immune response and may represent a more efficacious approach to the treatment of this uniformly lethal brain tumor.
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http://dx.doi.org/10.1038/s41591-018-0337-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6408961PMC
March 2019

Expression of PD-1 by T Cells in Malignant Glioma Patients Reflects Exhaustion and Activation.

Clin Cancer Res 2019 03 29;25(6):1913-1922. Epub 2018 Nov 29.

Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, University of California Los Angeles, Los Angeles, California.

Purpose: Glioblastoma (GBM) is the most common primary malignant tumor in the central nervous system. Our recent preclinical work has suggested that PD-1/PD-L1 plays an important immunoregulatory role to limit effective antitumor T-cell responses induced by active immunotherapy. However, little is known about the functional role that PD-1 plays on human T lymphocytes in patients with malignant glioma. In this study, we examined the immune landscape and function of PD-1 expression by T cells from tumor and peripheral blood in patients with malignant glioma.

Results: We found several differences between PD-1 tumor-infiltrating lymphocytes (TIL) and patient-matched PD-1 peripheral blood T lymphocytes. Phenotypically, PD-1 TILs exhibited higher expression of markers of activation and exhaustion than peripheral blood PD-1 T cells, which instead had increased markers of memory. A comparison of the T-cell receptor variable chain populations revealed decreased diversity in T cells that expressed PD-1, regardless of the location obtained. Functionally, peripheral blood PD-1 T cells had a significantly increased proliferative capacity upon activation compared with PD-1 T cells.

Conclusions: Our evidence suggests that PD-1 expression in patients with glioma reflects chronically activated effector T cells that display hallmarks of memory and exhaustion depending on its anatomic location. The decreased diversity in PD-1 T cells suggests that the PD-1-expressing population has a narrower range of cognate antigen targets compared with the PD-1 nonexpression population. This information can be used to inform how we interpret immune responses to PD-1-blocking therapies or other immunotherapies.
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http://dx.doi.org/10.1158/1078-0432.CCR-18-1176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6420851PMC
March 2019

Cytokines Produced by Dendritic Cells Administered Intratumorally Correlate with Clinical Outcome in Patients with Diverse Cancers.

Clin Cancer Res 2018 08 17;24(16):3845-3856. Epub 2018 Jul 17.

Northwest Biotherapeutics, Inc., Bethesda, Maryland.

Dendritic cells (DC) initiate adaptive immune responses through the uptake and presentation of antigenic material. In preclinical studies, intratumorally injected activated DCs (aDCs; DCVax-Direct) were superior to immature DCs in rejecting tumors from mice. This single-arm, open-label phase I clinical trial evaluated the safety and efficacy of aDCs, administered intratumorally, in patients with solid tumors. Three dose levels (2 million, 6 million, and 15 million aDCs per injection) were tested using a standard 3 + 3 dose-escalation trial design. Feasibility, immunogenicity, changes to the tumor microenvironment after direct injection, and survival were evaluated. We also investigated cytokine production of aDCs prior to injection. In total, 39 of the 40 enrolled patients were evaluable. The injections of aDCs were well tolerated with no dose-limiting toxicities. Increased lymphocyte infiltration was observed in 54% of assessed patients. Stable disease (SD; best response) at week 8 was associated with increased overall survival. Increased secretion of interleukin (IL)-8 and IL12p40 by aDCs was significantly associated with survival ( = 0.023 and 0.024, respectively). Increased TNFα levels correlated positively with SD at week 8 ( < 0.01). Intratumoral aDC injections were feasible and safe. Increased production of specific cytokines was correlated with SD and prolonged survival, demonstrating a link between the functional profile of aDCs prior to injection and patient outcomes. .
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http://dx.doi.org/10.1158/1078-0432.CCR-17-2707DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449174PMC
August 2018

Correction to: First results on survival from a large Phase 3 clinical trial of an autologous dendritic cell vaccine in newly diagnosed glioblastoma.

J Transl Med 2018 06 29;16(1):179. Epub 2018 Jun 29.

Northwest Biotherapeutics Inc., Bethesda, MD, USA.

Following publication of the original article [1], the authors reported an error in the spelling of one of the author names. In this Correction the incorrect and correct author names are indicated and the author name has been updated in the original publication. The authors also reported an error in the Methods section of the original article. In this Correction the incorrect and correct versions of the affected sentence are indicated. The original article has not been updated with regards to the error in the Methods section.
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http://dx.doi.org/10.1186/s12967-018-1552-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6026340PMC
June 2018

First results on survival from a large Phase 3 clinical trial of an autologous dendritic cell vaccine in newly diagnosed glioblastoma.

J Transl Med 2018 05 29;16(1):142. Epub 2018 May 29.

Northwest Biotherapeutics Inc., Bethesda, MD, USA.

Background: Standard therapy for glioblastoma includes surgery, radiotherapy, and temozolomide. This Phase 3 trial evaluates the addition of an autologous tumor lysate-pulsed dendritic cell vaccine (DCVax-L) to standard therapy for newly diagnosed glioblastoma.

Methods: After surgery and chemoradiotherapy, patients were randomized (2:1) to receive temozolomide plus DCVax-L (n = 232) or temozolomide and placebo (n = 99). Following recurrence, all patients were allowed to receive DCVax-L, without unblinding. The primary endpoint was progression free survival (PFS); the secondary endpoint was overall survival (OS).

Results: For the intent-to-treat (ITT) population (n = 331), median OS (mOS) was 23.1 months from surgery. Because of the cross-over trial design, nearly 90% of the ITT population received DCVax-L. For patients with methylated MGMT (n = 131), mOS was 34.7 months from surgery, with a 3-year survival of 46.4%. As of this analysis, 223 patients are ≥ 30 months past their surgery date; 67 of these (30.0%) have lived ≥ 30 months and have a Kaplan-Meier (KM)-derived mOS of 46.5 months. 182 patients are ≥ 36 months past surgery; 44 of these (24.2%) have lived ≥ 36 months and have a KM-derived mOS of 88.2 months. A population of extended survivors (n = 100) with mOS of 40.5 months, not explained by known prognostic factors, will be analyzed further. Only 2.1% of ITT patients (n = 7) had a grade 3 or 4 adverse event that was deemed at least possibly related to the vaccine. Overall adverse events with DCVax were comparable to standard therapy alone.

Conclusions: Addition of DCVax-L to standard therapy is feasible and safe in glioblastoma patients, and may extend survival. Trial registration Funded by Northwest Biotherapeutics; Clinicaltrials.gov number: NCT00045968; https://clinicaltrials.gov/ct2/show/NCT00045968?term=NCT00045968&rank=1 ; initially registered 19 September 2002.
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http://dx.doi.org/10.1186/s12967-018-1507-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5975654PMC
May 2018

Metabolic characterization of isocitrate dehydrogenase (IDH) mutant and IDH wildtype gliomaspheres uncovers cell type-specific vulnerabilities.

Cancer Metab 2018 17;6. Epub 2018 Apr 17.

2Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, Room 379 Neuroscience Research Building, 635 Charles E. Young Dr. South, Los Angeles, CA 90095 USA.

Background: There is considerable interest in defining the metabolic abnormalities of IDH mutant tumors to exploit for therapy. While most studies have attempted to discern function by using cell lines transduced with exogenous IDH mutant enzyme, in this study, we perform unbiased metabolomics to discover metabolic differences between a cohort of patient-derived IDH1 mutant and IDH wildtype gliomaspheres.

Methods: Using both our own microarray and the TCGA datasets, we performed KEGG analysis to define pathways differentially enriched in IDH1 mutant and IDH wildtype cells and tumors. Liquid chromatography coupled to mass spectrometry analysis with labeled glucose and deoxycytidine tracers was used to determine differences in overall cellular metabolism and nucleotide synthesis. Radiation-induced DNA damage and repair capacity was assessed using a comet assay. Differences between endogenous IDH1 mutant metabolism and that of IDH wildtype cells transduced with the IDH1 (R132H) mutation were also investigated.

Results: Our KEGG analysis revealed that IDH wildtype cells were enriched for pathways involved in de novo nucleotide synthesis, while IDH1 mutant cells were enriched for pathways involved in DNA repair. LC-MS analysis with fully labeled C-glucose revealed distinct labeling patterns between IDH1 mutant and wildtype cells. Additional LC-MS tracing experiments confirmed increased de novo nucleotide synthesis in IDH wildtype cells relative to IDH1 mutant cells. Endogenous IDH1 mutant cultures incurred less DNA damage than IDH wildtype cultures and sustained better overall growth following X-ray radiation. Overexpression of mutant IDH1 in a wildtype line did not reproduce the range of metabolic differences observed in lines expressing endogenous mutations, but resulted in depletion of glutamine and TCA cycle intermediates, an increase in DNA damage following radiation, and a rise in intracellular ROS.

Conclusions: These results demonstrate that IDH1 mutant and IDH wildtype cells are easily distinguishable metabolically by analyzing expression profiles and glucose consumption. Our results also highlight important differences in nucleotide synthesis utilization and DNA repair capacity that could be exploited for therapy. Altogether, this study demonstrates that IDH1 mutant gliomas are a distinct subclass of glioma with a less malignant, but also therapy-resistant, metabolic profile that will likely require distinct modes of therapy.
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http://dx.doi.org/10.1186/s40170-018-0177-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5905129PMC
April 2018

Precision Medicine in Pediatric Neurooncology: A Review.

ACS Chem Neurosci 2018 01 27;9(1):11-28. Epub 2017 Dec 27.

California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients' tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.
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http://dx.doi.org/10.1021/acschemneuro.7b00388DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6656379PMC
January 2018

Tissue microarray analysis for epithelial membrane protein-2 as a novel biomarker for gliomas.

Brain Tumor Pathol 2018 Jan 8;35(1):1-9. Epub 2017 Sep 8.

Department of Neurosurgery, University of California, Los Angeles, 300 Stein Plaza, Los Angeles, CA, 90095, USA.

Epithelial membrane protein-2 (EMP2) expression is noted in many human cancers. We evaluated EMP2 as a biomarker in gliomas. A large tissue microarray of lower grade glioma (WHO grades II-III, n = 19 patients) and glioblastoma (GBM) (WHO grade IV, n = 50 patients) was stained for EMP2. EMP2 expression was dichotomized to low or high expression scores and correlated with clinical data. The mean EMP2 expression was 1.68 in lower grade gliomas versus 2.20 in GBMs (P = 0.01). The percentage of samples with high EMP2 expression was greater in GBMs than lower grade gliomas (90.0 vs. 52.6%, P = 0.001). No significant difference was found between median survival among patients with GBM tumors exhibiting high EMP2 expression and survival of those with low EMP2 expression (8.38 vs. 10.98 months, P = 0.39). However, EMP2 expression ≥2 correlated with decreased survival (r = -0.39, P = 0.001). The EMP2 expression level also correlated with Ki-67 positivity (r = 0.34, P = 0.008). The mortality hazard ratio for GBM patients with EMP2 score of 3 or higher was 1.92 (CI 0.69-5.30). Our findings suggest that elevated EMP2 expression is associated with GBM. With other biomarkers, EMP2 may have use as a molecular target for the diagnosis and treatment of gliomas.
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http://dx.doi.org/10.1007/s10014-017-0300-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6118858PMC
January 2018

Detection of immune responses after immunotherapy in glioblastoma using PET and MRI.

Proc Natl Acad Sci U S A 2017 09 5;114(38):10220-10225. Epub 2017 Sep 5.

Department of Neurosurgery, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA 90095;

Contrast-enhanced MRI is typically used to follow treatment response and progression in patients with glioblastoma (GBM). However, differentiating tumor progression from pseudoprogression remains a clinical dilemma largely unmitigated by current advances in imaging techniques. Noninvasive imaging techniques capable of distinguishing these two conditions could play an important role in the clinical management of patients with GBM and other brain malignancies. We hypothesized that PET probes for deoxycytidine kinase (dCK) could be used to differentiate immune inflammatory responses from other sources of contrast-enhancement on MRI. Orthotopic malignant gliomas were established in syngeneic immunocompetent mice and then treated with dendritic cell (DC) vaccination and/or PD-1 mAb blockade. Mice were then imaged with [F]-FAC PET/CT and MRI with i.v. contrast. The ratio of contrast enhancement on MRI to normalized PET probe uptake, which we term the immunotherapeutic response index, delineated specific regions of immune inflammatory activity. On postmortem examination, FACS-based enumeration of intracranial tumor-infiltrating lymphocytes directly correlated with quantitative [F]-FAC PET probe uptake. Three patients with GBM undergoing treatment with tumor lysate-pulsed DC vaccination and PD-1 mAb blockade were also imaged before and after therapy using MRI and a clinical PET probe for dCK. Unlike in mice, [F]-FAC is rapidly catabolized in humans; thus, we used another dCK PET probe, [F]-clofarabine ([F]-CFA), that may be more clinically relevant. Enhanced [F]-CFA PET probe accumulation was identified in tumor and secondary lymphoid organs after immunotherapy. Our findings identify a noninvasive modality capable of imaging the host antitumor immune response against intracranial tumors.
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http://dx.doi.org/10.1073/pnas.1706689114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617282PMC
September 2017

Epithelial membrane protein-2 (EMP2) promotes angiogenesis in glioblastoma multiforme.

J Neurooncol 2017 Aug 9;134(1):29-40. Epub 2017 Jun 9.

Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, 90095, USA.

Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumor and is associated with an extremely poor clinical prognosis. One pathologic hallmark of GBM is excessive vascularization with abnormal blood vessels. Extensive investigation of anti-angiogenic therapy as a treatment for recurrent GBM has been performed. Bevacizumab, a monoclonal anti-vascular endothelial growth factor A (VEGF-A), suggests a progression-free survival benefit but no overall survival benefit. Developing novel anti-angiogenic therapies are urgently needed in controlling GBM growth. In this study, we demonstrate tumor expression of epithelial membrane protein-2 (EMP2) promotes angiogenesis both in vitro and in vivo using cell lines from human GBM. Mechanistically, this pro-angiogenic effect of EMP2 was partially through upregulating tumor VEGF-A levels. A potential therapeutic effect of a systemic administration of anti-EMP2 IgG1 on intracranial xenografts was observed resulting in both significant reduction of tumor load and decreased tumor vasculature. These results suggest the potential for anti-EMP2 IgG1 as a promising novel anti-angiogenic therapy for GBM. Further investigation is needed to fully understand the molecular mechanisms how EMP2 modulates GBM pathogenesis and progression and to further characterize anti-EMP2 therapy in GBM.
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http://dx.doi.org/10.1007/s11060-017-2507-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5695892PMC
August 2017

Immunosuppressive tumor-infiltrating myeloid cells mediate adaptive immune resistance via a PD-1/PD-L1 mechanism in glioblastoma.

Neuro Oncol 2017 06;19(6):796-807

Department of Neurosurgery, David Geffen School of Medicine at UCLA, University of California, Los Angeles, California, USA.

Background: Adaptive immune resistance in the tumor microenvironment appears to attenuate the immunotherapeutic targeting of glioblastoma (GBM). In this study, we identified a tumor-infiltrating myeloid cell (TIM) population that expands in response to dendritic cell (DC) vaccine treatment. The aim of this study was to understand how this programmed death ligand 1 (PD-L1)-expressing population restricts activation and tumor-cytolytic function of vaccine-induced tumor-infiltrating lymphocytes (TILs).

Methods: To test this hypothesis in our in vivo preclinical model, we treated mice bearing intracranial gliomas with DC vaccination ± murine anti-PD-1 monoclonal antibody (mAb) blockade or a colony stimulating factor 1 receptor inhibitor (CSF-1Ri) (PLX3397) and measured overall survival. We then harvested and characterized the PD-L1+ TIM population and its role in TIL activation and tumor cytolysis in vitro.

Results: Our data indicated that the majority of PD-L1 expression in the GBM environment is contributed by TIMs rather than by tumor cells themselves. While PD-1 blockade partially reversed the TIL dysfunction, targeting TIMs directly with CSF-1Ri altered TIM expression of key chemotactic factors associated with promoting increased TIL infiltration after vaccination. Neither PD-1 mAb nor CSF-1Ri had a demonstrable therapeutic benefit alone, but when combined with DC vaccination, a significant survival benefit was observed. When the tripartite regimen was given (DC vaccine, PD-1 mAb, PLX3397), long-term survival was noted together with an increase in the number of TILs and TIL activation.

Conclusion: Together, these studies elucidate the role that TIMs play in mediating adaptive immune resistance in the GBM microenvironment and provide evidence that they can be manipulated pharmacologically with agents that are clinically available. Development of immune resistance in response to active vaccination in GBM can be reversed with dual administration of CSF-1Ri and PD-1 mAb.
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http://dx.doi.org/10.1093/neuonc/now287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5464463PMC
June 2017

PD-1 blockade enhances the vaccination-induced immune response in glioma.

JCI Insight 2016 Jul;1(10)

Department of Neurosurgery, David Geffen School of Medicine at UCLA, UCLA, Los Angeles, California, USA; Brain Research Institute, David Geffen School of Medicine at UCLA, UCLA, Los Angeles, California, USA; Jonsson Comprehensive Cancer Center (JCCC), David Geffen School of Medicine at UCLA, UCLA, Los Angeles, California, USA; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, UCLA, Los Angeles, California, USA.

DC vaccination with autologous tumor lysate has demonstrated promising results for the treatment of glioblastoma (GBM) in preclinical and clinical studies. While the vaccine appears capable of inducing T cell infiltration into tumors, the effectiveness of active vaccination in progressively growing tumors is less profound. In parallel, a number of studies have identified negative costimulatory pathways, such as programmed death 1/programmed death ligand 1 (PD-1/PD-L1), as relevant mediators of the intratumoral immune responses. Clinical responses to PD-1 pathway inhibition, however, have also been varied. To evaluate the relevance to established glioma, the effects of PD-1 blockade following DC vaccination were tested in intracranial (i.c.) glioma tumor- bearing mice. Treatment with both DC vaccination and PD-1 mAb blockade resulted in long-term survival, while neither agent alone induced a survival benefit in animals with larger, established tumors. This survival benefit was completely dependent on CD8 T cells. Additionally, DC vaccine plus PD-1 mAb blockade resulted in the upregulation of integrin homing and immunologic memory markers on tumor-infiltrating lymphocytes (TILs). In clinical samples, DC vaccination in GBM patients was associated with upregulation of PD-1 expression in vivo, while ex vivo blockade of PD-1 on freshly isolated TILs dramatically enhanced autologous tumor cell cytolysis. These findings strongly suggest that the PD-1/PD-L1 pathway plays an important role in the adaptive immune resistance of established GBM in response to antitumor active vaccination and provide us with a rationale for the clinical translation of this combination therapy.
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http://dx.doi.org/10.1172/jci.insight.87059DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4951098PMC
July 2016

TCR Sequencing Can Identify and Track Glioma-Infiltrating T Cells after DC Vaccination.

Cancer Immunol Res 2016 05 11;4(5):412-418. Epub 2016 Mar 11.

Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.

Although immunotherapeutic strategies are emerging as adjunctive treatments for cancer, sensitive methods of monitoring the immune response after treatment remain to be established. We used a novel next-generation sequencing approach to determine whether quantitative assessments of tumor-infiltrating lymphocyte (TIL) content and the degree of overlap of T-cell receptor (TCR) sequences in brain tumors and peripheral blood were predictors of immune response and overall survival in glioblastoma patients treated with autologous tumor lysate-pulsed dendritic cell immunotherapy. A statistically significant correlation was found between a higher estimated TIL content and increased time to progression and overall survival. In addition, we were able to assess the proportion of shared TCR sequences between tumor and peripheral blood at time points before and after therapy, and found the level of TCR overlap to correlate with survival outcomes. Higher degrees of overlap, or the development of an increased overlap following immunotherapy, was correlated with improved clinical outcome, and may provide insights into the successful, antigen-specific immune response. Cancer Immunol Res; 4(5); 412-8. ©2016 AACR.
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http://dx.doi.org/10.1158/2326-6066.CIR-15-0240DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4873445PMC
May 2016

Efficacy of systemic adoptive transfer immunotherapy targeting NY-ESO-1 for glioblastoma.

Neuro Oncol 2016 Mar 1;18(3):368-78. Epub 2015 Sep 1.

Department of Neurosurgery, University of California Los Angeles, Los Angeles, California (R.G.E., J.P.A., D.N.L., H.S., R.S., M.C.G., C.A.K., L.M.L., R.M.P.); Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California (D.N.L., R.M.P.); Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California (W.H.Y.); Department of Biostatistics, University of California Los Angeles, Los Angeles, California (N.L., G.L.); Brain Research Institute, University of California Los Angeles, Los Angeles, California (C.A.K., L.M.L., R.M.P.); Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, University of California Los Angeles, Los Angeles, California (C.A.K., L.M.L., R.M.P.).

Background: Immunotherapy is an ideal treatment modality to specifically target the diffusely infiltrative tumor cells of malignant gliomas while sparing the normal brain parenchyma. However, progress in the development of these therapies for glioblastoma has been slow due to the lack of immunogenic antigen targets that are expressed uniformly and selectively by gliomas.

Methods: We utilized human glioblastoma cell cultures to induce expression of New York-esophageal squamous cell carcinoma (NY-ESO-1) following in vitro treatment with the demethylating agent decitabine. We then investigated the phenotype of lymphocytes specific for NY-ESO-1 using flow cytometry analysis and cytotoxicity against cells treated with decitabine using the xCelligence real-time cytotoxicity assay. Finally, we examined the in vivo application of this immune therapy using an intracranially implanted xenograft model for in situ T cell trafficking, survival, and tissue studies.

Results: Our studies showed that treatment of intracranial glioma-bearing mice with decitabine reliably and consistently induced the expression of an immunogenic tumor-rejection antigen, NY-ESO-1, specifically in glioma cells and not in normal brain tissue. The upregulation of NY-ESO-1 by intracranial gliomas was associated with the migration of adoptively transferred NY-ESO-1-specific lymphocytes along white matter tracts to these tumors in the brain. Similarly, NY-ESO-1-specific adoptive T cell therapy demonstrated antitumor activity after decitabine treatment and conferred a highly significant survival benefit to mice bearing established intracranial human glioma xenografts. Transfer of NY-ESO-1-specific T cells systemically was superior to intracranial administration and resulted in significantly extended and long-term survival of animals.

Conclusion: These results reveal an innovative, clinically feasible strategy for the treatment of glioblastoma.
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http://dx.doi.org/10.1093/neuonc/nov153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4767237PMC
March 2016

2-Hydroxyglutarate Inhibits ATP Synthase and mTOR Signaling.

Cell Metab 2015 Sep 16;22(3):508-15. Epub 2015 Jul 16.

Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA; Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA. Electronic address:

We discovered recently that the central metabolite α-ketoglutarate (α-KG) extends the lifespan of C. elegans through inhibition of ATP synthase and TOR signaling. Here we find, unexpectedly, that (R)-2-hydroxyglutarate ((R)-2HG), an oncometabolite that interferes with various α-KG-mediated processes, similarly extends worm lifespan. (R)-2HG accumulates in human cancers carrying neomorphic mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes. We show that, like α-KG, both (R)-2HG and (S)-2HG bind and inhibit ATP synthase and inhibit mTOR signaling. These effects are mirrored in IDH1 mutant cells, suggesting a growth-suppressive function of (R)-2HG. Consistently, inhibition of ATP synthase by 2-HG or α-KG in glioblastoma cells is sufficient for growth arrest and tumor cell killing under conditions of glucose limitation, e.g., when ketone bodies (instead of glucose) are supplied for energy. These findings inform therapeutic strategies and open avenues for investigating the roles of 2-HG and metabolites in biology and disease.
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http://dx.doi.org/10.1016/j.cmet.2015.06.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663076PMC
September 2015

pH-weighted molecular imaging of gliomas using amine chemical exchange saturation transfer MRI.

Neuro Oncol 2015 Nov 24;17(11):1514-24. Epub 2015 Jun 24.

Department of Radiological Sciences (R.J.H., W.B.P., B.M.E.), Department of Biomedical Physics (R.J.H., B.M.E.), Department of Neurology (T.F.C., A.L., P.L.N.), Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California (L.M.L., R.M.P., J.P.A.); Department of Biomedical Sciences and Imaging, Cedars-Sinai Medical Center, Los Angeles, California (D.L.); Department of Bioengineering (D.L., B.M.E.), Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California (W.H.Y.).

Background: Interstitial tissue acidosis resulting from abnormal perfusion and metabolism is a hallmark of cancer. The current study demonstrates that chemical exchange saturation transfer (CEST) MRI can be used as a noninvasive pH-weighted molecular imaging technique by targeting the chemical exchange between amine protons and protons in extracellular bulk water.

Methods: First, the sensitivity of amine CEST was validated in phantoms under a variety of conditions, including different magnetic field strengths, amino acid concentrations, and pH values. Amine CEST was compared with histology in both a preclinical GL261 intracranial glioma model at 7T and human patients at 3T. The association between physiologic and pH-weighted MRI was explored, along with the ability to predict time to progression to radiochemotherapy in 20 glioblastoma patients.

Results: z-Spectral asymmetry increased at 3 ppm (amine range) on CEST MRI with decreasing pH within the range observed in tumors for both 3T and 7T scanners. Lesions with acidic signatures showed active tumor and pseudopalisading tumor on histology and showed elevated FDOPA PET uptake, lactate on MR spectroscopy, and perfusion abnormalities. Patients with acidic lesions after surgery or stable/growing acidic lesions had a shorter time to progression following radiochemotherapy compared with patients with lesions demonstrating relatively low acidity (P < .001).

Conclusion: Results suggest pH-weighted MRI may provide new insight into brain tumor physiology beyond traditional imaging technologies.
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http://dx.doi.org/10.1093/neuonc/nov106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4648305PMC
November 2015

Radial mobility and cytotoxic function of retroviral replicating vector transduced, non-adherent alloresponsive T lymphocytes.

J Vis Exp 2015 Feb 11(96). Epub 2015 Feb 11.

Department of Neurosurgery, UCLA David Geffen School of Medicine; Brain Research Institute, UCLA David Geffen School of Medicine; Jonsson Comprehensive Cancer Center, UCLA David Geffen School of Medicine;

We report a novel adaptation of the Radial Monolayer Cell Migration assay, first reported to measure the radial migration of adherent tumor cells on extracellular matrix proteins, for measuring the motility of fluorescently-labeled, non-adherent human or murine effector immune cells. This technique employs a stainless steel manifold and 10-well Teflon slide to focally deposit non-adherent T cells into wells prepared with either confluent tumor cell monolayers or extracellular matrix proteins. Light and/or multi-channel fluorescence microscopy is used to track the movement and behavior of the effector cells over time. Fluorescent dyes and/or viral vectors that code for fluorescent transgenes are used to differentially label the cell types for imaging. This method is distinct from similar-type in vitro assays that track horizontal or vertical migration/invasion utilizing slide chambers, agar or transwell plates. The assay allows detailed imaging data to be collected with different cell types distinguished by specific fluorescent markers; even specific subpopulations of cells (i.e., transduced/nontransduced) can be monitored. Surface intensity fluorescence plots are generated using specific fluorescence channels that correspond to the migrating cell type. This allows for better visualization of the non-adherent immune cell mobility at specific times. It is possible to gather evidence of other effector cell functions, such as cytotoxicity or transfer of viral vectors from effector to target cells, as well. Thus, the method allows researchers to microscopically document cell-to-cell interactions of differentially-labeled, non-adherent with adherent cells of various types. Such information may be especially relevant in the assessment of biologically-manipulated or activated immune cell types, where visual proof of functionality is desired with tumor target cells before their use for cancer therapy.
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http://dx.doi.org/10.3791/52416DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354631PMC
February 2015

CD200 in CNS tumor-induced immunosuppression: the role for CD200 pathway blockade in targeted immunotherapy.

J Immunother Cancer 2014 16;2(1):46. Epub 2014 Dec 16.

Department of Pediatrics, hematology/oncology, University of Minnesota, Minneapolis, MN 55455 USA.

Background: Immunological quiescence in the central nervous system (CNS) is a potential barrier to immune mediated anti-tumor response. One suppressive mechanism results from the interaction of parenchyma-derived CD200 and its receptor on myeloid cells. We suggest that CD200/CD200R interactions on myeloid cells expand the myeloid-derived suppressor cell (MDSC) population and that blocking tumor-derived CD200 will enhance the efficacy of immunotherapy.

Methods: CD200 mRNA expression levels in human brain tumor tissue samples were measured by microarray. The amount of circulating CD200 protein in the sera of patients with brain tumors was determined by ELISA and, when corresponding peripheral blood samples were available, was correlated quantitatively with MDSCs. CD200-derived peptides were used as competitive inhibitors in a mouse model of glioblastoma immunotherapy.

Results: CD200 mRNA levels were measured in human brain tumors, with different expression levels being noted among the sub groups of glioblastoma, medulloblastoma and ependymoma. Serum CD200 concentrations were highest in patients with glioblastoma and correlated significantly with MDSC expansion. Similarly, in vitro studies determined that GL261 cells significantly expanded a MDSC population. Interestingly, a CD200R antagonist inhibited the expansion of murine MDSCs in vitro and in vivo. Moreover, inclusion of CD200R antagonist peptide in glioma tumor lysate-derived vaccines slowed tumor growth and significantly enhanced survival.

Conclusion: These data suggest that CNS-derived tumors can evade immune surveillance by engaging CD200. Because of the homology between mouse and human CD200, our data also suggest that blockade of CD200 binding to its receptor will enhance the efficacy of immune mediated anti-tumor strategies for brain tumors.
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http://dx.doi.org/10.1186/s40425-014-0046-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4296547PMC
January 2015

Dominant B-cell epitopes from cancer/stem cell antigen SOX2 recognized by serum samples from cancer patients.

Am J Clin Exp Immunol 2014 15;3(2):84-90. Epub 2014 Aug 15.

Department of Urology, David Geffen School of Medicine at UCLA Los Angeles, CA 90095, USA.

Human sex determining region Y-box 2 (SOX2) is an important transcriptional factor involved in the pluripotency and stemness of human embryonic stem cells. SOX2 plays important roles in maintaining cancer stem cell activities of melanoma and cancers of the brain, prostate, breast, and lung. SOX2 is also a lineage survival oncogene for squamous cell carcinoma of the lung and esophagus. Spontaneous cellular and humoral immune responses against SOX2 present in cancer patients classify it as a tumor-associated antigen (TAA) shared by lung cancer, glioblastoma, and prostate cancer among others. In this study, B-cell epitopes were predicted using computer-assisted algorithms. Synthetic peptides based on the prediction were screened for recognition by serum samples from cancer patients using ELISA. Two dominant B-cell epitopes, SOX2:52-87 and SOX2:98-124 were identified. Prostate cancer, glioblastoma and lung cancer serum samples that recognized the above SOX2 epitopes also recognized the full-length protein based on Western blot. These B-cell epitopes may be used in assessing humoral immune responses against SOX2 in cancer immunotherapy and stem cell-related transplantation.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4138131PMC
August 2014

The histone deacetylase inhibitor, LBH589, promotes the systemic cytokine and effector responses of adoptively transferred CD8+ T cells.

J Immunother Cancer 2014 15;2. Epub 2014 Apr 15.

Department of Molecular and Medical Pharmacology, 650 Charles E. Young Drive South, 23-120 Center for Health Sciences, Los Angeles, CA 90095-1735, USA ; Department of Neurosurgery, University of California-Los Angeles School of Medicine, Center for Health Sciences, Room 74-145 CHS, 10833 Le Conte Avenue, Box 956901, Los Angeles, CA 90095-6901, USA ; Jonsson Comprehensive Cancer Center, University of California-Los Angeles School of Medicine, 8-684 Factor Building, Box 951781, Los Angeles, CA 90095-1781, USA ; Brain Research Institute, University of California-Los Angeles School of Medicine, 695 Charles E. Young Drive South, Los Angeles, CA 90095, USA.

Background: Histone deacetylase (HDAC) inhibitors are a class of agents that have potent antitumor activity with a reported ability to upregulate MHC and costimulatory molecule expression. We hypothesized that epigenetic pharmacological immunomodulation could sensitize tumors to immune mediated cell death with an adoptive T cell therapy.

Methods: The pan-HDAC inhibitor, LBH589, was combined with gp100 specific T cell immunotherapy in an in vivo B16 melanoma model and in an in vivo non-tumor bearing model. Tumor regression, tumor specific T cell function and phenotype, and serum cytokine levels were evaluated.

Results: Addition of LBH589 to an adoptive cell transfer therapy significantly decreased tumor burden while sustaining systemic pro-inflammatory levels. Furthermore, LBH589 was able to enhance gp100 specific T cell survival and significantly decrease T regulatory cell populations systemically and intratumorally. Even in the absence of tumor, LBH589 was able to enhance the proliferation, retention, and polyfunctional status of tumor specific T cells, suggesting its effects were T cell specific. In addition, LBH589 induced significantly higher levels of the IL-2 receptor (CD25) and the co-stimulatory molecule OX-40 in T cells.

Conclusion: These results demonstrate that immunomodulation of adoptively transferred T cells by LBH589 provides a novel mechanism to increase in vivo antitumor efficacy of effector CD8 T cells.
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http://dx.doi.org/10.1186/2051-1426-2-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4105687PMC
July 2014

Cytokine responsiveness of CD8(+) T cells is a reproducible biomarker for the clinical efficacy of dendritic cell vaccination in glioblastoma patients.

J Immunother Cancer 2014 13;2:10. Epub 2014 May 13.

Departments of Neurosurgery, University of California Los Angeles, Los Angeles, CA 90095, USA.

Background: Immunotherapeutic approaches, such as dendritic cell (DC) vaccination, have emerged as promising strategies in the treatment of glioblastoma. Despite their promise, however, the absence of objective biomarkers and/or immunological monitoring techniques to assess the clinical efficacy of immunotherapy still remains a primary limitation. To address this, we sought to identify a functional biomarker for anti-tumor immune responsiveness associated with extended survival in glioblastoma patients undergoing DC vaccination.

Methods: 28 patients were enrolled and treated in two different Phase 1 DC vaccination clinical trials at UCLA. To assess the anti-tumor immune response elicited by therapy, we studied the functional responsiveness of pre- and post-vaccination peripheral blood lymphocytes (PBLs) to the immunostimulatory cytokines interferon-gamma (IFN-γ) and interleukin-2 (IL-2) in 21 of these patients for whom we had adequate material. Immune responsiveness was quantified by measuring downstream phosphorylation events of the transcription factors, STAT-1 and STAT-5, via phospho-specific flow cytometry.

Results: DC vaccination induced a significant decrease in the half-maximal concentration (EC-50) of IL-2 required to upregulate pSTAT-5 specifically in CD3(+)CD8(+) T lymphocytes (p < 0.045). Extended survival was also associated with an increased per cell phosphorylation of STAT-5 in cytotoxic T-cells following IL-2 stimulation when the median post/pre pSTAT-5 ratio was used to dichotomize the patients (p = 0.0015, log-rank survival; hazard ratio = 0.1834, p = 0.018). Patients whose survival was longer than two years had a significantly greater pSTAT-5 ratio (p = 0.015), but, contrary to our expectations, a significantly lower pSTAT-1 ratio (p = 0.038).

Conclusions: Our results suggest that monitoring the pSTAT signaling changes in PBL may provide a functional immune monitoring measure predictive of clinical efficacy in DC-vaccinated patients.
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http://dx.doi.org/10.1186/2051-1426-2-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4039989PMC
June 2014

Autologous tumor lysate-pulsed dendritic cell immunotherapy for pediatric patients with newly diagnosed or recurrent high-grade gliomas.

Anticancer Res 2013 May;33(5):2047-56

Department of Pediatrics, Division of Pediatric Hematology/ Oncology, Harbor-UCLA Medical Center/LA Biomed, David Geffen School of Medicine UCLA, Torrance, CA 90502, USA.

Immunotherapy has the potential to improve clinical outcomes with little toxicity for pediatric patients with brain tumors. We conducted a pilot feasibility study of tumor lysate-pulsed dendritic cell (DC) vaccination in pediatric patients (1 to 18 years old) with newly diagnosed or recurrent high-grade glioma (HGG). A total of nine DC vaccine doses, each containing 1 × 10(6) cells per dose were administered to three out of the seven originally enrolled patients. Toxicities were limited to mild side-effects, except in one case of elevated alkaline phosphatase, which resolved without clinical consequences. Two patients with primary lesions amongst the three vaccinated were alive at the time of writing, both without evidence of disease. Pre- and post-vaccination tumor samples from a patient with an anaplastic oligoastrocytoma that recurred failed to demonstrate immune cell infiltration by immunohistochemistry. Peripheral cytokine levels were evaluated in one patient following DC vaccination and demonstrated some changes in relation to vaccination. DC vaccine is tolerable and feasible with some limitations for pediatric patients with HGG. Dendritic cell based immunotherapy may provide some clinical benefit in pediatric patients with glioma, especially for patients with minimal residual disease, but further investigation of this modality is required.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018463PMC
May 2013

An essential requirement for the SCAP/SREBP signaling axis to protect cancer cells from lipotoxicity.

Cancer Res 2013 May 25;73(9):2850-62. Epub 2013 Feb 25.

Department of Pathology and Laboratory Medicine, University of California, Los Angeles 90095, USA.

The sterol regulatory element-binding proteins (SREBP) are key transcriptional regulators of lipid metabolism and cellular growth. It has been proposed that SREBP signaling regulates cellular growth through its ability to drive lipid biosynthesis. Unexpectedly, we find that loss of SREBP activity inhibits cancer cell growth and viability by uncoupling fatty acid synthesis from desaturation. Integrated lipid profiling and metabolic flux analysis revealed that cancer cells with attenuated SREBP activity maintain long-chain saturated fatty acid synthesis, while losing fatty acid desaturation capacity. We traced this defect to the uncoupling of fatty acid synthase activity from stearoyl-CoA desaturase 1 (SCD1)-mediated desaturation. This deficiency in desaturation drives an imbalance between the saturated and monounsaturated fatty acid pools resulting in severe lipotoxicity. Importantly, replenishing the monounsaturated fatty acid pool restored growth to SREBP-inhibited cells. These studies highlight the importance of fatty acid desaturation in cancer growth and provide a novel mechanistic explanation for the role of SREBPs in cancer metabolism.
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http://dx.doi.org/10.1158/0008-5472.CAN-13-0382-TDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3919498PMC
May 2013

Comparison of glioma-associated antigen peptide-loaded versus autologous tumor lysate-loaded dendritic cell vaccination in malignant glioma patients.

J Immunother 2013 Feb;36(2):152-7

Department of Neurosurgery, David Geffen School of Medicine at UCLA, University of California Los Angeles, Los Angeles, CA, USA.

Dendritic cell (DC) vaccination is emerging as a promising therapeutic option for malignant glioma patients. However, the optimal antigen formulation for loading these cells has yet to be established. The objective of this study was to compare the safety, feasibility, and immune responses of malignant glioma patients on 2 different DC vaccination protocols. Twenty-eight patients were treated with autologous tumor lysate (ATL)-pulsed DC vaccination, whereas 6 patients were treated with glioma-associated antigen (GAA) peptide-pulsed DCs. Safety, toxicity, feasibility, and correlative immune monitoring assay results were compared between patients on each trial. Because of HLA subtype restrictions on the GAA-DC trial, 6/15 screened patients were eligible for treatment, whereas 28/32 patients passed eligibility screening for the ATL-DC trial. Elevated frequencies of activated natural killer cells were observed in the peripheral blood from GAA-DC patients compared with the ATL-DC patients. In addition, a significant correlation was observed between decreased regulatory T lymphocyte (Treg) ratios (postvaccination/prevaccination) and overall survival (P = 0.004) in patients on both trials. In fact, Treg ratios were independently prognostic for overall survival in these patients, whereas tumor pathology was not in multivariate analyses. In conclusion, these results suggest that ATL-DC vaccination is associated with wider patient eligibility compared with GAA-DC vaccination. Decreased postvaccination/prevaccination Treg ratios and decreased frequencies of activated natural killer cells were associated with prolonged survival in patients from both trials, suggesting that these lymphocyte subsets may be relevant immune monitoring endpoints for immunotherapy protocols in malignant glioma patients.
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http://dx.doi.org/10.1097/CJI.0b013e3182811ae4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3568250PMC
February 2013