Practical guidance for direct oral anticoagulant use in the treatment of venous thromboembolism in primary and metastatic brain tumor patients.

Management of venous thromboembolism (VTE) in patients with primary and metastatic brain tumors (BT) is challenging because of the risk of intracranial hemorrhage (ICH). There are no prospective clinical trials evaluating safety and efficacy of direct oral anticoagulants (DOACs), specifically in patients with BT, but they are widely used for VTE in this population. A group of neuro-oncology experts convened to provide practical clinical guidance for the off-label use of DOACs in treating VTE in patients with BT. We searched PubMed for the following terms: BTs, glioma, glioblastoma (GBM), brain metastasis, VTE, heparin, low-molecular-weight heparin (LWMH), DOACs, and ICH. Although prospective clinical trials are needed, the recommendations presented aim to assist clinicians in making informed decisions regarding DOACs for VTE in patients with BT.

Functional connectivity of the default mode, dorsal attention and fronto-parietal executive control networks in glial tumor patients.

PURPOSE: Resting state functional magnetic resonance imaging (rsfMRI) is an emerging tool to explore the functional connectivity of different brain regions. We aimed to assess the disruption of functional connectivity of the Default Mode Network (DMN), Dorsal Attention Network(DAN) and Fronto-Parietal Network (FPN) in patients with glial tumors. METHODS: rsfMRI data acquired on 3T-MR of treatment-naive glioma patients prospectively recruited (2015-2019) and matched controls from the 1000 functional-connectomes-project were analyzed using the CONN functional toolbox. Seed-Based Connectivity Analysis (SBCA) and Independent Component Analysis (ICA, with 10 to 100 components) were performed to study reliably the three networks of interest. RESULTS: 35 patients with gliomas (17 WHO grade I-II, 18 grade III-IV) and 70 controls were included. Global increased DMN connectivity was consistently found with SBCA and ICA in patients compared to controls (Cluster1: Precuneus, height: p < 10-6; Cluster2: subcallosum; height: p < 10-5). However, an area of decreased connectivity was found in the posterior corpus callosum, particularly in high-grade gliomas (height: p < 10-5). The DAN demonstrated small areas of increased connectivity in frontal and occipital regions (height: p < 10-6). For the FPN, increased connectivity was noted in the precuneus, posterior cingulate gyrus, and frontal cortex. No difference in the connectivity of the networks of interest was demonstrated between low- and high-grade gliomas, as well as when stratified by their IDH1-R132H (isocitrate dehydrogenase) mutation status. CONCLUSION: Altered functional connectivity is reliably found with SBCA and ICA in the DMN, DAN, and FPN in glioma patients, possibly explained by decreased connectivity between the cerebral hemispheres across the corpus callosum due to disruption of the connections.

Racial and socioeconomic disparities differentially affect overall and cause-specific survival in glioblastoma.

INTRODUCTION: The prognostic role of racial and socioeconomic factors in patients with glioblastoma is controversially debated. We aimed to evaluate how these factors may affect survival outcomes in an overall and cause-specific manner using large, national cancer registry cohort data in the temozolomide chemoradiation era. METHODS: The National Cancer Institute's Surveillance, Epidemiology, and End Results database was queried for patients diagnosed with glioblastoma between 2005 and 2016. Overall survival was assessed using Cox proportional hazard models using disease intrinsic and extrinsic factors. Cause-specific mortality was assessed using cumulative incidence curves and modeled using multivariate cumulative risk regression. RESULTS: A total of 28,952 patients met the prespecified inclusion criteria and were included in this analysis. The following factors were associated with all-cause mortality: age, calendar year of diagnosis, sex, treatment receipt, tumor size, tumor location, extent of resection, median household income, and race. Asian/Pacific Islanders and Hispanic Whites had lower mortality compared to Non-Hispanic Whites. Cause-specific mortality was associated with both racial and socioeconomic groups. After adjusting for treatment and tumor-related factors, Asian/Pacific and black patients had lower glioblastoma-specific mortality. However, lower median household income and black race were associated with significantly higher non-glioblastoma mortality. CONCLUSIONS: Despite the aggressive nature of glioblastoma, racial and socioeconomic factors influence glioblastoma-specific and non-glioblastoma associated mortality. Our study shows that patient race has an impact on glioblastoma-associated mortality independently of tumor and treatment related factors. Importantly, socioeconomic and racial differences largely contribute to non-glioblastoma mortality, including death from other cancers, cardio- and cerebrovascular events.

Advances in Molecular Classification and Therapeutic Opportunities in Meningiomas.

PURPOSE OF REVIEW: Our understanding of the genetic and epigenetic alterations in meningioma and the underlying tumor biology of meningioma has significantly changed over the past decade and resulted in revision of prognostically relevant meningioma subclasses within and beyond the WHO classification of CNS tumors. RECENT FINDINGS: The 2016 WHO classification of CNS tumors recognizes WHO grade I, II, and III based on histopathological features. Recent work has identified genetic alterations with prognostic implications, including mutations of the TERT promoter, loss of function of the DMD gene, and inactivation of the tumor suppressor BAP-1. Studies of DNA methylation patterns in meningiomas have resulted in a novel and prognostically relevant meningioma subclassification schema. There have been major advances in our understanding of prognostically relevant genetic and epigenetic changes in meningioma which will hopefully allow for improvement in clinical trial design and the development of more effective therapies for meningioma.

Novel Therapies for Glioblastoma.

PURPOSE OF REVIEW: Glioblastoma (GBM) is the most common malignant primary brain tumor, and the available treatment options are limited. This article reviews the recent preclinical and clinical investigations that seek to expand the repertoire of effective medical and radiotherapy options for GBM. RECENT FINDINGS: Recent phase III trials evaluating checkpoint inhibition did not result in significant survival benefit. Select vaccine strategies have yielded promising results in early phase clinical studies and warrant further validation. Various targeted therapies are being explored but have yet to see breakthrough results. In addition, novel radiotherapy approaches are in development to maximize safe dose delivery. A multitude of preclinical and clinical studies in GBM explore promising immunotherapies, targeted agents, and novel radiation modalities. Recent phase III trial failures have once more highlighted the profound tumor heterogeneity and diverse resistance mechanisms of glioblastoma. This calls for the development of biomarker-driven and personalized treatment approaches.

Case report: Solitary mass of the sciatic nerve confirmed as a primary extranodal manifestation of diffuse large B-cell lymphoma in a geriatric patient.

Background: Neoplastic lesions affecting peripheral nerves are rare in the general population and, most often, are benign peripheral nerve sheath tumors. However, a minority of lesions represent high-grade malignancies associated with a poor prognosis, such as malignant peripheral nerve sheath tumors (MPNSTs). Very rarely, these tumors represent peripheral non-nerve sheath tumors (PNNSTs), such as hematological neoplasms that impair nerve function. These can be hard to distinguish from MPNSTs and other lesions arising from the nerve itself. In the present case report, we describe a rare case of direct infiltration of nerves by tumor cells of a hematological neoplasm. Methods: We report the case of a 90-year-old woman with acute onset of right-sided foot palsy, sensory loss, and pain, caused by an extensive solitary mass of the sciatic nerve in the thigh. We present and discuss the clinical presentation, multimodal diagnostic procedures, and treatment. Results: MRI of the right thigh and the caudal pelvis revealed a contrast-enhancing lesion infiltrating the sciatic nerve. Additionally performed staging imaging was non-revealing. After multidisciplinary discussion in the neuro-oncology tumor board, a MPNST was suspected and the patient underwent radical tumor resection. However, final histopathology revealed a diffuse large B-cell lymphoma (DLBCL). The patient received adjuvant palliative local radiotherapy which led to acceptable symptom control. Conclusion: Rare PNNSTs, including extranodal manifestations of DLBCL can have similar clinical and radiological diagnostical features as PNSTs. Comprehensive diagnostic workup of contrast-enhancing lesions affecting peripheral nerves including MRI and metabolic imaging are recommended. Discussion in interdisciplinary tumor boards facilitates finding individual treatment approaches.

Evaluation of the SSTR2-targeted Radiopharmaceutical 177Lu-DOTATATE and SSTR2-specific 68Ga-DOTATATE PET as Imaging Biomarker in Patients with Intracranial Meningioma.

PURPOSE: There are no effective medical therapies for patients with meningioma who progress beyond surgical and radiotherapeutic interventions. Somatostatin receptor type 2 (SSTR2) represents a promising treatment target in meningiomas. In this multicenter, single-arm phase II clinical study (NCT03971461), the SSTR2-targeting radiopharmaceutical 177Lu-DOTATATE is evaluated for its feasibility, safety, and therapeutic efficacy in these patients. PATIENTS AND METHODS: Adult patients with progressive intracranial meningiomas received 177Lu-DOTATATE at a dose of 7.4 GBq (200 mCi) every eight weeks for four cycles. 68Ga-DOTATATE PET-MRI was performed before and six months after the start of the treatment. The primary endpoint was progression-free survival (PFS) at 6 months (PFS-6). Secondary endpoints were safety and tolerability, overall survival (OS) at 12 months (OS-12), median PFS, and median OS. RESULTS: Fourteen patients (female = 11, male = 3) with progressive meningiomas (WHO 1 = 3, 2 = 10, 3 = 1) were enrolled. Median age was 63.1 (range 49.7-78) years. All patients previously underwent tumor resection and at least one course of radiation. Treatment with 177Lu-DOTATATE was well tolerated. Seven patients (50%) achieved PFS-6. Best radiographic response by modified Macdonald criteria was stable disease (SD) in all seven patients. A >25% reduction in 68Ga-DOTATATE uptake (PET) was observed in five meningiomas and two patients. In one lesion, this corresponded to >50% reduction in bidirectional tumor measurements (MRI). CONCLUSIONS: Treatment with 177Lu-DOTATATE was well tolerated. The predefined PFS-6 threshold was met in this interim analysis, thereby allowing this multicenter clinical trial to continue enrollment. 68Ga-DOTATATE PET may be a useful imaging biomarker to assess therapeutic outcome in patients with meningioma.

App-based assessment of patient-reported outcomes in the Molecular Tumor Board in the Center for Personalized Medicine-(TRACE).

Background: Biomarker-based therapies are increasingly used in cancer patients outside clinical trials. Systematic assessment of patient-reported outcomes (PRO) is warranted to take patients' perspectives during biomarker-based therapies into consideration. We assessed the feasibility of an electronic PRO assessment via a smartphone application. Methods: An interdisciplinary expert panel developed a smartphone application based on symptom burden and health-related quality of life (HRQoL) metrics reported in a retrospective analysis of 292 neuro-oncological patients. The app included validated assessments of health-related quality of life (HRQoL), the burden of symptoms, and psychological stress. Feasibility and usability were tested in a pilot study. Semi-structured interviews with patients and health care professionals (HCP) were conducted, transcribed, and analyzed according to Mayring´s qualitative content analysis. Furthermore, we assessed compliance and descriptive data of ePROs. Results: A total of 14 patients have been enrolled, (9 female, 5 male). A total of 4 HCPs, 9 patients, and 1 caregiver were interviewed regarding usability/feasibility. The main advantages were the possibility to complete questionnaires at home and comfortable implementation in daily life. Compliance was high, for example, 82% of the weekly distributed NCCN distress thermometer questionnaires were answered on time, however, with interindividual variability. We observed a median distress score of 5 (range 0-10, 197 results, n = 12, weekly assessed) and a median Global health score of 58.3 according to the EORTC QLQ-C30 instrument (range 16.7-100, 77 results, n = 12, monthly assessed). Conclusions: This pilot study proved the feasibility and acceptance of the app. We will therefore expand its application during biomarker-guided therapies to enable systematic PRO assessments.

ONC201 (Dordaviprone) in Recurrent H3 K27M-Mutant Diffuse Midline Glioma.

PURPOSE: Histone 3 (H3) K27M-mutant diffuse midline glioma (DMG) has a dismal prognosis with no established effective therapy beyond radiation. This integrated analysis evaluated single-agent ONC201 (dordaviprone), a first-in-class imipridone, in recurrent H3 K27M-mutant DMG. METHODS: Fifty patients (pediatric, n = 4; adult, n = 46) with recurrent H3 K27M-mutant DMG who received oral ONC201 monotherapy in four clinical trials or one expanded access protocol were included. Eligible patients had measurable disease by Response Assessment in Neuro-Oncology (RANO) high-grade glioma (HGG) criteria and performance score (PS) ≥60 and were ≥90 days from radiation; pontine and spinal tumors were ineligible. The primary end point was overall response rate (ORR) by RANO-HGG criteria. Secondary end points included duration of response (DOR), time to response (TTR), corticosteroid response, PS response, and ORR by RANO low-grade glioma (LGG) criteria. Radiographic end points were assessed by dual-reader, blinded independent central review. RESULTS: The ORR (RANO-HGG) was 20.0% (95% CI, 10.0 to 33.7). The median TTR was 8.3 months (range, 1.9-15.9); the median DOR was 11.2 months (95% CI, 3.8 to not reached). The ORR by combined RANO-HGG/LGG criteria was 30.0% (95% CI, 17.9 to 44.6). A ≥50% corticosteroid dose reduction occurred in 7 of 15 evaluable patients (46.7% [95% CI, 21.3 to 73.4]); PS improvement occurred in 6 of 34 evaluable patients (20.6% [95% CI, 8.7 to 37.9]). Grade 3 treatment-related treatment-emergent adverse events (TR-TEAEs) occurred in 20.0% of patients; the most common was fatigue (n = 5; 10%); no grade 4 TR-TEAEs, deaths, or discontinuations occurred. CONCLUSION: ONC201 monotherapy was well tolerated and exhibited durable and clinically meaningful efficacy in recurrent H3 K27M-mutant DMG.

Association of MTHFR Polymorphisms With Leukoencephalopathy Risk in Patients With Primary CNS Lymphoma Treated With Methotrexate-Based Regimens.

OBJECTIVES: The folate antagonist high-dose methotrexate (HD-MTX) is integral to induction chemotherapy for primary CNS lymphoma (PCNSL); however, it can be associated with leukoencephalopathy. Methylenetetrahydrofolate reductase (MTHFR) is involved in intracellular folate depletion. We assessed whether MTHFR polymorphisms affect the risk of leukoencephalopathy. METHODS: We retrospectively searched our database at the Massachusetts General Hospital for newly diagnosed PCNSL treated with HD-MTX (without radiotherapy nor intrathecal chemotherapy). RESULTS: Among 68 patients with PCNSL, MTHFR polymorphisms were found in 60 individuals (88.2%) including a 677C→T genotype, a 1298A→C genotype, or a combined 677C→T/1298A→C genotype. Neither MTX clearance nor response to induction therapy was affected by specific genotypes, and complete response was achieved in 72.1% of patients by HD-MTX-based induction. However, the 1298A→C genotype was associated with increased frequency and severity of leukoencephalopathy over time (odds ratio 4.0, CI 1.5-11.4). Such genotype predicted treatment-induced leukoencephalopathy with a sensitivity of 71.0% and a specificity of 62.2% (area under the curve 0.67, CI 0.5-0.8; p = 0.019). While progression-free survival did not differ in genotype-based subgroups, overall survival was lower for the 1298A→C genotype. DISCUSSION: The MTHFR 1298A→C genotype may serve to identify patients with PCNSL at elevated risk of HD-MTX-induced leukoencephalopathy. This seems to translate into reduced survival, potentially due to decreased functional status.

Clinical outcome of biomarker-guided therapies in adult patients with tumors of the nervous system.

Background: The clinical utility of molecular profiling and targeted therapies for neuro-oncology patients outside of clinical trials is not established. We aimed at investigating feasibility and clinical utility of molecular profiling and targeted therapy in adult patients with advanced tumors in the nervous system within a prospective observational study. Methods: molecular tumor board (MTB)@ZPM (NCT03503149) is a prospective observational precision medicine study for patients with advanced tumors. After inclusion of patients, we performed comprehensive molecular profiling, formulated ranked biomarker-guided therapy recommendations based on consensus by the MTB, and collected prospective clinical outcome data. Results: Here, we present initial data of 661 adult patients with tumors of the nervous system enrolled by December 31, 2021. Of these, 408 patients were presented at the MTB. Molecular-instructed therapy recommendations could be made in 380/408 (93.1%) cases and were prioritized by evidence levels. Therapies were initiated in 86/380 (22.6%) cases until data cutoff. We observed a progression-free survival ratio >1.3 in 31.3% of patients. Conclusions: Our study supports the clinical utility of biomarker-guided therapies for neuro-oncology patients and indicates clinical benefit in a subset of patients. Our data might inform future clinical trials, translational studies, and even clinical care.

Association of hyperglycemia and molecular subclass on survival in IDH-wildtype glioblastoma.

Background: Hyperglycemia has been associated with worse survival in glioblastoma. Attempts to lower glucose yielded mixed responses which could be due to molecularly distinct GBM subclasses. Methods: Clinical, laboratory, and molecular data on 89 IDH-wt GBMs profiled by clinical next-generation sequencing and treated with Stupp protocol were reviewed. IDH-wt GBMs were sub-classified into RTK I (Proneural), RTK II (Classical) and Mesenchymal subtypes using whole-genome DNA methylation. Average glucose was calculated by time-weighting glucose measurements between diagnosis and last follow-up. Results: Patients were stratified into three groups using average glucose: tertile one (<100 mg/dL), tertile two (100-115 mg/dL), and tertile three (>115 mg/dL). Comparison across glucose tertiles revealed no differences in performance status (KPS), dexamethasone dose, MGMT methylation, or methylation subclass. Overall survival (OS) was not affected by methylation subclass (P = .9) but decreased with higher glucose (P = .015). Higher glucose tertiles were associated with poorer OS among RTK I (P = .08) and mesenchymal tumors (P = .05), but not RTK II (P = .99). After controlling for age, KPS, dexamethasone, and MGMT status, glucose remained significantly associated with OS (aHR = 5.2, P = .02). Methylation clustering did not identify unique signatures associated with high or low glucose levels. Metabolomic analysis of 23 tumors showed minimal variation across metabolites without differences between molecular subclasses. Conclusion: Higher average glucose values were associated with poorer OS in RTKI and Mesenchymal IDH-wt GBM, but not RTKII. There were no discernible epigenetic or metabolomic differences between tumors in different glucose environments, suggesting a potential survival benefit to lowering systemic glucose in selected molecular subtypes.

Practical guidance for telemedicine use in neuro-oncology.

While the COVID-19 pandemic has catalyzed the expansion of telemedicine into nearly every specialty of medicine, few articles have summarized current practices and recommendations for integrating virtual care in the practice of neuro-oncology. This article identifies current telemedicine practice, provides practical guidance for conducting telemedicine visits, and generates recommendations for integrating virtual care into neuro-oncology practice. Practical aspects of telemedicine are summarized including when to use and not use telemedicine, how to conduct a virtual visit, who to include in the virtual encounter, unique aspects of telehealth in neuro-oncology, and emerging innovations.

Activity of Adagrasib (MRTX849) in Brain Metastases: Preclinical Models and Clinical Data from Patients with KRASG12C-Mutant Non-Small Cell Lung Cancer.

PURPOSE: Patients with KRAS-mutant non-small cell lung cancer (NSCLC) with brain metastases (BM) have a poor prognosis. Adagrasib (MRTX849), a potent oral small-molecule KRASG12C inhibitor, irreversibly and selectively binds KRASG12C, locking it in its inactive state. Adagrasib has been optimized for favorable pharmacokinetic properties, including long half-life (∼24 hours), extensive tissue distribution, dose-dependent pharmacokinetics, and central nervous system penetration; however, BM-specific antitumor activity of KRASG12C inhibitors remains to be fully characterized. EXPERIMENTAL DESIGN: A retrospective database query identified patients with KRAS-mutant NSCLC to understand their propensity to develop BM. Preclinical studies assessed physiochemical and pharmacokinetic properties of adagrasib. Mice bearing intracranial KRASG12C-mutant NSCLC xenografts (LU99-Luc/H23-Luc/LU65-Luc) were treated with clinically relevant adagrasib doses, and levels of adagrasib in plasma, cerebrospinal fluid (CSF), and brain were determined along with antitumor activity. Preliminary clinical data were collected from 2 patients with NSCLC with untreated BM who had received adagrasib 600 mg twice daily in the phase Ib cohort of the KRYSTAL-1 trial; CSF was collected, adagrasib concentrations measured, and antitumor activity in BM evaluated. RESULTS: Patients with KRAS-mutant NSCLC demonstrated high propensity to develop BM (≥40%). Adagrasib penetrated into CSF and demonstrated tumor regression and extended survival in multiple preclinical BM models. In 2 patients with NSCLC and untreated BM, CSF concentrations of adagrasib measured above the target cellular IC50. Both patients demonstrated corresponding BM regression, supporting potential clinical activity of adagrasib in the brain. CONCLUSIONS: These data support further development of adagrasib in patients with KRASG12C-mutant NSCLC with untreated BM. See related commentary by Kommalapati and Mansfield, p. 3179.

Efficacy of laser interstitial thermal therapy (LITT) for newly diagnosed and recurrent IDH wild-type glioblastoma.

Background: Treatment options for unresectable new and recurrent glioblastoma remain limited. Laser ablation has demonstrated safety as a surgical approach to treating primary brain tumors. The LAANTERN prospective multicenter registry (NCT02392078) data were analyzed to determine clinical outcomes for patients with new and recurrent IDH wild-type glioblastoma. Methods: Demographics, intraprocedural data, adverse events, KPS, health economics, and survival data were prospectively collected and then analyzed on IDH wild-type newly diagnosed and recurrent glioblastoma patients who were treated with laser ablation at 14 US centers between January 2016 and May 2019. Data were monitored for accuracy. Statistical analysis included individual variable summaries, multivariable differences in survival, and median survival numbers. Results: A total of 29 new and 60 recurrent IDH wild-type WHO grade 4 glioblastoma patients were treated. Positive MGMT promoter methylation status was present in 5/29 of new and 23/60 of recurrent patients. Median physician-estimated extent of ablation was 91%-99%. Median overall survival (OS) was 9.73 months (95% confidence interval: 5.16, 15.91) for newly diagnosed patients and median post-procedure survival was 8.97 months (6.94, 12.36) for recurrent patients. Median OS for newly diagnosed patients receiving post-LITT chemo/radiation was 16.14 months (6.11, not reached). Factors associated with improved survival were MGMT promoter methylation, adjuvant chemotherapy within 12 weeks, and tumor volume <3 cc. Conclusions: Laser ablation is a viable option for patients with new and recurrent glioblastoma. Median OS for IDH wild-type newly diagnosed glioblastoma is comparable to outcomes observed in other tumor resection studies when those patients undergo radiation and chemotherapy following LITT.

Neuro-Oncology Practice Clinical Debate: Early treatment or observation for patients with newly diagnosed oligodendroglioma and small-volume residual disease.

Advances in treatment of oligodendroglioma represent arguably the most significant recent development in the treatment of brain tumors, with multiple clinical trials demonstrating that median survival is approximately doubled in patients with World Health Organization grade II and III 1p/19q codeleted gliomas (ie, oligodendrogliomas) treated with procarbazine, lomustine, vincristine chemotherapy and radiation vs radiation alone. However, chemoradiotherapy itself is not without morbidity, including both short-term toxicities primarily related to chemotherapy and longer-term cognitive issues likely due to radiation. Patients and physicians both desire maximally effective therapy with minimal toxicity, and it remains unclear whether some patients with macroscopic residual disease after surgery can safely delay therapy, to avoid or delay toxicity, while simultaneously preserving the full benefits of treatment. In this article, experts in the field discuss the rationale for the approaches of up-front treatment with chemoradiotherapy and initial observation, respectively.

Clinical neuro-oncology for the neurologist.

PURPOSE OF REVIEW: Neuro-oncologic patients are routinely encountered in clinical practice. Neuro-oncology is a rapidly evolving field, so understanding the most classic paradigms and contemporary advances will optimize patient care. RECENT FINDINGS: We discuss the recent reclassification of tumors via molecular characteristics as it applies to direct clinical practice and review the contemporary standard of care for infiltrating gliomas, meningiomas, brain metastases, and CNS lymphoma. SUMMARY: We provide a straightforward primer on neuro-oncology with a focus on the brain tumors most commonly encountered by the adult neurologist and a clear emphasis on clinically relevant points including those which have recently become incorporated into our standard management. We cite key reviews to allow interested readers an opportunity to gain a more comprehensive understanding of specific topics.

Dissecting the immunosuppressive tumor microenvironments in Glioblastoma-on-a-Chip for optimized PD-1 immunotherapy.

Programmed cell death protein-1 (PD-1) checkpoint immunotherapy efficacy remains unpredictable in glioblastoma (GBM) patients due to the genetic heterogeneity and immunosuppressive tumor microenvironments. Here, we report a microfluidics-based, patient-specific 'GBM-on-a-Chip' microphysiological system to dissect the heterogeneity of immunosuppressive tumor microenvironments and optimize anti-PD-1 immunotherapy for different GBM subtypes. Our clinical and experimental analyses demonstrated that molecularly distinct GBM subtypes have distinct epigenetic and immune signatures that may lead to different immunosuppressive mechanisms. The real-time analysis in GBM-on-a-Chip showed that mesenchymal GBM niche attracted low number of allogeneic CD154+CD8+ T-cells but abundant CD163+ tumor-associated macrophages (TAMs), and expressed elevated PD-1/PD-L1 immune checkpoints and TGF-ß1, IL-10, and CSF-1 cytokines compared to proneural GBM. To enhance PD-1 inhibitor nivolumab efficacy, we co-administered a CSF-1R inhibitor BLZ945 to ablate CD163+ M2-TAMs and strengthened CD154+CD8+ T-cell functionality and GBM apoptosis on-chip. Our ex vivo patient-specific GBM-on-a-Chip provides an avenue for a personalized screening of immunotherapies for GBM patients.

Expression profiling of the adhesion G protein-coupled receptor GPR133 (ADGRD1) in glioma subtypes.

BACKGROUND: Glioma is a family of primary brain malignancies with limited treatment options and in need of novel therapies. We previously demonstrated that the adhesion G protein-coupled receptor GPR133 (ADGRD1) is necessary for tumor growth in adult glioblastoma, the most advanced malignancy within the glioma family. However, the expression pattern of GPR133 in other types of adult glioma is unknown. METHODS: We used immunohistochemistry in tumor specimens and non-neoplastic cadaveric brain tissue to profile GPR133 expression in adult gliomas. RESULTS: We show that GPR133 expression increases as a function of WHO grade and peaks in glioblastoma, where all tumors ubiquitously express it. Importantly, GPR133 is expressed within the tumor bulk, as well as in the brain-infiltrating tumor margin. Furthermore, GPR133 is expressed in both isocitrate dehydrogenase (IDH) wild-type and mutant gliomas, albeit at higher levels in IDH wild-type tumors. CONCLUSION: The fact that GPR133 is absent from non-neoplastic brain tissue but de novo expressed in glioma suggests that it may be exploited therapeutically.

Cell Surface Notch Ligand DLL3 is a Therapeutic Target in Isocitrate Dehydrogenase-mutant Glioma.

PURPOSE: Isocitrate dehydrogenase (IDH)-mutant glioma is a distinct glioma molecular subtype for which no effective molecularly directed therapy exists. Low-grade gliomas, which are 80%-90% IDH-mutant, have high RNA levels of the cell surface Notch ligand DLL3. We sought to determine DLL3 expression by IHC in glioma molecular subtypes and the potential efficacy of an anti-DLL3 antibody-drug conjugate (ADC), rovalpituzumab tesirine (Rova-T), in IDH-mutant glioma. EXPERIMENTAL DESIGN: We evaluated DLL3 expression by RNA using TCGA data and by IHC in a discovery set of 63 gliomas and 20 nontumor brain tissues and a validation set of 62 known IDH wild-type and mutant gliomas using a monoclonal anti-DLL3 antibody. Genotype was determined using a DNA methylation array classifier or by sequencing. The effect of Rova-T on patient-derived endogenous IDH-mutant glioma tumorspheres was determined by cell viability assay. RESULTS: Compared to IDH wild-type glioblastoma, IDH-mutant gliomas have significantly higher DLL3 RNA (P < 1 × 10-15) and protein by IHC (P = 0.0014 and P < 4.3 × 10-6 in the discovery and validation set, respectively). DLL3 immunostaining was intense and homogeneous in IDH-mutant gliomas, retained in all recurrent tumors, and detected in only 1 of 20 nontumor brains. Patient-derived IDH-mutant glioma tumorspheres overexpressed DLL3 and were potently sensitive to Rova-T in an antigen-dependent manner. CONCLUSIONS: DLL3 is selectively and homogeneously expressed in IDH-mutant gliomas and can be targeted with Rova-T in patient-derived IDH-mutant glioma tumorspheres. Our findings are potentially immediately translatable and have implications for therapeutic strategies that exploit cell surface tumor-associated antigens.