Response rate and molecular correlates to encorafenib and binimetinib in BRAF-V600E mutant high-grade glioma

PURPOSE

While fewer than 5% of high-grade gliomas (HGG) are BRAF-V600E mutated, these tumors are notable as BRAF-targeted therapy shows efficacy for some populations. The purpose of this study was to evaluate response to the combination of encorafenib with binimetinib in adults with recurrent BRAF-V600 mutated HGG.

PATIENTS AND METHODS

In this phase 2, open-label, Adult Brain Tumor Consortium (ABTC) trial (NCT03973918), encorafenib and binimetinib were administered at their FDA-approved doses continuously in 28-day cycles. Eligible patients were required to have high-grade glioma or glioblastoma with a BRAF-V600E alteration that was recurrent following at least one line of therapy including radiation.

RESULTS

Five patients enrolled between January 2020 and administrative termination in November 2021 (due to closure of the ABTC). Enrolled patients received treatment for 2-40 months; currently one patient remains on treatment. Centrally determined radiographic response rate was 60%, with one complete response and two partial responses. Methylation profiling revealed all tumors cluster most closely with anaplastic PXA. Transcriptional profile for MAPK-response signature was similar across all tumors at baseline and did not correlate with response in this small population. Circulating tumor DNA measured in plasma samples prior to treatment, during response, and upon progression showed feasibility of detection for the BRAF-V600E alteration. No new safety signal was detected.

CONCLUSIONS

Encorafenib and binimetinib exhibit positive tumor responses in patients with recurrent BRAF-V600E mutant HGG in this small series, warranting therapeutic consideration. Although toxicity remains a concern for BRAF-targeted therapies, no new safety signal was observed in these patients.

Adoptive cell therapy for high grade gliomas using simultaneous temozolomide and intracranial mgmt-modified γδ t cells following standard post-resection chemotherapy and radiotherapy: current strategy and future directions

Cellular therapies, including chimeric antigen receptor T cell therapies (CAR-T), while generally successful in hematologic malignancies, face substantial challenges against solid tumors such as glioblastoma (GBM) due to rapid growth, antigen heterogeneity, and inadequate depth of response to cytoreductive and immune therapies, We have previously shown that GBM constitutively express stress associated NKG2D ligands (NKG2DL) recognized by gamma delta (γδ) T cells, a minor lymphocyte subset that innately recognize target molecules via the γδ T cell receptor (TCR), NKG2D, and multiple other mechanisms. Given that NKG2DL expression is often insufficient on GBM cells to elicit a meaningful response to γδ T cell immunotherapy, we then demonstrated that NKG2DL expression can be transiently upregulated by activation of the DNA damage response (DDR) pathway using alkylating agents such as Temozolomide (TMZ). TMZ, however, is also toxic to γδ T cells. Using a p140K/MGMT lentivector, which confers resistance to TMZ by expression of O(6)-methylguanine-DNA-methyltransferase (MGMT), we genetically engineered γδ T cells that maintain full effector function in the presence of therapeutic doses of TMZ. We then validated a therapeutic system that we termed Drug Resistance Immunotherapy (DRI) that combines a standard regimen of TMZ concomitantly with simultaneous intracranial infusion of TMZ-resistant γδ T cells in a first-in-human Phase I clinical trial (NCT04165941). This manuscript will discuss DRI as a rational therapeutic approach to newly diagnosed GBM and the importance of repeated administration of DRI in combination with the standard-of-care Stupp regimen in patients with stable minimal residual disease.

Clinical trials of R-(-)-gossypol (AT-101) in newly diagnosed and recurrent glioblastoma: NABTT 0602 and NABTT 0702

PURPOSE

AT-101 is an oral bcl-2 family protein inhibitor (Bcl-2, Bcl-XL, Mcl-1, Bcl-W) and potent inducer of proapoptotic proteins. A prior study of the parent compound, racemic gossypol, demonstrated objective and durable responses in patients with malignant glioma. AT-101 has demonstrated synergy with radiation in animal models. The objectives of trial NABTT 0602 were to determine the MTD of AT-101 concurrent with temozolomide (TMZ) and radiation therapy (RT) (Arm I) and to determine the MTD of AT-101 when given with adjuvant TMZ after completion of standard chemoradiation (Arm 2). Separately in trial NABTT 0702, the survival and response rates of single agent AT-101 were evaluated in patients with recurrent glioblastoma.

METHODS

In NABTT 0602 Phase I, a 3+3 design was used to define MTDs after maximal safe resection, patients with newly diagnosed glioblastoma received standard concurrent RT (60 Gy) and TMZ 75 mg/m2/day followed by adjuvant TMZ 150-200 mg/m2 days 1-5 in 28-day cycles (Stupp regimen). In Arm I, AT-101 was administered M-F during the six weeks of RT beginning 20 mg qd. In Arm 2, concurrent with each adjuvant cycle of TMZ, AT-101 was administered at a starting dose of 20 mg, days 1-21 followed by 7-day break for a maximum of 6 cycles. The PK blood samples were collected in the first three patients in each cohort of arm 1. In NABTT 0702 patients with recurrent glioblastoma received 20 mg p.o. per day for 21 of 28 days in repeated cycles to assess overall survival (OS).

RESULTS

A total of sixteen patients were enrolled on the two study arms of NABTT 0602. In Arm 1 AT-101 was escalated from 20 to 30 mg where one of six patients experienced DLT (grade 3 GI ulcer). On Arm 2 one patient treated at 20 mg experienced DLT (grade 3 ileus, nausea and diarrhea). The cohort was expanded to include seven patients without observation of DLT. PK results were consistent with drug levels from non-CNS studies. At study closure six patients are still alive. The median survival times for Arm I and Arm II are 15.2 months and 18.2 months, respectively. In NABTT 0702 fifty-six patients were enrolled and forty-three were eligible for imaging response. Sixteen patients (29%) had stable disease as best response and one partial response was observed. The median OS with single agent AT-101 was 5.7 months (95%CI: 3.8-7.6 months) for patients with rGBM.

CONCLUSIONS

AT-101 can be safely administered with radiation therapy and TMZ in patients with newly diagnosed glioblastoma without toxicity unique to patients with CNS tumors. Because of toxicity observed in non-CNS AT-101 clinical trials, further dose-escalation was not attempted. The recommended dose for future studies that utilize continual AT-101 exposure is 20 mg days M-F concurrent with RT/TMZ and 20 mg days 1-21 for each 28-day cycle of TMZ. AT-101 has limited activity as a single agent in unselected patients with recurrent glioblastoma. Future trials should attempt to better understand resistance mechanisms and consider combination therapy.

Phase 1 trial of TPI 287, a microtubule stabilizing agent, in combination with bevacizumab in adults with recurrent glioblastoma

Background

Recurrent glioblastoma (rGBM) has limited treatment options. This phase 1 protocol was designed to study the safety and preliminary efficacy of TPI 287, a central nervous system penetrant microtubule stabilizer, in combination with bevacizumab (BEV) for the treatment of rGBM.

Methods

GBM patients with up to 2 prior relapses without prior exposure to anti-angiogenic therapy were eligible. A standard 3 + 3 design was utilized to determine the maximum tolerated dose (MTD) of TPI 287. Cohorts received TPI 287 at 140-220 mg/m2 every 3 weeks and BEV 10 mg/kg every 2 weeks during 6-week cycles. An MRI was performed after each cycle, and treatment continued until progression as determined via response assessment in neuro-oncology criteria.

Results

Twenty-four patients were enrolled at 6 centers. Treatment was generally well tolerated. Fatigue, myelosuppression, and peripheral neuropathy were the most common treatment emergent adverse events. Dose-limiting toxicity was not observed, thus the MTD was not determined. Twenty-three patients were evaluable for median and 6-month progression-free survival, which were 5.5 months (mo) and 40%, respectively. Median and 12-month overall survival were 13.4 mo and 64%, respectively. The optimal phase 2 dose was determined to be 200 mg/m2.

Conclusions

TPI 287 can be safely combined with BEV for the treatment of rGBM and preliminary efficacy supports further investigation of this combination.

Undesired impact of iron supplement on MRI assessment of post-treatment glioblastoma

Glioblastoma (GBM) is the most common malignant adult brain and has a poor prognosis. Routine post-treatment MRI evaluations are required to assess treatment response and disease progression. We present a case of an 83-year-old female who underwent MRI assessment of post-treatment GBM after intravenous iron replacement therapy, ferumoxytol. The brain MRI revealed unintended alteration of MRI signal characteristics from the iron containing agent which confounded diagnostic interpretation and subsequently, the treatment planning. Ferumoxytol injection prior to contrast enhanced MRI must be screened in post-treatment GBM patients to accurately evaluate tumor activity.

Abstract 1173: Maintenance-phase Temozolomide as a lymphodepletion platform for intracranialadoptiveγδ T cell-basedtherapy in primary high-grade gliomas

Introduction: Lymphodepletion is a key factor for responses in both autologous and allogeneic cell therapies. We are currently evaluating in a Phase I trial, the combination of Temozolomide (TMZ) chemotherapy with methylguanine-DNA methyltransferase (MGMT) modified γδ T cells (Drug Resistant Immunotherapy, or DRI) during maintenance TMZ in patients receiving the Stupp protocol. In this report, we examine both DRI graft and circulating lymphocyte phenotype and function during the treatment phase.

Methods: Patients meeting enrollment criteria undergo tumor resection, placement of a Rickham catheter in the tumor cavity, and an apheresis collection immediately prior to standard chemoradiotherapy (CRT). DRI follows TMZ on Day 1 of maintenance and consists of 150mg/m2 IV TMZ and concurrent intracranial injection of 1.0 x 107 DRI γδT cells. Peripheral blood (PB) was collected at apheresis and immediately prior to the start of each 28-day maintenance cycle. Flow cytometric (FACS) analysis of PB and DRI grafts using antibodies to CD3, CD4, CD8, CD16/56, CD19, TCR-γδ, Vδ1, Vδ2, CD197, CD27, CD28, CD57, CD45RA, Th1/Th2/Th17 PB serum cytokines, and DRI cytotoxic graft function were obtained. When applicable, FFPE sections of recurrent resected GBM tissues were examined for immune infiltration.

Results: DRI grafts contained 74-93% activated γδ T cells with 0.3-0.5 MGMT copies/cell. Cytotoxicity against K562 ranged from 30% to 75% at 40:1 (E:T). Peripheral lymphodepletion was evident throughout TMZ treatment in the Stupp protocol. T cell counts fell precipitously after CRT and cycle 1 (1647+774 vs 609+214 cells/mL) and remained low throughout maintenance phase (range 214-1450 T cells/mL). NK counts remained normal and showed uneven recovery through the first three cycles but failed to recover for the remainder of maintenance phase. γδ T cells also recovered modestly through the first two cycles but failed to recover after additional cycles. Interestingly, CD45RA+CD27- effector T cells showed only slight increases for each patient throughout TMZ maintenance. Cytokine analysis did not show a clear trend except for consistent T cell expression of perforin and IP-10. One patient with recurrent GBM was successfully resected 110d following DRI. Histopathology revealed widespread necrosis with significant infiltration of CD4+ and CD8+ T cells and γδ T cells in the tumor parenchyma.

Conclusions: Standard of care TMZ is lymphodepleting and DRI therapy can be conducted in an environment favorable to T cell persistence and sustained immune response. One treated patient demonstrated infiltration of both αβ and γδ T cells 110 days following a single dose of DRI γδ T cells. TMZ maintenance during the Stupp regimen prolongs lymphodepletion, thereby presenting a favorable setting for adoptive cell therapy.

Citation Format: Lawrence S. Lamb, Lei Ding, Ryan C. Miller, Mariska ter Haak, Caitlyn Lucas, Becca Weekley, Samantha Youngblood, Cathy Langford, Guoling Chen, Louis B. Nabors. Maintenance-phase Temozolomide as a lymphodepletion platform for intracranialadoptiveγδ T cell-basedtherapy in primary high-grade gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1173.

Phase I study of drug-resistant immunotherapy (DRI) with gene-modified autologous γδ T cells in patients with newly diagnosed glioblastoma multiforme (GBM) receiving maintenance temozolomide (TMZ)

2044

Background: γδ T cells, MHC unrestricted immune cells, target NKG2D ligands differentially expressed on tumor cells. DeltEx drug resistant immunotherapy (DRI), a novel ex vivo expanded, activated γδ T cell expresses MGMT, conveying TMZ resistance. NCT04165941 , a phase 1 trial assessing the safety of single and multiple infusions of autologous DeltEx DRI cells presents updated safety and efficacy data. Methods: Adult newly diagnosed GBM patients with adequate organ function and KPS≥70% are enrolled. Cells engineered from apheresis after tumor resection were infused through a Rickham catheter placed during surgery. Cohort (C) 1, 2 and 3 receive 1, 3 and 6 doses of cells respectively on day (D) 1 of each 28-day maintenance cycle. Patients receive 1 x 107 γδ T cells intratumorally on D1 with 150 mg/m2 of TMZ intravenously with the Stupp regimen. Primary endpoint is safety; secondary endpoints include progression free and overall survival. Immunologic and genomic correlative analyses are being conducted. Dose limiting toxicities (DLTs) are defined as treatment related ≥ grade 3 cardiopulmonary or hepatic toxicity, grade 4 toxicity exceeding 72 hours or neurologic deterioration that exceeds 2 weeks. Results: 12 patients (58% male; median age 66.5 (range: 21-76); 66.7% IDH-WT, 66.7% MGMT unmethylated) were enrolled with 6 dosed (3 in C1, 3 in C2). No patients had DLTs, cytokine release syndrome (CRS), or neurotoxicity. The most common adverse events (AEs) were Grade 1/2 events including fever, leukopenia, nausea, and vomiting attributable to TMZ or radiotherapy. One subject had Grade 3 treatment related AEs of UTI, dehydration, and thrombocytopenia. Three evaluable C1 patients have PFS of 8.3, 11.9, 7.4 months and OS of 15.6, 17.7 and 9.6 months respectively. In C2, three patients have been dosed, with one patient with stable disease at 8.2 months after receiving all three doses and no DLTs. Patient recruitment continues with anticipated completion in 2022. Conclusions: Data demonstrates that single, repeat doses of DRI T cells have manageable toxicity with encouraging trend in PFS.

Prognostic significance of therapy-induced myelosuppression in newly diagnosed glioblastoma

2055

Background: Myelosuppression is the major toxicity encountered during temozolomide chemoradiotherapy for newly diagnosed glioblastoma. Methods: We assessed the association of myelosuppression (neutropenia, thrombocytopenia, anemia, lymphopenia) during temozolomide chemoradiotherapy alone or in combination with experimental agents with progression-free survival (PFS) or overall survival (OS) in 2073 patients with newly diagnosed glioblastoma enrolled into five clinical trials: CENTRIC, CORE, EORTC 26082, AVAglio, and EORTC 26981. A landmark analysis approached was used. For each primary association analysis, a significance level of 1.7% was used. Results: Lower neutrophil counts at baseline were associated with better PFS (p = 0.011) and OS (p < 0.001), independently of steroid intake. Females experienced uniformly more myelotoxicity than males. Lymphopenia during concomitant chemoradiotherapy was associated with OS (p = 0.009): low-grade (1-2) lymphopenia might be associated with superior OS (HR 0.78, 98.3% CI 0.58-1.06) whereas high-grade (3-4) lymphopenia might be associated with inferior OS (HR 1.08, 98.3% CI 0.75-1.54). There were no associations of altered hematological parameters during concomitant chemoradiotherapy with PFS. During maintenance chemoradiotherapy, no significant association was found between any parameter of myelosuppression and PFS or OS, although exploratory analysis at 5% significance level indicated that either mild-to-moderate (HR 0.76, 95% CI 0.62-0.93) or high-grade lymphopenia (HR 0.65, 95% CI 0.46-0.92) were associated with superior OS (p = 0.013), but not PFS. Conclusions: The association of higher neutrophil counts at baseline with inferior PFS and OS requires further prospective evaluation. The link of therapy-induced lymphopenia to better outcome may guide the design for immunotherapy trials in newly diagnosed glioblastoma.

Feasibility and conduct of INSIGhT, a platform trial of patients with glioblastoma using Bayesian adaptive randomization

2012

Background: Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial is a phase II platform trial using response adaptive randomization and deep genomic profiling to more efficiently test experimental agents in MGMT unmethylated glioblastoma and potentially accelerate identification of novel therapies for phase III testing. We report on the feasibility and conduct of this approach. Methods: Tumor genotyping was performed prior to treatment assignment on eligible participants with newly diagnosed MGMT-unmethylated glioblastoma to identify biomarker signatures. Initial randomization was 1:1:1:1 between control (temozolomide) and 3 experimental arms (abemaciclib, CC-115, and neratinib). Subsequent randomization was adapted based on Bayesian estimation of biomarker-naïve and biomarker-specific probabilities of treatment impact on progression-free survival (PFS). Ineffective or toxic arms were discontinued by protocol amendment. The primary endpoint was overall survival (OS). Results: INSIGhT randomized 71 patients to the control arm, 73 patients to the abemaciclib arm, 12 patients to the CC-115 arm, and 81 patients to the neratinib arm between 2/9/2017 and 5/14/2021. Following the initial equal randomization period, early data were repeatedly analyzed during the study to capture early signals of treatment effects across the enrolled population or in specific biomarker subgroups. The results of these interim analyses influenced the randomization probability for future enrolled patients. In total, 77% of the participants were randomized before assessing their biomarker profile and 23% were biomarker randomized. The CC-115 arm opened and closed three times during the safety lead-in. The randomization probability to the CC-115 arm decreased based on poor early PFS results and the arm eventually closed after 12 patients due to toxicity. The randomization probability to the abemacicilb arm increased based on promising early PFS results. After the completion of accrual into the abemaciclib arm, the trial switched to block randomization to finish enrolling into the remaining neratinib and control arms. A total of 28 interim analyses and 32 randomization tables were created throughout the course of the trial with 4 adjustments (3 due to CC-115 closures and 1 due to completion of the abemaciclib arm). Biomarker association trends for neratinib and abemaciclib were similar to those seen in preclinical modeling of the trial. Conclusions: Relative to a standard randomization design, the adaptive platform design facilitated more efficient and economical testing of experimental arms by sharing a control arm, decreasing the probability of enrollment to potentially ineffective arms, and increasing the probability of enrollment to potentially effective arms. Additional future arms are planned on INSIGhT. Clinical trial information: NCT02977780.

The versatile role of HuR in Glioblastoma and its potential as a therapeutic target for a multi-pronged attack

Glioblastoma (GBM) is a malignant and aggressive brain tumor with a median survival of ∼15 months. Resistance to treatment arises from the extensive cellular and molecular heterogeneity in the three major components: glioma tumor cells, glioma stem cells, and tumor-associated microglia and macrophages. Within this triad, there is a complex network of intrinsic and secreted factors that promote classic hallmarks of cancer, including angiogenesis, resistance to cell death, proliferation, and immune evasion. A regulatory node connecting these diverse pathways is at the posttranscriptional level as mRNAs encoding many of the key drivers contain adenine- and uridine rich elements (ARE) in the 3' untranslated region. Human antigen R (HuR) binds to ARE-bearing mRNAs and is a major positive regulator at this level. This review focuses on basic concepts of ARE-mediated RNA regulation and how targeting HuR with small molecule inhibitors represents a plausible strategy for a multi-pronged therapeutic attack on GBM.

Routine use of low-dose glucarpidase following high-dose methotrexate in adult patients with CNS lymphoma: an open-label, multi-center phase I study

Background

High-dose methotrexate (HD-MTX) has broad use in the treatment of central nervous system (CNS) malignancies but confers significant toxicity without inpatient hydration and monitoring. Glucarpidase is a bacterial recombinant enzyme dosed at 50 units (u)/kg, resulting in rapid systemic MTX clearance. The aim of this study was to demonstrate feasibility of low-dose glucarpidase to facilitate MTX clearance in patients with CNS lymphoma (CNSL).

Methods

Eight CNSL patients received HD-MTX 3 or 6 g/m² and glucarpidase 2000 or 1000u 24 h later. Treatments repeated every 2 weeks up to 8 cycles.

Results

Fifty-five treatments were administered. Glucarpidase 2000u yielded > 95% reduction in plasma MTX within 15 min following 33/34 doses (97.1%) and glucarpidase 1000u yielded > 95% reduction following 15/20 doses (75%). Anti-glucarpidase antibodies developed in 4 patients and were associated with MTX rebound. In CSF, glucarpidase was not detected and MTX levels remained cytotoxic after 1 (3299.5 nmol/L, n = 8) and 6 h (1254.7 nmol/L, n = 7). Treatment was safe and well-tolerated. Radiographic responses in 6 of 8 patients (75%) were as expected following MTX-based therapy.

Conclusions

This study demonstrates feasibility of planned-use low-dose glucarpidase for MTX clearance and supports the hypothesis that glucarpidase does not impact MTX efficacy in the CNS.

Clinical trial registration

NCT03684980 (Registration date 26/09/2018).

Multimodal platform for assessing drug distribution and response in clinical trials

BACKGROUND

Response to targeted therapy varies between patients for largely unknown reasons. Here, we developed and applied an integrative platform using mass spectrometry imaging (MSI), phosphoproteomics, and multiplexed tissue imaging for mapping drug distribution, target engagement, and adaptive response to gain insights into heterogeneous response to therapy.

METHODS

Patient-derived xenograft (PDX) lines of glioblastoma were treated with adavosertib, a Wee1 inhibitor, and tissue drug distribution was measured with MALDI-MSI. Phosphoproteomics was measured in the same tumors to identify biomarkers of drug target engagement and cellular adaptive response. Multiplexed tissue imaging was performed on sister sections to evaluate spatial co-localization of drug and cellular response. The integrated platform was then applied on clinical specimens from glioblastoma patients enrolled in the phase 1 clinical trial.

RESULTS

PDX tumors exposed to different doses of adavosertib revealed intra- and inter-tumoral heterogeneity of drug distribution and integration of the heterogeneous drug distribution with phosphoproteomics and multiplexed tissue imaging revealed new markers of molecular response to adavosertib. Analysis of paired clinical specimens from patients enrolled in the phase 1 clinical trial informed the translational potential of the identified biomarkers in studying patient's response to adavosertib.

CONCLUSIONS

The multimodal platform identified a signature of drug efficacy and patient-specific adaptive responses applicable to preclinical and clinical drug development. The information generated by the approach may inform mechanisms of success and failure in future early phase clinical trials, providing information for optimizing clinical trial design and guiding future application into clinical practice.

Prospective biomarker study in newly diagnosed glioblastoma: Cyto-C clinical trial

Background

Glioblastoma (GBM) has a 5-year survival rate of 3%-5%. GBM treatment includes maximal resection followed by radiotherapy with concomitant and adjuvant temozolomide (TMZ). Cytochrome C oxidase (CcO) is a mitochondrial enzyme involved in the mechanism of resistance to TMZ. In a prior retrospective trial, CcO activity in GBMs inversely correlated with clinical outcome. The current Cyto-C study was designed to prospectively evaluate and validate the prognostic value of tumor CcO activity in patients with newly diagnosed primary GBM, and compared to the known prognostic value of MGMT promoter methylation status.

Methods

This multi-institutional, blinded, prospective biomarker study enrolled 152 patients with newly diagnosed GBM who were to undergo surgical resection and would be candidates for standard of care. The primary end point was overall survival (OS) time, and the secondary end point was progression-free survival (PFS) time. Tumor CcO activity and MGMT promoter methylation status were assayed in a centralized laboratory.

Results

OS and PFS did not differ by high or low tumor CcO activity, and the prognostic validity of MGMT promoter methylation was confirmed. Notably, a planned exploratory analysis suggested that the combination of low CcO activity and MGMT promoter methylation in tumors may be predictive of long-term survival.

Conclusions

Tumor CcO activity alone was not confirmed as a prognostic marker in GBM patients. However, the combination of low CcO activity and methylated MGMT promoter may reveal a subgroup of GBM patients with improved long-term survival that warrants further evaluation. Our work also demonstrates the importance of performing large, multi-institutional, prospective studies to validate biomarkers. We also discuss lessons learned in assembling such studies.

The 1994 National Cancer Institute’s strategy to fund multi-institutional, multidisciplinary consortia to design and conduct early phase clinical trials in patients with high grade gliomas

2003

Background: : In the early 1990’s, the NCI suspended activities of the Brain Tumor Study Group seeking to shift clinical brain tumor research from phase III trials to innovative and correlative rich phase I/II studies. In 1994, NCI funded three early phase brain tumor consortia, later reduced to two consortia in 1999 and one in 2009. In 2020, the NCI announced it would discontinue funding the brain tumor consortium and emphasize pre-clinical glioblastoma drug development (RFA-CA-20-047). Methods: The activities of the New Approaches to Brain Tumor Therapy (NABTT: 1994-2009) and Adult Brain Tumor Consortium (ABTC: 2009-2021) were summarized using data from the Central Operations Office that served the consortia for 27 years. Results: From 1994-2020, 48 consortium meetings were held to discuss, develop, conduct, and evaluate early phase clinical trials. These involved multidisciplinary brain tumor experts (neuro-oncologists, neurosurgeons, radiation oncologists, neuropathologists, statisticians, pharmacologists, imaging experts, immunologists, etc) from 27 US academic centers and hospitals. 85 clinical trials were written, approved by NCI and the Brain Malignancy Steering Committee, and conducted. Most trials evaluated NCI-provided therapeutic agents. 34 trials were conducted in collaboration with 27 pharmaceutical companies eager to develop malignant brain tumor therapeutics; for 9 of these the consortia held the IND. 4870 patients were accrued: 3375 to therapeutic and 1495 to non-therapeutic studies. 49 grant proposals were submitted to fund consortium activities with a 46% approval rate. 91 peer reviewed manuscripts were published, with 174 presentations and abstracts. 18 pharmaceutical symposia were conducted to attract new agents toward early phase brain tumor research. Consortia sponsored 34 Guest Lectureships and multidisciplinary symposia to focus on relevant critical research areas. Additionally, the consortia provided unique opportunities for young faculty to lead multicenter NABTT/ABTC trials with appropriate support and mentorship. Conclusions: Therapeutic progress for high grade gliomas has been slow for many reasons (95% of systemically administered agents do not penetrate the blood-brain barrier, inherent treatment resistance, immunologically “cold” phenotype, etc). NABTT/ABTC focused multidisciplinary, multi-institutional experts on major challenges unique to brain tumor research. The consortia developed innovative early phase clinical studies rich in correlative endpoints, fostered research grants, hosted relevant topical symposia, and provided leadership roles for young investigators while bringing together the NCI, industry, and committed multidisciplinary academicians to explore novel therapeutic options for patients with primary brain tumors.

Preliminary results of the abemaciclib arm in the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT): A phase II platform trial using Bayesian adaptive randomization

2014

Background: The cyclin D-CDK4/6-Rb pathway is activated in most glioblastomas. Abemaciclib is a potent CDK4/6 inhibitor with good brain penetration approved for HR+/HER2- breast cancer. In order to efficiently evaluate the potential impact of abemaciclib on overall survival (OS) in newly diagnosed glioblastoma and to simultaneously develop information regarding potential genomic biomarker associations, abemaciclib was included as an arm on the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial. INSIGhT is a phase II platform trial using response adaptive randomization and deep genomic profiling to more efficiently test experimental agents in MGMT unmethylated glioblastoma and potentially accelerate identification of novel therapies for phase III testing. Initial randomization was equal between abemaciclib, control, and two other experimental arms but subsequent randomization was adapted based on efficacy as determined by progression-free survival (PFS). Ineffective arms were discontinued and new arms added by protocol amendment. We report preliminary results for the abemaciclib arm which has completed accrual. Methods: Patients with newly diagnosed MGMT-unmethylated glioblastoma were randomized to receive either radiotherapy with concomitant and adjuvant temozolomide at standard doses or standard radiochemotherapy followed by adjuvant abemaciclib (150-200 mg orally BID). Treatment continued until progression or development of unacceptable toxicities. The primary endpoint was OS which was assessed using the log-rank test estimated via the Kaplan Meier method using a type I error of 5%. The hazard ratio (HR) was estimated using a cox proportional hazards model. Association between abemaciclib efficacy and cyclin D-CDK4/6-Rb pathway genomic alterations was also investigated. Results: There were 142 patients (69 control; 73 treated with abemaciclib). Abemaciclib was generally well-tolerated with no new toxicity signals identified. PFS was significantly longer (HR 0.67; p = 0.03, logrank test) with abemaciclib (median 6.54 months) compared to the control arm (median 5.88 months). For patients with activation of the CDK4 pathway the PFS HR was 0.64 (p-value = 0.04). However, there was no significant improvement in overall survival (HR 0.9; p-value > 0.05) between abemaciclib (median 15.5) compared to the control arm (median 15.5). Conclusions: Abemaciclib was well-tolerated and prolonged PFS but there is no evidence of an overall survival improvement compared to standard radiochemotherapy. Clinical trial information: NCT02977780.

Digital measurement of functional status of patients with glioblastoma

2016

Background: Among the primary aims of new therapies for glioblastoma (GBM) are the reduction of morbidity and restoration or preservation of quality of life (QoL). Selinexor (SEL) is a first-in class, oral, selective inhibitor of nuclear export which blocks exportin 1 (XPO1), forcing the nuclear retention and reactivation of tumor suppressor proteins, ultimately causing cell death in cancer cells. SEL is approved for the treatment of previously treated multiple myeloma and DLBCL. XPORT-GBM-029 (NCT04421378) is a phase 1 dose finding study followed by an open-label randomized phase 2, 3-arm trial to evaluate SEL in combination with standard therapies for newly diagnosed and recurrent GBM: Arm A (ndGBM, uMGMT) – radiation +/- SEL; Arm B (ndGBM, mMGMT) – radiation and temozolomide +/- SEL; Arm C (rGBM) – lomustine +/- SEL at first relapse. We look to identify sensitive, reliable, and clinically meaningful digital assessments of the functional status of ndGBM and rGBM patients via a patient-centric approach. Methods: XPORT-GBM-029 incorporates standard clinical and imaging evaluations of GBM progression with novel digital tools that objectively measure motor and cognitive function. The study is conducted at 50 sites globally with the aim of enrolling 350 patients with newly diagnosed and recurrent GBM. Following discussions with KOLs and patient advocacy partners at EndbrainCancer, we surveyed GBM patients and their caregivers to identify disease manifestations critical to patients’ QoL. The survey revealed four key areas impacting patients’ QoL that can be affected by GBM therapies and can be objectively monitored: cognitive function, lateralization, fatigue, and sleep. In this trial we use objective measurements to evaluate SEL’s effects on GBM patients’ QoL. Patients wear inertial sensors to measure their activity and sleep and complete a cognitive battery at baseline and before each MRI. Results: Associations between objective digital measures of activity, gait, fatigue, sleep, and cognition will be examined with respect to clinical assessments including physical examinations, modified Response Assessment in Neuro-Oncology (mRANO), Neurologic Assessment in Neuro-Oncology (NANO), Karnofsky Performance Score (KPS) and Patient Reported Outcome (PRO) QoL questionnaires. Descriptive summary statistics and plots are employed in exploratory data analysis, and other advanced data mining methods may also be considered. Conclusions: XPORT-GBM-029 trial is probably the first large, prospective, longitudinal study in GBM patients employing digital markers and may provide useful information regarding the utility of wearable and mobile devices for measuring functional outcomes in clinical trials. Clinical trial information: NCT04421378.

Phase 1 trial of drug resistant immunotherapy: A first-in-class combination of MGMT-modified γδ t cells and temozolomide chemotherapy in newly diagnosed glioblastoma

2057

Background: Temozolomide (TMZ) transiently upregulates NKG2D ligands targeted by innate immune effector cells. Lymphodepletion impairs this immune response, however, genetic modification of ex vivo expanded γδ T cells with an MGMT-expressing lentivector confers resistance to TMZ, allowing concurrent chemotherapy and γδ T cell infusion, thereby targeting the tumor when NKG2DL are maximally expressed. This Drug Resistant Immunotherapy (DRI) is currently being evaluated in a Phase 1 first in human study (NCT04165941) and interim safety and biologic correlative analysis are detailed here for the first dosing cohort. Methods: Adults with newly diagnosed, untreated glioblastoma (GBM), adequate organ function, and a KPS≥70% will be enrolled. Subjects undergo subtotal resection and placement of a Rickham reservoir followed 3-4 weeks by apheresis from which γδ T cells are expanded, transduced with an MGMT-expressing lentivector, harvested, and cryopreserved. Standard of care induction TMZ/radiation therapy is initiated followed by 6 cycles of maintenance TMZ. Intravenous TMZ (150mg/m2) and intracranial dosing of 1 x 107 γδ T cells occur on day 1 of each maintenance cycle. Daily oral TMZ 150mg/m2 follows for Days 2-5. Dose level 1 (DL1) subjects receive 1 fixed dose of γδ T cells and DL2 receive 3 doses administered on Day 1 of each of first 3 cycles of TMZ dependent on absence of dose limiting toxicity. Primary endpoint is safety; secondary endpoints include progression free and overall survival. Immunologic and genomic correlative analyses are being conducted at specific time points from peripheral blood and cerebral spinal fluid collected from the Rickham. Results: Six subjects (4 females, 2 males) have been enrolled in DL1. All subjects were IDH1-WT with 5 subjects MGMT unmethylated and 1 methylated. Of these, 1 generated inadequate gd T cells and 2 withdrew consent prior to DRI treatment. For the 3 that received DRI, treatment-related adverse events with maximum CTCAE Grade 3 occurred in 1 subject; UTI, dehydration, and thrombocytopenia. The most common Grade 1/2 events included: fever, leukopenia, nausea, and vomiting which were attributable to TMZ or radiotherapy. Circulating T cells remained below normal range throughout maintenance phase in 2/3 subjects. NK and gd T cell numbers remained within low normal range for 3/3 and 2/3 subjects, respectively. Serum Th1 (IFNg, IL-2, TNFa) and Th2 (IL4, IL5, IL-10) cytokines were within clinical range although TNFa remained elevated from the gdT cell infusion through day +30 in 2 subjects. Conclusions: Administration of MGMT-gene modified gdT cells and TMZ as DRI is feasible in lymphodepleted subjects during TMZ maintenance phase and sufficiently safe to warrant further investigation at additional doses. Clinical trial information: NCT04165941.

Evaluating the benefit of adaptive randomization in the CC-115 arm of the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT): A phase II randomized Bayesian adaptive platform trial in newly diagnosed MGMT unmethylated glioblastoma

2006

Background: Adaptive randomization adjusts enrollment rates based upon early trial results, which can allow for decreased enrollment for therapies less likely to meet the primary endpoint of a trial. CC-115, a CNS-penetrant, oral inhibitor of mammalian target of rapamycin kinase (mTOR) and deoxyribonucleic acid-dependent protein kinase (DNA-PK), was evaluated in the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial. As CC-115 was discontinued due to concerns about toxicity and unfavorable risk-to-benefit ratio, we sought to investigate the impact of adaptive randomization in its testing. Methods: In INSIGhT, adults with newly diagnosed MGMT-unmethylated glioblastoma and available genomic data are adaptively randomized to an experimental arm or the control arm of standard radiotherapy with concurrent and adjuvant temozolomide. Patients randomized to CC-115 received it (10mg po BID) with radiotherapy and as adjuvant monotherapy, and a safety lead-in 3+3 design was used for this arm. By simulating the INSIGhT trial with standard uniform randomization, we estimated the reduction of enrollment rate and sample size of the CC-115 arm that was attributable to adaptive randomization. Results: Twelve patients were randomized to CC-115; 58% (n = 7) patients had possible treatment-related CTCAE grade > 3 toxicity. Compared to the control arm, there was no significant difference in progression-free survival (PFS, HR 0.66, 95% CI 0.32-1.36, p = 0.3) or overall survival (OS, HR 0.93, 95% CI 0.43-2.03, p = 0.8). Based on early PFS results, randomization probability to CC-115 decreased from 25% to 16%. At the time of the CC-115 arm closure, 14% of enrolled INSIGhT patients had been randomized to this arm. Compared to average expected enrollment by standard randomization, the use of adaptive randomization decreased the number of patients randomized to CC-115 by 50% (12 patients vs. 18 patients [95% CI 11-25 patients]). Conclusions: The INSIGhT trial, designed with adaptive randomization, facilitated more efficient testing of CC-115 and decreased the number of patients allocated to the CC-115 arm relative to a standard randomization design. Clinical trial information: NCT02977780.

Targeting the HuR Oncogenic Role with a New Class of Cytoplasmic Dimerization Inhibitors

The development of novel therapeutics that exploit alterations in the activation state of key cellular signaling pathways due to mutations in upstream regulators has generated the field of personalized medicine. These first-generation efforts have focused on actionable mutations identified by deep sequencing of large numbers of tumor samples. We propose that a second-generation opportunity exists by exploiting key downstream "nodes of control" that contribute to oncogenesis and are inappropriately activated due to loss of upstream regulation and microenvironmental influences. The RNA-binding protein HuR represents such a node. Because HuR functionality in cancer cells is dependent on HuR dimerization and its nuclear/cytoplasmic shuttling, we developed a new class of molecules targeting HuR protein dimerization. A structure-activity relationship algorithm enabled development of inhibitors of HuR multimer formation that were soluble, had micromolar activity, and penetrated the blood-brain barrier. These inhibitors were evaluated for activity validation and specificity in a robust cell-based assay of HuR dimerization. SRI-42127, a molecule that met these criteria, inhibited HuR multimer formation across primary patient-derived glioblastoma xenolines (PDGx), leading to arrest of proliferation, induction of apoptosis, and inhibition of colony formation. SRI-42127 had favorable attributes with central nervous system penetration and inhibited tumor growth in mouse models. RNA and protein analysis of SRI-42127-treated PDGx xenolines across glioblastoma molecular subtypes confirmed attenuation of targets upregulated by HuR. These results highlight how focusing on key attributes of HuR that contribute to cancer progression, namely cytoplasmic localization and multimerization, has led to the development of a novel, highly effective inhibitor. SIGNIFICANCE: These findings utilize a cell-based mechanism of action assay with a structure-activity relationship compound development pathway to discover inhibitors that target HuR dimerization, a mechanism required for cancer promotion.

Seven-Year Experience From the National Institute of Neurological Disorders and Stroke-Supported Network for Excellence in Neuroscience Clinical Trials

Importance

One major advantage of developing large, federally funded networks for clinical research in neurology is the ability to have a trial-ready network that can efficiently conduct scientifically rigorous projects to improve the health of people with neurologic disorders.

Observations

National Institute of Neurological Disorders and Stroke Network for Excellence in Neuroscience Clinical Trials (NeuroNEXT) was established in 2011 and renewed in 2018 with the goal of being an efficient network to test between 5 and 7 promising new agents in phase II clinical trials. A clinical coordinating center, data coordinating center, and 25 sites were competitively chosen. Common infrastructure was developed to accelerate timelines for clinical trials, including central institutional review board (a first for the National Institute of Neurological Disorders and Stroke), master clinical trial agreements, the use of common data elements, and experienced research sites and coordination centers. During the first 7 years, the network exceeded the goal of conducting 5 to 7 studies, with 9 funded. High interest was evident by receipt of 148 initial applications for potential studies in various neurologic disorders. Across the first 8 studies (the ninth study was funded at end of initial funding period), the central institutional review board approved the initial protocol in a mean (SD) of 59 (21) days, and additional sites were added a mean (SD) of 22 (18) days after submission. The median time from central institutional review board approval to first site activation was 47.5 days (mean, 102.1; range, 1-282) and from first site activation to first participant consent was 27 days (mean, 37.5; range, 0-96). The median time for database readiness was 3.5 months (mean, 4.0; range, 0-8) from funding receipt. In the 4 completed studies, enrollment met or exceeded expectations with 96% overall data accuracy across all sites. Nine peer-reviewed manuscripts were published, and 22 oral presentations or posters and 9 invited presentations were given at regional, national, and international meetings.

Conclusions and Relevance

NeuroNEXT initiated 8 studies, successfully enrolled participants at or ahead of schedule, collected high-quality data, published primary results in high-impact journals, and provided mentorship, expert statistical, and trial management support to several new investigators. Partnerships were successfully created between government, academia, industry, foundations, and patient advocacy groups. Clinical trial consortia can efficiently and successfully address a range of important neurologic research and therapeutic questions.

ELAVL1 Role in Cell Fusion and Tunneling Membrane Nanotube Formations with Implication to Treat Glioma Heterogeneity

Homotypic and heterotypic cell fusions via permanent membrane fusions and temporal tunneling nanotube formations in the glioma microenvironment were recently documented in vitro and in vivo and mediate glioma survival, plasticity, and recurrence. Chronic inflammation, a hypoxic environment, aberrant mitochondrial function, and ER stress due to unfolded protein accumulation upregulate cell fusion events, which leads to tumor heterogeneity and represents an adaptive mechanism to promote tumor cell survival and plasticity in cytotoxic, nutrient-deprived, mechanically stressed, and inflammatory microenvironments. Cell fusion is a multistep process, which consists of the activation of the cellular stress response, autophagy formation, rearrangement of cytoskeletal architecture in the areas of cell-to-cell contacts, and the expression of proinflammatory cytokines and fusogenic proteins. The mRNA-binding protein of ELAV-family HuR is a critical node, which orchestrates the stress response, autophagy formation, cytoskeletal architecture, and the expression of proinflammatory cytokines and fusogenic proteins. HuR is overexpressed in gliomas and is associated with poor prognosis and treatment resistance. Our review provides a link between the HuR role in the regulation of cell fusion and tunneling nanotube formations in the glioma microenvironment and the potential suppression of these processes by different classes of HuR inhibitors.

Glioma-initiating cells at tumor edge gain signals from tumor core cells to promote their malignancy

Intratumor spatial heterogeneity facilitates therapeutic resistance in glioblastoma (GBM). Nonetheless, understanding of GBM heterogeneity is largely limited to the surgically resectable tumor core lesion while the seeds for recurrence reside in the unresectable tumor edge. In this study, stratification of GBM to core and edge demonstrates clinically relevant surgical sequelae. We establish regionally derived models of GBM edge and core that retain their spatial identity in a cell autonomous manner. Upon xenotransplantation, edge-derived cells show a higher capacity for infiltrative growth, while core cells demonstrate core lesions with greater therapy resistance. Investigation of intercellular signaling between these two tumor populations uncovers the paracrine crosstalk from tumor core that promotes malignancy and therapy resistance of edge cells. These phenotypic alterations are initiated by HDAC1 in GBM core cells which subsequently affect edge cells by secreting the soluble form of CD109 protein. Our data reveal the role of intracellular communication between regionally different populations of GBM cells in tumor recurrence.

Intratumoural spatial heterogeneity is crucial to enhance therapeutic resistance in glioblastoma. Here, the authors show a paracrine signaling mechanism where glioblastoma-initiating cells located in the tumour edge elevate their malignancy by interaction with core-located tumour cells.

Abstract 3335: Characterization and analysis of the complement immune system in glioblastoma (GBM)

The purpose of this study is to determine the role of the complement immune system in glioma and/or glioma therapy. Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. It is accompanied by a devastating prognosis; the median survival is 12-14 months, with less than 10 percent of patients living for more than two years after diagnosis. Unfortunately, current treatment options are limited, and many initially promising drugs have failed phase three clinical trials.

One potential and relatively unexplored target for co-therapy in GBM is the complement immune system. Historically, the focus of work with complement has been on its role in innate immunity, where it can aid in the recognition and elimination of pathogens or undesired host material. More recent work, however, has revealed a key function of complement as a “double-edged sword” in the CNS. While the cascade is necessary for CNS development and homeostasis, overactive complement can lead to the hallmark neuroinflammation and neurodegeneration seen in conditions like Alzheimer's, multiple sclerosis, and traumatic brain injuries. Yet despite the presence of complement receptors on nearly all CNS cells and the direct role that complement plays in multiple neuroinflammatory diseases, very few studies have examined complement expression in brain tumors.

The current project seeks to bridge this gap in knowledge by assessing the impact of complement on glioma. This effort began by selecting candidate genes, as the complement family contains over 50 members. To do so, data from the publicly available Cancer Genome Atlas (TCGA) was mined, providing 14 targets of interest for further analysis. Cell-based experiments were performed in three GBM patient-derived xenolines (PDx): XD456, JX6, and JX10. mRNA expression was determined via TaqMan real-time PCR. Protein levels were assessed via Western blot. Overall, seven of the 14 initial targets demonstrated clear over-expression in all three human GBM PDx cell lines. This expression was not changed upon treatment with glioma growth factors such as epidermal or fibroblast growth factor (EGF or FGF). Intriguingly, however, the degree of over-expression varied by cell line, even when these lines were derived from patients assigned to the same molecular GBM subtype. For example, at the RNA level and in comparison to other cell lines, complement factor H (a C3 inhibitor) was up to six times higher in XD456, and clusterin (a MAC inhibitor) was nearly 18-fold higher in JX10. These data suggest that the current system for classifying tumor subtype may be missing important factors. Finally, when compared back to TCGA data, overexpression of these targets was associated with significantly worse tumor phenotype and patient survival.

This project has critically identified components of the complement system that are upregulated in GBM and strongly correlated to survival. Ultimately, these data may provide the first potential targets for complement-based co-therapeutics to be explored in future studies.

Citation Format: Emily Nicole Hayward, Xiuhua Yang, Natalia Filippova, Jennifer A. Calano, David Namkoong, Stefan Kovac, Louis B. Nabors. Characterization and analysis of the complement immune system in glioblastoma (GBM) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3335.

Management of Central Nervous System Tumors

Meningiomas represent a full spectrum of tumors that are the most common type of brain tumor in adults. Although most are benign, recent research has shown that the recurrence rate is high, especially for WHO grades 2 and 3, and overall survival is poor for these grades. Treatment is evolving, and recently sunitinib and bevacizumab have shown promise compared with historical treatments. However, more research is needed to identify better treatments for meningiomas. Treatment of brain metastases is another evolving field. Studies suggest that stereotactic radiosurgery is preferable to whole-brain radiation therapy and that immune checkpoint inhibitors and therapies targeted to the T790M mutation and ALK can improve outcomes in patients with non-small cell lung cancer and brain metastases.

Phase I trial of drug resistant immunotherapy: A first-in-class combination of MGMT-modified γδ t cells and temozolomide chemotherapy in newly diagnosed glioblastoma multiforme

TPS3150

Background: Temozolomide (TMZ) transiently upregulates GBM-specific stress-induced NKG2D ligands that are targeted by innate immune effector cells. Leveraging this effect is problematic, however, due to the lymphodepleting effects of TMZ.Genetic modification of ex vivo expanded and activated with an MGMT-expressing lentivector allows simultaneous chemotherapy and γδ T cell therapy that targets the tumor when NKG2DL are maximally expressed. We have termed this Drug Resistant Immunotherapy (DRI). Patient-derived xenograft mouse models of both primary and recurrent GBM treated with DRI have shown a significant survival advantage that were otherwise impervious to either cell therapy or TMZ. These preclinical findings and associated safety data provide the rationale to initiate a Phase I trial of DRI in primary GBM. Methods: This first in human study will evaluate the safety and optimal dosing frequency of the DRI with TMZ (NCT04165941).Eligibility criteria include the following: GBM eligible for resection, ≥18y, adequate organ and marrow function, and KPS≥70. Six to 12patients with newly diagnosed GBM are being enrolled in a 3 + 3 design into 1 of 2 fixed dose levels (DL) of DRI. Following tumor resection and immediately prior to induction chemo/radiotherapy, an apheresis product is collected and γδ T cells expanded in Zoledronic Acid (Novartis) and rhIL-12 (Miltenyi) and transduced with a P140K-MGMT lentivector (Miltenyi Lentigen, Gaithersburg, MD), harvested, and cryopreserved. At initiation of maintenance phase TMZ therapy, patients receive 150mg/m2 intravenous TMZ concurrently with intracranial injection of 1 x 107 γδ T cells (DL1) delivered through a Rickham reservoir previously inserted into the tumor cavity at resection. The patient then receives 4 daily doses of oral TMZ followed by 24d rest. Treatment cycles escalate from 1 to 3 (DL2) DRI doses following a safety observation period and absence of dose limiting toxicity. Maintenance TMZ treatment will continue for 6 cycles. Safety evaluations consist of routine laboratory analyses, clinical measurements (physical exams, vital signs), neurological function and evidence DRI γδ T cell related toxicity. Peripheral blood will be obtained for comprehensive immuno-phenotyping and T cell function analysis. Clinical benefit of DRI will be characterized by evaluating responses (CR, PR, SD and PD) and determining progression-free, median, and overall survival. As of February 2020, enrollment into DL 1 is ongoing. Clinical trial information: NCT04165941 .

Updated safety phase I trial of anti-LAG-3 alone and in combination with anti-PD-1 in patients with recurrent GBM

2512

Background: Preclinical GBM data targeting the checkpoint molecule Lag-3 have shown promising anti-tumor immune response with resultant improved survival when combined with anti-PD-1. Here we report our experience from a multi-arm safety study in patients with recurrent GBM treated with anti-Lag-3 and in combination with anti-PD-1. Methods: A phase I, open label, multicenter, multi-arm dose-finding/safety study of anti-LAG-3 (BMS-986016) alone or in combination with anti-PD-1 in patients at first recurrence of GBM was carried out in The Adult Brain Tumor Consortium (ABTC) (1501). The primary objectives were safety and to define MTD (DLT rate < 33%) for both the mono and combination arms. The major secondary objective was efficacy. The key inclusion criteria were: adults with first recurrence of GBM following RT+TMZ, TLC≥1000/ul, KPS≥ 60%, on a stable corticosteroid regimen, measurable disease, and written informed consent. Three pre specified dose levels of anti-Lag-3 at 80mg, 160mg, and 800mg were tested. Anti-PD-1was given at a flat dose of 240 mg in combination with anti-LAG-3 at 80 mg and 160 mg. Results: To date, the phase I portion of study completed its accrual and 33 patients were enrolled into the anti-LAG-3 alone or in combination with anti-PD-1 arms. The median age and KPS was 56 and 90 respectively. 39% tumors were MGMT methylated and the median treatment cycle was 3. The highest safe dose for Anti-LAG-3 alone is 800 mg without a DLT. Two DLT were observed in combination arms of Anti-LAG-3 +anti-PD-1 (80 mg/240mg), a grade 3 muscle weakness and a grade 4 edema. Three DLTs were observed in the higher Anti-LAG-3 + anti-PD-1 group (160 mg/240mg): grade 3 hypertension, syncope, and edema. 80% of the DLTs occurred after cycle 2 of the treatment. The estimated overall mOS was 8 months. Seven (44%) patients in the combination arm are still alive and 3 out of the 7 are living beyond 20 months suggesting a subset benefit. Conclusions: The phase I part of trial has completed enrollment. The MTD is 800mg for anti-LAG-3 as a monotherapy. For the combination arms, 160 mg of Anti-LAG-3 and 240 mg of anti-PD-1 was the MTD. DLTs were late onset events. Clinical trial information: NCT02658981 .

Intratumoral drug distribution of adavosertib in patients with glioblastoma: Interim results of phase I study

2568

Background: Wee1 is a key regulator of the G2/M checkpoint and is frequently overexpressed in glioblastoma (GB). Adavosertib is a first-in-class oral, small molecule inhibitor of Wee1 that acts primarily as a DNA damage sensitizer. A phase I clinical trial was conducted to evaluate its safety and establish the recommended phase II dosing. Studies were undertaken to evaluate whether potentially therapeutic concentrations of the drug are achieved in recurrent tumor and adjacent non-enhancing brain regions with presumed intact blood-brain barrier (BBB). Methods: Twelve patients received five daily doses of adavosertib pre-operatively at either the maximum tolerated dose (MTD) for concurrent radiation or adjuvant temozolomide. Tissue from contrast enhancing (CE) and non-enhancing (NE) brain regions was obtained for analysis during surgical resection. A second stage is being conducted using microdialysis (MD) to facilitate continuous sampling of extracellular fluid (ECF) and measuring free drug concentrations in: normal-appearing brain, contrast enhancing tumor, and a peritumoral T2 hyperintense area. The concentration of total adavosertib in plasma and tissue homogenates and free drug in ECF were determined by validated LC/MS/MS methods. Results: Geometric mean concentrations of adavosertib after a 200 mg dose were 644 ng/mL and 119 ng/mL in CE and NE tissue specimens, respectively (6 patients). At the 425 mg dose, the mean concentrations were 3,576 ng/mL in CE tissue and 885 ng/mL in NE tissue (6 patients). MD was performed in 2 patients. Samples from functional MD catheters were collected from NE brain in patient no. 1 and from two NE areas and a FLAIR hyperintense region in patient no. 2, with the following results in the table. Conclusions: The total drug concentration in tissue samples was notably lower in regions of the brain with a relatively intact BBB as compared to contrast enhancing tissue. Concentrations of adavosertib measured by MD vary markedly depending on catheter location. Free drug levels in ECF within brain with a functional BBB, although considerably lower than total drug levels in tissue, were 2-10 times below the previously reported IC50 for antiproliferative activity against sensitive GB cell lines (127 ng/mL). Whether or not the target of the drug is effectively inhibited at these concentrations remains to be demonstrated. Clinical trial information: NCT01849146 . [Table: see text]

An Update on Neurofibromatosis Type 1-Associated Gliomas

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome that affects children and adults. Individuals with NF1 are at high risk for central nervous system neoplasms including gliomas. The purpose of this review is to discuss the spectrum of intracranial gliomas arising in individuals with NF1 with a focus on recent preclinical and clinical data. In this review, possible mechanisms of gliomagenesis are discussed, including the contribution of different signaling pathways and tumor microenvironment. Furthermore, we discuss the recent notable advances in the developing therapeutic landscape for NF1-associated gliomas including clinical trials and collaborative efforts.

Methylmercury exposure, genetic variation in metabolic enzymes, and the risk of glioma

Methylmercury (MeHg) is an environmental neurotoxin with human exposure mainly from dietary intake of contaminated fish. Exposure to MeHg has been implicated in neurological damage, but research on its role in cancers, specifically glioma, is limited. In a glioma case-control study, we examined associations between toenail mercury (Hg) and glioma risk. We also examined genetic polymorphisms in 13 genes related to MeHg metabolism for association with glioma risk; genetic associations were also studied in the UK Biobank cohort. Median toenail Hg in cases and controls, respectively, was 0.066 μg/g and 0.069 μg/g (interquartile range (IQR): 0.032-0.161 and 0.031-0.150 μg/g). Toenail Hg was not found to be significantly associated with glioma risk (Odds Ratio: 1.02; 95% Confidence Interval: 0.91, 1.14; p = 0.70 in analysis for ordinal trend with increasing quartile of toenail MeHg). No genetic variant was statistically significant in both of the studies; one variant, rs11859163 (MMP2) had a combined p-value of 0.02 though it was no longer significant after adjustment for multiple testing (Bonferroni corrected p = 1). This study does not support the hypothesis that exposure to MeHg plays a role in the development of glioma at levels of exposure found in this study population.

Abstract 2262: Chemotherapy, checkpoint inhibition, and MGMT-modified adoptive gamma-delta (γδ) T cell-based therapy to treat post-resection, primary glioblastomas

Introduction: Recent evidence supports the crucial contribution of innate immunity to chemotherapy-based cancer treatments. Our previous in vitro modeling shows improved killing of glioblastoma (GBM) cell lines when γδ T cells are combined with alkylating agents such as Temozolomide (TMZ), which cause DNA damage but are also lymphodepleting. We now report findings from combined TMZ therapy with MGMT-modified γδ T cells (Drug Resistant Immunotherapy - DRI) in a xenograft (PDXT) mouse model of primary and recurrent GBM.

Methods: Effectorγδ T cells were manufactured from apheresis product in media containing 5mM Zoledronic Acid and 50U/mL rhIL-12. Cultures were transduced with a P140K-MGMT lentivector, maintained for up to 14 days, harvested, and evaluated in vitro for PDXT lysis +PD-1, CTLA-4 and PD-L1 by flow cytometry. Primary (P) and recurrent TMZ-resistant (T) GBM were modeled orthotopically using classical JX12P and mesenchymal JX59P intracranial (IC) xenografts versus JX12T, JX22T and JX59T. After placement of IC xenografts, mice received concurrent intraperitoneal TMZ 60mg/kg and 1 x 106IC DRI γδ T cells on post-tumor days 6, 8,13 and 15. Control mice received either γδ T cells, TMZ, or no therapy. Survival was assessed by Kaplan-Meier analysis.NKG2DL and PD-L1 expression was assessed on FFPE sections of tumor during therapy and at termination.

Results: DRI-treated JX12P mice showed significant improvement in median survival (MS) over TMZ alone (p=0.0001) with 80% tumor-free survivors. DRI also improved survival for JX59P-bearing mice with 60% survivors as compared to 30% for mice receiving TMZ alone (p=0.044). TMZ reduced tumor growth in primary but not TMZ-resistant PDXT-bearing mice while γδ T cells alone had no survival benefit over untreated controls for any model. For JX12T, DRI improved MS from 27 to 38 days (+41%) over TMZ alone (p=0.017). JX22T and JX59T tumors were resistant to DRI (p=0.0966 and 0.1390). DRI γδ T cells upregulated PD-1 and CTLA-4 over baseline and showed improved function against TMZ-resistant xenolines after blockade of PD-1 and/or CTLA-4 by as much as 200%. TMZ induced upregulation of NKG2DL (MIC-A/B, ULBP-4), and PD-L1 on both primary and TMZ-resistant PDXT following TMZ injection and for several days thereafter.

Conclusions: Primary GBM PDXT are significantly more sensitive to DRI than TMZ-resistant GBM suggesting that DRI would be more effective if administered as adjuvant therapy in the TMZ-maintenance phase following primary resection and chemo/radiotherapy. Additionally, TMZ increases GBM immunogenicity by upregulating NKG2DL expression but also PD-L1. Checkpoint blockade improves γδ T cell function. These findings show the potential to augment the effect of DRI and improve immune effectiveness against more resistant tumors.

Citation Format: Sailesh Pillai, George Y. Gillespie, Louis B. Nabors, Samantha Langford, Catherine P. Langford, Lawrence S. Lamb. Chemotherapy, checkpoint inhibition, and MGMT-modified adoptive gamma-delta (γδ) T cell-based therapy to treat post-resection, primary glioblastomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2262.

Safety and activity of a first-in-class oral HIF2-alpha inhibitor, PT2385, in patients with first recurrent glioblastoma (GBM)

2027

Background: Hypoxia inducible factor 2-alpha (HIF2a) mediates cellular responses to hypoxia and is overexpressed in GBM. PT2385 is an oral HIF2a inhibitor with in vivo activity against GBM. Methods: A two-stage single-arm open-label phase II study of adults with first recurrent GBM following chemoradiation with measurable disease was conducted through the Adult Brain Tumor Consortium. PT2385 was administered at the phase II dose (800 mg b.i.d.). The primary outcome was objective radiographic response (CR+PR); secondary outcomes were safety and survival. Exploratory objectives included PK (day 15 Cmin), PD, and pH-weighted amine-CEST MRI to quantify tumor acidity at baseline and explore associations with drug response. Stage 1 enrolled 24 patients with early stoppage for ≤1 response. Results: Of the 24 patients, mean age was 61±11 years, median KPS 80, MGMT promoter methylated in 46%. PT2385 was well tolerated. Grade ≥3 drug-related AEs were hypoxia (n = 2), anemia (1), hyperglycemia (1), hyponatremia (2) and lymphopenia (2). No objective radiographic responses were observed; median PFS was 1.8 months (95%CI 1.6-3.1). Drug exposure varied widely (Table) and did not differ by corticosteroid use (p = 0.12), antiepileptics (p = 0.09), or sex (p = 0.37). Patients with high systemic exposure had significantly longer PFS (6.7 vs 1.8 months, 0.009). Non-enhancing infiltrative disease with high acidity gave rise to recurrence. Baseline acidity correlated significantly with treatment duration (R2= 0.49, p = 0.017). Conclusions: Drug exposure to PT2385 was variable. Signals of activity were observed in GBM patients with high systemic exposure and acidic (e.g. hypoxic) lesions on baseline imaging. A second-generation HIF2a inhibitor is being studied. Clinical trial information: NCT03216499. [Table: see text]

Updated phase I trial of anti-LAG-3 or anti-CD137 alone and in combination with anti-PD-1 in patients with recurrent GBM

2017

Background: Preclinical GBM data targeting the checkpoint molecules Lag-3 and CD137 have shown promising anti-tumor immune response with resultant improved survival when combined with anti-PD-1. Here we report our experience from a multi-arm safety study in patients with recurrent GBM treated with anti-Lag-3 and anti-CD137. Methods: The Adult Brain Tumor Consortium (ABTC) 1501 trial is a phase I, open label, multicenter, multi-arm dose-finding/safety study of anti-LAG-3 (BMS-986016) or anti-CD137 (BMS-663513) alone and in combination with anti-PD-1 in patients at first recurrence of GBM. The primary objective is to define MTD for the mono and combinational treatment. The major secondary objective is to explore for a signal in efficacy. The key inclusion criteria are adults, first recurrence of GBM following RT+TMZ, TLC≥1000/ul, KPS≥ 60%, stable corticosteroid regimen, measurable disease, and written informed consent. Sequential allocation was used for the treatment assignment at starting dose of 80mg for anti-LAG-3 and 8mg for anti-CD137. Anti-PD-1was given at a flat dose of 240 mg in the combination treatment arms. The 3+3 design is used for the dose finding with a target DLT rate < 33%. Results: to date 44 patients were enrolled into the trial with median age at 57, median KPS at 90. Median treatment cycle was 3 and 39% tumors were MGMT methylated. The highest safe dose for Anti-LAG-3 alone is 800 mg without a DLT. The safe dose for anti-CD137 alone arm is 8mg with 1 DLT, and 2 grade 3 elevated serum ALT at end of cycle 2. Combination arms of Anti-LAG-3 +anti-PD-1 (160 mg/240mg as the highest dose combination) had one DLT (hypertension) and no toxicities were seen in the combination arm of Anti-CD137+Anti-PD-1 (3 mg/240 mg). mOS was 14 months for anti-CD137 alone, 8 months for Anti-Lag-3, and 7 months for Anti-Lag-3 + Anti-PD-1. Correlative data will be discussed. Conclusions: The trial is ongoing. The RP2D is 800mg for anti-LAG-3 as a monotherapy and 8mg for anti-CD137. For the combination arms, 160 mg of Anti-LAG-3 and 240 mg of anti-PD-1 and 3 mg of anti-CD137 and 240 mg antiPD-1 were the RP2D. Clinical trial information: NCT02658981.

Diagnosing growth in low-grade gliomas with and without longitudinal volume measurements: A retrospective observational study

BACKGROUND

Low-grade gliomas cause significant neurological morbidity by brain invasion. There is no universally accepted objective technique available for detection of enlargement of low-grade gliomas in the clinical setting; subjective evaluation by clinicians using visual comparison of longitudinal radiological studies is the gold standard. The aim of this study is to determine whether a computer-assisted diagnosis (CAD) method helps physicians detect earlier growth of low-grade gliomas.

METHODS AND FINDINGS

We reviewed 165 patients diagnosed with grade 2 gliomas, seen at the University of Alabama at Birmingham clinics from 1 July 2017 to 14 May 2018. MRI scans were collected during the spring and summer of 2018. Fifty-six gliomas met the inclusion criteria, including 19 oligodendrogliomas, 26 astrocytomas, and 11 mixed gliomas in 30 males and 26 females with a mean age of 48 years and a range of follow-up of 150.2 months (difference between highest and lowest values). None received radiation therapy. We also studied 7 patients with an imaging abnormality without pathological diagnosis, who were clinically stable at the time of retrospective review (14 May 2018). This study compared growth detection by 7 physicians aided by the CAD method with retrospective clinical reports. The tumors of 63 patients (56 + 7) in 627 MRI scans were digitized, including 34 grade 2 gliomas with radiological progression and 22 radiologically stable grade 2 gliomas. The CAD method consisted of tumor segmentation, computing volumes, and pointing to growth by the online abrupt change-of-point method, which considers only past measurements. Independent scientists have evaluated the segmentation method. In 29 of the 34 patients with progression, the median time to growth detection was only 14 months for CAD compared to 44 months for current standard of care radiological evaluation (p < 0.001). Using CAD, accurate detection of tumor enlargement was possible with a median of only 57% change in the tumor volume as compared to a median of 174% change of volume necessary to diagnose tumor growth using standard of care clinical methods (p < 0.001). In the radiologically stable group, CAD facilitated growth detection in 13 out of 22 patients. CAD did not detect growth in the imaging abnormality group. The main limitation of this study was its retrospective design; nevertheless, the results depict the current state of a gold standard in clinical practice that allowed a significant increase in tumor volumes from baseline before detection. Such large increases in tumor volume would not be permitted in a prospective design. The number of glioma patients (n = 56) is a limitation; however, it is equivalent to the number of patients in phase II clinical trials.

CONCLUSIONS

The current practice of visual comparison of longitudinal MRI scans is associated with significant delays in detecting growth of low-grade gliomas. Our findings support the idea that physicians aided by CAD detect growth at significantly smaller volumes than physicians using visual comparison alone. This study does not answer the questions whether to treat or not and which treatment modality is optimal. Nonetheless, early growth detection sets the stage for future clinical studies that address these questions and whether early therapeutic interventions prolong survival and improve quality of life.

Safety and efficacy of depatuxizumab mafodotin + temozolomide in patients with EGFR-amplified, recurrent glioblastoma: results from an international phase I multicenter trial

Background

Patients with glioblastoma (GBM) have a dismal prognosis. Nearly all will relapse with no clear standard of care for recurrent disease (rGBM). Approximately 50% of patients have tumors harboring epidermal growth factor receptor (EGFR) amplification. The antibody-drug conjugate depatuxizumab mafodotin (depatux-m) binds cells with EGFR amplification, is internalized, and releases a microtubule toxin, killing the cell. Here we report efficacy, safety and pharmacokinetics (PK) of depatux-m + temozolomide (TMZ) in patients with EGFR-amplified rGBM.

Methods

M12-356 (NCT01800695) was an open-label study encompassing patients with newly diagnosed or rGBM across 3 treatment arms. Results are reported for adults with EGFR-amplified, measurable rGBM who received depatux-m (0.5-1.5 mg/kg) on days 1 and 15, and TMZ (150-200 mg/m2) on days 1-5 in a 28-day cycle. Patients were bevacizumab and nitrosourea naïve.

Results

There were 60 patients, median age 56 years (range, 20-79). Fifty-nine patients previously received TMZ. Common adverse events (AEs) were blurred vision (63%), fatigue (38%), and photophobia (35%). Grades 3/4 AEs were split between ocular and non-ocular AEs, occurring in 22% of patients each. Systemic PK exposure of depatux-m was dose proportional. The objective response rate was 14.3%, the 6-month progression-free survival rate was 25.2%, and the 6-month overall survival rate was 69.1%.

Conclusions

Depatux-m + TMZ displayed an AE profile similar to what was described previously. Antitumor activity in this TMZ-refractory population was encouraging. Continued study of depatux-m in patients with EGFR-amplified, newly diagnosed, or recurrent GBM is ongoing in 2 global, randomized trials (NCT02573324, NCT02343406).

Blocking PD1/PDL1 Interactions Together with MLN4924 Therapy is a Potential Strategy for Glioma Treatment

Objective:

MLN4924, a pharmacological inhibitor of cullin neddylation, resulted in glioma cell apoptosis, deregulation of the S-phase of DNA synthesis and thus, offers great potential for the treatment of brain tumours. However, targeting the neddylation pathway with an MLN4924 treatment stabilized the hypoxia-inducible factor 1A (HIF1A), which is one of the main transcriptional enhancers of the immune checkpoint molecule PDL1 (programmid death ligand-1) in cancer cells. The influence of immune checkpoint molecules on glioma progression has recently been discovered; PDL1 overexpression in gliomas corresponds to a significant shortening of patient survival and a decrease of the anti-tumour immune response. We hypothesize that i) PDL1 is up-regulated in gliomas after treatment with MLN4924 and induces T-cell energy; ii) co-utilization of the PD1/PDL1 blockage with MLN4924 therapy may reduce T-cell energy and may engage MLN4924-induced tumour disruption with the immune response.

Methods:

PDL1 expression and its immunosuppressive role in gliomas, glioma microenvironments, and after treatments with MLN4924 were assessed by utilizing methods of immunohistochemistry, molecular biology, and biochemistry.

Results:

We confirmed PDL1 overexpression in clinical brain tumour samples, PDGx and established glioma cell lines, extracellular media from glioma cells, and CSF (cerebrospinal fluid) samples from tumour-bearing mice. Our primary T-cell based assays verified that the up-regulation of PDL1 in tumour cells protects gliomas from T-cell treatment and reduces T-cell activation. We found that a pharmacological inhibitor of cullin neddylation, MLN4924, exhibited strong cytotoxicity towards PDGx and established glioma cell lines, in vitro, with an IC50’s range from 0.2 to 3 uM. However, we observed a significant increase of HIF1A and PDL1 in mRNA and protein levels in all glioma cell lines after treatment with MLN4924. The MLN4924-dependent induction of PDL1 in gliomas resulted in T-cell energy, which was blocked by a blockage of the PD1/PDL1 interaction.

Conclusion:

We conclude that i) PDL1 up-regulation in gliomas and the glioma microenvironment is an important chemotherapeutic target; ii) MLN4924 therapy, combined with a blockage of the PD1/PDL1 pathway, should be considered as a potential strategy for glioma treatment.

Timed sequential therapy of the selective T-type calcium channel blocker mibefradil and temozolomide in patients with recurrent high-grade gliomas

Background

Mibefradil (MIB), previously approved for treatment of hypertension, is a selective T-type calcium channel blocker with preclinical activity in high-grade gliomas (HGGs). To exploit its presumed mechanism of impacting cell cycle activity (G1 arrest), we designed a phase I study to determine safety and the maximum tolerated dose (MTD) of MIB when given sequentially with temozolomide (TMZ) in recurrent (r)HGG.

Methods

Adult patients with rHGG ≥3 months from TMZ for initial therapy received MIB in 4 daily doses (q.i.d.) for 7 days followed by standard TMZ at 150-200 mg/m2 for 5 days per 28-day cycle. MIB dose escalation followed a modified 3 + 3 design, with an extension cohort of 10 patients at MTD who underwent 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET imaging, to image proliferation before and after 7 days of MIB.

Results

Twenty-seven patients were enrolled (20 World Health Organization grade IV, 7 grade III; median age 50 y; median KPS 90). The MTD of MIB was 87.5 mg p.o. q.i.d. Dose-limiting toxicities were elevation of alanine aminotransferase/aspartate aminotransferase (grade 3) and sinus bradycardia. The steady-state maximum plasma concentration of MIB at the MTD was 1693 ± 287 ng/mL (mean ± SD). 18F-FLT PET imaging showed a significant decline in standardized uptake value (SUV) signal in 2 of 10 patients after 7 days of treatment with MIB.

Conclusions

MIB followed by TMZ was well tolerated in rHGG patients at the MTD. The lack of toxicity and presence of some responses in this selected patient population suggest that this regimen warrants further investigation.

Final results from the dose-escalation stage of a phase 1/2 trial of TPI 287, a brain penetrable microtubule inhibitor, plus bevacizumab in patients with recurrent glioblastoma

2021

Background: Microtubule inhibitors, including taxanes, are active in preclinical models of glioblastoma (GBM), however, clinical benefit is hampered by poor blood-brain barrier (BBB) accumulation. TPI 287, a third-generation taxane designed to evade P-glycoprotein mediated efflux, readily penetrates the BBB and overcomes this limitation. CB-017 is a multi-center phase 1/2 trial designed to determine the optimal dose of TPI 287 and potential efficacy in patients treated with this drug plus bevacizumab (BEV) for treatment of recurrent GBM. Final results of the dose escalation Phase 1 stage of this trial are reported. Methods: GBM patients at first or second relapse after standard therapy and without prior exposure to anti-angiogenic agents were eligible for enrollment. BEV was administered at 10 mg/kg every 2 weeks and TPI 287 every 3 weeks via IV infusion. MRIs were obtained every six weeks with response assessed via RANO criteria. TPI 287 dose escalation was based on a traditional 3+3 design. Results: Twenty-four patients were enrolled in 7 TPI 287 dose-escalation cohorts (140-220 mg/m2) from 6 U.S. centers. Twenty and 23 patients were evaluable for response and survival, respectively. Median follow-up was 28 months. Results are shown in the table below. Of the 9 patients from which biomarker data was available, tumors from 8 patients (89%) harbored an unmethylated MGMT promoter, an established negative prognostic indicator for survival. No DLTs were reported and myelosuppression (n=3) was the only drug-related grade 3/4 adverse event. Conclusions: TPI 287 in combination with BEV is safe and well tolerated at doses up to 220 mg/m2. Final survival results from the Phase 1 portion of this study compare favorably with historical controls and support further investigation of TPI 287 plus BEV for treatment of recurrent GBM. Clinical trial information: NCT01933815. [Table: see text]

Phase I study of AZD1775 with radiation therapy (RT) and temozolomide (TMZ) in patients with newly diagnosed glioblastoma (GBM) and evaluation of intratumoral drug distribution (IDD) in patients with recurrent GBM

2005

Background: The standard of care treatment for newly diagnosed GBM is maximal safe surgical resection followed by two DNA damaging agents, RT and TMZ. Cellular response to DNA damage involves checkpoints that halt the cell cycle to allow DNA repair. AZD1775 is an oral small molecular inhibitor of a nuclear tyrosine kinase Wee1, a key regulator of the G2/M checkpoint. Abrogation of the G2/M checkpoint prevents repair and pushes cells into mitosis with unrepaired DNA damage. AZD1775 was shown to enhance TMZ and RT effects in preclinical models. Methods: The Adult Brain Tumor Consortium 1202 trial (NCT01849146) is a phase I, open label, multicenter dose-finding study of AZD1775 in combination with standard RT and TMZ followed by an IDD study for patients undergoing surgery for recurrent GBM. The dose finding portion is comprised of two arms, one with AZD1775 given Monday through Friday during concurrent RT/TMZ and a second arm given with adjuvant TMZ qd x 5d/28d cycle. Each arm had standard 3+3 design. A combination cohort with both concurrent and adjuvant AZD1775 at MTD and analysis of PK/PD and IDD at MTD in patients undergoing surgery for recurrent GBM followed. Results: 51 patients enrolled in the dose finding arms. For the concurrent arm, the MTD was 200 mg. At 275 mg one patient had grade 3 fatigue and another had grade 4 thrombocytopenia and neutropenia. Two of 6 total patients enrolled at 200 mg experienced DLTs (grade 4 neutropenia and grade 3 ALT elevation). The MTD for the adjuvant arm was 425 mg as 1 of 6 patients had DLT (grade 4 decrease in ANC). At 500 mg, 2 of 3 patients experienced intolerable diarrhea despite prophylaxis. Enrollment in the combination cohort is completed and evaluation of safety is underway. The drug concentration in contrast enhancing and non-enhancing brain tumor was 4-8 x and 0.5-2.6 x greater than plasma, respectively for patients on IDD portion. Conclusions: The MTD for AZD1775 in combination with RT/TMZ is 200 mg qd M-F with concurrent RT/TMZ and 425 mg qd x 5d/28d cycle in combination with adjuvant TMZ. IDD and PK/PD analysis is ongoing to inform the decision to proceed to phase II testing. Clinical trial information: NCT01849146.

Efficacy analysis of ABT-414 with or without temozolomide (TMZ) in patients (pts) with EGFR-amplified, recurrent glioblastoma (rGBM) from a multicenter, international phase I clinical trial

2003

Background: GBM is the most common malignant primary brain tumor in adults. Pts with rGBM have a poor prognosis. EGFR is amplified (amp) in ~50% of GBMs and is a compelling therapeutic target. ABT-414 is an antibody-drug conjugate composed of an EGFR-directed antibody conjugated to a microtubule toxin, MMAF. ABT-414 binds a unique epitope exposed during EGFR activation, either through ligand stimulation or mutation such as EGFR variant III (EGFRvIII), releasing MMAF into the cancer cell. Here, we report a pooled safety and efficacy analysis of ABT-414 +/- TMZ in EGFR amp, rGBM. Methods: M12-356 is a Phase 1, open-label, multi-arm study. Results from the 2 arms accruing rGBM pts were pooled for analysis. Eligible adults had rGBM, centrally confirmed EGFR amp, and KPS ≥ 70. Pts received 0.5-1.25 mg/kg ABT-414 on days 1 and 15 +/- 150-200 mg/m2 TMZ on days 1-5 of 28-day cycles until progression (per RANO). Results: As of 11 January 2017, 126 pts were treated. The most common adverse events (AEs, ≥ 25% pts) were ocular (90%) and included blurred vision (64%) and photophobia (31%), which were mainly reversible. Common non-ocular AEs were fatigue (36%) and headache (30%). Grade 3/4 AEs (≥ 5% pts) included ocular toxicities (29%) and decreased platelets/thrombocytopenia (10%). Serious AEs included seizure and keratitis (2% each). Of 125 pts evaluable by RANO, 52% had improvement or stabilization as best response (2 CR, 9 PR, 54 SD), and the remaining 60 (48%) had PD. Of 115 pts with measurable disease at baseline, the objective response rate (ORR) was 10% (2 CR + 9 PR). For 5 pts, re-resection for radiographic PD revealed mostly necrotic tissue and pts were classified as SD, suggesting the ORR may be an underestimate. Of all 126 pts, the 6-month PFS rate (PFS6) was 26%; median OS was 8.5 months. Conclusions: In this Phase 1 trial of EGFR amp, rGBM, we observed encouraging disease control (52%, CR + PR + SD) and PFS6 (26%) rates. Toxicity was mainly ocular, and reversible. A global, randomized trial of ABT-414 vs. ABT-414 + TMZ vs. TMZ/lomustine in EGFR amp, rGBM has completed accrual with results expected later this year (NCT02343406). Clinical trial information: NCT01800695.

Individualized screening trial of innovative glioblastoma therapy (INSIGhT)

TPS2079

Background: Patient with glioblastoma (GBM) with unmethylated MGMT promoters derive limited benefit from temozolomide (TMZ) and have dismal outcome. Prioritizing the numerous available therapies and biomarkers for late stage testing requires an efficient clinical testing platform. INSIGhT (NCT02977780) is a biomarker-based, Bayesian adaptively randomized, multi-arm phase II platform screening trial for patients with newly diagnosed GBM and unmethylated MGMT promoters. Methods: INSIGhT compares experimental arms to a common control of standard concurrent TMZ and radiation therapy (RT) followed by adjuvant TMZ. The primary endpoint is overall survival (OS). Patients with newly diagnosed, unmethylated GBM that are IDH R132H mutation negative, and with genomic data available or who consent to whole exome sequencing through the ALLELE companion study for biomarker grouping are eligible. Two experimental arms consist of concurrent RT/TMZ followed by adjuvant neratinib (EGFR, HER2, and HER4 inhibitor) or abemaciclib CDK 4/6 inhibitor), respectively, in place of TMZ. The other experimental arm is CC-115 (TORC1/2 and DNA PK inhibitor), which replaces TMZ in both the concurrent and adjuvant phases. Biomarker groups include: EGFR + patients with EGFR amplification/mutation; PI3K + patients with PIK3CA mutation/amplification, PIK3R1 mutation, AKT3amplification, PIK3C2B > 1 copy gain, or PTEN dual loss; CDK: + patients with wild-type RB1 and CDK4 amplification, CDK6 amplification, or CDKN2A > 1 copy loss. Given the lack of pretrial biomarker data and the anticipated overlap of the groups, randomization will initially be equal. As the trial progresses, randomization probabilities will be adapted based on the Bayesian estimation of the probability of treatment impact on progression-free survival (PFS). These randomization probabilities can vary among the biomarker groups so predictive biomarkers will be identified and utilized if present. Treatment arms may drop due to low probability of treatment impact on OS, and new arms may be added. Experimental arms are compared only with control and should be thought of as discrete experimental questions, with INSIGhT being open to new investigators with proposed therapeutic hypotheses. Clinical trial information: NCT02977780.

SLC7A11 expression is associated with seizures and predicts poor survival in patients with malignant glioma

Glioma is the most common malignant primary brain tumor. Its rapid growth is aided by tumor-mediated glutamate release, creating peritumoral excitotoxic cell death and vacating space for tumor expansion. Glioma glutamate release may also be responsible for seizures, which complicate the clinical course for many patients and are often the presenting symptom. A hypothesized glutamate release pathway is the cystine/glutamate transporter System xc (-) (SXC), responsible for the cellular synthesis of glutathione (GSH). However, the relationship of SXC-mediated glutamate release, seizures, and tumor growth remains unclear. Probing expression of SLC7A11/xCT, the catalytic subunit of SXC, in patient and mouse-propagated tissues, we found that ~50% of patient tumors have elevated SLC7A11 expression. Compared with tumors lacking this transporter, in vivo propagated and intracranially implanted SLC7A11-expressing tumors grew faster, produced pronounced peritumoral glutamate excitotoxicity, induced seizures, and shortened overall survival. In agreement with animal data, increased SLC7A11 expression predicted shorter patient survival according to genomic data in the REMBRANDT (National Institutes of Health Repository for Molecular Brain Neoplasia Data) database. In a clinical pilot study, we used magnetic resonance spectroscopy to determine SXC-mediated glutamate release by measuring acute changes in glutamate after administration of the U.S. Food and Drug Administration-approved SXC inhibitor, sulfasalazine (SAS). In nine glioma patients with biopsy-confirmed SXC expression, we found that expression positively correlates with glutamate release, which is acutely inhibited with oral SAS. These data suggest that SXC is the major pathway for glutamate release from gliomas and that SLC7A11 expression predicts accelerated growth and tumor-associated seizures.

Analgesic use and the risk of primary adult brain tumor

Glioma and meningioma are uncommon tumors of the brain with few known risk factors. Regular use of aspirin has been linked to a lower risk of gastrointestinal and other cancers, though evidence for an association with brain tumors is mixed. We examined the association of aspirin and other analgesics with the risk of glioma and meningioma in a large US case-control study. Cases were persons recently diagnosed with glioma or meningioma and treated at medical centers in the southeastern US. Controls were persons sampled from the same communities as the cases combined with friends and other associates of the cases. Information on past use of analgesics (aspirin, other anti-inflammatory agents, and acetaminophen) was collected in structured interviews. Logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs) for analgesic use adjusted for potential confounders. All associations were considered according to indication for use. A total of 1123 glioma cases, 310 meningioma cases and 1296 controls were included in the analysis. For indications other than headache, glioma cases were less likely than controls to report regular use of aspirin (OR 0.69; CI 0.56, 0.87), in a dose-dependent manner (P trend < 0.001). No significant associations were observed with other analgesics for glioma, or any class of pain reliever for meningioma. Results suggest that regular aspirin use may reduce incidence of glioma.