MGMT Unmethylated Glioblastoma Research Articles

Abstract CT125: A phase 0/2 ‘trigger’ trial of pamiparib or olaparib plus radiotherapy in patients with newly-diagnosed or recurrent glioblastoma

Abstract Background: This Phase 0/2 clinical trial evaluates the pharmacokinetic (PK), pharmacodynamic (PD), and clinical response of newly-diagnosed and recurrent glioblastoma (GBM) patients to the PARP1/2 selective inhibitors, pamiparib and olaparib, in combination with radiotherapy. Materials/Methods: In this study, newly-diagnosed (Arm A) and recurrent GBM (Arm B) patients received 4 days of pamiparib (60 mg BID) prior to planned resection at 2-4 or 8-12 hours following the final dose. Arm C included recurrent GBM patients who received 4 days of olaparib (200 mg BID) prior to resection. In the Phase 0 component of the study total and unbound drug concentrations were measured using validated LC-MS/MS methods. A PK ‘trigger’, defined as unbound drug > 5-fold biochemical IC50 in Gd-nonenhancing tumor, determined eligibility for Phase 2. PARP inhibition was assessed via ex vivo tumor tissue radiation and quantification of PAR levels compared to non-irradiated control. When demonstrating a PK response, newly-diagnosed, MGMT-unmethylated GBM or recurrent GBM patients were eligible for Phase 2 dosing of pamiparib (Arms A and B) or olaparib (Arm C) with concurrent RT followed by maintenance pamiparib or olaparib. Results: A total of 41 patients (Arm A, n=16; Arm B, n=19; Arm C, n=6) were enrolled in the Phase 0 component of the study. In Arms A and B, mean unbound concentrations of pamiparib in Gd-nonenhancing tumor were 167.3 nM and 104.3 nM respectively, and in Arm C the mean unbound concentration of olaparib was 5.2 nM. All patients in the pamiparib arms (n=35) but only 1 of 6 patients in the olaparib Arm C exceeded the PK threshold. Radiation-induced PAR expression was 2.44-fold in untreated control vs 1.16 in Arm A (p<0.05), 0.82 in Arm B (p<0.01) and 1.11 in Arm C patients. In Arm A, 7 of 11 MGMT-unmethylated GBM patients advanced to Phase 2. Two patients were ineligible due to clinical status, 1 patient was ineligible per physician decision, and 1 patient declined to participate. In Arm B, 11 of 19 patients advanced to Phase 2. Eight patients were ineligible due to clinical status. At a mean follow-up of 5.8 months, median progression-free survival (PFS) was 5.8, 6.0, and 3.8 months for Arms A (n=7), B (n=11), and C (n=1), respectively. Grade 3+ toxicities related to pamiparib occurred in 4 patients, with 2 adverse events resulted in treatment discontinuation. No grade 3+ toxicities were documented in the olaparib arm. Conclusions: Pamiparib achieved pharmacologically-relevant concentrations in Gd-nonenhancing GBM tissue and suppressed induction of PAR levels ex vivo post-radiation. The majority of newly-diagnosed patients with MGMT-unmethylated GBM and recurrent GBM patients advanced to therapeutic dosing in this trial, and pamiparib was generally well-tolerated in these patients. Citation Format: Nader Sanai, Yu-Wei Chang, Jun Jiang, Jennifer Molloy, Chelsea Pennington-Krygier, Jocelyn Harmon, Amy Hong, John Wanebo, William Kennedy, Michael Garcia, Igor Barani, Wonsuk Yoo, Artak Tovmasyan, An-Chi Tien, Jing Li, Shwetal Mehta. A phase 0/2 ‘trigger’ trial of pamiparib or olaparib plus radiotherapy in patients with newly-diagnosed or recurrent glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT125.

Abstract CT044: A phase 0/1b study of AZD1390 plus radiotherapy in newly-diagnosed, MGMT-unmethylated glioblastoma patients

Abstract Background: ATM inhibition has been hypothesized to potentiate the effects of radiation by preventing acute phase DNA damage repair, and a Phase 1 trial of this combination in patients with GBM is ongoing (NCT03423628). To test this hypothesis, this Phase 0/1b study evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) of AZD1390, a first-in-class ATM inhibitor, in combination with radiation in newly-diagnosed GBM patients (NCT05182905). Methods: Presumed newly-diagnosed GBM patients received 3 days of AZD1390 prior to planned resection at 4-6 or 23-25 hours following the final dose. Tumor tissue, cerebrospinal fluid (CSF), and plasma were collected. Total and unbound drug concentrations were measured using validated LC-MS/MS methods. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase. ATM inhibition was assessed via ex vivo tissue radiation, quantifying pRAD50 levels compared to non-radiated control. Patients exceeding the PK threshold (2 nM unbound drug levels in Gd-non-enhancing tumor region) with unmethylated MGMT promoter were eligible for the expansion phase of study drug, combining AZD1390 with 6 weeks of radiotherapy. Results: Seventeen patients were enrolled into the study. All tested patients (n=14) exceeded the PK threshold and qualified for the expansion phase. Three patients were excluded from the PK analysis due to dosing deviation (n=1) and non-GBM diagnosis (n=2). The mean unbound concentration of AZD1390 in Gd-nonenhancing tumor was 12.4 and 4.4 pmol/g, respectively, for the 4-6 and 23-25-hours cohort. Following 5Gy ex vivo radiation of surgical specimen, pRAD50 expression was significantly suppressed in AZD1390 treated patients compared to untreated controls (median 0.2% for 4-6-hours cohorts and 1.9% for 23-25-hours cohort vs 32.3% for control cohort, average 99% and 95% reduction, respectively, p<0.01 for both cohorts vs control). As of 11/30/2023, 3 patients with unmethylated MGMT promoter are undergoing therapeutic dosing of AZD1390 plus radiotherapy, with median clinical follow-up of 2.3 months. Conclusion: AZD1390 is well-tolerated in newly-diagnosed GBM patients, achieving pharmacologically relevant concentrations in Gd-nonenhancing tumor tissue, and substantially suppressing radiation-induced increases in pRAD50 levels. These data are the first in GBM patients demonstrating AZD1390-mediated pharmacodynamic and pharmacokinetic response. Citation Format: Nader Sanai, Siddhi Desai, Tigran Margaryan, Jennifer Molloy, Costanza LoCascio, Mackenna Elliott, Jocelyn Harmon, Amy Hong, Ernesto Luna Melendez, John Wanebo, Kelly Braun, William Kennedy, Michael Garcia, Wonsuk Yoo, Artak Tovmasyan, An-Chi Tien, Shwetal Mehta. A phase 0/1b study of AZD1390 plus radiotherapy in newly-diagnosed, MGMT-unmethylated glioblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT044.

Identification of MGMT promoter methylation as a specific lipid metabolism biomarker, reveals the feasibility of atorvastatin application in glioblastoma

BackgroundGlioblastoma is one of the deadliest tumors, and limited improvement in managing glioblastoma has been achieved in the past decades. The unmethylated promoter area of 6-O-Methylguanine-DNA Methyltransferase (MGMT) is a significant biomarker for recognizing a subset of glioblastoma that is resistant to chemotherapy. Here we identified MGMT methylation can also work as a specific biomarker to classify the lipid metabolism patterns between methylated and unmethylated glioblastoma and verify the potential novel therapeutic strategy for unmethylated MGMT glioblastoma. MethodsLiquid Chromatograph Mass Spectrometer has been applied for non-targeted metabolome and targeted lipidomic profiling to explore the metabolism pattern correlated with MGMT promoter methylation. Transcriptome has been performed to explore the biological differences and the potential mechanism of lipid metabolism in glioblastoma samples. In vivo and ex vivo assays were performed to verify the anti-tumor activity of atorvastatin in the administration of glioblastoma. ResultsMulti-omics assay has described a significant difference in lipid metabolism between MGMT methylated and unmethylated glioblastoma. Longer and unsaturated fatty acyls were found enriched in MGMT-UM tumors. Lipid droplets have been revealed remarkably decreased in MGMT unmethylated glioblastoma. In vivo and ex vivo assays revealed that atorvastatin and also together with temozolomide showed significant anti-tumor activity, and atorvastatin alone was able to achieve better survival and living conditions for tumor-hosting mice. ConclusionsMGMT promoter methylation status might be a well-performed biomarker of lipid metabolism in glioblastoma. The current study can be the basis of further mechanism studies and implementation of clinical trials, and the results provide preclinical evidence of atorvastatin administration in glioblastoma, especially for MGMT unmethylated tumors.

Abstract IA006: Multifaceted effects of DNA damage response inhibitors on radiation responses of glioblastoma and the normal brain

Abstract PARP inhibitors (PARPi) and ATM inhibitors (ATMi) enhance radiation sensitivity in multiple cancer models, both in vitro and in vivo. Our observation that the radiosensitizing properties of PARPi are most pronounced in rapidly proliferating cells is reflected in early phase clinical trial data showing exacerbation of acute radiation toxicity in rapidly proliferating tissues such as oropharyngeal and esophageal mucosa. Lack of radiosensitization in late responding, slowly proliferating normal tissues indicates that PARPi may be more effectively combined with radiation therapy (RT) in patients with brain tumors. ATMi are much more potent radiosensitizers than PARPi but less is known about their impact on normal tissue toxicity since they have only recently progressed to the clinic, although preclinical in vivo data are encouraging. We are evaluating the oral PARPi olaparib and the oral ATMi AZD1390 in combination with RT +/- temozolomide (TMZ) in the treatment of glioblastoma (GBM), the most prevalent and most aggressive primary brain tumor. Patients with GBM experience very poor outcomes in terms of both median survival (c.1 year) and neurocognitive decline, which is caused primarily by RT. Early phase testing of the olaparib-RT combination is underway in three populations of patients with newly diagnosed GBM. Patients aged >65 with MGMT unmethylated GBM are being recruited to a randomized, placebo-controlled phase II study (PARADIGM, ISRCTN52658296) after a phase I dose escalation study showed that olaparib (200 mg twice daily) was extremely well tolerated when combined with brain irradiation (40 Gray in 15#). Good performance status patients aged under 70 are being recruited to PARADIGM-2 (ISRCTN51253312) which comprises two parallel phase I dose escalation studies: patients with MGMT unmethylated tumors are receiving daily olaparib with RT (60 Gy in 30#) without TMZ, while patients with MGMT methylated tumors are receiving intermittent olaparib with standard chemoradiation. AZD1390 is being evaluated in a first-in-human phase I dose escalation study (NCT03423628) in combination with re-irradiation (35 Gy in 10#) in patients with recurrent GBM, and with first-line radical radiotherapy (60 Gy in 30#) in patients with newly diagnosed, MGMT unmethylated GBM. In parallel, we are undertaking preclinical studies to investigate the impact of PARPi and ATMi on RT induced neurotoxicity. In vivo imaging studies support the emerging concept that RT induced neuroinflammation is important in the pathogenesis of neurotoxicity, and we have generated preliminary behavioral data indicating that both PARPi and ATMi can alleviate the neurotoxic effects of RT. Ongoing experiments are defining the roles of microglia, astrocytes and neurogenesis in this phenomenon. We will present these diverse datasets in the context of our hypothesis that combining PARPi or ATMi with RT has potential to improve outcomes for GBM patients by enhancing tumor control while simultaneously suppressing neuroinflammation and alleviating RT related neurocognitive decline. Citation Format: Anthony J. Chalmers. Multifaceted effects of DNA damage response inhibitors on radiation responses of glioblastoma and the normal brain [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr IA006.

PATH-24. A CASE SERIES OF LONGER THAN EXPECTED SURVIVAL IN IDH-WILDTYPE, MGMT-UNMETHYLATED GLIOBLASTOMA PATIENTS

Abstract Despite interventions with surgery, radiation, and chemotherapy, Glioblastoma (GBM) remains a difficult cancer to treat. Only 6.9% of patients survive five years post-diagnosis1 and the median overall survival is reported to be in the range of 14-15 months.2Glioblastoma patients who harbor an IDH-mutation have a known improved survival rate over their IDH-wildtype counterparts and under the recent WHO 2021 Classification of CNS tumors, IDH-mutational status is now an established criteria for the classification of high-grade gliomas. MGMT methylation status is also a well-described prognostic factor in GBM. MGMT methylated patients have a more favorable prognosis and better response to conventional treatment with temozolomide.3 It is rare but there are some IDH-wildtype, MGMT-unmethylated GBM patients who survive longer than 4 years. Therefore, it is important to identify other potential favorable factors for longer survival in the unfavorable cohort of patients with IDH-wildtype and MGMT-unmethylated GBM. Case Series: Eighty-five GBM patients who had next generation sequencing completed at the University of California, Irvine were reviewed. Of 85 patients, 4 patients (4.7%) were IDH-wildtype, MGMT-unmethylated and lived longer than 4 years. We evaluated the pathology, clinical characteristics, treatment course, and molecular findings of these 4 long term GBM survivors with IDH-wildtype and MGMT-unmethylated status. Discussion: This case series of 4 cases of patients with IDH-wildtype, MGMT-unmethylated GBM with longer than expected survival did not reveal a ubiquitously prevalent molecular marker for long term survival based on review of next-generation sequencing results. 2 out of the 4 patients harbored an uncommon MTAP copy number loss mutation, which may warrant further investigation into the significance of this mutation on prognosis. 3 out of 4 patients received a vaccine-based intervention through clinical trial which may support ongoing investigation into the additional benefit this specific population of GBM patients may have from vaccine-based therapy.

DNAR-10. HETEROGENEOUS MGMT PROMOTER METHYLATION IN A MULTIFOCAL GLIOBLASTOMA: A CASE REPORT

Abstract MGMT promoter methylation status is an important predictive biomarker for treatment response in glioblastoma. MGMT unmethylated glioblastoma has elevated levels of MGMT which ultimately leads to chemoresistance. Clinicians consider the MGMT methylation status when treatment recommendations are given, and clinical trials use this marker for the selection of a homogenous group of glioblastoma patients based on prognosis. Here, we present a case of multifocal glioblastoma with heterogeneous MGMT methylation status. A 56-year-old male presented with left leg weakness for 2 months and left arm weakness for 1 month. Imaging revealed a calcified, rim enhancing right temporoparietal cystic lesion and a heterogeneously enhancing right parietal mass. Perilesional edema surrounded and connected the two lesions. The patient underwent gross total resection of the parietal mass and pathology revealed a WHO grade 4 glioblastoma, IDH wildtype, unmethylated tumor. Postoperatively, the patient was neurologically intact. He completed a 6-week long course of concomitant chemoradiation without any significant side effects. Two weeks later the patient developed rapidly worsening headaches, nausea, vomiting, dizziness, and left side weakness. Imaging revealed significant enlargement of the previously unresected temporoparietal cystic lesion with marked increase in surrounding edema and a 2-3 mm right to left midline shift. Patient underwent craniotomy with cyst drainage and tumor resection of the right cystic temporoparietal lesion, demonstrating a WHO grade 4 glioblastoma, IDH wildtype, methylated tumor. Post-operatively the patient was again neurologically intact and started adjuvant temozolomide. MGMT methylation status of glioblastoma can alter recommendations for chemotherapy with temozolomide. MGMT methylation status might vary in distinct parts of the tumor as molecular heterogeneity is a hallmark of glioblastoma. This heterogeneity should be considered by clinicians when treatments are recommended and by clinical trials for glioblastoma patients, especially when multifocal lesions have a distinct radiographic appearance.

EXTH-67. LP-184, AN MGMT-AGNOSTIC SMALL MOLECULE, HAS POTENT SYNERGY WITH SPIRONOLACTONE TO EFFECTIVELY INHIBIT ORTHOTOPIC GBM XENOGRAFT TUMORS

Abstract Temozolomide (TMZ) is currently the most effective standard-of-care chemotherapy based on its ability to extend survival of patients with newly diagnosed MGMT-methylated glioblastoma (GBM). Blood-brain barrier (BBB) permeable agents effective against TMZ-resistant GBMs (i.e. recurrent GBM, MGMT-unmethylated GBM) are needed. Lantern Pharma is advancing LP-184, an acylfulvene prodrug activated by the enzyme PTGR1. In MGMT-expressing TMZ-resistant GBM cultures, LP-184 was found to be ~5000X more potent than TMZ with LP-184 IC50s ranging from 20-200 nM. DNA damage induced by acylfulvenes is primarily repaired via transcription-coupled nucleotide excision repair (TC-NER) mediated by ERCC complexes. ERCC3 is proteolytically degraded in response to the FDA approved BBB permeable diuretic, spironolactone (SP). We found that SP induces rapid ERCC3 degradation by up to 95% in GBM cells and validated that SP-induced ERCC3 loss led to substantial increases in LP-184 responses (DNA damage, tumor cell death) in vitro and in subcutaneous (s.c.) tumor xenografts. Co-treatment of GBM cells with LP-184 and SP resulted in a 3-6 fold decrease in LP-184 IC50s in PDX-derived (M1123 and Mayo39) and cell line (U87) cultures in vitro. Systemic SP sensitized pre-established s.c. and orthotopic (i.c.) GBM xenografts to LP-184 therapy. Pre-established s.c. U87 tumors recurred after initial regression in 5/5 animals following treatment with LP-184 alone whereas tumors showed durable complete regression without recurrence in 4/5 animals following treatment with LP-184 + SP. Pre-established M1123 i.c. xenografts treated with LP-184 + SP were ~3-fold smaller than those treated with LP-184 alone. LP-184 is a promising agent with potential clinical translation in GBM patients. Our results indicate that LP-184 is MGMT-agnostic and effective in TMZ-resistant preclinical GBM models. The first-in-human LP-184 dose escalation Phase 1A trial enrolling solid tumor patients including GBM is planned to launch Q3 2023.

CTNI-62. INTERIM DATA ON DUAL INHIBITION OF POST-RADIOGENIC ANGIO-VASCULOGENESIS BY OLAPTESED PEGOL (NOX-A12) AND BEVACIZUMAB IN GLIOBLASTOMA FROM THE FIRST EXPANSION ARM OF THE PHASE 1/2 GLORIA TRIAL

Abstract BACKGROUND We recently reported favorable safety and preliminary efficacy signals for treatment with radiotherapy (RT), the CXCL12 neutralizing L-RNA aptamer olaptesed pegol (NOX-A12) and bevacizumab for glioblastoma (GBM) in the German multicenter phase 1/2 GLORIA trial (NCT04121455). Here, we report updated outcomes on dual inhibition of vasculogenesis (NOX-A12) and angiogenesis (bevacizumab). METHODS Six patients with incompletely resected, MGMT-unmethylated GBM, ECOG≤ 2 were enrolled, receiving standard RT (60 Gy in 30 fractions), continuous i.v. infusions of NOX-A12 (600 mg/week) and i.v. infusions of bevacizumab (10 mg/kg q2w). The primary endpoint was safety. Secondary endpoints included radiographic response according to modified RANO criteria (mRANO) as well as perfusion/diffusion imaging. RESULTS Combination treatment was well-tolerated and safe. Of all G≥2 AEs (n = 79), two G2 events (2.5%) were deemed related to NOX-A12 only. There were no dose-limiting toxicities and no treatment-related deaths. At a median follow-up of 14.6 months, one patient deceased due to distant leptomeningeal spread. Median overall survival (OS) has not yet been reached. With an overall response rate (ORR) of 83.3% under treatment, one patient achieved confirmed complete response (CR), four patients partial response (PR) and one patient stable disease (SD). The median best response under treatment was -68.9% (-53,8% to -100%) for target lesion sums and -100% (-99.9% to -100%) for non-target lesion (NTL) sums. In all three patients with NTLs at least one lesion disappeared. The median best change from baseline of the highly perfused-tumor fraction was -98.2% (-61.3% to -100%) and the median best change of the apparent diffusion coefficient was 24.9% (7.3% to 59.1%). CONCLUSIONS Interim data of the ongoing trial confirm the previously established safety profile of NOX-A12 for combinatory treatment with bevacizumab while demonstrating improved efficacy with deeper and longer-lasting responses and a higher ORR compared to treatment with RT and NOX-A12 only.

CTIM-11. MRNA AGGREGATES ELICIT RAPID IMMUNOLOGIC RESPONSE AND PSEUDOPROGRESSION IN GLIOBLASTOMA PATIENTS

Abstract BACKGROUND Glioblastoma immunotherapy trials remain limited by heterogeneity and the immunosuppressive tumor microenvironment (TME). To overcome these challenges, we developed a novel cancer immunotherapy that leverages use of mRNA lamellar aggregates (RNA-LPA) encoding for personalized glioblastoma antigens to simultaneously reprogram the GBM TME while inducing tumor specific immunity in the periphery. METHODS In a Phase I trial (PNOC020) with an embedded acceleration titration design (ATD) for patients with newly-diagnosed MGMT unmethylated glioblastoma, we sought to assess whether intravenous administration of RNA-LPAs encoding for pp65 mRNA (tumor associated antigen) mixed with personalized tumor mRNA (extracted and amplified from patient specific biopsies) could activate peripheral immunity while simultaneously reprogramming the GBM TME. All patients received surgical resection with adjuvant chemoradiation followed by escalating doses of RNA-LPA (0.625-1.5 µg/kg). RESULTS We have treated 3 patients on the ATD and one patient on the expanded Phase I trial. In all patients treated to date, RNA-LPAs elicited a rapid response (within hours) characterized by release of cytokines (IL-12, TNF-α, IFN-α), chemokines (CCL2, CCL4, CXCL9-10), increase in plasmacytoid dendritic cells and recruitment of peripheral blood mononuclear cells. Over time there was expansion of antigen specific T cells; T cell receptor (TCR) sequencing pre- and post-infusion demonstrated changes to the most prevalent clonotypes by ~10-20%. In the first subject treated on the expanded phase I trial, we observed significant immunologic response after the fourth vaccine, including 20-fold increase in IFN-γ inducible protein-10. One month after vaccine administration, there was marked increase in the enhancing areas on MRI, which on biopsy demonstrated no viable tumor cells and only reactive gliosis, necrosis, and lymphocytic infiltrates. CONCLUSION RNA-LPAs elicit rapid immune activation in the periphery and reprogram the GBM TME into a proinflammatory milieu as evidenced by tissue confirmed pseudoprogression.

CTNI-42. PHASE I CLINICAL TRIAL OF PEPOSERTIB PLUS RADIATION IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GLIOBLASTOMA

Abstract BACKGROUND DNA-dependent protein kinase (DNA-PK) is a pivotal component of DNA damage repair (DDR) pathways and is an attractive target in glioblastoma because its expression renders tumors less vulnerable to radiotherapy. Peposertib is a small molecule DNA-PK inhibitor that has been shown to potentiate radiotherapy and regress glioblastoma tumors pre-clinically. We conducted a two-stage phase I trial of peposertib plus radiation in newly-diagnosed MGMT-unmethylated glioblastoma (NCT04555577). Method: In stage 1, patients received peposertib plus standard-of-care radiotherapy to determine the maximum-tolerated dose (MTD) based on the Bayesian Optimal Interval design (maximum n = 24). Stage 2 is a window-of-opportunity expansion cohort and will include 5 surgical patients to evaluate tumor drug concentration. Both groups receive adjuvant temozolomide for 6-cycles. RESULTS Fifteen completed the 10-week dose-limiting toxicity (DLT) period; 3-50mg, 3-100mg, 3-200mg, 6-300mg. One DLT (G3 radiation necrosis [RN] at 300mg) was observed. Most notable toxicity was 3 patients with transient G3 dermatitis of the scalp (not DLT per protocol) (2-200mg, 1-300mg). Therefore, radiation dose constrains to the skin were incorporated and subsequent patients did not experience this toxicity. Next-generation sequencing (NGS) was available for 13 archival tissue. Two patients had pathology-proven RN (one within and one outside of the DLT period). Both tumors had mutations in DDR genes (i.e. ATRX, DICER1). Recurrent tissue was available for one patient after treatment with peposertib showed gain of two ATM mutations. CONCLUSION The initial safety data of peposertib plus radiation in newly-diagnosed MGMT unmethylated glioblastoma is favorable. The cases with RN in tumors with DDR mutations, the gain of two ATM mutations in a recurrent tumor and the cases of scalp dermatitis suggest that peposertib is active and possibly potentiates the effect of radiation. Safety and survival data and correlations with genomics will be presented. The study was supported by EMD Serono (CrossRef Funder ID: 10.13039/100004755).

CTNI-17. APPLICATION OF THE GBM-X DATA PLATFORM TO ESTIMATE TREATMENT EFFECTS OF THE EXPERIMENTAL THERAPIES OF THE RANDOMIZED PHASE 2 INDIVIDUALIZED SCREENING TRIAL OF INNOVATIVE GLIOBLASTOMA THERAPIES

Abstract BACKGROUND Leveraging external data has the potential to increase efficiency and precision of drug development in glioblastoma by complementing or replacing data from in-trial controls. We used an external control arm (ECA) to re-analyze data of the abemaciclib, neratinib and CC-115 arms of the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial. METHODS INSIGhT (NCT02977780) is an ongoing phase 2 adaptive platform trial in newly diagnosed MGMT unmethylated glioblastoma with a shared control arm of patients receiving radiation therapy with concurrent and maintenance temozolomide. The initial experimental arms (abemaciclib, neratinib, CC-115) have not shown a survival benefit relative to the shared control arm. We re-analyzed the experimental arm data and replaced the shared control arm with an ECA. The ECA was developed from a collection of trial datasets and real-world data available through the Glioblastoma External (GBM-X) Data Platform (). Propensity score matching was used to adjust for possible differences between pretreatment covariates (age, sex, resection, KPS) in the ECA and shared control arm. Cox proportional hazards models were used to estimate treatment effects. RESULTS On INSIGhT, patients were randomized to abemaciclib (n = 74), neratinib (n = 80), and CC-115 (n = 12). There were 687 unmethylated MGMT patients in the GBM-X ECA. After propensity score matching, there was no significant treatment effect associated with abemaciclib (HR 1.091, 95%CI:0.834-1.433, p = 0.536), neratinib (HR = 1.043, 95%CI:0.787-1.383, p = 0.770), or CC-115 (HR 1.088, 95%CI:0.834-1.433, p = 0.794) compared to the ECA. CONCLUSION In comparison to an ECA, there was no significant survival benefit with abemaciclib, neratinib and CC-115. Treatment effects estimates were similar to the primary analyses based on the original shared control arm of INSIGhT. The use of external control arms in early phase testing of new therapies is supported by our findings and could significantly reduce costs and time to conduct trials in newly diagnosed glioblastoma.

A Combined Phase 0/2 "Trigger" Trial Evaluating Pamiparib or Olaparib with Concurrent Radiotherapy in Patients with Newly-Diagnosed or Recurrent Glioblastoma

This study evaluates the pharmacokinetic (PK) and pharmacodynamic (PD) profiles and clinical efficacy of PARP1/2 selective inhibitors, pamiparib and olaparib, in newly-diagnosed or recurrent glioblastoma (GBM) patients in combination with radiotherapy (RT). In this combined phase 0/2 trial presumed newly-diagnosed (Arm A) or recurrent (Arm B) GBM patients received 4 days of pamiparib (60 mg BID) prior to resection either 2-4 or 8-12 hours following the final dose. Arm C enrolled patients with recurrent GBM to 4 days of olaparib (200 mg BID) prior to resection. Enhancing and nonenhancing tumor tissue, cerebrospinal fluid (CSF) and plasma were collected. Total and unbound drug concentrations were measured using validated LC-MS/MS methods. A PK 'trigger', defined as unbound drug and gt; 5-fold biochemical IC 50 in nonenhancing tumor, determined eligibility for the therapeutic expansion phase 2. PARP inhibition was assessed via ex vivo radiation and quantification of PAR levels compared to non-radiated control. Newly-diagnosed MGMT unmethylated GBMs and recurrent GBMs exceeding the PK threshold were eligible for an expansion phase of pamiparib (Arms A and B) or olaparib (Arm C) with concurrent RT followed by maintenance pamiparib or olaparib. RT was 60 Gy in 30 fractions in newly-diagnosed patients and 40 Gy in 15 fractions in recurrent patients, delivered using volumetric-modulated arc therapy (VMAT). A total of 38 patients (Arm A, n = 16; Arm B, n = 16; Arm C, n = 6) were enrolled in the initial phase 0 study. The mean unbound concentrations of pamiparib in nonenhancing tumor region for Arm A and Arm B were 167.3 nM and 109.4 nM respectively, and in Arm C the mean unbound concentration of olaparib was 5.2 nM. All patients in the pamiparib arms (n = 32/32) but only 1 of 6 patients in the olaparib Arm C exceeded the PK threshold. Radiation-induced PAR expression was 2.44-fold in untreated control vs 1.16 in Arm A (p<0.05), 0.85 in Arm B (p<0.01) and 1.11 in Arm C patients, respectively. In Arm A, 11 patients had unmethylated tumors, and of those, 7 patients enrolled in phase 2. In Arm B, 9 of the 16 clinically eligible patients with positive PK results were enrolled in phase 2. At a median follow-up of 8.4 months [range: 1.3-15.7 months], the median progression-free survival (PFS) was 5.4, 6.0, and 3.8 months for Arms A (n = 7), B (n = 9), and C (n = 1), respectively. Grade 3+ toxicities related to pamiparib occurred in 4 patients, with 2 adverse events resulting in treatment discontinuation. No grade 3+ toxicities were documented in the olaparib arm. Pamiparib achieved pharmacologically-relevant concentrations in nonenhancing GBM tissue and suppressed induction of PAR levels ex vivo post-radiation. The majority of patients with MGMT-unmethylated GBM advanced to the phase 2 portion of the trial, and pamiparib was generally well-tolerated in these patients.

CRISPR-Based Epigenome Editing and Genome Wide Screening Define Mediators of Chemotherapy Response in Glioblastoma

Alkylating chemotherapies exhibit survival benefit for patients with glioblastoma (GBM), the most common malignant primary brain tumor. CRISPRoff is a programmable epigenetic memory writer that stably and heritably silences any gene through DNA methylation. Epigenetic silencing of MGMT via promoter methylation is predictive of response to alkylating agents as well as prognostic for progression free and overall survival. Here we performed epigenome editing using CRISPRoff to stably silence MGMT through induced promoter methylation, as a therapeutically tractable approach for potentiating GBM to temozolomide (TMZ) or lomustine (CCNU). We then used genome-wide engineered CRISPR/Cas9 systems to broadly define sensitizers of GBM cells to alkylating agents, as a platform to discover novel sensitizing targets. Targeted epigenome editing was performed through electroporation of modified mRNAs encoding CRISPRoff machinery comprising deactivated Cas9 fused to a DNA methyltransferase complex, combined with sgRNAs, into MGMT unmethylated GBM cell lines (LN18, T98G) and then treated with either vehicle, TMZ, or CCNU. Parallel experiments were performed through electroporation of sgRNA/Cas9 ribonucleoproteins. Gene silencing was assessed using bisulfite targeted sequencing, RT-qPCR, and western blot. Drug sensitization was determined using luminescent cell viability assays. Genome-wide CRISPR interference (CRISPRi) screens were performed in triplicate cultures. Epigenomic silencing of the MGMT promoter through CRISPRoff-induced methylation reduced MGMT transcript levels by 96.7% and generated up to 88-fold sensitization to TMZ mediated cell death in GBM cells, with IC50 superior to GBM cells with baseline methylated MGMT. In addition, CRISPRoff of MGMT induced 20-fold sensitization to CCNU. CRISPRoff methylation of MGMT was equivalent to CRISPR/Cas9 homozygous deletion of the MGMT gene for drug sensitization and was superior to polyclonal Cas9 mediated deletion of MGMT by a factor of 10. To define additional mediators of chemotherapy response in GBM, CRISPRi screens revealed 185 and 266 genetic sensitizers to TMZ treatment in LN18 and T98G cells, respectively, in addition to validating MGMT. One hundred eighty and 238 sensitizers to CCNU were identified in LN18 and T98G cells, respectively. TMZ sensitizing genes conserved across cell lines were enriched for the ATR (i.e., BCRA2), DNA repair (i.e., REV1), and cell cycle pathways (i.e., PSMD13), while CCNU sensitizing genes were enriched for the Fanconi anemia pathway (i.e., FANCI, FANCD2). In contrast, gene hits that resulted in resistance to alkylating agents were enriched for the mismatch repair pathway (i.e., MSH2, PMS2). We integrate targeted epigenome editing with unbiased genome-wide approaches to build a novel discovery and therapeutic platform in glioblastoma, a framework that is well suited for targeting diseases with known or suspected epigenetic vulnerabilities.

P11.40.A GLIOBLASTOMA WITH OSSEOUS METASTASES: A SINGLE INSTITUTION CASE SERIES

Abstract BACKGROUND Although glioblastoma (GBM) is the most common malignant primary brain tumor in adults, extracranial metastasis is rare, occurring in <2% of cases. This rarity has been attributed to the blood brain barrier, immunologic factors, lack of traditional lymphatics in the brain, and the poor prognosis of GBM, limiting its opportunity to metastasize. When GBM does metastasize, bone is the most common destination. GBM may spread hematogenously to bone, especially to vertebral bodies via the surrounding venous plexus. In this single-institution study, we review the clinical characteristics of GBM patients with osseous metastases and evaluate potential risk factors and prognostic significance. MATERIAL AND METHODS Using an institutional database, we identified and retrospectively analyzed 6 GBM patients with osseous metastases and studied their demographics, tumor genetics, clinical courses, and outcomes. RESULTS Five of 6 (83%) GBM patients with osseous metastases were male, with a median age of 46 years at GBM diagnosis (range: 20-84). All patients had IDH wild type and MGMT unmethylated GBM with mutations in TP53. Two patients (33%) were initially diagnosed with gliosarcoma. All patients were treated with surgical resection followed by radiation with concurrent and adjuvant temozolomide. Five patients (83%) received bevacizumab for vasogenic edema (n=4) or intracranial tumor progression (n=1) prior to bone metastasis diagnosis. Bone metastases were diagnosed a median of 12.2 months (range: 5.3-35.2) after GBM diagnosis and 4.8 months after starting bevacizumab (range: 3.5-13.2). Two patients (33%) received immune checkpoint inhibitor therapy and two patients (33%) received tumor-treating fields prior to bone metastasis discovery. Bone metastases were symptomatic in 2 patients, presenting with back pain (n=1) and leg weakness and urinary incontinence (n=1). Three patients (50%) had concurrent metastases to other organs. Osseous metastases were biopsy-confirmed in 3 (50%) cases, while the other 3 patients had no known alternative malignancy to explain their bone metastases. After osseous metastasis discovery, the median survival was 27 days (range: 13-225). CONCLUSION Most of our GBM patients with osseous metastases were male and most, but not all, were young at GBM diagnosis. Tumor genetics common to all patients included IDH wild type, MGMT unmethylated status, and TP53 mutation, which may be important for osseous metastasis. Most patients received bevacizumab, which may be associated with earlier metastasis. While rare, metastatic GBM should be within the differential for GBM patients with bone pain or progressive neurologic symptoms, as osseous metastases portend a dismal prognosis in an already aggressive malignancy.

The proneural subtype is not associated with survival benefit from bevacizumab in newly diagnosed glioblastoma: a secondary analysis of the GLARIUS trial

PurposeThe AVAglio trial reported a significant survival benefit for first line bevacizumab treatment in patients with IDH wildtype glioblastoma of the proneural gene expression subtype. We here aim to replicate these findings in an independent trial cohort.MethodsWe evaluate the treatment benefit of bevacizumab according to gene expression subtypes of pretreatment tumor samples (n = 123) in the GLARIUS trial (NCT00967330) for MGMT unmethylated glioblastoma patients with Kaplan-Meier analyses, log-rank tests and Cox regression models.ResultsEmploying the Phillips classifier, bevacizumab conferred a significant PFS advantage in patients with proneural IDH wild-type tumors (10.4 vs. 6.0 months, p = 0.002), but no OS advantage (16.4 vs. 17.4 months, p = 0.6). Multivariable analysis adjusting for prognostic covariates confirmed the absence of a significant OS advantage from bevacizumab (hazard ratio, 1.05, 95% CI, 0.42 to 2.64; p = 0.14). Further, there was no interaction between the proneural subtype and treatment arm (p = 0.15). These results were confirmed in analyses of tumor subgroups according to the Verhaak classifier.ConclusionIn contrast to AVAglio, glioblastoma gene expression subgroups were not associated with a differential OS benefit from first-line bevacizumab in the GLARIUS trial.

A phase 0/Ia study of BI 907828 concentrations in brain tissue and a nonrandomized, open-label, dose escalation study of BI 907828 in combination with radiotherapy in patients with newly diagnosed glioblastoma (GBM).

TPS2081 Background: Murine double minute 2 (MDM2) directly regulates the stability of the tumor suppressor p53, and dysregulation of this pathway can critically disrupt cellular response to genomic stress and lead to cell death. BI 907828 is a highly potent inhibitor of the MDM2-p53 interface that triggers accumulation of p53 and subsequent apoptosis in multiple GBM patient-derived xenografts (PDXs) with wild-type p53. Moreover, the combination of BI 907828 and radiotherapy provides significant survival extension in multiple orthotopic GBM PDXs. Methods: An integrated Phase 0/1 trial design is being used to evaluate the potential for BI 907828 to achieve a therapeutic concentration in brain tumor tissue and to test the safety of the combination with radiation. The co-primary endpoints for the Phase 0 study are i) measured total concentration of BI 907828 and ii) calculated unbound concentration of BI 907828 in contrast and non-contrast enhancing regions of tumor. Key inclusion criteria for the Phase 0 study are patients at least 18 years of age, ECOG performance status of 0 or 1, histologic or radiologic new diagnosis of GBM, and planned surgical resection. The first approximately 6 patients enrolled in the Phase 0 will be treated at the starting dose of 30 mg, and the future patients enrolled will be dosed at higher levels (45 mg or 60 mg) provided there are no safety concerns. If dose-limiting toxicities (DLTs) are encountered, then a Bayesian Logistic Regression Model (BLRM) with overdose control will be used to guide the dose level decisions for the additional patients. Multiple, image-registered tumor samples and intra-operative plasma samples will be analyzed for BI 907828 by LC-MS/MS. Intra-tumoral variation in BI 907828 will be correlated with pharmacodynamic effects of MDM2 inhibition (elevation of p53, p21, MDM2, GDF15, PUMA). Those patients completing the Phase 0 study and who meet additional eligibility criteria can enroll on the Phase 1a portion of the study. The pathologic inclusion criteria are TP53 wild-type, IDH1/2 wild-type, MGMT unmethylated GBM. Co-primary endpoints for the Phase 1a trial are i) occurrence of DLTs during and within 21 days after completion of radiation therapy, and ii) occurrence of adverse events throughout the treatment period. Tolerability of inter-patient dose-escalation of BI 907828 (30, 45, 60 mg) combined with radiation therapy (60 Gy in 30 fractions) will be evaluated with dose-escalation guided by a two-parameter BLRM with overdose control. Patients will remain on BI 907828 monotherapy following completion of radiotherapy until progression. To date, two patients have enrolled on the Phase 0 study, and one patient went on to enroll on the Phase 1a portion of the study. Clinical trial information: NCT05376800 .

Phase I and pharmacodynamic study of arsenic trioxide plus radiotherapy for newly diagnosed glioblastoma.

2061 Background: Arsenic Trioxide (ATO) demonstrated prolonged survival in a transplanted rodent glioblastoma (GBM) model. Given the lack of effective therapies before temozolomide was available, the NCI funded NABTT Brain Tumor Consortium initiated a Phase I study of ATO with radiation in patients with newly diagnosed glioblastoma. Dose escalations using two different schedules of ATO were studied. Methods: Patients with newly diagnosed GBM (MGMT and IDH mutation status unknown) were assigned to receive ATO once or twice weekly during the 6-week course of radiation. The starting ATO dose was 0.25 mg/kg. This was escalated by 0.05 mg/kg until an MTD was reached. Patients did not receive ATO or other adjuvant therapy once the radiation was completed. As ATO affected tumor vasculature and blood flow in experimental imaging studies, perfusion MRIs were obtained before ATO administration and one and six weeks later. Survival was a secondary endpoint. Results: Thirty-one patients were enrolled: median age 54.9 years, 68% male, 77% patients KPS >90, 77% had tumor resection. The MTD was determined to be 0.4mg/kg on the weekly schedule and 0.3mg/kg on the biweekly schedule. ATO was well tolerated with 81% of patients completing the 6 weeks combined treatment. Major dose limiting toxicities were increased aspartate and alanine aminotransferases and one case of hyperkalemia. For all patients the median overall survival (mOS) was 17.7 months and the median progression-free survival (mPFS) was 5.4 months. However, there was a significant survival difference between the two ATO dose schedules across all doses with a mOS of 22.8 months in the biweekly schedule, vs 12.1 months in the weekly schedule (P = 0.039). There was a similar difference in mPFS (10.2 months vs 3.2 months, respectively, P = 0.004). Similarly, there were significant differences in perfusion imaging between the two ATO dose schedules with relative cerebral blood flow showing a significant decrease after one week of ATO treatment on the biweekly schedule (p = 0.007). Conclusions: TheMTDs of ATO in patients with GBM administered once or twice weekly for six weeks with standard radiation were determined. This regimen was well tolerated. Survival in patients on the biweekly schedule was much better (22.8 months) than expected in patients not receiving temozolomide. In addition, patients on biweekly ATO also had significant changes on MRI perfusion studies suggesting a pharmacodynamic effect of this agent. These finding should be explored further in patients with newly diagnosed MGMT unmethylated GBM where temozolomide has very limited activity. Clinical trial information: NCT00045565 .

Phase II trial of concurrent sunitinib, temozolomide, and radiotherapy with adjuvant temozolomide for newly diagnosed MGMT unmethylated glioblastoma.

The overall prognosis of glioblastoma (GBM) remains dismal, particularly for patients with unmethylated O6-methylguanine-DNA-methyltransferase (MGMT) promoter. In this phase II trial, we tested the combination of the antiangiogenic agent sunitinib with radiotherapy and temozolomide (TMZ) for newly diagnosed unmethylated MGMT GBM patients. We enrolled 37 patients with unmethylated MGMT promoter GBM, age 18-70, and KPS ≥70. Patients received 12.5 mg of daily sunitinib for 7 days, followed by concurrent chemoradiation plus 12.5 mg sunitinib, then adjuvant TMZ. The primary endpoint was progression-free survival (PFS), and secondary endpoints were overall survival (OS), safety, and neutrophil-to-lymphocyte ratio (NLR) biomarker. At a median follow-up time of 15.3 months (range: 3.1-71.3 months), the median PFS was 7.15 months (95% CI: 5.4-10.5) and the 6-month PFS was 54.0%. Median OS was 15.0 months (95% CI: 13.8-19.4) and 2-year OS rate was 17.1%. Patients receiving >3 cycles of adjuvant TMZ, undergoing surgery at progression, and presenting a post-concurrent NLR ≤6 experienced a significant improved OS with hazard ratios of 0.197 (P = .001), 0.46 (P = .049), and 0.38 (P = .021), respectively, on multivariable analysis. Age >65 years predicted for worse OS with hazard ratio of 3.92 (P = .037). Grade ≥3 thrombocytopenia occurred in 22.9%, grade ≥3 neutropenia in 20%, and grade ≥3 thromboembolic events in 14.3% of patients. There were no grade 5 events. Our findings suggest a potential benefit of combining sunitinib with chemoradiation in newly diagnosed GBM patients with unmethylated MGMT status and provide a strong rationale to test this combination in future studies.

RADT-15. 18F-DOPA PET/CT SURVEILLANCE FOR GLIOBLASTOMA: A RADIOMIC MODEL FROM A PROSPECTIVE PHASE II CLINICAL TRIAL PREDICTING SURVIVAL IN IDH-WILDTYPE, MGMT-UNMETHYLATED PATIENTS

Abstract BACKGROUND Interpretation of serial magnetic resonance imaging (MRI) for glioblastoma following radiation therapy (RT) is complicated by difficulty differentiating tumor from treatment-related changes, even using updated RANO criteria. The incorporation of novel imaging such as 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine (18F-DOPA) PET/CT to post-treatment serial imaging may improve prognostication and better facilitate future treatment decisions. METHODS The secondary analysis of a recent phase II prospective clinical trial of 18F-DOPA PET/CT-directed dose-escalated RT included patients with IDH-wildtype, MGMT-unmethylated glioblastoma who underwent post-treatment serial 18F-DOPA PET/CT surveillance. Quantitative features were extracted from pre-RT and post-RT serial PET/CT images, and robust prognostic features were selected using an in-house workflow. Both an automated machine learning (ML) algorithm and an interpretable ML algorithm were utilized to correlate surveillance PET image features with subsequent survival of greater than 12 months versus less than 12 months from the surveillance timepoint. Changes from pre-RT to post-RT PET/CT (delta model) were also assessed for association with post-RT survival and validated with a separate cohort. RESULTS Thirty-five patients with IDH-wildtype, MGMT-unmethylated glioblastoma who had at least one available (range: 1-14) post-treatment 18F-DOPA PET/CT were included. Twenty-four were used for model training, while 11 were used for validation. Ultimately, a five-feature post-RT model utilizing two shape, two texture, and one first-order radiomic feature was selected. For the delta model, five texture, two shape, and one first order radiomic feature were selected. The models show 90% accuracy in predicting survival < 12 months post-surveillance on the training set, and 68%-73% accuracy (AUC 0.64-0.73) for the validation cohort. Delta features were significantly associated with overall survival (p < 0.05). CONCLUSIONS Post-RT serial 18F-DOPA PET/CT imaging can help distinguish true tumor progression in patients with glioblastoma using a radiomics model. Tumor response evaluated for changes from pre-RT to post-RT 18F-DOPA PET/CT also predicted subsequent overall survival.

CTNI-42. GENOME-WIDE DNA METHYLATION PATTERNS IN VERTU: A RANDOMIZED PHASE II TRIAL OF VELIPARIB, RADIOTHERAPY AND TEMOZOLOMIDE IN PATIENTS WITH MGMT-UNMETHYLATED GLIOBLASTOMA

Abstract BACKGROUND VERTU was a randomized phase II trial evaluating veliparib, a brain-penetrant PARP inhibitor, combined with radiotherapy and temozolomide, for patients with newly diagnosed MGMT-unmethylated glioblastoma. As part of planned correlative work after study completion, we assessed genome-wide DNA methylation patterns to predict methylation class, glioblastoma subtype and MGMT status. METHODS Patients were randomized 2:1 to experimental (60Gy/30 fractions with veliparib 200mg bid, then temozolomide 150-200mg/m2 D1-5 + veliparib 40mg bid D1-7 Q28D for 6 cycles) versus standard arm (60Gy/30 fractions with temozolomide 75mg/m2 daily, then temozolomide 150-200mg/m2 D1-5 Q28D for 6 cycles). The primary objective to improve 6-month progression-free survival (PFS-6m) was not met (doi: 10.1093/neuonc/noab111). Methylation data were generated using the Illumina Infinium Methylation EPIC bead chip array. Tumor tissues were categorized using the Heidelberg methylation-based classifier. RESULTS Methylation data were successfully generated for 98/125 patients (poor quality DNA [n = 12], no consent [n = 11], insufficient tissue [n = 4]). Those with classifier scores below 0.5 (n = 25), tumor microenvironment only (n = 6) and rediagnosis as pleomorphic xanthoastrocytoma (n = 1) were excluded, leaving n = 66. Methylation classes were GBM RTK II (n = 23, PFS-6m 43% [95%CI 23-62]), RTK I (n = 20, PFS-6m 50% [95%CI 27-69]), MES (n = 20, PFS-6m 40% [95%CI 19-60]), MID (n = 2) and G34 (n = 1). Glioblastoma subtypes were mesenchymal (n = 28, PFS-6m 50% [95%CI 30-66]), proneural (n = 24, PFS-6m 50% [95%CI 29-68]) and classical (n = 14, PFS-6m 36% [95%CI 13-59]). MGMT status were unmethylated (n = 58, PFS-6m 48% [95%CI 35-60]) and methylated (n = 8, PFS-6m 38% [95%CI 9-67]). There was no evidence of interaction between treatment arm and methylation class (excluding GBM MID and G34, P = 0.45), glioblastoma subtype (P = 0.68) or MGMT status (P = 0.52). CONCLUSIONS Genome-wide DNA methylation patterns in VERTU identified a spectrum of methylation-defined subgroups, reflecting tumoral heterogeneity. This may have utility for future clinical trials and practice. The effect of veliparib in VERTU appeared to be consistent across subgroups. ACTRN12615000407594.