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Purpose: We evaluated the efficacy of bevacizumab, alone and in combination with irinotecan, in patients with recurrent glioblastoma in a phase II, multicenter, open-label, noncomparative trial., Patients and Methods: One hundred sixty-seven patients were randomly assigned to receive bevacizumab 10 mg/kg alone or in combination with irinotecan 340 mg/m 2 or 125 mg/m 2 (with or without concomitant enzyme-inducing antiepileptic drugs, respectively) once every 2 weeks. Primary end points were 6-month progression-free survival and objective response rate, as determined by independent radiology review. Secondary end points included safety and overall survival., Results: In the bevacizumab-alone and the bevacizumab-plus-irinotecan groups, estimated 6-month progression-free survival rates were 42.6% and 50.3%, respectively; objective response rates were 28.2% and 37.8%, respectively; and median overall survival times were 9.2 months and 8.7 months, respectively. There was a trend for patients who were taking corticosteroids at baseline to take stable or decreasing doses over time. Of the patients treated with bevacizumab alone or bevacizumab plus irinotecan, 46.4% and 65.8%, respectively, experienced grade ≥ 3 adverse events, the most common of which were hypertension (8.3%) and convulsion (6.0%) in the bevacizumab-alone group and convulsion (13.9%), neutropenia (8.9%), and fatigue (8.9%) in the bevacizumab-plus-irinotecan group. Intracranial hemorrhage was noted in two patients (2.4%) in the bevacizumab-alone group (grade 1) and in three patients (3.8%) patients in the bevacizumab-plus-irinotecan group (grades 1, 2, and 4, respectively)., Conclusion: Bevacizumab, alone or in combination with irinotecan, was well tolerated and active in recurrent glioblastoma.

Background: Epidermal growth factor receptor (EGFR) amplification is found in nearly 40%-50% of glioblastoma cases. Several EGFR inhibitors have been tested in glioblastoma but have failed to demonstrate long-term therapeutic benefit, presumably because of acquired resistance. Targeting EGFR downstream signaling with mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) inhibitors would be a more effective approach to glioblastoma treatment. We tested the therapeutic potential of MEK1/2 inhibitors in glioblastoma using 3D cultures of glioma stem-like cells (GSCs) and mouse models of glioblastoma., Methods: Several MEK inhibitors were screened in an unbiased high-throughput platform using GSCs. Cell death was evaluated using flow cytometry and Western blotting (WB) analysis. RNA-seq, real-time quantitative polymerase chain reaction, immunofluorescence, and WB analysis were used to identify and validate neuronal differentiation., Results: Unbiased screening of multiple MEK inhibitors in GSCs showed antiproliferative and apoptotic cell death in sensitive cell lines. An RNA-seq analysis of cells treated with trametinib, a potent MEK inhibitor, revealed upregulation of neurogenesis and neuronal differentiation genes, such as achaete-scute homolog 1 (ASCL1), delta-like 3 (DLL3), and neurogenic differentiation 4 (NeuroD4). We validated the neuronal differentiation phenotypes in vitro and in vivo using selected differentiation markers (β-III-tubulin, ASCL1, DLL3, and NeuroD4). Oral treatment with trametinib in an orthotopic GSC xenograft model significantly improved animal survival, with 25%-30% of mice being long-term survivors., Conclusions: Our findings demonstrated that MEK1/2 inhibition promotes neuronal differentiation in glioblastoma, a potential additional mechanism of action of MEK1/2 inhibitors. Thus, MEK inhibitors could be efficacious in glioblastoma patients with activated EGFR/MAPK signaling., Competing Interests: J.F.D. is consulting/advisory board member for Carthera, Haihe Pharmaceuticals, MundiPharma, Insightec, BioAsis Technologies, Kintara, Kazia, Monteris Medical, Karyopharm, Sumitomo Dainippon Pharma Oncology, Merck, Sapience, VBI Vaccines, Chimerix, Midatech, Aucentra Therapeutics, Servier, Telix, Alpha Pharmaceuticals, Chimerix, and Cure Brain Cancer Foundation. W.K.A.Y. serves as a consultant with DNATrix, Roche, and Denovo. The rest of the authors have no conflicts of interest to disclose., (© The Author(s) 2023. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

Histone 3 lysine27-to-methionine (H3-K27M) mutations most frequently occur in diffuse midline gliomas (DMGs) of the childhood pons but are also increasingly recognized in adults. Their potential heterogeneity at different ages and midline locations is vastly understudied. Here, through dissecting the single-cell transcriptomic, epigenomic and spatial architectures of a comprehensive cohort of patient H3-K27M DMGs, we delineate how age and anatomical location shape glioma cell-intrinsic and -extrinsic features in light of the shared driver mutation. We show that stem-like oligodendroglial precursor-like cells, present across all clinico-anatomical groups, display varying levels of maturation dependent on location. We reveal a previously underappreciated relationship between mesenchymal cancer cell states and age, linked to age-dependent differences in the immune microenvironment. Further, we resolve the spatial organization of H3-K27M DMG cell populations and identify a mitotic oligodendroglial-lineage niche. Collectively, our study provides a powerful framework for rational modeling and therapeutic interventions., (© 2022. The Author(s).)

Background: There is an urgent need for additional therapies to treat recurrent glioblastoma (GBM). Preclinical studies suggest that high dose macitentan, an oral dual endothelin receptor antagonist, enhances the cytotoxic effects of temozolomide (TMZ) in GBM, improving survival. This phase I trial investigated the maximum tolerated dose of macitentan combined with TMZ in patients with recurrent GBM and assessed the safety and tolerability of high dose macitentan in these patients (NCT01499251)., Methods: Adults with recurrent GBM received ascending doses of macitentan from 30 mg once daily concomitantly with TMZ. Safety and tolerability were assessed in addition to exploratory efficacy and pharmacokinetic endpoints. An ancillary study examined biomarker expression following macitentan treatment prior to surgical resection of recurrent GBM., Results: Thirty-eight patients with recurrent GBM were administered macitentan doses up to 300 mg once daily; no dose-limiting toxicities were observed, and a maximum tolerated dose was not determined. All patients experienced at least one treatment-emergent adverse event (TEAE), the majority associated with GBM or TMZ treatment. TEAEs related to macitentan and TMZ were reported for 16 (42.1%) and 26 (68.4%) patients, respectively, with no serious macitentan-related TEAEs. Macitentan concentrations increased with dose, with no plateau in exposure. Substantial heterogeneity was observed in the expression of efficacy biomarkers within tumors. The Kaplan-Meier estimate of median overall survival across all dose groups was 9.4 (95% CI 8.5, 13.4) months., Conclusion: High-dose macitentan was well tolerated in recurrent GBM patients concomitantly receiving TMZ. TEAEs were consistent with those seen in patients receiving either drug individually., (© The Author(s) 2021. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

On July 24, 2020, a workshop sponsored by the National Brain Tumor Society was held on innovating brain tumor clinical trials based on lessons learned from the COVID-19 experience. Various stakeholders from the brain tumor community participated including the US Food and Drug Administration (FDA), academic and community clinicians, researchers, industry, clinical research organizations, patients and patient advocates, and representatives from the Society for Neuro-Oncology and the National Cancer Institute. This report summarizes the workshop and proposes ways to incorporate lessons learned from COVID-19 to brain tumor clinical trials including the increased use of telemedicine and decentralized trial models as opportunities for practical innovation with potential long-term impact on clinical trial design and implementation., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Temozolomide (TMZ) resistance in glioblastoma multiforme (GBM) is mediated by the DNA repair protein O6-methylguanine DNA methyltransferase (MGMT). MGMT promoter methylation (occurs in about 40% of patients) is associated with loss of MGMT expression (MGMT-) that compromises DNA repair, leading to a favorable response to TMZ therapy. The 60% of patients with unmethylated MGMT (MGMT+) GBM experience resistance to TMZ; in these patients, understanding the mechanism of MGMT-mediated repair and modulating MGMT activity may lead to enhanced TMZ activity. Here, we report a novel mode of regulation of MGMT protein activity by poly(ADP-ribose) polymerase (PARP)., Methods: MGMT-PARP interaction was detected by co-immunoprecipitation. PARylation of MGMT and PARP was detected by co-immunoprecipitation with anti-PAR antibody. O6-methylguanine (O6-MetG) adducts were quantified by immunofluorescence assay. In vivo studies were conducted in mice to determine the effectiveness of PARP inhibition in sensitizing GBM to TMZ., Results: We demonstrated that PARP physically binds with MGMT and PARylates MGMT in response to TMZ treatment. In addition, PARylation of MGMT by PARP is required for MGMT binding to chromatin to enhance the removal of O6-MetG adducts from DNA after TMZ treatment. PARP inhibitors reduced PARP-MGMT binding and MGMT PARylation, silencing MGMT activity to repair O6-MetG. PARP inhibition restored TMZ sensitivity in vivo in MGMT-expressing GBM., Conclusion: This study demonstrated that PARylation of MGMT by PARP is critical for repairing TMZ-induced O6-MetG, and inhibition of PARylation by PARP inhibitor reduces MGMT function rendering sensitization to TMZ, providing a rationale for combining PARP inhibitors to sensitize TMZ in MGMT-unmethylated GBM., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Neuro-Oncology.)

Glioblastoma (GBM), the most aggressive primary brain tumor, has a dismal prognosis. Despite our growing knowledge of genomic and epigenomic alterations in GBM, standard therapies and outcomes have not changed significantly in the past two decades. There is therefore an urgent unmet need to develop novel therapies for GBM. The inter- and intratumoral heterogeneity of GBM, inadequate drug concentrations in the tumor owing to the blood-brain barrier, redundant signaling pathways contributing to resistance to conventional therapies, and an immunosuppressive tumor microenvironment, have all hindered the development of novel therapies for GBM. Given the high frequency of DNA damage pathway alterations in GBM, researchers have focused their efforts on pharmacologically targeting key enzymes, including poly(ADP-ribose) polymerase (PARP), DNA-dependent protein kinase, ataxia telangiectasia-mutated, and ataxia telangiectasia and Rad3-related. The mainstays of GBM treatment, ionizing radiation and alkylating chemotherapy, generate DNA damage that is repaired through the upregulation and activation of DNA damage response (DDR) enzymes. Therefore, the use of PARP and other DDR inhibitors to render GBM cells more vulnerable to conventional treatments is an area of intense investigation. In this review, we highlight the growing body of data behind DDR inhibitors in GBM, with a focus on putative predictive biomarkers of response. We also discuss the challenges involved in the successful development of DDR inhibitors for GBM, including the intracranial location and predicted overlapping toxicities of DDR agents with current standards of care, and propose promising strategies to overcome these hurdles., (© The Author(s) 2021. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

Glioblastoma is the most common malignant primary brain tumor in adults and is almost invariably fatal. Despite our growing understanding of the various mechanisms underlying treatment failure, the standard-of-care therapy has not changed over the last two decades, signifying a great unmet need. The challenges of treating glioblastoma are many and include inadequate drug or agent delivery across the blood-brain barrier, abundant intra- and intertumoral heterogeneity, redundant signaling pathways, and an immunosuppressive microenvironment. Here, we review the innate and adaptive molecular mechanisms underlying glioblastoma's treatment resistance, emphasizing the intrinsic challenges therapeutic interventions must overcome-namely, the blood-brain barrier, tumoral heterogeneity, and microenvironment-and the mechanisms of resistance to conventional treatments, targeted therapy, and immunotherapy.

Diffuse infiltrating gliomas are a clinically and molecularly heterogeneous group of tumors that are uniformly incurable. Despite our growing knowledge of genomic and epigenomic alterations in gliomas, standard treatments have not changed in the past 2 decades and remain limited to surgical resection, ionizing radiation, and alkylating chemotherapeutic agents. Development of novel therapeutics for diffuse gliomas has been challenging due to inter- and intra-tumoral heterogeneity, diffuse infiltrative nature of gliomas, inadequate tumor/drug concentration due to blood-brain barrier, and an immunosuppressive tumor microenvironment. Given the high frequency of DNA damage pathway alterations in gliomas, researchers have focused their efforts in targeting the DNA damage pathways for the treatment of gliomas. A growing body of data has shed light on the role of poly(ADP-ribose) polymerase (PARP) in combination with radiation and temozolomide in high-grade gliomas. Furthermore, a novel therapeutic strategy in low-grade glioma is the recent elucidation for a potential role of PARP inhibitors in gliomas with IDH1/2 mutations. This review highlights the concepts behind targeting PARP in gliomas with a focus on putative predictive biomarkers of response. We further discuss the challenges involved in the successful development of PARP inhibitors in gliomas, including the intracranial location of the tumor and overlapping toxicities with current standards of care, and promising strategies to overcome these hurdles., Competing Interests: Conflicts of Interest: John de Groot is a paid consultant for Celldex; Deciphera Pharmaceuticals, AbbVie, FivePrime Therapeutics, Inc., GW Pharma, Carthera, Eli Lilly, Kadmon, Boston Biomedical Inc., Taiho Pharmaceuticals, Kairos Venture Investments, Syneos Health, Monteris, Agios, Mundipharma Research, GenomiCare, Blue Earth Diagnostics, Del Mar Pharmaceuticals, Insightec, Voyager Therapeutics, Inc., Merck & Co., Tocagen, Bioasis Technologies, Inc., and ResTORbio, Inc.; is on the advisory boards of Genentech, Celldex, Foundation Medicine, Inc., Novogen, Deciphera, Astrazeneca, Insys Therapeutics, Merck, Eli Lilly, Novella Clinical, Karyopharm Therapeutics, Blue Earth Diagnostics, Kiyatec, Vanquish Oncology, Orsenix, Insightec, Prelude Therapeutics, Debiopharm Therapeutics, Inc., and Janssen Global Services, LLC; has other relevant financial or material interests in data safety and monitoring board (DSMB): VBL Therapeutics [Glioblastoma (VB111)], DSMB: Novella [Glioblastoma (ICT-107)], and VBI Vaccines, Inc [Glioblastoma (VBI-1901)]; owns stock in Ziopharm Oncology and Gilead; and his spouse is employed with Ziopharm Oncology. Timothy A. Yap is a consultant for Almac, Aduro, AstraZeneca, Atrin, Axiom, Bayer, Bristol Myers Squibb, Calithera, Clovis, Cybrexa, EMD Serono, F-Star, Guidepoint, Ignyta, I-Mab, Jansen, Merck, Pfizer, Repare, Roche, Rubius, Schrodinger, Seattle Genetics, Varian, and Zai Labs. W. K. Alfred Yung is a consultant for Roche and is on the advisory boards of DNAtrix, Denovo, Quadriga, and ILCT. Nazanin Majd has nothing to disclose., (© Innovative Healthcare Institute.)

Background: Bevacizumab has promising activity against recurrent glioblastoma (GBM). However, acquired resistance to this agent results in tumor recurrence. We hypothesized that vorinostat, a histone deacetylase (HDAC) inhibitor with anti-angiogenic effects, would prevent acquired resistance to bevacizumab., Methods: This multicenter phase II trial used a Bayesian adaptive design to randomize patients with recurrent GBM to bevacizumab alone or bevacizumab plus vorinostat with the primary endpoint of progression-free survival (PFS) and secondary endpoints of overall survival (OS) and clinical outcomes assessment (MD Anderson Symptom Inventory Brain Tumor module [MDASI-BT]). Eligible patients were adults (≥18 y) with histologically confirmed GBM recurrent after prior radiation therapy, with adequate organ function, KPS ≥60, and no prior bevacizumab or HDAC inhibitors., Results: Ninety patients (bevacizumab + vorinostat: 49, bevacizumab: 41) were enrolled, of whom 74 were evaluable for PFS (bevacizumab + vorinostat: 44, bevacizumab: 30). Median PFS (3.7 vs 3.9 mo, P = 0.94, hazard ratio [HR] 0.63 [95% CI: 0.38, 1.06, P = 0.08]), median OS (7.8 vs 9.3 mo, P = 0.64, HR 0.93 [95% CI: 0.5, 1.6, P = 0.79]) and clinical benefit were similar between the 2 arms. Toxicity (grade ≥3) in 85 evaluable patients included hypertension (n = 37), neurological changes (n = 2), anorexia (n = 2), infections (n = 9), wound dehiscence (n = 2), deep vein thrombosis/pulmonary embolism (n = 2), and colonic perforation (n = 1)., Conclusions: Bevacizumab combined with vorinostat did not yield improvement in PFS or OS or clinical benefit compared with bevacizumab alone or a clinical benefit in adults with recurrent GBM. This trial is the first to test a Bayesian adaptive design with adaptive randomization and Bayesian continuous monitoring in patients with primary brain tumor and demonstrates the feasibility of using complex Bayesian adaptive design in a multicenter setting., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Receptor tyrosine kinases such as epidermal growth factor receptors (EGFRs) and their downstream signaling pathways such as the Ras-Raf-mitogen-activated protein kinase (MAPK) pathway play important roles in glioblastoma (GBM). This study investigated the safety, pharmacokinetics, and efficacy of sorafenib (Ras/Raf/MAPK inhibitor) in combination with erlotinib (EGFR inhibitor) for treatment of recurrent GBMs., Methods: Patients with recurrent GBM were eligible. A novel sequential accrual trial design was used, where patients were sequentially accrued into separate treatment arms in phase I and phase II investigations to optimize recruitment efficiency. In phase I, a standard 3 + 3 format was used to identify dose-limiting toxicities (DLTs), determine maximum tolerated dose (MTD), and investigate pharmacokinetics. Phase II followed a 2-stage design with the primary endpoint being 6-month progression-free survival (PFS6)., Results: Sixteen patients were recruited for phase I, and the MTD was determined to be sorafenib 200 mg twice daily and erlotinib 100 mg once daily. DLTs include Grade 3 hypertension, Grade 3 elevated liver transaminases, and Grade 4 elevated lipase. While erlotinib did not affect sorafenib levels, sorafenib reduced erlotinib levels. In phase II, 3 of 19 stage 1 participants were progression free at 6 months. This did not meet the predetermined efficacy endpoint, and the trial was terminated., Conclusion: This study identified the MTD and DLTs for sorafenib and erlotinib combination therapy for recurrent GBMs; however, efficacy data did not meet the primary endpoint. This study also demonstrates the feasibility of a novel sequential accrual clinical trial design that optimizes patient recruitment for multiarm studies, which is particularly effective for multicenter clinical trials., (Published by Oxford University Press on behalf of the Society for Neuro-Oncology and the European Association of Neuro-Oncology 2020.)

Background: We sought to ascertain the immune effector function of pembrolizumab within the glioblastoma (GBM) microenvironment during the therapeutic window., Methods: In an open-label, single-center, single-arm phase II "window-of-opportunity" trial in 15 patients with recurrent (operable) GBM receiving up to 2 pembrolizumab doses before surgery and every 3 weeks afterward until disease progression or unacceptable toxicities occurred, immune responses were evaluated within the tumor., Results: No treatment-related deaths occurred. Overall median follow-up time was 50 months. Of 14 patients monitored, 10 had progressive disease, 3 had a partial response, and 1 had stable disease. Median progression-free survival (PFS) was 4.5 months (95% CI: 2.27, 6.83), and the 6-month PFS rate was 40%. Median overall survival (OS) was 20 months, with an estimated 1-year OS rate of 63%. GBM patients' recurrent tumors contained few T cells that demonstrated a paucity of immune activation markers, but the tumor microenvironment was markedly enriched for CD68+ macrophages., Conclusions: Immune analyses indicated that pembrolizumab anti-programmed cell death 1 (PD-1) monotherapy alone can't induce effector immunologic response in most GBM patients, probably owing to a scarcity of T cells within the tumor microenvironment and a CD68+ macrophage preponderance., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose: Exploration of novel strategies to extend the benefit of PARP inhibitors beyond BRCA -mutant cancers is of great interest in personalized medicine. Here, we identified EGFR amplification as a potential biomarker to predict sensitivity to PARP inhibition, providing selection for the glioblastoma (GBM) patient population who will benefit from PARP inhibition therapy., Experimental Design: Selective sensitivity to the PARP inhibitor talazoparib was screened and validated in two sets [test set ( n = 14) and validation set ( n = 13)] of well-characterized patient-derived glioma sphere-forming cells (GSC). FISH was used to detect EGFR copy number. DNA damage response following talazoparib treatment was evaluated by γH2AX and 53BP1 staining and neutral comet assay. PARP-DNA trapping was analyzed by subcellular fractionation. The selective monotherapy of talazoparib was confirmed using in vivo glioma models., Results: EGFR -amplified GSCs showed remarkable sensitivity to talazoparib treatment. EGFR amplification was associated with increased reactive oxygen species (ROS) and subsequent increased basal expression of DNA-repair pathways to counterelevated oxidative stress, and thus rendered vulnerability to PARP inhibition. Following talazoparib treatment, EGFR -amplified GSCs showed enhanced DNA damage and increased PARP-DNA trapping, which augmented the cytotoxicity. EGFR amplification-associated selective sensitivity was further supported by the in vivo experimental results showing that talazoparib significantly suppressed tumor growth in EGFR -amplified subcutaneous models but not in nonamplified models., Conclusions: EGFR -amplified cells are highly sensitive to talazoparib. Our data provide insight into the potential of using EGFR amplification as a selection biomarker for the development of personalized therapy., (©2019 American Association for Cancer Research.)

Purpose: To estimate the maximum tolerated dose (MTD) and/or identify the recommended Phase II dose (RP2D) for combined INC280 and buparlisib in patients with recurrent glioblastoma with homozygous phosphatase and tensin homolog (PTEN) deletion, mutation or protein loss., Methods: This multicenter, open-label, Phase Ib/II study included adult patients with glioblastoma with mesenchymal-epithelial transcription factor (c-Met) amplification. In Phase Ib, patients received INC280 as capsules or tablets in combination with buparlisib. In Phase II, patients received INC280 only. Response was assessed centrally using Response Assessment in Neuro-Oncology response criteria for high-grade gliomas. All adverse events (AEs) were recorded and graded., Results: 33 patients entered Phase Ib, 32 with altered PTEN. RP2D was not declared due to potential drug-drug interactions, which may have resulted in lack of efficacy; thus, Phase II, including 10 patients, was continued with INC280 monotherapy only. Best response was stable disease in 30% of patients. In the selected patient population, enrollment was halted due to limited activity with INC280 monotherapy. In Phase Ib, the most common treatment-related AEs were fatigue (36.4%), nausea (30.3%) and increased alanine aminotransferase (30.3%). MTD was identified at INC280 Tab 300 mg twice daily + buparlisib 80 mg once daily. In Phase II, the most common AEs were headache (40.0%), constipation (30.0%), fatigue (30.0%) and increased lipase (30.0%)., Conclusion: The combination of INC280/buparlisib resulted in no clear activity in patients with recurrent PTEN-deficient glioblastoma. More stringent molecular selection strategies might produce better outcomes., Trial Registration: NCT01870726.

The evolutionary processes that drive universal therapeutic resistance in adult patients with diffuse glioma remain unclear 1,2 . Here we analysed temporally separated DNA-sequencing data and matched clinical annotation from 222 adult patients with glioma. By analysing mutations and copy numbers across the three major subtypes of diffuse glioma, we found that driver genes detected at the initial stage of disease were retained at recurrence, whereas there was little evidence of recurrence-specific gene alterations. Treatment with alkylating agents resulted in a hypermutator phenotype at different rates across the glioma subtypes, and hypermutation was not associated with differences in overall survival. Acquired aneuploidy was frequently detected in recurrent gliomas and was characterized by IDH mutation but without co-deletion of chromosome arms 1p/19q, and further converged with acquired alterations in the cell cycle and poor outcomes. The clonal architecture of each tumour remained similar over time, but the presence of subclonal selection was associated with decreased survival. Finally, there were no differences in the levels of immunoediting between initial and recurrent gliomas. Collectively, our results suggest that the strongest selective pressures occur during early glioma development and that current therapies shape this evolution in a largely stochastic manner.

PI3K-targeting therapy represents one of the most sought-after therapies for glioblastoma (GBM). Several small-molecule inhibitors have been evaluated in clinical trials, however, the emergence of resistance limits treatment potential. Here, we generated a patient-derived glioma sphere-forming cell (GSC) xenograft model resistant to the PI3K-specific inhibitor BKM-120. Integrated RNA sequencing and high-throughput drug screening revealed that the Aurora A kinase (Aurora A)/Polo-like kinase 1 (PLK1)/cyclin-dependent kinase 1 (CDK1) signaling pathway was the main driver of PI3K inhibitor resistance in the resistant xenografts. Aurora kinase was upregulated and pCDK1 was downregulated in resistant tumors from both xenografts and tumor tissues from patients treated with the PI3K inhibitor. Mechanistically, the tyrosine kinase receptor Tie2 physically interacted with FGFR1, promoting STAT3 phosphorylation and binding to the AURKA promoter, which increased Aurora A expression in resistant GSCs. Concurrent inhibition of Aurora A and PI3K signaling overcame PI3K inhibitor-induced resistance. This study offers a proof of concept to target PI3K and the collateral-activated pathway to improve GBM therapy. SIGNIFICANCE: These findings provide novel insights into the mechanisms of PI3K inhibitor resistance in glioblastoma., (©2019 American Association for Cancer Research.)

Malignant gliomas are a group of intracranial cancers associated with disproportionately high mortality and morbidity. Here, we report ultradeep targeted sequencing of a prospective cohort of 237 tumors from 234 patients consisting of both glioblastoma (GBM) and lower-grade glioma (LGG) using our customized gene panels. We identified 2,485 somatic mutations, including single-nucleotide substitutions and small indels, using a validated in-house protocol. Sixty-one percent of the mutations were contributed by 12 hypermutators. The hypermutators were enriched for recurrent tumors and had comparable outcome, and most were associated with temozolomide exposure. TP53 was the most frequently mutated gene in our cohort, followed by IDH1 and EGFR We detected at least one EGFR mutation in 23% of LGGs, which was significantly higher than 6% seen in The Cancer Genome Atlas, a pattern that can be partially explained by the different patient composition and sequencing depth. IDH hotspot mutations were found with higher frequencies in LGG (83%) and secondary GBM (77%) than primary GBM (9%). Multivariate analyses controlling for age, histology, and tumor grade confirm the prognostic value of IDH mutation. We predicted 1p/19q status using the panel sequencing data and received only modest performance by benchmarking the prediction to FISH results of 50 tumors. Targeted therapy based on the sequencing data resulted in three responders out of 14 participants. In conclusion, our study suggests ultradeep targeted sequencing can recapitulate previous findings and can be a useful approach in the clinical setting., (©2019 American Association for Cancer Research.)

Background: It is estimated only 8-11% of patients with glioblastoma (GBM) enrol in clinical trials, limiting treatment development. We analysed the clinical and demographic features of patients with GBM enroled in clinical trials at the University of Texas MD Anderson Cancer Center (MDACC)., Methods: We reviewed the records of adult patients treated for primary GBM between 2007 and 2012 at the MDACC. A total of 755 patients were identified: 133 were deemed non-eligible, 111 were deemed trial eligible but received standard care and 511 participated in a clinical trial (311 for newly diagnosed glioblastoma [nGBM] and 200 for recurrent glioblastoma [rGBM]). Population characteristics were analysed using descriptive statistics, and survival end-points were evaluated with the Kaplan-Meier method., Results: The median age of clinical trial participants and trial eligible patients was 53.2 years (standard deviation 12.1). Most patients (49.4%) were enroled in a clinical trial protocol for nGBM. The majority of nGBM trial participants were male patients (65.1%), white (86.3%), married (84.4%) and in state (59.9%). Employment status, education, symptoms, tumour location, performance status, extent of resection and treatment facility differed between nGBM trial participants and non-participants. Patients who were eligible but did not enrol tended to be older, have worse performance status and live farther away from the MDACC., Conclusion: Numerous disease and demographic barriers exist in trial enrolment in patients with GBM. This study highlights some of these obstacles, which require attention to improve patient enrolment to clinical trials. Patient and physician engagement in novel therapeutic strategies is essential to improving outcomes in this disease., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Purpose: Phosphatidylinositol 3-kinase (PI3K) signaling is highly active in glioblastomas. We assessed pharmacokinetics, pharmacodynamics, and efficacy of the pan-PI3K inhibitor buparlisib in patients with recurrent glioblastoma with PI3K pathway activation., Methods: This study was a multicenter, open-label, multi-arm, phase II trial in patients with PI3K pathway-activated glioblastoma at first or second recurrence. In cohort 1, patients scheduled for re-operation after progression received buparlisib for 7 to 13 days before surgery to evaluate brain penetration and modulation of the PI3K pathway in resected tumor tissue. In cohort 2, patients not eligible for re-operation received buparlisib until progression or unacceptable toxicity. Once daily oral buparlisib 100 mg was administered on a continuous 28-day schedule. Primary end points were PI3K pathway inhibition in tumor tissue and buparlisib pharmacokinetics in cohort 1 and 6-month progression-free survival (PFS6) in cohort 2., Results: Sixty-five patients were treated (cohort 1, n = 15; cohort 2, n = 50). In cohort 1, reduction of phosphorylated AKT S473 immunohistochemistry score was achieved in six (42.8%) of 14 patients, but effects on phosphoribosomal protein S6 S235/236 and proliferation were not significant. Tumor-to-plasma drug level was 1.0. In cohort 2, four (8%) of 50 patients reached 6-month PFS6, and the median PFS was 1.7 months (95% CI, 1.4 to 1.8 months). The most common grade 3 or greater adverse events related to treatment were lipase elevation (n = 7 [10.8%]), fatigue (n = 4 [6.2%]), hyperglycemia (n = 3 [4.6%]), and elevated ALT (n = 3 [4.6%])., Conclusion: Buparlisib had minimal single-agent efficacy in patients with PI3K-activated recurrent glioblastoma. Although buparlisib achieved significant brain penetration, the lack of clinical efficacy was explained by incomplete blockade of the PI3K pathway in tumor tissue. Integrative results suggest that additional study of PI3K inhibitors that achieve more-complete pathway inhibition may still be warranted.

Purpose DNX-2401 (Delta-24-RGD; tasadenoturev) is a tumor-selective, replication-competent oncolytic adenovirus. Preclinical studies demonstrated antiglioma efficacy, but the effects and mechanisms of action have not been evaluated in patients. Methods A phase I, dose-escalation, biologic-end-point clinical trial of DNX-2401 was conducted in 37 patients with recurrent malignant glioma. Patients received a single intratumoral injection of DNX-2401 into biopsy-confirmed recurrent tumor to evaluate safety and response across eight dose levels (group A). To investigate the mechanism of action, a second group of patients (group B) underwent intratumoral injection through a permanently implanted catheter, followed 14 days later by en bloc resection to acquire post-treatment specimens. Results In group A (n = 25), 20% of patients survived > 3 years from treatment, and three patients had a ≥ 95% reduction in the enhancing tumor (12%), with all three of these dramatic responses resulting in > 3 years of progression-free survival from the time of treatment. Analyses of post-treatment surgical specimens (group B, n = 12) showed that DNX-2401 replicates and spreads within the tumor, documenting direct virus-induced oncolysis in patients. In addition to radiographic signs of inflammation, histopathologic examination of immune markers in post-treatment specimens showed tumor infiltration by CD8 + and T-bet + cells, and transmembrane immunoglobulin mucin-3 downregulation after treatment. Analyses of patient-derived cell lines for damage-associated molecular patterns revealed induction of immunogenic cell death in tumor cells after DNX-2401 administration. Conclusion Treatment with DNX-2401 resulted in dramatic responses with long-term survival in recurrent high-grade gliomas that are probably due to direct oncolytic effects of the virus followed by elicitation of an immune-mediated antiglioma response.

From 1990 to 1994, patients with newly diagnosed malignant gliomas were enrolled and randomized between hyperfractionated radiation (HFX) of 72.0 Gy in 60 fractions given twice daily and 60.0 Gy in 30 fractions given once daily. All patients received 80 mg/m 2 of 1,3 bis(2 chloroethyl)-1 nitrosourea on days 1-3 q8 weeks for 1 year. Patients were stratified by age, KPS, and histology. The primary endpoint was overall survival (OS), with secondary endpoints including progression-free survival (PFS) and toxicity. Out of the 712 patients accrued, 694 (97.5%) were analyzable cases (350 HFX, 344 standard arm). There was no significant difference between the arms on overall acute or late treatment-related toxicity. No statistically significant effect for HFX, as compared to standard therapy, was found on either OS, with a median survival time (MST) of 11.3 versus 13.1 months (p = 0.20) or PFS, with a median PFS time of 5.7 versus 6.9 months (p = 0.18). The treatment effect on OS remained insignificant based on the multivariate analysis (hazard ratio 1.16; p = 0.0682). When OS was analyzed by histology subgroup there was also no significant difference between the two arms for patients with glioblastoma multiforme (MST: 10.3 vs. 11.2 months; p = 0.34), anaplastic astrocytoma (MST: 69.8 vs. 50.0 months; p = 0.91) or anaplastic oligodendroglioma (MST: 92.1 vs. 66.5 months; p = 0.33). Though this trial provided many invaluable secondary analyses, there was no trend or indication of a benefit to HFX radiation to 72.0 Gy in any subset of malignant glioma patients.

Glioblastoma (GBM) is a deadly disease with few effective therapies. Although much has been learned about the molecular characteristics of the disease, this knowledge has not been translated into clinical improvements for patients. At the same time, many new therapies are being developed. Many of these therapies have potential biomarkers to identify responders. The result is an enormous amount of testable clinical questions that must be answered efficiently. The GBM Adaptive Global Innovative Learning Environment (GBM AGILE) is a novel, multi-arm, platform trial designed to address these challenges. It is the result of the collective work of over 130 oncologists, statisticians, pathologists, neurosurgeons, imagers, and translational and basic scientists from around the world. GBM AGILE is composed of two stages. The first stage is a Bayesian adaptively randomized screening stage to identify effective therapies based on impact on overall survival compared with a common control. This stage also finds the population in which the therapy shows the most promise based on clinical indication and biomarker status. Highly effective therapies transition in an inferentially seamless manner in the identified population to a second confirmatory stage. The second stage uses fixed randomization to confirm the findings from the first stage to support registration. Therapeutic arms with biomarkers may be added to the trial over time, while others complete testing. The design of GBM AGILE enables rapid clinical testing of new therapies and biomarkers to speed highly effective therapies to clinical practice. Clin Cancer Res; 24(4); 737-43. ©2017 AACR ., (©2017 American Association for Cancer Research.)

Background: Oncogenic activation of phosphatidylinositol-3 kinase (PI3K) signaling plays a pivotal role in the development of glioblastoma (GBM). However, pharmacological inhibition of PI3K has so far not been therapeutically successful due to adaptive resistance through a rapid rewiring of cancer cell signaling. Here we identified that WEE1 is activated after transient exposure to PI3K inhibition and confers resistance to PI3K inhibition in GBM., Methods: Patient-derived glioma-initiating cells and established GBM cells were treated with PI3K inhibitor or WEE1 inhibitor alone or in combination, and cell proliferation was evaluated by CellTiter-Blue assay. Cell apoptosis was analyzed by TUNEL, annexin V staining, and blotting of cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase. Both subcutaneous xenograft and orthotropic xenograft studies were conducted to evaluate the effects of the combination on tumorigenesis; the tumor growth was monitored by bioluminescence imaging, and tumor tissue was analyzed by immunohistochemistry to validate signaling changes., Results: PI3K inhibition activates WEE1 kinase, which in turn phosphorylates cell division control protein 2 homolog (Cdc2) at Tyr15 and inhibits Cdc2 activity, leading to G2/M arrest in a p53-independent manner. WEE1 inhibition abrogated the G2/M arrest and propelled cells to prematurely enter into mitosis and consequent cell death through mitotic catastrophe and apoptosis. Additionally, combination treatment significantly suppressed tumor growth in a subcutaneous model but not in an intracranial model due to limited blood-brain barrier penetration., Conclusions: Our findings highlight WEE1 as an adaptive resistant gene activated after PI3K inhibition, and inhibition of WEE1 potentiated the effectiveness of PI3K targeted inhibition, suggesting that a combinational inhibition of WEE1 and PI3K might allow successful targeted therapy in GBM., (© The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com)

Recurrent glioblastoma (GBM) has a very low 6-month progression free survival (PFS) with currently available treatments. Combination chemotherapy to target multiple cell signaling pathways is currently being investigated in order to improve prognosis for recurrent disease. The purpose of this phase I study was to determine the maximum tolerated dose (MTD) for the combination of tipifarnib and sorafenib for the treatment of recurrent GBM. Patients with pathologically proven WHO grade IV GBM and radiographically proven tumor recurrence were eligible for this study. Treatments included sorafenib at twice daily and escalating dosages of tipifarnib. Dose-limiting toxicity (DLT) was determined over the first 28-days of treatments, and the MTD was determined in a 3 + 3 study design. We enrolled 24 patients, and 21 patients completed the MTD period. The study was stopped early with no MTD determination for excessive toxicities. The last dose level reached was sorafenib at 200 mg twice a day and tipifarnib 100 mg twice a day on an alternating week schedule. The DLTs included diarrhea, lipase elevation, hypophosphatemia, and arthralgia. The combination of sorafenib and tipifarnib has excessive toxicities and full single agent dosages could not be achieved in combination.

Glioblastoma (GBM) is an ideal candidate disease for signal transduction targeted therapy because the majority of these tumors harbor genetic alterations that result in aberrant activation of growth factor signaling pathways. Loss of heterozygosity of chromosome 10, mutations in the tumor suppressor gene PTEN, and PI3K mutations are molecular hallmarks of GBM and indicate poor prognostic outcomes in many cancers. Consequently, inhibiting the PI3K pathway may provide therapeutic benefit in these cancers. PI3K inhibitors generally block proliferation rather than induce apoptosis. To restore the sensitivity of GBM to apoptosis induction, targeted agents have been combined with conventional therapy. However, the molecular heterogeneity and infiltrative nature of GBM make it resistant to traditional single agent therapy. Our objectives were to test a dual PI3K/mTOR inhibitor that may cross the blood-brain barrier (BBB) and provide the rationale for using this inhibitor in combination regimens to chemotherapy-induced synergism in GBM. Here we report the preclinical potential of a novel, orally bioavailable PI3K/mTOR dual inhibitor, DS7423 (hereafter DS), in in-vitro and in-vivo studies. DS was tested in mice, and DS plasma and brain concentrations were determined. DS crossed the BBB and led to potent suppression of PI3K pathway biomarkers in the brain. The physiologically relevant concentration of DS was tested in 9 glioma cell lines and 22 glioma-initiating cell (GIC) lines. DS inhibited the growth of glioma tumor cell lines and GICs at mean 50% inhibitory concentration values of less than 250 nmol/L. We found that PI3K mutations and PTEN alterations were associated with cellular response to DS treatment; with preferential inhibition of cell growth in PI3KCA-mutant and PTEN altered cell lines. DS showed efficacy and survival benefit in the U87 and GSC11 orthotopic models of GBM. Furthermore, administration of DS enhanced the antitumor efficacy of temozolomide against GBM in U87 glioma models, which shows that PI3K/mTOR inhibitors may enhance alkylating agent-mediated cytotoxicity, providing a novel regimen for the treatment of GBM. Our present findings establish that DS can specifically be used in patients who have PI3K pathway activation and/or loss of PTEN function. Further studies are warranted to determine the potential of DS for glioma treatment.

Antiangiogenic therapy can rapidly reduce vascular permeability and cerebral edema but high doses of bevacizumab may induce selective pressure to promote resistance. This trial evaluated the efficacy of low dose bevacizumab in combination with lomustine (CCNU) compared to standard dose bevacizumab in patients with recurrent glioblastoma. Patients (N = 71) with recurrent glioblastoma who previously received radiation and temozolomide were randomly assigned 1:1 to receive bevacizumab monotherapy (10 mg/kg) or low dose bevacizumab (5 mg/kg) in combination with lomustine (90 mg/m(2)). The primary end point was progression-free survival (PFS) based on a blinded, independent radiographic assessment of post-contrast T1-weighted and non-contrast T2/FLAIR weighted magnetic resonance imaging (MRI) using RANO criteria. For 69 evaluable patients, median PFS was not significantly longer in the low dose bevacizumab + lomustine arm (4.34 months, CI 2.96-8.34) compared to the bevacizumab alone arm (4.11 months, CI 2.69-5.55, p = 0.19). In patients with first recurrence, there was a trend towards longer median PFS time in the low dose bevacizumab + lomustine arm (4.96 months, CI 4.17-13.44) compared to the bevacizumab alone arm (3.22 months CI 2.5-6.01, p = 0.08). The combination of low dose bevacizumab plus lomustine was not superior to standard dose bevacizumab in patients with recurrent glioblastoma. Although the study was not designed to exclusively evaluate patients at first recurrence, a strong trend towards improved PFS was seen in that subgroup for the combination of low dose bevacizumab plus lomustine. Further studies are needed to better identify such subgroups that may most benefit from the combination treatment.