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Background Glioblastoma is the deadliest brain tumor in adults, and the standard of care consists of surgery followed by radiation and treatment with temozolomide. Overall survival times for patients suffering from glioblastoma are unacceptably low indicating an unmet need for novel treatment options. Methods Using patient-derived HK-157, HK-308, HK-374, and HK-382 glioblastoma lines, the GL261 orthotopic mouse models of glioblastoma, and HK-374 patient-derived orthotopic xenografts, we tested the effect of radiation and the dopamine receptor antagonist quetiapine on glioblastoma self-renewal in vitro and survival in vivo. A possible resistance mechanism was investigated using RNA-sequencing. The blood-brain-barrier–penetrating statin atorvastatin was used to overcome this resistance mechanism. All statistical tests were 2-sided. Results Treatment of glioma cells with the dopamine receptor antagonist quetiapine reduced glioma cell self-renewal in vitro, and combined treatment of mice with quetiapine and radiation prolonged the survival of glioma-bearing mice. The combined treatment induced the expression of genes involved in cholesterol biosynthesis. This rendered GL261 and HK-374 orthotopic tumors vulnerable to simultaneous treatment with atorvastatin and further statistically significantly prolonged the survival of C57BL/6 (n = 10 to 16 mice per group; median survival not reached; log-rank test, P Conclusions Our results indicate promising therapeutic efficacy with the triple combination of quetiapine, atorvastatin, and radiation treatment against glioblastoma without increasing the toxicity of radiation. With both drugs readily available for clinical use, our study could be rapidly translated into a clinical trial.

Glioblastomas are the most common form of malignant primary brain tumor and an important cause of morbidity and mortality. In recent years there have been important advances in understanding the molecular pathogenesis and biology of these tumors, but this has not translated into significantly improved outcomes for patients. In this consensus review from the Society for Neuro-Oncology (SNO) and the European Association of Neuro-Oncology (EANO), the current management of isocitrate dehydrogenase wildtype (IDHwt) glioblastomas will be discussed. In addition, novel therapies such as targeted molecular therapies, agents targeting DNA damage response and metabolism, immunotherapies, and viral therapies will be reviewed, as well as the current challenges and future directions for research.

We describe an analytical method for profiling lactate production in single cells, via the use of coupled enzyme reactions on surface-grafted resazurin molecules. The immobilization of the redox-labile probes was achieved through chemical modifications on resazurin, followed by bio-orthogonal click reactions. The lactate detection scheme was demonstrated to be sensitive and specific. The method was incorporated into the single cell barcode chip platform for simultaneous quantification of aerobic glycolysis activities and oncogenic signaling phosphoproteins in cancer. We interrogated the interplay between glycolysis and oncogenic signaling activities on a glioblastoma cell line. Results revealed a drug-induced oncogenic signaling reliance accompanying shifted metabolic paradigms. A drug combination that exploits this induced reliance exhibited synergistic effects in growth inhibition.

The epidermal growth factor receptor (EGFR) is altered in nearly 60% of glioblastoma (GBM) tumors, however, EGFR tyrosine kinase inhibitors (TKIs) have failed to improve outcomes for patients with GBM. This can be attributed to the inability of clinically available EGFR TKIs (e.g., erlotinib, gefitinib, lapatinib, afatinib, cetuximab) to effectively cross the blood-brain-barrier (BBB) and reach adequate pharmacological levels for a tumor response. Herein, we performed a structure-activity relationship (SAR) to obtain EGFR TKIs with both high brain penetrance and potency against EGFR-activated GBM cells. From over 80 novel compounds synthesized, our lead EGFR TKI—JCN068—exhibited exceptional BBB penetration (350% brain to plasma) while also having optimal ADME properties (60% oral bioavailability, ~5 hr half-life, >100 µg/mL solubility, etc). Moreover, JCN068 demonstrated picomolar potency against purified EGFR kinase, 1000-fold selectivity for EGFR relative to other kinases, and nanomolar activity against EGFR-altered, GBM patient-derived cells in culture. Importantly, JCN068 demonstrated superior efficacy—with negligible toxicity—compared to clinically available small molecule EGFR TKIs (erlotinib and lapatinib) against multiple EGFR-altered patient-derived orthotopic GBM xenografts. Due to these excellent drug-like properties, JCN068 is currently progressing towards clinical development for EGFR-activated GBM patients.

MYC is a central driver of tumorigenesis in many malignancies, including the universally lethal glioblastoma (GBM). However, developing direct inhibitors of MYC have proven challenging. One appealing alternative strategy to target MYC-driven cancers is to interfere with the signaling program necessary to facilitate MYC-dependent transcription. Cyclin-dependent kinase 9 (CDK9) has emerged as an attractive candidate through its function as a critical regulator in the transcriptional elongation of MYC and its target genes. Using a panel of patient-derived GBM cells, here we demonstrate that CDK9 inhibition with the brain-penetrant multi-CDK inhibitor, TG02, potently suppresses GBM cell growth. Importantly, the anti-GBM efficacy of TG02 strongly correlates with MYC expression and appears to be independent of methylation status, suggesting a critical role for CDK9 in MYC-driven GBMs. These preliminary results indicate that CDK9 may be an actionable therapeutic target in GBM with aberrant MYC signaling and, importantly, the clinical stage oral small molecule, TG02, is an appealing drug candidate for GBM with elevated MYC activity. Ongoing in vivo efficacy studies are evaluating TG02 in clinically relevant MYC-driven GBM mouse models.

Cross-talk among oncogenic signaling and metabolic pathways may create opportunities for new therapeutic strategies in cancer. Here we show that although acute inhibition of EGFR-driven glucose metabolism induces only minimal cell death, it lowers the apoptotic threshold in a subset of patient-derived glioblastoma (GBM) cells. Mechanistic studies revealed that after attenuated glucose consumption, Bcl-xL blocks cytoplasmic p53 from triggering intrinsic apoptosis. Consequently, targeting of EGFR-driven glucose metabolism in combination with pharmacological stabilization of p53 with the brain-penetrant small molecule idasanutlin resulted in synthetic lethality in orthotopic glioblastoma xenograft models. Notably, neither the degree of EGFR-signaling inhibition nor genetic analysis of EGFR was sufficient to predict sensitivity to this therapeutic combination. However, detection of rapid inhibitory effects on [18F]fluorodeoxyglucose uptake, assessed through noninvasive positron emission tomography, was an effective predictive biomarker of response in vivo. Together, these studies identify a crucial link among oncogene signaling, glucose metabolism, and cytoplasmic p53, which may potentially be exploited for combination therapy in GBM and possibly other malignancies.