Siada, Ruby

Abstract Background H3K27M-mutant diffuse midline glioma (DMG) is a lethal brain tumor that usually occurs in children. Despite advances in our understanding of its underlying biology, efficacious therapies are severely lacking. Methods We screened a library of drugs either FDA-approved or in clinical trial using a library of patient-derived H3K27M-mutant DMG cell lines with cell viability as the outcome. Results were validated for clinical relevance and mechanistic importance using patient specimens from biopsy and autopsy, patient-derived cell lines, inhibition by gene knockdown and small molecule inhibitors, and patient-derived xenografts. Results Kinase inhibitors were highly toxic to H3K27M-mutant DMG cells. Within this class, STAT3 inhibitors demonstrated robust cytotoxic activity in vitro. Mechanistic analyses revealed one form of activated STAT3, phospho-tyrosine- 705 STAT3 (pSTAT3), was selectively upregulated in H3K27M-mutant cell lines and clinical specimens. STAT3 inhibition by CRISPR/Cas9 knockout, shRNA or small molecule inhibition reduced cell viability in vitro, and partially restored expression of the polycomb repressive mark H3K27me3, which is classically lost in H3K27M-mutant DMG. Putative STAT3-regulated genes were enriched in an H3K27M-knockout DMG cell line, indicating relative gain of STAT3 signaling in K27M-mutant cells. Treatment of patient-derived intracranial xenografts with WP1066, a STAT3 pathway inhibitor currently in clinical use for pediatric brain tumors, resulted in stasis of tumor growth, and increased overall survival. Finally, pSTAT3(Y705) was detected in circulating plasma extracellular vesicles of patients with H3K27M-mutant DMG. Conclusions STAT3 is a biologically relevant therapeutic target in H3K27M-mutant DMG. STAT3 inhibition should be considered in future clinical trials.

Abstract ONC201, a bitopic DRD2 antagonist and allosteric ClpP agonist, has shown encouraging efficacy in H3 K27M-mutant glioma. Given that the thalamus has the highest extra-striatal expression of DRD2, we performed an integrated preclinical and clinical analysis of ONC201 in thalamic H3 K27M-mutant glioma. ONC201 was effective in mouse intra-uterine electroporation (IUE)-generated H3 K27M-mutant gliomas, with an in vitro IC50 of 500 nM and 50% prolongation of median survival in vivo (p=0.02, n=14). We analyzed thalamic H3 K27M-mutant glioma patients treated with ONC201 on active clinical trials as of 5/22/19 enrollment (n=19 recurrent and 10 post-radiation, non-recurrent; 5–70 years old). As of 12/18/2019, PFS6 and OS12 are 26.3% and 36.8%, respectively, in the recurrent group. For non-recurrent patients, with median follow up of 21.9 months (8.6–26.6) from diagnosis, median PFS or OS have not been reached. This surpasses historical OS of 13.5 months. Best response by RANO includes 1 CR, 3 PR, 4 SD, 8 PD for recurrent patients and 2 PR, 4 SD, 1 PD for non-recurrent patients (4 on-trial patients experienced regressions that are yet unconfirmed responses). Median duration of response for recurrent patients is 14.0 months (2.0–33.1). Furthermore, H3 K27M cell-free tumor DNA in plasma and CSF correlated with MRI response. In summary, single agent ONC201 administered at recurrence, or adjuvantly following radiation, demonstrates promising clinical efficacy in thalamic H3 K27M-mutant glioma patients who currently have no effective treatments following radiation. Investigations are ongoing to assess whether micro-environmental DRD2 expression explains the early exceptional responses in thalamic H3 K27M-mutant glioma.

OBJECTIVEGlioblastoma (GBM) during infancy is rare, and the clinical outcomes of congenital GBM are not well understood. Correspondingly, the aim of this study was to present a long-term survivor case from the authors’ institution, and establish an integrated cohort of cases across the published literature to better understand the clinical course of this disease in this setting.METHODSThe authors report the outcomes of an institutional case of congenital GBM diagnosed within the first 3 months of life, and performed a comprehensive literature search for published cases from 2000 onward for an integrated survival analysis. All cases were integrated into 1 cohort, and Kaplan-Meier estimations, Fisher’s exact test, and logistic regression were used to interrogate the data.RESULTSThe integrated cohort of 40 congenital GBM cases consisted of 23 (58%) females and 17 (42%) males born at a median gestational age of 38 weeks (range 22–40 weeks). Estimates of overall survival (OS) at 1 month was 67%, at 1 year it was 59%, and at 10 years it was 45%, with statistically superior outcomes for subgroups in which patients survived to be treated by resection and chemotherapy. In the overall cohort, multivariable analysis confirmed resection (p < 0.01) and chemotherapy (p < 0.01) as independent predictors of superior OS. Gestational age > 38 weeks (p < 0.01), Apgar scores ≥ 7 at 5 minutes (p < 0.01), absence of prenatal hydrocephalus (p < 0.01), and vaginal delivery (p < 0.01) were associated with greater odds of surgical diagnosis versus autopsy diagnosis.CONCLUSIONSCongenital GBM can deviate from the expected poor prognosis of adult GBM in terms of OS. Both resection and chemotherapy confer statistically superior prognostic advantages in those patients who survive within the immediate postnatal period, and should be first-line considerations in the initial management of this rare disease.