Ji, Sunjong

Abstract H3K27M-mutant diffuse midline glioma (DMG) patients have no proven effective therapies beyond radiation. ONC201, a mitochondrial protease ClpP agonist, has recently demonstrated efficacy in these patients, but the mechanism behind this remains unknown. We assessed clinical outcomes, tumor sequencing, and tissue samples from patients treated in two completed multi-site clinical studies (n=71). Patients treated with ONC201 monotherapy following initial radiation but prior to recurrence (n=35) demonstrated a median overall survival of 21.7 months and a median progression-free survival of 12.2 months. Radiographic response was associated with increased expression of key tricarboxylic acid cycle-related genes in baseline tumor sequencing. Similar survival benefits were observed using in utero electroporation and orthotopic mouse models of H3K27M-DMG (median 107 versus 77 days [p=0.02] and median 97 versus 141 days [p=0.004], respectively). Integrated transcriptomic and metabolomic analysis of ONC201-treated H3K27M-DMG cells revealed downregulation of TCA cycle, glycolysis, and pyruvate metabolism genes, most notably oxoglutarate dehydrogenase (OGDH), and concomitant changes in levels of associated metabolites including ɑ-ketoglutarate (ɑ-KG). Interestingly, L-2-hydroxyglutarate (L-2HG), a known inhibitor of the Jumonji C domain family of histone lysine demethylases, was also increased. This corresponded with increases in repressive H3K27me3 in vitro and in human tumors accompanied by epigenetic downregulation of cell cycle regulation and neuro-glial differentiation genes. Genetic knockdown of OGDH recapitulated ONC201-mediated increases in H3K27me3. In contrast, genetic knockdown of ClpP or lactate dehydrogenase A or overexpression of L-2-hydroxyglutarate dehydrogenase (L-2HGDH), but not D-2HGDH, abrogated ONC201-mediated increases in H3K27me3, demonstrating that ONC201 induces the production of L-2HG in H3K27M-DMG cells leading to increased H3K27me3. Overall, our data demonstrates the efficacy of ONC201 in H3K27M-mutant DMG and supports ONC201 as the first monotherapy to improve outcomes in patients with H3K27M-mutant DMG for whom few therapeutic options currently exist. Mechanistically, ONC201 disrupts integrated metabolic and epigenetic pathways and reverses pathognomonic H3K27me3 reduction.

Abstract Patients with H3K27M-mutant diffuse midline glioma (DMG) have no proven effective therapies. ONC201 has recently demonstrated efficacy in these patients, but the mechanism behind this finding remains unknown. We assessed clinical outcomes, tumor sequencing, and tissue/cerebrospinal fluid (CSF) correlate samples from patients treated in two completed multisite clinical studies. Patients treated with ONC201 following initial radiation but prior to recurrence demonstrated a median overall survival of 21.7 months, whereas those treated after recurrence had a median overall survival of 9.3 months. Radiographic response was associated with increased expression of key tricarboxylic acid cycle–related genes in baseline tumor sequencing. ONC201 treatment increased 2-hydroxyglutarate levels in cultured H3K27M-DMG cells and patient CSF samples. This corresponded with increases in repressive H3K27me3 in vitro and in human tumors accompanied by epigenetic downregulation of cell cycle regulation and neuroglial differentiation genes. Overall, ONC201 demonstrates efficacy in H3K27M-DMG by disrupting integrated metabolic and epigenetic pathways and reversing pathognomonic H3K27me3 reduction. Significance: The clinical, radiographic, and molecular analyses included in this study demonstrate the efficacy of ONC201 in H3K27M-mutant DMG and support ONC201 as the first monotherapy to improve outcomes in H3K27M-mutant DMG beyond radiation. Mechanistically, ONC201 disrupts integrated metabolic and epigenetic pathways and reverses pathognomonic H3K27me3 reduction. This article is featured in Selected Articles from This Issue, p. 2293

Abstract Background Female underrepresentation in oncology clinical trials can result in outcome disparities. We evaluated female participant representation in US oncology trials by intervention type, cancer site, and funding. Materials and Methods Data were extracted from the publicly available Aggregate Analysis of ClinicalTrials.gov database. Initially, 270,172 studies were identified. Following the exclusion of trials using Medical Subject Heading terms, manual review, those with incomplete status, non-US location, sex-specific organ cancers, or lacking participant sex data, 1650 trials consisting of 240,776 participants remained. The primary outcome was participation to prevalence ratio (PPR): percent females among trial participants divided by percent females in the disease population per US Surveillance, Epidemiology, and End Results Program data. PPRs of 0.8-1.2 reflect proportional female representation. Results Females represented 46.9% of participants (95% CI, 45.4-48.4); mean PPR for all trials was 0.912. Females were underrepresented in surgical (PPR 0.74) and other invasive (PPR 0.69) oncology trials. Among cancer sites, females were underrepresented in bladder (odds ratio [OR] 0.48, 95% CI 0.26-0.91, P = .02), head/neck (OR 0.44, 95% CI 0.29-0.68, P < .01), stomach (OR 0.40, 95% CI 0.23-0.70, P < .01), and esophageal (OR 0.40 95% CI 0.22-0.74, P < .01) trials. Hematologic (OR 1.78, 95% CI 1.09-1.82, P < .01) and pancreatic (OR 2.18, 95% CI 1.46-3.26, P < .01) trials had higher odds of proportional female representation. Industry-funded trials had greater odds of proportional female representation (OR 1.41, 95% CI 1.09-1.82, P = .01) than US government and academic-funded trials. Conclusions Stakeholders should look to hematologic, pancreatic, and industry-funded cancer trials as exemplars of female participant representation and consider female representation when interpreting trial results.

Abstract Background Diffuse Midline Glioma (DMG) with the H3K27M mutation is a lethal childhood brain cancer, with patients rarely surviving 2 years from diagnosis. Methods We conducted a multi-site Phase 1 trial of the imipridone ONC201 for children with H3K27M-mutant glioma (NCT03416530). Patients enrolled on Arm D of the trial (n = 24) underwent serial lumbar puncture for cell-free tumor DNA (cf-tDNA) analysis and patients on all arms at the University of Michigan underwent serial plasma collection. We performed digital droplet polymerase chain reaction (ddPCR) analysis of cf-tDNA samples and compared variant allele fraction (VAF) to radiographic change (maximal 2D tumor area on MRI). Results Change in H3.3K27M VAF over time (“VAF delta”) correlated with prolonged PFS in both CSF and plasma samples. Nonrecurrent patients that had a decrease in CSF VAF displayed a longer progression free survival (P = .0042). Decrease in plasma VAF displayed a similar trend (P = .085). VAF “spikes” (increase of at least 25%) preceded tumor progression in 8/16 cases (50%) in plasma and 5/11 cases (45.4%) in CSF. In individual cases, early reduction in H3K27M VAF predicted long-term clinical response (>1 year) to ONC201, and did not increase in cases of later-defined pseudo-progression. Conclusion Our work demonstrates the feasibility and potential utility of serial cf-tDNA in both plasma and CSF of DMG patients to supplement radiographic monitoring. Patterns of change in H3K27M VAF over time demonstrate clinical utility in terms of predicting progression and sustained response and possible differentiation of pseudo-progression and pseudo-response.

85 Background: Females are thought to be underrepresented in clinical trials, which may lead to care disparities. We characterized female enrollment trends in U.S. oncology trials registered on ClinicalTrials.gov and identified features associated with accurate representation. Methods: We employed a cross-sectional study design with descriptive, logistic regression, and cox regression analyses. We downloaded 270,172 studies registered on the Aggregate Analysis of the ClinicalTrials.gov database from October 1, 2008 to March 9, 2020, excluding non-interventional and reproductive organ specific trials. We then applied cancer/oncology specific Medical Subject Heading terms and manually reviewed the remaining 27,521 trials for true oncology content. Prevalence-corrected estimates for female participation were calculated as the percentage of females among trial participants divided by the percentage of females in the disease population per U.S. Surveillance, Epidemiology, and End Results Program (SEER) data (participation to prevalence ratio [PPR]), with a range between 0.8 and 1.2 reflecting accurate female representation in the trial. Results: Of 26,894 trials meeting eligibility criteria, 9,059 trials were completed in the U.S., 2,499 trials reported completed study status, and only 1,256 trials reported sex. Among 1,256 oncology trials and 229,056 participants, overall female representation was 46.9% (95% CI, 45.4-48.4%). 43% of trials were industry funded, 29% academic, and 28% U.S. government. Females were underrepresented compared to their disease burden in anal canal (PPR 0.21), thyroid (PPR 0.57), stomach (PPR 0.68), kidney (PPR 0.77), and bone (PPR 0.79) cancer trials. They were accurately represented in head and neck (PPR 0.80), lung (PPR 0.84), bladder (PPR 0.85), skin (PPR 0.88), pancreas (PPR 0.88), colon (PPR 0.90), hematologic (PPR 0.91), liver (PPR 1.01), CNS (PPR 1.03), soft tissue (PPR 1.05), and esophagus (PPR 1.05) cancer trials. Accurate representation was significantly associated with industry funding and pancreas cancer trial focus, but not associated with trial type (medical, surgical, radiation, other invasive, other) (Table). Conclusions: Females are underrepresented compared to their disease burden in many solid tumor clinical trials. Stakeholders can look to industry funded and pancreas cancer trials as models of improvement, but must increase female representation in clinical trials to improve cancer care. [Table: see text]