Carl Koschmann

Background This study evaluated the safety and pharmacokinetics (PK) of oral ONC201 administered twice-weekly on consecutive days (D1D2) in pediatric patients with newly diagnosed DIPG and/or recurrent/refractory H3 K27M glioma. Methods This phase 1 dose-escalation and expansion study included pediatric patients with H3 K27M-mutant glioma and/or DIPG following ≥1 line of therapy (NCT03416530). ONC201 was administered D1D2 at three dose levels (DLs; -1, 1, and 2). Actual administered dose within DLs was dependent on weight. Safety was assessed in all DLs; PK analysis was conducted in DL2. Patients receiving once-weekly ONC201 (D1) served as a PK comparator.1 Results Twelve patients received D1D2 ONC201 (DL-1, n=3; DL1, n=3; DL2, n=6); no dose-limiting toxicities or grade ≥3 treatment-related adverse events occurred. PK analyses at DL2 (D1-250mg, n=3; D1-625mg, n=3; D1D2-250mg, n=2; D1D2-625mg, n=2) demonstrated variability in Cmax, AUC0-24, and AUC0-48, with comparable exposures across weight groups. No accumulation occurred with D1D2 dosing; the majority of ONC201 cleared before administration of the second dose. Cmax was variable between groups but did not appear to increase with D1D2 dosing. AUC0-48 was greater with D1D2 than once-weekly. Conclusions ONC201 given D1D2 was well-tolerated at all DLs and associated with greater AUC0-48.