ACT001 for the Treatment of Diffuse Intrinsic Pontine Gliomas and H3K27-altered High Grade Gliomas

Patients will be enrolled on either Cohort A for newly diagnosed DIPG or on Cohort B \[ENROLLMENT PAUSED\] for those with progressive / refractory DIPG or progressive / recurrent / refractory H3K27-altered HGG. Each cohort will receive ACT001 at 875 mg/m2 orally BID for 28 days (1 cycle of treatment), up to a maximum dose of 1700 mg BID. If patients are experiencing clinical benefit from study therapy, they will continue to receive ACT001 in repeat 28-day cycles for up to 26 cycles (approximately 2 years) or until disease progression, whichever occurs first. Continuation of treatment beyond 26 cycles may be considered if patients are receiving clinical benefit from the study, at the discretion of the sponsor and treating physician.