A Phase 1b Study of PTC596 in Children With Newly Diagnosed Diffuse Intrinsic Pontine Glioma and High Grade Glioma

The goal of this study is to evaluate the safety of the study drug PTC596 (Unesbulin) taken in combination with radiotherapy (RT) when given to pediatric patients newly diagnosed with High-Grade Glioma (HGG) including diffuse intrinsic pontine glioma (DIPG). The main aims of the study are to: * Find the safe dose of the study drug PTC596that can be given without causing serious side effects. * Find out the amount of drug that enters blood (in all patients) and tumor (in patients who receive drug prior to a planned surgery for removal of their brain tumor) During the first cycle (6-7weeks), patients will receive drug orally twice a week in combination with daily RT. During subsequent cycles (4 weeks each), they will receive only the study drug orally twice a week. Funding Source - FDA OOPD