Optune for Children With High-Grade Glioma or Ependymoma, and Optune With Radiation Therapy for Children With DIPG

Inclusion Criteria: * Age: at the time of enrollment Stratum 1: ≥ 5 years but ≤ 21 Stratum 2: ≥ 3 years but ≤ 21 * Diagnosis: Stratum 1: Patients must have a histologically confirmed diagnosis of supratentorial high-grade glioma or supratentorial ependymoma that is recurrent, progressive or refractory. Stratum 2: Patients with newly diagnosed DIPG * Patients with a typical DIPG on MR imaging, defined as a tumor with a pontine epicenter and diffuse involvement of more than 2/3 of the pons, are eligible without histologic confirmation. * Note: Patients with typical DIPG who undergo a biopsy are eligible provided the tumor is a diffuse glioma WHO Grade II-IV with OR without H3 K27M mutation. * Patients with pontine lesions that do not meet these MR imaging criteria will be eligible if there is histologic confirmation diffuse glioma WHO Grade II-IV with H3 K27M-mutation. * Disease Status: Patients must have bi-dimensionally measurable disease, defined as at least one lesion that can be accurately measured in at least two planes Stratum 1: * This disease must be located primarily in the supratentorial region * Patients with significant disease that is metastatic outside of the supratentorial region are ineligible Stratum 2: * This disease must be located primarily in the pons * Prior Therapy: Stratum 1: Patients must have recovered from the acute treatment related toxicities (defined as ≤ grade 1) of all prior chemotherapy, immunotherapy, or radiotherapy prior to en…