NCT02359565 2026-05-13Pembrolizumab in Treating Younger Patients With Recurrent, Progressive, or Refractory High-Grade Gliomas, Diffuse Intrinsic Pontine Gliomas, Hypermutated Brain Tumors, Ependymoma or MedulloblastomaNational Cancer Institute (NCI)Phase 1 Active not recruiting71 enrolled