Abstract
This phase I trial studies the side effects and best dose of pembrolizumab and to see how
well it works in treating younger patients with high-grade gliomas (brain tumors that are
generally expected to be fast growing and aggressive), diffuse intrinsic pontine gliomas
(brain stem tumors), brain tumors with a high number of genetic mutations, ependymoma or
medulloblastoma that have come back (recurrent), progressed, or have not responded to
previous treatment (refractory). Immunotherapy with monoclonal antibodies, such as
pembrolizumab, may induce changes in the body's immune system, and may interfere with the
ability of tumor cells to grow and spread.
