Adavosertib and Local Radiation Therapy in Treating Children With Newly Diagnosed Diffuse Intrinsic Pontine Gliomas

Inclusion Criteria: * Patients with newly diagnosed DIPGs, defined as tumors with a pontine epicenter and diffuse involvement of the pons, are eligible without histologic confirmation * Patients with brainstem tumors that do not meet these criteria or are not considered to be typical intrinsic pontine gliomas will only be eligible if the tumors are biopsied and proven to be an anaplastic astrocytoma, glioblastoma, gliosarcoma, diffuse midline glioma with histone H3 K27M mutation, or anaplastic mixed glioma; patients with pilocytic astrocytoma, fibrillary astrocytoma, gangliogliomas, or other mixed gliomas without anaplasia are not eligible * Patients with disseminated disease are not eligible, and magnetic resonance imaging (MRI) of spine must be performed if disseminated disease is suspected by the treating physician * Enrollment must be no later than 28 days after the date of radiographic diagnosis or surgery, whichever is the later date * Patients must have a body surface area \>= 0.35 m\^2 at the time of study enrollment * Karnofsky \>= 50% for patients \> 16 years of age and Lansky \>= 50 for patients =\< 16 years of age; patients who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score * Patients must not have received any prior anti-cancer therapy such as chemotherapy, radiation therapy, immunotherapy or bone marrow transplant for the treatment of DIPG; prior de…