RecruitingDrug trialMAPK Inhibition Combined With Anti-PD1 Therapy for BRAF-altered Pediatric GliomasPediatric gliomas harboring BRAF-alterations, commonly BRAFV600 mutation or KIAA1549-BRAF fusion, are currently treated with either chemotherapy or mitogen activated protein kinase (MAPK) inhibitors, such as, dabrafenib and/or trametinib. Unfortunately, some BRAF-altered gliomas can progress or have rebound growth after discontinuation of therapy. Data from BRAFV600E-mutant melanoma has shown potential synergy between MAPK inhibition and anti-programmed cell death 1 (anti-PD1) checkpoint blockade. Anti-PD1 therapy, such as, nivolumab can block the PD1 receptor on T cells, a marker of T cell exhaustion, allowing a continued or more robust anti-tumor immune response. Here, investigators will combine MAPK inhibition with anti-PD1 therapy in recurrent, refractory low grade BRAF-altered glioma and newly diagnosed or recurrent BRAF-altered or NF-altered high grade glioma.