Selumetinib in Treating Young Patients With Recurrent or Refractory Low Grade Glioma

Inclusion Criteria: * Imaging evaluations necessary to establish eligibility for study entry must be done within three (3) weeks prior to registration * All other evaluations necessary to establish eligibility for study entry must be done within two (2) weeks prior to registration * Patients must start therapy within 7 calendar days of registration * Laboratory values must be no older than seven (7) days prior to the start of therapy; if a test that is repeated after registration and prior to therapy is outside the limits for eligibility, it must be rechecked within 48 hours prior to the start of therapy; if laboratory values still fail to meet eligibility criteria, the patient may not receive protocol therapy * All patients must meet the following inclusion and exclusion criteria; NO EXCEPTIONS WILL BE GIVEN * Participant is willing to sign a screening consent and provide adequate pre-trial tumor material for BRAF testing (both for BRAF V\^600E mutation and BRAF KIAA1549 fusion assessments) * All patients who are candidates for enrollment in stratum 5 based on their tumor histology must be pre-screened * Screening may be applied to potential stratum 1 and 2 patients * Patients whose prior BRAF testing was performed at another lab (Clinical Laboratory Improvement Amendments \[CLIA\]/College of American Pathologist \[CAP\] certified or otherwise) must send additional tumor material to Brigham and Women's Hospital (BWH) for confirmation; however, to preserve available tum…