Study of MEK162 for Children With Low-Grade Gliomas

Patients with recurrent or progressive disease, as defined in the following three strata below, will be eligible. For eligibility determination, tumor imaging from at least two time-points must be available to document radiographic progression or recurrence. Patients with non-progressive refractory tumors will not be eligible. * Stratum 1: patients with LGG with a BRAF truncated fusion that is measurable in at least two dimensions on imaging. * Stratum 2: patients with NF1 and LGG that is measurable in at least two dimensions on imaging. * Stratum 3: Pediatric patients with a recurrent or progressive tumor thought to involve the Ras/Raf/ERK pathway but not included in strata 1 or 2 that is measurable in at least two dimensions on imaging. This includes any LGG not included in strata 1 or 2 (i.e., any LGG without a BRAF truncated fusion in a patient without NF1), any tumor other than LGG in a patient with NF1, and any other tumor with a documented activating BRAF, NRAS, or KRAS mutation. * Stratum 4 (surgical arm, target validation): Patients who meet criteria for stratum 1, 2, or 3 for whom tumor biopsy and/or resection is clinically indicated. * Tumor tissue for correlative studies must be available for all patients except those with NF1 and LGG (stratum 2) or any patient with optic pathway glioma (stratum 2 or 3), for whom tumor tissue is optional. * Patients must have received at least one prior chemotherapy or radiation regimen prior to progression. * At the time of enro…