Phase II Study of Binimetinib in Children and Adults With NF1 Plexiform Neurofibromas

Inclusion Criteria * Clinical diagnosis of NF1 using the NIH Consensus Conference criteria OR a documented constitutional NF1 mutation * Plexiform neurofibroma(s) that are progressive or causing significant morbidity * Presence of new plexiform neurofibroma on MRI or CT (documented by comparison with prior MRI or CT) * Measurable plexiform neurofibroma(s) amenable to volumetric MRI analysis. Tumors must be at least 3 mL in volume (most PNs 3 cm in longest diameter will meet this criteria) * Patients must be ≥ 18 years of age at the time of enrollment. * Performance Level: Karnofsky or Lansky ≥ 50%. If unable to walk due to paralysis, but in a wheelchair, patients will be considered ambulatory for the purpose of assessing the performance level * Ability to swallow capsules/tablets * Ability to comply with follow up procedures * The effects of binimetinib on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and 3 months after completion of binimetinib administration. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. * Negative urine or serum β-HCG test (females of childbearing potential only). Prior Therapy: * Patients are eligible if complete resectio…