In this study subjects will receive 730 Days of oral difluoromethylornithine (DFMO) at a dose of 2500 mg/m2 BID on each day of study.~Subjects will be evaluated in 3 Cohorts:~Cohort 1: Molecular High Risk Medulloblastoma Cohort 2: Molecular Very High Risk Medulloblastoma Cohort 3: Relapsed/Refractory Medulloblastoma~A total of 118 subjects across all cohorts will be enrolled to ensure that there will be 107 evaluable subjects (32-39 per cohort)
Difluoromethylornithine (DFMO) will be used in an open label, multicenter, study as Maintenance Therapy for Molecular High Risk/Very High Risk and Relapsed/Refractory Medulloblastoma.