RecruitingPhase 2Drug trialEflornithine (DFMO) for Ewing Sarcoma and OsteosarcomaEwing sarcoma (EWS) and osteosarcoma primarily affect adolescents and young adults. Common treatments include chemotherapy, surgery and radiation, however, there have been few recent advancements in the standard of care. By incorporating eflornithine (DFMO) as an additional therapy and/or maintenance therapy we hope to safely observe improved event-free survival and overall survival. There are 5 cohorts covered under this master protocol.