Safety of Clofarabine With Multiagent Chemotherapy in Childhood Acute Lymphoblastic Leukemia (Vandevol)

The purpose of this study is to determine Maximum Tolerated Dosage (MTD), Dosage Limited Toxicities (DLT), and the Rate Phase 2 Dosage of clofarabine when used in combination with etoposide, asparaginase, mitoxantrone and dexamethasone and to assess the feasibility and safety of this combination regimen to treat children with high risk relapsed or refractory acute lymphoblastic leukemia (ALL).