Clofarabine 40 mg/m2/day, 2-hour IV infusion Days 1-5 Etoposide 100 mg/m2/day, 2-hour IV infusion Days 1-5 Cyclophosphamide 300 mg/m2/day, 30-60 minute IV infusion Days 1-5 Dexamethasone 8 mg/m2/day (divided t.i.d) Days 1-5