Prednisone 40 mg/m2/day PO Days 5 - 32 Vincristine 1.5 mg/m2/week IV Days 5, 12, 19, 26 Daunorubicin 25 mg/m2/week IV Days 5, 12 L-asparaginase 10,000 Unit/m2/dose IM Days 6, 8, 10, 12, 14, 16 (19, 21, 23) Cyclophosphamide 1000 mg/m2/dose IV Day 26 Cytarabine 75 mg/m2/dose IV Days 27-30, 34-37 6-Mercaptopurine 60 mg/m2/dose PO Days 26-39 Imatinib 40 mg/m2 bid for Ph positive patients starting Day 22 of induction. Intrathecal therapy will be administered on day 1 and 19, dose age dependent. Patients with high risk of CNS relapse will receive additional IT treatments on days 8 and 26.