INDUCTION THERAPY** (ALL PATIENTS): Patients receive cytarabine intrathecally (IT) on day 1; vincristine intravenously (IV) and daunorubicin hydrochloride IV over 15 minutes on days 1, 8, 15, and 22; prednisone orally or IV twice daily (BID) on days 1-28; study drug IV over 1 hour on day 4; and methotrexate IT on days 8, 15*, 22*, and 29. Patients are assessed for response on day 8 and/or day 15 and day 29. Patients who achieve M1 marrow on day 8 or 15 and negative MRD (i.e., < 0.1%) on day 29 are considered RER. Patients who achieve M2 or M3 marrow on day 15 OR MRD >= 0.1% but < 1% on day 29 are considered SER. Patients with M3 bone marrow are removed from the study. RER and SER proceed to consolidation therapy. Patients with M2 marrow or M1 marrow with >= 1% MRD receive extended induction therapy. Patients also receive dexamethasone PO or IV BID on days 1-14 (patients < 10 years) or prednisone BID on days 1-28 (patients >= 10 years)