 INDUCTION THERAPY: weeks 1-5 Patients receive cytarabine intrathecally IT on day 1; vincristine sulfate IV and daunorubicin hydrochloride IV on days 1, 8, 15, and 22; prednisone IV or orally PO twice daily BID on days 1-28; pegaspargase intramuscularly IM or IV over 1-2 hours on day 4, 5, OR 6; and methotrexate MTX IT on days 8 and 29. Patients with Down syndrome DS also receive leucovorin calcium PO at 48 and 60 hours after each MTX dose DS patients excluded as of 092910. 