- Remission induction therapy: Patients receive intrathecal (IT) cytarabine on day 1; vincristine IV on days 1, 8, 15, and 22; prednisone IV or orally twice daily on days 1-28; daunorubicin hydrochloride IV on days 1, 8, 15, and 22; pegaspargase IV or intramuscularly (IM) on day 4 or 5 or 6; and IT methotrexate on days 8 and 29*. Patients undergo bone marrow aspirate (BMA) and biopsy on day 29 to assess induction response and minimal residual disease status. Patients with M1 marrow (< 1% lymphoblasts) proceed to remission consolidation therapy. Patients with M2 marrow (> 5% but < 25% lymphoblasts) proceed to extended remission induction therapy. Patients with M3 marrow are removed from protocol therapy.