- Arm IV: Patients receive CTX IV and ARA-C IV continuously on day 1, oral mercaptopurine on days 8-28, and oral MTX on days 8, 15, and 22 during months 4, 7, 11, 13, 17, 21, 25, and 29. Patients receive MTX IV over 30 minutes on day 1, leucovorin calcium IV or orally every 6 hours on days 2-4, asparaginase IV over 1 hour or intramuscularly on day 2, oral mercaptopurine on days 8-28, and oral MTX on days 8, 15, and 22 during months 6, 10, 12, 15, 19, 23, and 27. Patients receive VAD or VAP as in arm III beginning at month 8. Patients without CNS disease at presentation receive CNS prophylaxis comprising whole brain radiotherapy and MTX IT on day 1 of radiotherapy during month 5. Patients with CNS disease at presentation receive CNS therapy as in arm III.