- Group II (closed to accrual as of 6/24/04 except for patients first enrolled in group I): Patients receive induction therapy comprising cytarabine IV continuously, daunorubicin IV continuously, and oral thioguanine twice daily on days 0-3. Treatment repeats every 28 days for 4 courses. Patients with no CNS disease at diagnosis receive cytarabine intrathecally (IT) on day 0. Patients with CNS disease at diagnosis receive cytarabine IT on days 0, 5, and 7. If CNS disease persists on day 7, patients receive up to 6 courses of cytarabine IT, hydrocortisone IT, and methotrexate IT, twice weekly beginning on day 10.