NOTE: *Central nervous system (CNS)-positive patients do not receive methotrexate IT. In both arms, CNS-positive patients receive intrathecal triple therapy (ITT) comprising methotrexate IT, hydrocortisone IT, and cytarabine IT on days 1, 8, 15, 22, and 29. CNS-positive patients not achieving remission after induction therapy 1 receive one additional dose of ITT on day 36. Patients in both arms then proceed to induction therapy 2**.