CONSOLIDATION: Following completion of AZACITIDINE BLOCK I, patients receive cyclophosphamide IV over 30-60 minutes on days 1 and 29, mercaptopurine PO or NG daily on days 1-28, cytarabine IV or subcutaneously (SC) daily on days 3-6, 10-13, 17-20, and 24-27 and IT on day 10, methotrexate IT on day 24, and hydrocortisone sodium succinate IT on days 10 and 24 in the absence of disease progression or unacceptable toxicity.