DELAYED INTENSIFICATION PART I: Following completion of AZACITIDINE BLOCK III, patients receive pegaspargase IV over 1-2 hours or IM on day 1, dexamethasone PO, NG, or IV TID on days 1-14 and 15-21 with a taper on days 15-21, thioguanine PO or NG daily on days 1-28, vincristine sulfate IV over 1 minute on days 1, 8, 15, and 22, daunorubicin hydrochloride IV over 1-15 minutes on days 1, 8, 15, and 22, cytarabine IV or SC on days 2-5, 9-12, 16-19, and 23-26 and IT on days 1 and 15, and hydrocortisone sodium succinate IT on days 1 and 15 in the absence of disease progression or unacceptable toxicity.