INDUCTION CHEMOTHERAPY: Patients receive methotrexate intrathecally (IT) on days 1 and 29, prednisolone orally (PO) or nasogastrically (NG) three times daily (TID) on days 1-7, daunorubicin hydrochloride intravenously (IV) over 1-15 minutes on days 8-9, cytarabine IV over 30 minutes on days 8-21 and IT on day 15, dexamethasone PO, NG, or IV TID on days 8-28, vincristine sulfate IV over 1 minute on days 8, 15, 22, and 29, pegaspargase IV over 1-2 hours or intramuscularly (IM) on day 12, and hydrocortisone sodium succinate IT on days 15 and 29 in the absence of disease progression or unacceptable toxicity. Only patients with KMT2A-R continue to post-induction chemotherapy.