CONTINUATION I (WEEKS 20-49): Patients receive vincristine sulfate, dexamethasone, triple IT chemotherapy, methotrexate, mercaptopurine, etoposide, high-dose cytarabine, pegaspargase or asparaginase, and filgrastim as in post-induction therapy B continuation I. Patients also receive lestaurtinib PO on days 2-6 in weeks 20 and 24; days 27-41 in weeks 27-29; days 45-56 in weeks 30-32.