OBJECTIVES:

• Determine if multidrug delayed-intensification therapy improves outcome in children with newly diagnosed standard-risk acute lymphocytic leukemia.
• Compare the efficacy and toxicity of methotrexate administered over 4 hours vs methotrexate administered over 24 hours in this patient population.
• Determine the correlation between event-free survival, minimal residual disease, and early response in this patient population treated with this multiple drug regimen.

OUTLINE: This is a randomized, multicenter study.

• Induction (weeks 1-4): Patients receive induction therapy on POG 9900.

• Consolidation (weeks 5-32): Patients are randomized to one of four treatment arms. Patients with t(1;19) are randomized to either arm III or arm IV.

  • Arm I (weeks 5-24): Patients receive IT methotrexate (MTX) on day 1 followed by MTX IV over 20 minutes followed by MTX continuously over 23.6 hours on weeks 7, 10, 13, 16,19, and 22. At 42 hours after the beginning of the MTX infusion, patients receive oral leucovorin calcium every 6 hours for a total of 3 doses. Patients also receive oral mercaptopurine daily beginning on week 5 and continuing until the completion of consolidation therapy; oral dexamethasone twice daily on days 1-7 of weeks 8 and 17; and vincristine IV on day 1 of weeks 8, 9, 17, and 18.
  • Arm II (weeks 5-24): Patients receive MTX IV over 4 hours on weeks 7, 10, 13, 16, 19, and 22. At 42 hours after the beginning of the MTX infusion, patients receive oral leucovorin calcium as in arm I. Patients also receive mercaptopurine, dexamethasone, vincristine, and IT MTX as in arm I.
  • Arm III (weeks 5-32): Patients receive MTX IV as in arm I on weeks 7, 10, 13, 24, 27, and 30; leucovorin calcium as in arm I; pegaspargase IM on day 2, 3, OR 4 of week 16; and oral mercaptopurine daily on weeks 5-13, and from week 24 until the completion of consolidation therapy. Patients also receive IT MTX as in arm I on weeks 7, 10, 13, 16, 20, 21, and 30; oral dexamethasone twice daily on weeks 8, 16-18, and 28 for a total of 35 days; vincristine IV on day 1 of weeks 8, 9, 16, 17, 18, 28, and 29; daunorubicin IV on day 1 of weeks 16-18; cyclophosphamide IV over 30 minutes on day 1 of week 20; cytarabine IV or subcutaneously daily on days 2-5 of weeks 20 and 21; and oral thioguanine daily on weeks 20-21.
  • Arm IV (weeks 5-32): Patients receive MTX IV as in arm II on weeks 7, 10, 13, 24, 27, and 30; leucovorin calcium as in arm I; and pegaspargase, mercaptopurine, IT MTX, dexamethasone, vincristine, daunorubicin, cyclophosphamide, cytarabine, and thioguanine as in arm III.
• Intensive continuation (weeks 25-80): At weeks 25-72 for arms I and II, and at weeks 33-80 for arms III and IV, patients receive oral MTX every 6 hours for 4 doses on weeks 1, 3, 5, 7, 9, and 11; oral mercaptopurine daily; oral leucovorin calcium every 12 hours for 2 doses beginning 48 hours after the start of MTX; IT MTX and vincristine IV on day 1 of week 12; and oral dexamethasone twice daily on days 1-7, beginning with the administration of vincristine. Treatment repeats every 12 weeks for 4 courses.
• Additional continuation (weeks 73-130): At weeks 73-130 for arms I and II, and at weeks 81-130 for arms III and IV, patients receive oral MTX weekly; oral mercaptopurine daily; vincristine IV on day 1 every 12 weeks; oral dexamethasone as during intensive continuation therapy; and IT MTX on day 1 every 12 weeks, beginning with the last week of the first course (in place of oral MTX).

Patients are followed monthly for 1 year, every 2 months for 1 year, every 3 months for 1 year, every 6 months for 1 year, and then every 6-12 months for

1 year.

PROJECTED ACCRUAL: A total of 1,014 patients will be accrued for this study within 3.22 years.