RATIONALE: Drugs used in chemotherapy work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more cancer cells. It is not yet known which combination chemotherapy regimen is more effective in treating young patients with acute lymphoblastic leukemia.

PURPOSE: Thisphase III trial is studying several different combination chemotherapy regimens to compare how well they work in treating young patients with acute lymphoblastic leukemia.

OBJECTIVES:

• Compare the relative efficacy of induction therapy comprising dexamethasone or prednisone, in terms of a higher rate of event-free survival (EFS) and overall survival and a reduced rate of relapse, in pediatric patients with intermediate-risk or high-risk acute lymphoblastic leukemia (ALL).
• Compare the relative safety of a reduced-intensity reintensification regimen comprising dexamethasone, vincristine, cyclophosphamide, and anthracyclines vs a standard treatment regimen in pediatric patients with standard-risk ALL identified by fast clearance of leukemic cells.
• Compare the efficacy of a second delayed reintensification regimen vs standard reintensification therapy, in terms of improved EFS, in pediatric patients with intermediate-risk ALL.
• Compare the efficacy of extended reintensification therapy (triple reinduction) vs standard reintensification therapy (intensive pulses and one reintensification) in pediatric patients with high-risk ALL.

OUTLINE: This is a randomized, multicenter study.

• Prednisone prephase therapy: Patients receive oral prednisone on days 1-7 and one dose of methotrexate (MTX) intrathecally (IT) on day 1.

• Induction/consolidation therapy, protocol I: Patients are randomized to 1 of 2 treatment arms.

  • Arm I (closed to accrual as of 6/30/2006): Patients receive prednisone (PRED) on days 8-28.
  • Arm II (closed to accrual as of 6/30/2006): Patients receive dexamethasone (DEXA) on days 8-28.

Patients in both arms also receive vincristine (VCR) and daunorubicin hydrochloride (DNR) once weekly in weeks 2-5; asparaginase (ASP) on days 12-33; cyclophosphamide (CPM) on days 36 and 64; cytarabine (ARA-C) in weeks 6-9; mercaptopurine (MP) on days 36-63; and MTX IT on days 1, 12, 33, 45, and 59.*

NOTE: *Patients with CNS disease also receive MTX IT on days 18 and 27.

After completion of induction/consolidation therapy, patients are stratified according to risk group based on disease response (standard-risk [SR] group [negative minimal residual disease (MRD) on day 33 and before protocol M, day 78] vs high-risk [HR] group [MRD ≥ 10^-³ on day 78] vs intermediate-risk [IR] group [all nonSR/nonHR]).* Patients with SR and IR disease proceed to extracompartment therapy. Patients with HR disease proceed to reintensification therapy.

NOTE: *Patients meeting any of the following criteria are placed in the HR group regardless of MRD response: Philadelphia chromosome-positive disease (BCR/ABL or t[9;22]; translocations [t4;11][q11;q23] or MLL/AF4); "prednisone-poor-response" (≥ 1,000 blasts/mm³ in the peripheral blood on day 8 after prednisone prephase therapy); or no response to study induction therapy (M2/3 at day 33).

• Extracompartment therapy, protocol M: Patients receive MP on days 1-56 and MTX on days 8, 22, 36, and 50.

After completion of extracompartment therapy, SR and IR patients proceed to reintensification therapy. SR patients are randomized to arms I or II. IR patients are randomized to arms I or III. HR patients who have completed induction/consolidation therapy are randomized to arms IV or V.

• Reintensification therapy:

  • Arm I (standard reinduction therapy, protocol II [closed to accrual as of 6/30/2006]): SR and IR patients receive DEXA on days 1-22; VCR and doxorubicin hydrochloride (DOX) in weeks 2-5; ASP on days 8, 11, 15, and 18; CPM on day 36; ARA-C and thioguanine (TG) on days 36-49; and MTX IT on days 38 and 45.* Patients then proceed to maintenance therapy.

NOTE: *Patients with CNS disease also receive MTX IT on days 1 and 18.

• Arm II (reduced-intensity reinduction therapy, protocol III [closed to accrual as of 6/30/2006]): SR patients receive DEXA on days 1-15; VCR and DOX on days 1 and 8; ASP on days 1, 4, 8, and 11; CPM on day 15; ARA-C and TG on days 15-28; and MTX IT on days 17 and 24.* Patients then proceed to maintenance therapy.

NOTE: *Patients with CNS disease also receive MTX on day 1.

• Arm III (reduced-intensity reinduction/second delayed reinduction therapy [double reintensification therapy] [closed to accrual as of 6/30/2006]): IR patients receive reduced-intensity reintensification therapy as in arm II. After a 10-week interim maintenance phase, treatment repeats once for a second delayed course of reintensification therapy. Patients then proceed to maintenance therapy.

• Arm IV (standard reintensification therapy [closed to accrual as of 6/30/2006]): HR patients receive two sequences of the following HR therapy elements (i.e., in this order: 1, 2, 3, 1, 2, 3) following reintensification therapy as in arm I. Patients then proceed to maintenance therapy.

  • Element HR-1: Patients receive DEXA on days 1-5; VCR on days 1 and 6; ARA-C twice on day 5; MTX and CPM every 12 hours on days 2-4 (5 doses); ASP on days 6 and 11; and MTX/ARA-C/PRED IT on day 1.
  • Element HR-2: Patients receive DEXA on days 1-5; vindesine on days 1 and 6; DNR on day 5; MTX and ifosfamide every 12 hours on days 2-4 (5 doses); ASP on days 6 and 11; and MTX/ARA-C/PRED IT on day 1.* NOTE: *HR patients with CNS disease also receive IT therapy on day 5.
  • Element HR-3: Patients receive DEXA on days 1-5; ARA-C every 12 hours on days 1-2 (4 doses); etoposide five times daily on days 3-5; ASP on days 6 and 11; and MTX/ARA-C/PRED IT on day 1.

• Arm V (extended reintensification therapy [triple protocol III] [closed to accrual as of 6/30/2006]): HR patients receive HR therapy elements 3, 2, and 1 as in arm IV following reintensification therapy as in arm II repeated the therapy element twice with 4-week interim maintenance phases in between. Patients then proceed to maintenance therapy.

  • Interim maintenance/maintenance therapy: Patients receive MTX once weekly and MP daily until week 104.
  • Radiotherapy: HR patients or patients with T-cell acute lymphoblastic leukemia or CNS disease undergo CNS radiotherapy.

PROJECTED ACCRUAL: A total of 2,000 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically confirmed acute lymphoblastic leukemia (ALL)
• No secondary ALL

PATIENT CHARACTERISTICS:

• No prior disease that would preclude treatment with chemotherapy

PRIOR CONCURRENT THERAPY:

• More than 4 weeks since prior chemotherapy
• More than 4 weeks since prior steroids