RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Combining more than one drug may kill more cancer cells. It is not yet known which regimen of combination chemotherapy is more effective for childhood acute lymphoblastic leukemia.

PURPOSE: This randomized phase III trial is comparing different regimens of combination chemotherapy to see how well they work in treating children with acute lymphoblastic leukemia.

OBJECTIVES:

• Compare the efficacy and toxicity of short methotrexate infusion vs longer infusion in patients with low-risk acute lymphoblastic leukemia.
• Compare the efficacy of these regimens of methotrexate, with or without multidrug intensification, in these patients.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to genetics (stratum 1: trisomy 4/10 but not TEL/AML1 vs stratum 2: TEL/AML1 with or without trisomy 4/10).

All patients receive induction therapy (weeks 1-4) on another protocol (POG-9900).

Stratum 1

• Consolidation therapy begins on week 5. Patients are randomized to arm I or II.

  • Arm I: Patients receive methotrexate (MTX) IV over 24 hours on day 1 and oral leucovorin calcium (CF) every 6 hours for 3 doses beginning 42 hours after initiation of MTX infusion during weeks 7, 10, 13, 16, and 19.
  • Arm II: Patients receive MTX IV over 4 hours on day 1 and oral CF as in arm I during weeks 7, 10, 13, 16, and 19.

• Patients in arms I and II also receive MTX intrathecally (IT) on weeks 7, 10, 13, 16, 19, and 22; oral mercaptopurine (6-MP) daily on weeks 5-24; oral dexamethasone (DM) twice daily on days 1-7 of weeks 8 and 17; and vincristine (VCR) IV on day 1 of weeks 8, 9, 17, and 18.

Stratum 2

• Consolidation therapy begins on week 5 and delayed intensification therapy begins on week 16. Patients are randomized to delayed intensification or no delayed intensification. Patients randomized to no delayed intensification are then randomized to consolidation therapy on arm I or II. Patients randomized to delayed intensification are then randomized to arm III or IV. Patients with trisomy 4/10 are not randomized to arms III and IV.

  • Arm III: Patients receive MTX IV and CF as in arm I on weeks 7, 10, 13, 24, 27, and 30.
  • Arm IV: Patients receive MTX IV and CF as in arm II on weeks 7, 10, 13, 24, 27, and 30.

• Patients in arms III and IV also receive oral 6-MP daily on weeks 5-13 and then beginning on week 24 and continuing until the end of consolidation; MTX IT on weeks 7, 10, 13, 16, 20, 21, and 30; oral DM twice daily on days 1-7 of weeks 8, 16-18, and 28; VCR IV on day 1 of weeks 8, 9, 16-18, 28, and 29; pegaspargase intramuscularly on week 16; daunorubicin IV on day 1 of weeks 16-18; cyclophosphamide IV on day 1 of week 20; cytarabine IV or subcutaneously on days 2-5 of weeks 20 and 21; and oral thioguanine daily on days 1-14 of weeks 20 and 21.

All patients then receive continuation therapy beginning on week 25 for arms I and II and week 33 for arms III and IV and continuing until week 130 for all arms.

Continuation

• Arms I and II: Patients receive oral 6-MP daily on weeks 25-130; oral DM twice a day on days 1-7 and VCR IV on days 1 and 8 during weeks 25, 41, 57, 73, 89, and 105; oral MTX weekly on weeks 25-130 (except during weeks of IT MTX); and MTX IT on weeks 25, 37, 49, 61, 73, 85, 97, and 109.
• Arms III and IV: Patients receive oral 6-MP daily on weeks 33-130; oral DM twice a day on days 1-7 and VCR IV on days 1 and 8 during weeks 41, 57, 73, 89, and 105; oral MTX weekly on weeks 33-130 (except during weeks of IT MTX); and MTX IT on weeks 37, 49, 61, 73, 85, 97, and 109.

Patients are followed every 2 months for 2 years, every 3 months for 1 year, every 6 months for 2 years, and then annually thereafter.

PROJECTED ACCRUAL: A total 902 patients will be accrued for this study within 3.22 years.

DISEASE CHARACTERISTICS:

• Diagnosis of B-cell precursor acute lymphoblastic leukemia

  • Registered on POG-9900 Classification Study

• Registered within 7 days of documenting complete response (CR) after induction therapy on day 29 or, if 2 more weeks of induction are required, within 7 days of CR determination

• Classified as low-risk:

  • WBC less than 50,000/mm^3

  • Age 1 to 9

  • No adverse translocations [E2A-PBX1, t(1;19) or BCR/ABL, t(9;22); and MLL rearrangements]

  • No CNS 3 disease (CSF WBC at least 5/mm^3 with blasts present)

  • No testicular disease

  • At least one of the following present:

    • TEL/AML1, t(12;21)
    • Simultaneous trisomy of chromosomes 4 and 10

PATIENT CHARACTERISTICS:

Age:

• 1 to 9

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• See Disease Characteristics

Hepatic:

• Not specified

Renal:

• Not specified

Other:

• Not pregnant or nursing
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• Not specified

Endocrine therapy

• Not specified

Radiotherapy

• Not specified

Surgery

• Not specified