DISEASE CHARACTERISTICS:

• Histologically confirmed leukemia of any of the following types:

  • Acute lymphoblastic leukemia
  • Acute myeloid leukemia
  • Chronic myelogenous leukemia in blast crisis
• Refractory or recurrent disease
• Immunophenotypic confirmation of disease at initial diagnosis or recurrence
• More than 25% blasts in the bone marrow (M3)
• Active extramedullary disease allowed except for leptomeningeal disease
• No known curative therapy or therapy proven to prolong survival with an acceptable quality of life
• No active CNS disease

PATIENT CHARACTERISTICS:

Age

• 1 to 21

Performance status

• Karnofsky 50-100% (for patients > 10 years of age)
• Lansky 50-100% (for patients ≤ 10 years of age)

Life expectancy

• Not specified

Hematopoietic

• WBC < 30,000/mm^3 (hydroxyurea or leukapheresis allowed at the discretion of the principal investigator)
• Platelet count ≥ 20,000/mm^3 (platelet transfusions allowed)
• Hemoglobin ≥ 8.0 g/dL (red blood cell transfusions allowed)

Hepatic

• ALT ≤ 5 times upper limit of normal (ULN)
• Albumin ≥ 2 g/dL
• Bilirubin ≤ 1.5 times ULN

Renal

• Creatinine normal for age OR
• Creatinine clearance OR radioisotope glomerular filtration rate ≥ 70 mL/min/1.73 m^2

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No uncontrolled infection

PRIOR CONCURRENT THERAPY:

Biologic therapy

• At least 7 days since prior biologic therapy, including immunotherapy

• At least 3 months since prior stem cell transplantation

  • No evidence of active graft-vs-host disease
• No concurrent biologic therapy
• No concurrent immunotherapy

Chemotherapy

• Recovered from prior chemotherapy
• At least 6 weeks since prior nitrosoureas
• Prior therapy with hydroxyurea allowed for up to 24 hours before initiation of study drug
• No other concurrent chemotherapy

Endocrine therapy

• Concurrent hydrocortisone or other corticosteroids allowed as premedications prior to blood product transfusions in patients with prior severe allergic reactions

Radiotherapy

• Recovered from prior radiotherapy
• No concurrent radiotherapy

Surgery

• Not specified

Other

• No other concurrent anticancer agents
• No other concurrent investigational drugs