DISEASE CHARACTERISTICS: Histologically or cytologically proven acute leukemia (M3 marrow) that is refractory to conventional therapy or for which no effective therapy exists No CNS leukemia No solid tumors

PATIENT CHARACTERISTICS: Age: 21 and under Performance status: Karnofsky 50-100% OR Lansky at least 50 (for infants) Life expectancy: At least 8 weeks Hematopoietic: Not specified Hepatic: Bilirubin less than 1.5 mg/dL SGPT less than 5 times normal Renal: Normal creatinine for age OR GFR at least 70 mL/min Other: No significant systemic illness such as infection No significant third space fluid collections Not pregnant or nursing

PRIOR CONCURRENT THERAPY: Biologic therapy: Recovered from acute toxic effects of prior immunotherapy At least 6 months since prior bone marrow transplant with no evidence of graft-versus-host disease At least 10 days since prior biologic therapy At least 1 week since prior growth factors Chemotherapy: At least 2 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosourea) and recovered Endocrine therapy: No concurrent steroids Radiotherapy: Recovered from acute toxic effects of all prior radiotherapy At least 2 weeks since prior local palliative radiotherapy (small port) At least 6 months since prior substantial bone marrow radiation Surgery: Not specified Other: No other concurrent anticancer therapy or investigational agents No concurrent nonsteroidal anti-inflammatory agents