Temozolomide in Treating Young Patients With Refractory or Recurrent Leukemia

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