DISEASE CHARACTERISTICS:

• Diagnosis of 1 of the following:

  • Histologically confirmed myelodysplastic syndromes (MDS) by bone marrow aspiration and/or biopsy

    • International Prognostic Scoring System (IPSS) score of intermediate-1, intermediate-2, or high
    • Low IPSS score allowed provided patient has a clinically significant cytopenia (i.e., absolute neutrophil count < 1,000/mm^3, untransfused hemoglobin < 8 g/dL, platelet count < 20,000/mm^3, or anemia requiring transfusion)
  • Chronic myelomonocytic leukemia

  • Acute myeloid leukemia (AML)

    • Relapsed or refractory disease

    • Untreated AML allowed provided patient meets ≥ 1 of the following criteria:

      • Age 60 and over
      • AML arising in the setting of an antecedent hematologic disorder (including MDS-AML)
      • High-risk cytogenetic abnormalities (e.g., abnormalities of chromosome 5 or 7 or complex cytogenetic abnormalities)
      • Medical conditions that may compromise the ability to give cytotoxic chemotherapy as the primary modality
      • Refused cytotoxic chemotherapy
    • WBC < 30,000/mm^3 for ≥ 2 weeks before study entry
    • Acute promyelocytic leukemia allowed provided patient is in at least second relapse and has already received treatment regimens containing arsenic trioxide and isotretinoin
• No clinical evidence of CNS or pulmonary leukostasis or CNS leukemia

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• Zubrod 0-2

Life expectancy

• At least 6 months

Hematopoietic

• See Disease Characteristics
• Hemoglobin ≥ 8 g/dL (transfusion allowed)
• No disseminated intravascular coagulation

Hepatic

• Bilirubin normal unless due to hemolysis or Gilbert's syndrome
• AST and ALT ≤ 2.5 times upper limit of normal

Renal

• Creatinine normal OR
• Creatinine clearance ≥ 60 mL/min

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after study treatment
• No untreated, active infection
• No other serious or uncontrolled medical condition

PRIOR CONCURRENT THERAPY:

Biologic therapy

• More than 3 weeks since prior hematopoietic growth factors for this malignancy

Chemotherapy

• See Disease Characteristics
• At least 3 weeks since prior hydroxyurea (2 weeks for AML patients)
• No concurrent hydroxyurea

Endocrine therapy

• Not specified

Radiotherapy

• Not specified

Surgery

• Not specified

Other

• Recovered from all prior therapy
• At least 2 weeks since prior cytotoxic therapy (AML patients)
• More than 3 weeks since other prior therapy for this malignancy
• No other concurrent investigational or commercial agents or therapies for this malignancy
• No concurrent valproic acid