Decitabine in Treating Patients With Myelodysplastic Syndromes or Acute Myeloid Leukemia

Inclusion Criteria: * One of the following diagnoses: * High-risk myelodysplastic syndromes (MDS) * Acute myeloid leukemia (AML) * De novo, secondary, or relapsed disease * Any number of prior regimens for primary or relapsed disease * Ineligible for or refuses aggressive management * Measurable disease, defined as: * More than 5% blasts in bone marrow of patients with MDS * More than 30% blasts in bone marrow of patients with AML * Involvement of cerebrospinal fluid allowed * Performance status - ECOG 0-2 * Performance status - Karnofsky 60-100% * See Disease Characteristics * Bilirubin no greater than 1.25 times upper limit of normal (ULN) * AST and/or ALT no greater than 1.25 times ULN * Creatinine less than 1.7 mg/dL * Creatinine clearance at least 60 mL/min * No symptomatic congestive heart failure * No unstable angina pectoris * No cardiac arrhythmia * No ongoing or active infection * No other uncontrolled illness that would preclude study participation * No psychiatric illness or social situation that would preclude study compliance * No prior allergic reactions to compounds of similar chemical or biological composition to decitabine * No other active malignancy * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * At least 4 weeks since prior biologic therapy (e.g., interferon, filgrastim \[G-CSF\], sargramostim \[GM-CSF\], thrombopoietin, or epoetin alfa) * No concurrent hematopoietic growth factors (GM-CSF, thrombopoietin, or epoetin alfa) * No concurrent prophylactic G-CSF * Prior intrathecal cytarabine allowed for patients with cerebrospinal fluid involvement * At least 4 weeks since prior chemotherapy (except low-dose chemotherapy administered to maintain WBC counts) (6 weeks for nitrosoureas or mitomycin) and recovered * At least 24 hours since prior hydroxyurea * Concurrent intrathecal cytarabine allowed for patients with cerebrospinal fluid involvement * No prior radiotherapy greater than 3,000 cGy to marrow-producing areas * At least 4 weeks since prior radiotherapy and recovered * Prior investigational therapy allowed * No other concurrent investigational agents * No concurrent combination antiretroviral therapy for HIV-positive patients * No other concurrent anticancer therapy