Azacitidine in Treating Patients With Chronic Myelomonocytic Leukemia

DISEASE CHARACTERISTICS: * Diagnosis of 1 of the following: * All chronic myelomonocytic leukemia (CMML)-2 patients * CMML-1 patients meeting any of the following criteria: * Symptomatic bone marrow failure/myeloproliferation defined as any of the following: * Red cell transfusion dependence and pre-transfusion hemoglobin \< 9.0 g/dL * Symptomatic anemia (hemoglobin \< 11.5 g/dL) * Thrombocytopenia (platelet count \< 50 x 10\^9/L) * Symptomatic bleeding due to platelet functional defect or disseminated intravascular coagulation (DIC)/fibrinolysis * White cell count (WCC) \> 50 x 10\^9/L * Düsseldorf Score of intermediate or high risk for proliferative CMML-1 (i.e., WCC \> 12 x 10\^9/L) * International Prognostic Scoring System (IPSS) score of intermediate-2 or high risk for non-proliferative CMML-1 (i.e., WCC \< 12 x 10\^9/L) * Systemic symptoms including weight loss with no alternative explanation (10% of baseline weight within the past 6 months) * Symptomatic splenomegaly * Symptomatic extramedullary involvement (e.g. skin infiltration or serous effusions) * No CMML with eosinophilia and 5q33 abnormality PATIENT CHARACTERISTICS: * WHO performance status 0-2 * Creatinine ≤ 2 times upper limit of normal * Not pregnant or nursing * Negative urine pregnancy test * Fertile patients must use at least 2 forms of effective contraception during study and for 3 months after completion of study therapy * No other active malignant disease including basal cell or squamous cell carcinoma of the skin * No known HIV or infectious hepatitis B or hepatitis C * No active infection * No known hypersensitivity to azacitidine or mannitol PRIOR CONCURRENT THERAPY: * At least 28 days since other prior experimental drug or therapy * No prior chemotherapy for this disease except hydroxycarbamide * No other concurrent anticancer or investigational agents