Azacitidine and Arsenic Trioxide in Treating Patients With Myelodysplastic Syndromes or Chronic Myelomonocytic Leukemia

DISEASE CHARACTERISTICS: Diagnosis of myelodysplastic syndrome or chronic myelomonocytic leukemia International Prognostic Scoring System (IPSS) score ≥ intermediate-1 Low IPSS score allowed provided patient meets ≥ 1 of the following criteria: Platelet count ≤ 50,000/mm^3 Required platelet or packed red cell transfusions within the past 4 weeks Neutropenic (i.e., absolute neutrophil count < 1,000/mm^3) AND has infections requiring antibiotic treatment No prior leukemia or refractory anemia with excess blasts in transformation PATIENT CHARACTERISTICS: Age 18 and over Performance status ECOG 0-2 Life expectancy More than 12 weeks Hematopoietic See Disease Characteristics Hepatic Bilirubin ≤ 1.5 times upper limit of normal (ULN) AST and ALT ≤ 2.5 times ULN Renal Creatinine ≤ 1.5 times ULN Cardiovascular No symptomatic congestive heart failure No unstable angina pectoris No cardiac arrhythmia Baseline QTc < 500 msec QTc interval < 460 msec with potassium > 4.0 mEq/L and magnesium > 1.8 mg/L Immunologic No history of allergic reaction attributed to compounds of similar chemical or biologic composition to study drugs No ongoing or active infection HIV negative Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 6 months after study participation No psychiatric illness or social situation that would preclude study compliance No other uncontrolled illness No other malignancy within the past 12 months PRIOR CONCURRENT THERAPY: Biologic therapy More than 4 weeks since prior administration of any of the following: Interferon Filgrastim (G-CSF), sargramostim (GM-CSF), epoetin alfa, or other hematopoietic cytokines Thalidomide or thalidomide analogs No concurrent epoetin alfa Chemotherapy More than 4 weeks since prior chemotherapy No prior arsenic trioxide or azacitidine No other concurrent chemotherapy Endocrine therapy More than 4 weeks since prior steroids No concurrent androgenic steroids Concurrent steroids for adrenal failure or as prophylaxis for nausea allowed Radiotherapy Not specified Surgery Not specified Other More than 4 weeks since prior retinoids No other concurrent investigational agents No other concurrent anticancer therapy