Decitabine Versus Supportive Care in Adults With Advanced-stage MDS

Inclusion: * MDS (de novo or secondary) fitting any of the recognized French-American-British, FAB, classifications or chronic myelomonocytic leukemia (CMML) with WBC \< 12,000/mm3, AND International Prognostic Scoring System (IPSS) \>/= 0.5 as determined by CBC, bone marrow assessment and bone marrow cytogenetics within 30 days of randomization * 18 years or older * Female patients of child-bearing potential must have a negative serum hCG within 24 hours prior to randomization, must practice a medically approved method of birth control for the past 30 days, and agree to continue this practice for the trial duration and must not be breast-feeding * ECOG or WHO performance status of 0-2 * Written informed consent * Normal renal and hepatic function (creatinine \</= 2 mg/dL, bilirubin \</= 1.5 mg/dL, SGPT \</= 2 times the upper limit of normal range) Exclusion: * Acute Myeloid Leukemia (AML) (\>/=30% bone marrow blasts) or other progressive malignant disease * Patients must have recovered from the toxic effects of prior therapy and must be off all chemotherapy for a minimum of 4 weeks prior to study entry to the protocol (a minimum of six weeks for prior nitrosoureas and bone marrow transplantation) * Ongoing treatment with androgenic hormones, danazol, colony-stimulating factors, or other agents used to treat MDS within 7 days of study initiation. * Administration of any investigational agent within the 30 days preceding study initiation. * Uncontrolled cardiac disease or congestive heart failure * Uncontrolled restrictive or obstructive pulmonary disease * Active viral or bacterial infection * Superimposed autoimmune hemolytic anemia or thrombocytopenia * Known positive serology for HIV * Mental illness or other condition preventing full cooperation with the treatment and monitoring requirements of the study.