A Clinical Trial Evaluating the Efficacy of Ultra Low Dose of Decitabine in Myelodysplastic Syndromes (MDS)

Inclusion Criteria: 1. Men or women aged 18 to 80 years; 2. Patients at high risk of MDS assessed by International Prostate Symptom Score (IPSS); 3. Chronic myelomonocytic leukemia (CMML) patients with abnormal white blood cell counts, extremely low platelet count or organ infiltration (such as hepatomegaly, splenomegaly) that required therapy; 4. Patients at low risk of MDS identified by IPSS score who had secondary MDS, platelet count of \< 20\*10\^9/L, no response to erythropoietin (EPO) (non-5q deletion syndrome) in the presence of disease symptoms or blood transfusion dependence, or no response to EPO/lenalidomide (5q deletion syndrome) in the presence of disease symptoms or blood transfusion dependence; 5. Patients with a Eastern Cooperative Oncology Group (ECOG) of 0 to 2; 6. Patients with an expected lifespan of over 6 months; 7. Patients with a aspartate aminotransferase (AST) of \< 2.5 times higher than the normal upper limit, alanine aminotransferase (ALT) of \< 2.5 times higher than the normal upper limit, total bilirubin of \< 1.5 times higher than the normal upper limit, and serum creatinine of \< 1.5 times higher than the normal upper limit; 8. Subjects who had recovery of toxicity, did not undergo any therapy 4 weeks prior to the first trial, and did not receive nitrosourea therapy and bone marrow transplantation 6 weeks prior to the first trial; 9. Female subjects were menopausal, underwent surgical sterilization, or had effective contraception (oral contraceptive, injectable contraceptive, intrauterine device, contraceptive patch, male sterilization) prior to enrollment and during the trial, and were negative for serum or urine pregnancy test at screening; 10. No insemination was given to male subjects during the treatment and within 2 months post-treatment; 11. Subjects complying with the study protocol; 12. Subjects that signed the informed consent, which indicated they understood the purpose, the procedure and potential benefits of the trial and were willing to participate in the trial. Exclusion Criteria: 1. Patients that were diagnosed as acute myeloid leukemia (primitive bone marrow cell proportion of 20% or higher) or other progressive malignant diseases; 2. Patients that received treatment with other drugs within 30 days prior to the first administration of decitabine; 3. Patients that received radiotherapy within 14 days prior to the first administration of decitabine; 4. Patients with uncontrolled heart disease or congestive heart failure; 5. Patients with uncontrolled restrictive or obstructive pulmonary disease; 6. Patients with active viral, bacterial or invasive fungal infections; 7. Patients that were complicated by autoimmune hemolytic anemia or immune thrombocytopenia; 8. Patients with a history of use of azacitidine or decitabine; 9. Patients that were sero-positive for HIV; 10. Patients with mental or other disorders that cannot completely cooperate with the treatment or follow up; 11. Patients bone marrow cannot be sampled; 12. Subjects that were allergic to decitabine vehicle; 13. Pregnant or lactating women.