To determine the impact of maintenance therapy in patients with MDS/AML in remission.

We propose a phase II study to determine the impact of maintenance therapy with 5-azacytidine and GM-CSF in patients with poor-risk AML or MDS, who are in remission after definitive treatment with either stem cell transplant or cytarabine-based consolidation chemotherapy.

In order to precede relapse and to avoid lead time bias, treatment would need to commence within 185 days of definitive therapy. Furthermore, approximately 50% of relapses occur within the first year and up to 80% within two years after SCT, therefore we would limit the duration of maintenance therapy to one year, followed by two years of follow-up.

Inclusion Criteria:

1. Age > 6 months
2. Initial diagnosis of poor -risk AML or MDS (defined in section 3.2), treated with either stem cell transplant or cytarabine-based consolidation chemotherapy, within the past 60-185 days
3. ECOG performance status 0-2
4. No morphologic evidence of leukemia or active MDS as determined by JHH Hematopathologist independent review of a bone marrow aspirate and biopsy done following the completion of therapy and within 14 days prior to enrollment
5. Peripheral blood count recovery: Neutrophil count ≥ 1000 /µL, platelet count ≥ 50x 109 /µL without platelet transfusions, and adequate hematocrit independent of red cell transfusions .
6. No evidence of extramedullary leukemia, such as CNS or soft tissue involvement
7. Adequate end organ function as measured by the following: AST and ALT < 4 x normal, total serum bilirubin < 2 x upper limit normal (unless due to hemolysis, Gilbert's syndrome, or ineffective erythropoiesis), creatinine < 2 x upper limit of normal
8. Ability to give informed consent
9. In agreement to use an effective barrier method of birth control to avoid pregnancy during the study and for a minimum of 30 days after study treatment, for all male and female patients who are fertile

Exclusion Criteria:

1. Patients with untreated or uncontrolled infections
2. Patients with untreated or uncontrolled grade 3 or 4 GVHD
3. Pregnancy and lactation
4. Concurrent use of any other investigational agents.
5. Known HIV-positive patients.
6. Known hypersensitivity to 5AC or GM-CSF

2 years