Mycophenolate mofetil Active Not Recruiting Phase 1 Trials for Acute Myeloid Leukemia Arising From Previous Myelodysplastic Syndrome / Refractory Anemia With Ring Sideroblasts / Chronic Myelomonocytic Leukemia / Previously Treated Myelodysplastic Syndromes / CD45-Positive Neoplastic Cells Present / Adult Acute Myeloid Leukemia in Remission / Refractory Cytopenia With Multilineage Dysplasia / Refractory Cytopenia With Multilineage Dysplasia and Ring Sideroblasts / Refractory Anemia With Excess Blasts / Adult Acute Lymphoblastic Leukemia in Remission Treatment