Mycophenolate mofetil Active Not Recruiting Phase 1 Trials for Adult Acute Lymphoblastic Leukemia in Complete Remission / Acute Lymphoblastic Leukemia in Remission / Recurrent Adult Acute Myeloid Leukemia / Recurrent Childhood Acute Lymphoblastic Leukemia / Previously Treated Myelodysplastic Syndromes / Recurrent Adult Acute Lymphoblastic Leukemia / Acute myeloid leukaemia (in remission) / Childhood Acute Lymphoblastic Leukemia in Complete Remission / Recurrent Childhood Acute Myeloid Leukemia Treatment