1. Patients should have a diagnosis of AML (de novo or transformed from hematologic malignancies), MDS or chronic myelomonocytic leukemia (CMML) with one of the following features: (A) Patients with MDS or CMML should have failed prior therapy with a hypomethylating agent and/or with lenalidomide (Cohorts 2 and 3). (B) Patients with AML should have failed any prior therapy or have relapsed after prior therapy (Cohorts 2 and 3). For patients in Cohort 3 prior therapy should have included a FLT3 inhibitor. (C) Patients with MDS or CMML who received therapy with a hypomethylating agent and progress to AML are eligible at the time of diagnosis of AML regardless any prior therapy for AML. The World Health Organization (WHO) classification will be used for AML. These patients will be assigned to Cohort 1. Patients with MDS, CMML or AML who have received no prior therapy are eligible if age 65 and greater or if, at the time of enrollment, are not candidates to receive or refuse standard therapy (Cohort 1 only)