Inclusion Criteria:  Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2 White Blood Cell count < 20 x 109/L. Adequate organ function Relapsed/refractory AML or MDS/CMML patients who have failed up to 2 prior therapeutic regimens.  Exclusion Criteria:  Acute Promyelocytic leukemia Symptomatic central nervous system (CNS) leukemia or patients with poorly controlled CNS leukemia Life-threatening (grade 4) immune-mediated adverse event related to prior immunotherapy Immune-mediated adverse reaction that required discontinuation of prior immunotherapy Past or current history of autoimmune disease or immune deficiency History of severe interstitial lung disease or severe pneumonitis or active pneumonitis Clinically significant and poorly compensated liver disease Prior organ allografts (such as renal transplant) requiring active immunosuppression Active graft versus host disease Treatment with systemic immunostimulatory within 4 weeks prior to initiation of study treatment Treatment with any CD47/SIRPα targeting agent or immune agonists Known allergy or hypersensitivity to any of the test compounds, materials or contraindication to test product Received live, attenuated vaccine within 4 weeks prior to first dose of study treatment Active Hepatitis B or C infection History or evidence of any other clinically unstable/uncontrolled disorder, condition, or disease Pregnant or breast feeding or planning to become pregnant while enrolled in the study