In recent years, immunotherapies have been clinically investigated in AML and 
other myeloid malignancies. While most of these are focused on stimulating the 
adaptive immune system (including T cell checkpoint inhibitors), several key 
approaches targeting the innate immune system have been identified. Macrophages 
are a key cell type in the innate immune response with CD47 being identified as 
a dominant macrophage checkpoint. CD47 is a "do not eat me" signal, 
overexpressed in myeloid malignancies that leads to tumor evasion of 
phagocytosis by macrophages. Blockade of CD47 leads to engulfment of leukemic 
cells and therapeutic elimination. Pre-clinical data has demonstrated robust 
anti-cancer activity in multiple hematologic malignancies including AML and 
myelodysplastic syndrome (MDS). In addition, clinical studies have been underway 
with CD47 targeting agents in both AML and MDS as monotherapy and in 
combination. This review will describe the role of CD47 in myeloid malignancies 
and pre-clinical data supporting CD47 targeting. In addition, initial clinical 
data of CD47 targeting in AML/MDS will be reviewed, and including the 
first-in-class anti-CD47 antibody magrolimab.