The Physiological and Therapeutic Role of CD47 in Macrophage Function and Cancer

Background Immunotherapy is an emerging strategy in cancer therapeutics aimed at modulating the immune system to inhibit pro-tumor pathways and increase a tumor's sensitivity to chemotherapy. Several clinically approved immunotherapy treatments, such as monoclonal antibody treatments, have been successful in solid tumors such as breast, colorectal, and pancreatic. However, an outstanding challenge of these strategies is tumor cell resistance. One target of interest for immune cell modulation is targeting macrophages that enter the tumor microenvironment. More specifically, an immune checkpoint of interest is CD47. CD47 is a transmembrane protein that inhibits phagocytic activity by acting as a "don't eat me" signal. In both mice and humans, healthy cells can express CD47, while solid malignancies like colorectal and breast cancer express it most strongly.