The Macrophage ‘Do not eat me’ signal, CD47, is a clinically validated cancer immunotherapy target

CD47 is a potent ‘do not eat me’ signal that enables cancer cells to evade detection by the innate immune system, thereby avoiding destruction by first responder cells, such as macrophages. CD47 overexpression is common in solid and hematological tumors including acute leukemia, non-Hodgkin’s lymphoma (NHL), colorectal, and ovarian cancers. In many malignancies, its expression correlates with an aggressive phenotype and an overall poor clinical prognosis. Inhibition of CD47 signaling enhances macrophage phagocytic activity, and in preclinical models, leads to impaired tumor growth, inhibition of metastatic spread, and tumor regression.