Promoting macrophage phagocytosis of cancer cells for effective cancer immunotherapy.

Cancer therapy has been revolutionized by immunotherapeutic agents exploiting adaptive antitumor immunity in the past two decades. However, the overall response rate of these immunotherapies is limited, and patients also develop resistance upon treatment, promoting a rapidly growing exploration of anti-tumor innate immunity for effective cancer therapy. Among these, macrophage immunotherapy through harnessing macrophage phagocytosis has been thrust into the spotlight due to its potential for simultaneously inducing cancer cell killing effect and mobilizing adaptive antitumor responses. Here in this review, we summarize the current macrophage immunotherapy such as therapeutic antibodies, phagocytosis checkpoint blockades, and CAR-macrophages with a particular emphasis on the resistant mechanisms limiting their therapeutic effects. Moreover, we further survey the efforts being placed to seek synergistic mechanisms and combination strategies for promoting macrophage phagocytosis which might stand as next-generation cancer immunotherapy.