Research and progress of CAR-macrophage cell therapy for solid tumors

Though chimeric antigen receptor T cell (CAR-T) technology has emerged as an effective breakthrough against hematological malignancies, its application to solid tumors remains challenging and is restricted by the high complicacy of the tumor microenvironment (TME). Macrophages are innate immune cells that are inherently equipped with a wide range of therapeutic effects, including elevated infiltration rate, enhanced phagocytosis and cytotoxicity, mediation of immune suppression, and antigen presentation. In light of these unique biological functions and their ability to penetrate tumors, macrophages have emerged as a promising approach for the treatment of solid tumors. This review initially clarifies the biological characteristics of macrophages and tumor-associated macrophages (TAMs), then reviews macrophage sources and the CAR design structure, outlines the ways to deliver CAR to macrophages and the preparation of CAR-macrophages (CAR-Ms), and finally summarizes the application and prospects for the treatment of solid tumors by CAR-Ms in recent years.