Progress in targeting tumor-associated macrophages in cancer immunotherapy

As the member of immune cells, macrophages are necessary to fight against pathogenic invasion and activate T cell-mediated adaptive immune responses. In the tumor microenvironment (TME), macrophages play a complex role in tumorigenesis and tumor progression. Tumor-associated macrophages (TAMs) can promote tumor progression through supporting the growth of tumor cells and inhibiting the tumoricidal activity of lymphocytes. Therefore, TAMs become an important target for cancer immunotherapy. TAMs-targeted therapeutic strategies comprise pro-tumor TAMs inhibition and anti-tumor TAMs activation. This article summarizes the feasible strategies of targeting TAMs in cancer immunotherapy and highlights the synergistic effect of TAMs-targeted therapy with other immunotherapies.