Because complement products in the TME promote MDSC-mediated immunosuppression in multiple ways [300,301,302,303,304] and C5aR and C3aR are almost exclusively expressed in myeloid cells in the immune system, traditional cancer therapies/anti-PD-1 therapy coupled with blocking complement signaling can be an excellent strategy to treat cancer types where the complement system actively contributes to tumorigenesis. Here, C3AR1 is linked to cancer.