CD274 and breast cancer: Herein, we reported a cyclic RGD (cRGD)–modified liposomal delivery system loading the anti–PD–L1 antibody and the photosensitizer pheophorbide A (Pa), allowing a targeting of the low PD–L1 expressing 4T1 mouse breast cancer cells through the recognition of an overexpression of αvβ3 integrin on the tumor cells.