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. 2022 Jan 28;20:14. doi: 10.1186/s12964-021-00816-w

Fig. 3.

Fig. 3

The mechanism of action of anti-PD-1/PD-L1 drugs and the potential mechanism underlying the exosomal PD-L1-mediated resistance to anti-PD-L1 drugs. ① Anti-PD-1/PD-L1 drugs can interact with PD-1/PD-L1, free T cells from the checkpoint block, and restore immune responses. ② and ③ Exo-PD-L1 is thought to contribute to resistance during immunotherapy through two mechanisms. In one, exo-PD-L1 binds to anti-PD-L1 monoclonal antibody (mAb), leading to PD-L1 exposure on the tumor surface (②); in the other, Although anti-PD-L1 mAb can interact with PD-L1 on the surface of tumor, exo-PD-L1 can directly interact with PD-1 on the surface of T cells to inhibit immunity (③)