Figure 6.
Scheme: the proposed mechanism of local PD-L1-targeted NIR-PIT–induced cancer immunotherapy. Near-infrared photoimmunotherapy targeting of PD-L1 showed antitumor effects via the following pathways: (1) direct photocytotoxicity; (2) releasing damage-associated molecular patterns; (3) depleting MDSCs, (4) activating CD8 T cells and NK cells; and (5) PD-L1-F(ab′)2-IR700 blocks the PD-1/PD-L1 axis. This antitumor immune enhancement leads to unexpected regression of the treated tumor, whereas PD-L1 expression on the tumor was low. These antitumor immune augmentations systematically induce photo-abscopal effects on distant tumors. MDSCs, myeloid-derived suppressor cells; NIR-PIT, near-infrared photoimmunotherapy; PD-1, programmed death-1; PD-L1, programmed death-ligand 1.