PDCD1 and cancer: Given the fact that anti-tumor immune responses may be suppressed due to the effects of tumor cells on T cells via the programmed cell death 1 ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) immune checkpoint axis, PDT mediated cancer immunotherapy may be enhanced through targeting PD-L1 in tumor cells (Han et al., 2020; Lotfinejad et al., 2020).