CD274 and cancer: At present, the photosensitizers commonly used for combination with immunotherapy include ICG (Shirata et al., 2017), Ce6 (Li et al., 2014), temoporfin (Tan et al., 2010), pheophorbide A (PPa) (Tang et al., 2010), etc. In the study from Wang et al. (2016), they demonstrated that PDT-mediated cancer immunotherapy could be augmented by PD-L1 knockdown in the tumor cells [Figures 7B,C, (Wang et al., 2016)].