PDCD1 and neoplasm: The interaction of PD-L1 on tumor cells and CD80 on T cells suppresses T cell activation and survival, suggesting that dual blocking PD-1 and CD80 interaction with PD-L1 might be more favorable for improving the immunotherapy efficacy compared with single PD-1 blockade (Butte et al., 2007; Rollins and Gibbons Johnson, 2017).