PDCD1 and neoplasm: The mechanism of action of PD-1 and PD-L1 immunosuppressants is to block the PD-1 and PD-L1 signaling pathways of NSCLC cells (Figure 1), activate the immune activity of T cells, leading to the inhibition on the growth and proliferation of tumor cells, then achieving its final apoptosis (Li et al., 2018b).