Programmed cell death 1(PD-1)/programmed cell death-ligand 1 (PD-L1) is a classic immune checkpoint [6]. PD-L1 is expressed by tumor cells which bind with PD-1 on T cells, B cells, dendritic cells, and natural killer (NK) cells and enable escape of the tumor cells from immune attack via immunosuppression. Here, PDCD1 is linked to neoplasm.