The programmed cell death-1 (PD-1) and its major ligand, programmed cell death-ligand 1 (PD-L1) signaling pathway, are a critical immune checkpoint, and its inhibition using monoclonal antibodies could reverse T cell dysfunction or exhaustion, which can provide a systemic therapy, including local tumor and metastatic lesion25,26. Here, PDCD1 is linked to neoplasm.