For the past few years, clinical results revealed that immune checkpoint inhibitor (ICI) treatment, such as programmed death-1 (PD-1) and its ligand 1 (PD-L1) checkpoint blockade, have shown an exhilaratingly long-term effect in a variety of cancer patients and have become a research focus in current tumor immunotherapy [1,2,3]. Here, PDCD1 is linked to neoplasm.