Immune checkpoint inhibitors (ICI), including cytotoxic T lymphocyte-associated antigens-4 (CTLA-4) inhibitors, programmed cell death 1 (PD-1) inhibitors and programmed cell death ligand 1 (PD-L1) inhibitors, counteract the immunosuppressive effect of tumors and reactivate the immune response of T cells to inhibit tumor cell growth (4). Here, PDCD1 is linked to neoplasm.