The objective response rate (ORR) for immunotherapy treatment for melanoma has increased from 16% during the period of high-dose interleukin (IL)-2 therapy to 61% with the combination treatment of anti-programmed cell death-1 (PD-1) antibody Nivolumab and anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) antibody Ipilimumab[10,11]. Here, PDCD1 is linked to melanoma.