For metastatic melanoma, only a few options were clinically available for treating the disease such as targeting BRAF and MEK using small molecule inhibitors, immunotherapeutic antibodies against the immune checkpoints T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell-death protein 1 (PD-1) and the modified oncolytic herpes virus talimogene laharparepvec (T-VEC) and the 5-year survival rate of patients has been improved to some extent [2–14]. This evidence concerns the gene PDCD1 and metastatic melanoma.