PDCD1 and cutaneous melanoma: In the last years, the outcomes of patients with cutaneous melanoma are improved thanks to the introduction of two distinct classes of drugs that are the monoclonal antibodies targeting the cytotoxic T lymphocyte-associated antigen 4 and the programmed cell death 1, and the small molecule inhibitors of MAPK signaling pathway (which act on patients with melanoma who have BRAF mutations).