PDCD1 and melanoma: In addition, immune checkpoint inhibitors (ICIs), such monoclonal antibodies against cytotoxic T-lymphocyte-associated protein (CTLA-4) (8) and programmed cell death protein 1 (PD-1) (9), have provided meaningful results in the clinical outcomes against advanced melanoma, as demonstrated by improved survival and a greater curative effect for an increasing proportion of patients with CM.