The increased understanding of MCC biology, along with the documented high immunogenicity of MCC and expression of programmed death ligand-1 (PD-L1) in tumors, has prompted the development of immunotherapies relying on programmed death-1/ligand-1 inhibitors (anti-PD-(L)1), which have shown promising clinical efficacy. This evidence concerns the gene CD274 and Merkel cell skin cancer.