CD274 and Merkel cell skin cancer: Immunotherapies with programmed death-1/ligand-1 inhibitors (anti-PD-(L)1) such as avelumab (anti-PD-L1), pembrolizumab, and nivolumab (both anti-PD-1) have shown promising efficacy for advanced MCC (Paulson and Bhatia, 2018; Kakish et al., 2024; Mo et al., 2025).