Approved in 2023, it is indicated for patients with metastatic or recurrent Merkel cell carcinoma (MCC), a highly aggressive neuroendocrine skin cancer often associated with Merkel cell polyomavirus.107 Retifanlimab disrupts PD-1-mediated immune suppression, thereby reinvigorating cytotoxic T-cell activity against tumor cells. Here, PDCD1 is linked to Merkel cell skin cancer.