These findings support ongoing clinical trials that are exploring the use of NIO in MCC.5 Importantly, the adverse events of immunotherapy and the role of other predictive markers (such as PD-L1 status, tumor mutational burden, MCPyV status, T cell immunity), which are not included in the NCDB, will be important considerations when discussing the use of NIO for MCC. This evidence concerns the gene CD274 and Merkel cell skin cancer.