CD274 and Merkel cell skin cancer: Immune checkpoint blockade (ICB) targeting PD-1/PD-L1 signaling has produced remarkable clinical benefits in cancer patients with Hodgkin’s lymphoma, Merkel cell carcinoma, skin cancer, non-small-cell lung carcinoma (NSCLC), or bladder cancer, as well as other cancer types15, demonstrating the importance of regulating PD-1/PD-L1 signaling in cancer treatment.