PDCD1 and Merkel cell skin cancer: Anti–PD-1 antibody (approved in 2014) and PD-L1 blockades, atezolizumab in urothelial carcinoma and NSCLC, durvalumab in urothelial carcinoma, and avelumab in Merkel cell carcinoma and urothelial carcinoma, were recently approved by the US Food and Drug Administration.