RecruitingPhase 2Drug trialNeoadjuvant PD-1 Blockade in Resectable Merkel Cell CarcinomaThe main purpose of this study is to determine the response of Merkel cell carcinoma to pembrolizumab before surgery and to determine whether it further reduces the risk for disease recurrence. Another purpose of this study is to look at the side effects that occur when the experimental drug pembrolizumab is given to people with Merkel cell carcinoma before and after their standard of care surgery to remove the Merkel cell carcinoma.