In this case report, a patient with PD-L1-negative and MCPyV-negative MCC who had disease progression following ECT experienced complete tumor regression with avelumab treatment, suggesting, for the first time to our knowledge, that ECT may help to establish a tumor microenvironment favorable to immunotherapy <i>via</i> a potential abscopal effect. This evidence concerns the gene CD274 and Merkel cell skin cancer.