Besides in ESCC, the association of immunohistochemical PD-L1 expression to a beneficial outcome has been observed in several entities like colorectal carcinoma [39], non-small cell lung cancer [40], melanoma [41], Merkel cell carcinoma [42] or breast cancer [43], although the mechanisms underlying the observed positive effects remain poorly understood. This evidence concerns the gene CD274 and Merkel cell skin cancer.