Early reports evidenced that primary PC specimens expressed little or no PD-L1; nonetheless, a number of recent studies have described significant PD-L1 expression in both mCRPC and primary PC (up to 20% and 92%, respectively) [39,40], and interestingly, the expression of PD-L1 does not appear to be a reliable biomarker of response to immune checkpoint monoclonal antibodies in PC [41]. Here, CD274 is linked to pachyonychia congenita.