There are a few immunohistochemical studies that have tested the expression of PD-1 and PD-L1 in prostate cancer [129,130,131], and the majority of them have shown increased expression in both the neoplastic tissue and the tumor-infiltrating lymphocytes compared to normal controls, with a gradual increase in expression with the progression of the disease stage [129] and in metastatic CRPC compared with the primary tumor [112]. The gene discussed is CD274; the disease is neoplasm.