The limited efficacy of immune checkpoint inhibitors in prostate cancer can be attributed to multifarious factors, including the relatively low tumor mutation burden of prostate cancers, the cold tumor microenvironment with attenuated CD8+ T cell infiltration and diminished Major Histocompatibility Complex (MHC) class I expression [46,50,51,52]. The gene discussed is CD8A; the disease is Familial prostate cancer.