The early diagnosis of prostate cancer (PCa) has increased since the introduction of the prostate-specific antigen (PSA) blood test > 25 yr ago, but many patients still fail initial treatment and progress to castration-resistant prostate cancer (CRPC) or metastatic castration-resistant prostate cancer (mCRPC) [1–3]. The gene discussed is KLK3; the disease is prostate carcinoma.