Despite improvements in prostate-specific antigen (PSA) testing, multiparametric magnetic resonance imaging (MRI), and risk-adapted local therapies, a substantial fraction of patients still progress to locally advanced or metastatic disease [4], survival gains for advanced disease—particularly castration-resistant prostate cancer (CRPC)—remain limited [5,6,7]. The gene discussed is KLK3; the disease is metastatic neoplasm.