KLK3 and metastatic prostate carcinoma: Ever since Huggins and Hodges demonstrated that castration induces remission in prostate cancer patients, androgen deprivation therapy (ADT) has formed the cornerstone of treatment for patients with recurrent and metastatic prostate cancer.2,3 However, the overwhelming majority of patients inevitably develop progressive disease on ADT, a state which is often accompanied by elevations in prostate-specific antigen (PSA), which itself is an AR-regulated gene.