KLK3 and prostate cancer: According to the recommendation of the Prostate Cancer Clinical Trials Working Group 2, castration-resistant prostate cancer (CRPC) is defined as a radiographic progression or prostate-specific antigen (PSA) progression, which is an increase of PSA ≥ 25% and ≥ 2 ng/mL from the nadir, despite testosterone levels of < 50 ng/dL3.