PC-SPES mediated an anti-proliferative effect on prostate cancer cells (LNCaP, DU145, and PC3) in vivo and in vitro, induced apoptosis of LNCaP cells in a dose- and time-dependent manner and reduced prostate specific antigen (PSA) or AR levels in LNCaP cells and in more than 80% of individuals with prostate cancer. The gene discussed is KLK3; the disease is Familial prostate cancer.