Prostate cancer is an excellent target for targeted therapies for several reasons: (1) the prostate is a nonvital organ, thereby allowing targeting of tissue-specific antigens, (2) prostate cancer metastases predominantly involve lymph nodes and bones, locations that receive high levels of circulating antibodies, (3) prostate cancer metastases are typically small in volume, allowing good antibody access and penetration, and (4) the prostate-specific antigen (PSA) serum marker provides a means for the early detection of metastases and the monitoring of therapeutic efficacy [9]. Here, KLK3 is linked to prostate cancer.