Context: Castration-resistant prostate cancer (CRPC) refers to patients who no longer respond to surgical or medical castration. Standard treatment options are limited. Objective: To review the concepts and rationale behind targeted agents currently in late-stage clinical testing for patients with CRPC. Evidence acquisition: Novel targeted therapies in clinical trials were identified from registries. The MEDLINE database was searched for all relevant reports published from 1996 to October 2009. Bibliographies of the retrieved articles and major international meeting abstracts were hand-searched to identify additional studies. Evidence synthesis: Advances in our understanding of the molecular mechanisms underlying prostate cancer (PCa) progr...