This clinical trial is for patients who have metastatic castration resistant prostate cancer (mCRPC) and failed to respond to abiraterone acetate or enzalutamide (but not both) and to taxane-based chemotherapy. Study of AMG 509 in Subjects with Metastatic Castration-Resistant Prostate Cancer Patient Summary This clinical trial is for patients who have metastatic castration resistant prostate cancer (mCRPC) and failed to respond to abiraterone acetate or enzalutamide (but not both) and to taxane-based chemotherapy. This study is investigating the safety and effects (good or bad) of using...