This is an exploratory single centre, non-randomized, open-label, study in male subjects with metastatic, castrate-resistant PCa (CRPC) being treated with a second-line anti-androgen therapy (enzalutamide or abiraterone). The purpose of the study is to assess if 18F-DCFPyL PET/CT: 1. Shows more sites of metastatic, castrate-resistant PCa (CRPC) compared with standard imaging (bone scan and CT) at baseline and follow-up, 2. Shows response to therapy that is associated with clinical outcome.