Previously untreated patients in this phase III research receiving enzalutamide with or without abiraterone acetate and prednisone (AAP) were being treated for metastatic castration-resistant prostate cancer (mCRPC). Median overall survival (OS), the main outcome, did not differ statistically between the two groups. Enzalutamide plus AAP, however, resulted in a longer radiographic progression-free survival (rPFS) than enzalutamide alone. Abiraterone clearance was two to three times higher when administered with enzalutamide than when given alone, according to pharmacokinetic studies. In the combo arm, there were more high-grade adverse events, such as atrial fibrillation, transaminitis, hypertension, and fatigue. Patients with mCRPC did not have their OS lengthened by the addition of AAP to enzalutamide, and the authors theorize that this may have been due to the combination arm’s higher abiraterone clearance.