Medivation and partner Astellas Pharma have announced positive results from the Phase III trial PREVAIL investigating Xtandi (enzalutamide) in patients with chemotherapy-naive metastatic prostate cancer (mPRC) which have failed androgen-deprivation therapy and have few or no symptoms. The randomised, double-blind, placebo-controlled, multi-national trial enrolled more than 1,700 patients across the United States, Canada, Europe, Australia, Russia, Israel, and Asian countries including Japan. The study met its co-primary endpoint as treatment with enzalutamide resulted in a significant improvement in overall survival compared to placebo, reducing the risk of death by 29% Other adverse events included hypertension (13.4% versus 4.1% in placebo) and Grade 3 cardiac events (2.8% versus 2.1% in placebo). The data will be presented at the American Society of Clinical Oncology (ASCO) meeting in San Francisco on 30 January 2014.