Enzalutamide (ENZA) in men with chemotherapy-Naïve metastatic castration-resistant prostate cancer (mCRPC): Final analysis of the phase 3 PREVAIL study.

5036 Background: PREVAIL (NCT01212991) was a phase 3 trial that investigated the impact of ENZA vs placebo (PBO) on overall survival (OS) and radiographic progression-free survival (rPFS) in asymptomatic or mildly symptomatic chemotherapy-naive men with mCRPC. ENZA improved OS (hazard ratio [HR] 0.71; 95% confidence interval [CI] 0.60–0.84; P < 0.0001) and rPFS (HR 0.19; 95% CI 0.15–0.23; P < 0.0001) in a planned interim analysis after 540 deaths (Sep 16, 2013, data cutoff). On the basis of these results, ENZA was approved for chemotherapy-naive mCRPC in the US and Europe. Final OS analysis was planned after at least 765 deaths. Methods: Patients (pts) were randomized 1:1 to ENZA 160 mg/day or PBO. OS and rPFS were coprimary endpoints and analyzed in the intent-to-treat population. Planned sample size was 1680 with at least 765 deaths to achieve 80% power to detect a target OS HR of 0.815, with a type I error rate of 0.049 and a single interim analysis. After the interim analysis, eligible PBO pts had the...