Enzalutamide in chemotherapy-naive patients with metastatic castration-resistant prostate cancer: A retrospective Korean multicenter study in a real-world setting

Purpose: This study aimed to evaluate the clinical efficacy of enzalutamide in chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC) patients using real-world data from Korean patients. Materials and Methods: We retrospectively reviewed the medical records of 199 chemotherapy-naive patients with mCRPC at 13 tertiary centers in Korea between 2014 and 2017. All patients received enzalutamide daily and 89 patients received concurrent androgen deprivation therapy (ADT). Results: The median age of the patients was 74 years. Initial results showed that 81.5% of the patients had Gleason score >= 8 and 33.3% of the patients had European Cooperative Oncology Group Performance Status 0. The overall mortality rate was 12%. The median OS was not archieved and 76.7% of patients were alive at 30 months. Median time until PSA progression was 6 months. The overall survival rate at 2 years was significantly higher (84.6% vs. 71.7%, p=0.015) and the duration of PSA progression-free survival was significantly longer (8.0 vs. 4.6 months, p=0.008) in patients receiving concurrent ADT than in those receiving enzalutamide alone. The incidence of adverse events of grade 3 or higher was 1.7%. Multivariate Cox proportional hazard analysis indicated that ADT administered concurrently with enzalutamide significantly improved the overall survival (hazard ratio, 0.346; 95% confidence interval, 0.125-0.958). Conclusions: Enzalutamide is effective and safe for chemotherapy-naive patients with mCRPC. Furthermore, the overall survival was significantly higher in patients receiving enzalutamide and concurrent ADT than in patients receiving enzalutamide alone.