Introduction & Objectives
Enzalutamide significantly suppress the growth of prostate cancer, particularly metastatic Castration-Resistant Prostate Cancer (mCRPC), by targeting androgen receptor signaling pathway. However, there are paucity of evidences on the clinical benefits of enzalutamide in Korea. Here, we analyzed the real-world outcomes of enzalutamide treatment in Korean men with mCRPC following chemotherapy.
Material & Methods
We retrospectively reviewed the medical records of 110 mCRPC patients who received oral enzalutamide at a dose of 160 mg per day following chemotherapy in three tertiary centers in Korea between 2014 and 2016. Primary endpoint was Overall Survival (OS). Secondary endpoints were time-to first Skeletal-Related Event (SRE), time-to PSA progression and the PSA responsiveness. Kaplan-Meier analysis and log-rank tests were adopted to compare these oncological outcomes according to the various clinicopathological variables. Multivariate Cox regression model was used to identify the predictors for OS.
All-cause mortality rate was 18.4% (N=18). The median overall and PSA progression-free were 18.2 months (95% confidence interval [CI], not yet reached) and 9.5 months (95% CI, 6.4 – 12.5), respectively. Notably, patients with poor ECOG scores (≥ 2), visceral metastasis, prior abiraterone treatment, and no concomitant hormonal therapy showed significant worse OS outcomes in Kaplan-Meier analysis (Fig.1). Conversely, there were comparable PSA responses in these subgroups. After adjusting confounding factors among various clinicopathological factors, we finally identified ECOG scores (≥ 2) [hazard ratio (HR), 3.28; 95% CI, 1.11 – 9.68], prior abiraterone treatment (HR, 5.29; 95% CI, 1.68 – 16.67), and concomitant androgen deprivation therapy (HR, 0.19; 95% CI, 0.05 – 0.76) as the independent predictors for OS.
In sum, this is the first report for the real-world outcomes of the post-chemotherapeutic enzalutamide in Korean men with mCRPC. Although our study included a small number of patients, it suggests the valuable information for the treatment of mCPRC in a Korean population.