Comparative Assessment of Clinical Outcomes Between Abiraterone Acetate and Enzalutamide in Patients With Docetaxel-Naive Metastatic Castration-Resistant Prostate Cancer: Experience in Real-World Clinical Practice in Japan

Abstract

BackgroundThe objective of the present study was to comprehensively compare the clinical outcomes between abiraterone acetate (AA) and enzalutamide (Enz) in Japanese patients with docetaxel-naive metastatic castration-resistant prostate cancer (mCRPC). Patients and MethodsThe present study retrospectively included 280 consecutive mCRPC patients, consisting of 113 and 167 who had received AA and Enz, respectively, without previous treatment with docetaxel. ResultsOf the several baseline characteristics examined, some parameters, including performance status (PS), prostate-specific antigen (PSA) value, and incidence of lymph node metastasis, significantly favored the Enz over the AA group. The PSA response rate in the Enz group was significantly greater than that in the AA group, and the PSA progression-free survival in the Enz group was significantly superior to that in the AA group. Multivariate analyses of several parameters identified the following independent predictors of PSA progression-free survival: duration of androgen deprivation therapy and PS for the AA group, age and PS for the Enz group, and PS but not the introduced agent (ie, AA vs. Enz) for the overall patients. The common adverse events observed in the present series were fatigue (19.4%) and liver toxicity (11.5%) in the AA group and fatigue (32.3%) and appetite loss (19.2%) in the Enz group. In addition, the proportion of patients with adverse events grade ≥ 3 in the Enz group (11.4%) was significantly greater than that in the AA group (4.4%). ConclusionBoth AA and Enz were effective and tolerable for patients with docetaxel-naive mCRPC in the routine clinical setting.