Efficacy And Safety Of Enzalutamide In A Real-World Cohort Of Japanese Patients With Castration-Resistant Prostate Cancer

Background/Aim: It has been reported that some adverse events (AEs) of enzalutamide (ENZ) occur more frequently in Japanese patients with castration-resistant prostate cancer (CRPC) due to higher steady-state trough plasma concentrations of ENZ (C-SS,C- ENZ) and its active metabolite (NDE), (C-SS,C- NDE). Thus, we investigated the efficacy, safety, and pharmacokinetics of ENZ in Japanese patients with CRPC. Patients and Methods: Fourteen patients were administered ENZ at a standard dose (160 mg/ day) or reduced doses (80 or 120 mg/ day). Prostate-specific antigen (PSA), AEs, C-SS,C- ENZ, and C-SS,C- NDE were examined. Results: A maximum PSA decrement of >= 50% from baseline was achieved in 92% of patients. AEs were few (> 20%) and mild. No differences in C-SS,C- ENZ and C-SS,C- NDE between other ethnic groups in previous literature and our subjects was observed. Conclusion: ENZ shows adequate efficacy and safety in Japanese patients with CRPC, even if administered at reduced doses in real-world conditions.