Efficacy and Safety of Enzalutamide in a Real-World Cohort of Japanese Patients With Castration-resistant Prostate Cancer

Abstract

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, ENZ}) and its active metabolite (NDE), (C_{SS, 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, ENZ}, and C_{SS, 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, ENZ} and C_{SS, 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.

Keywords: Enzalutamide; N-desmethyl enzalutamide; castration-resistant prostate cancer; pharmacokinetics; reduced dose.