Radium-223 plus Enzalutamide Versus Enzalutamide in Metastatic Castration-Refractory Prostate Cancer: Final Safety and Efficacy Results

Abstract

Lessons Learned: Long-term safety of radium-223 with enzalutamide was confirmed in this clinical trial. PSA-PFS2 was prolonged with the combination compared with enzalutamide alone. Background: Previously, we showed the combination of radium-223 and enzalutamide to be safe and associated with improved efficacy based on a concomitant decline in serum bone metabolism markers compared with enzalutamide alone in a phase II trial of men with metastatic castration-resistant prostate cancer (mCRPC) [1]. Methods: Secondary endpoints were not included in our initial report, and we include them herein, after a median follow-up of 22 months. These objectives included long-term safety, prostate-specific antigen (PSA)–progression-free survival (PFS), and radiographic progression-free survival; PSA-PFS2 (time from start of protocol therapy to PSA progression on subsequent therapy); time to next therapy (TTNT); and overall survival (OS). Survival analysis and log-rank tests were performed using the R statistical package v.4.0.2 (https://www.r-project.org). Statistical significance was defined as p