Final overall survival results from EORTC 1333/PEACE-3 trial of enzalutamide plus radium-223 in metastatic castration-resistant prostate cancer.

BACKGROUND

The primary analysis of the European Organisation for Research and Treatment of Cancer (EORTC) 1333/PEACE-3 study demonstrated that enzalutamide plus radium-223 (Ra223) improved radiological progression-free survival (rPFS) compared with enzalutamide alone in patients with metastatic castration-resistant prostate cancer (mCRPC). The primary endpoint was rPFS, while overall survival (OS) was a key secondary endpoint. Interim OS results were reported at the time of primary analysis. Here, we report the final OS analysis.

PATIENTS AND

METHODS

From November 2015 to March 2023, 446 patients were randomly assigned to receive enzalutamide alone or enzalutamide combined with six cycles of Ra223. Co-administration of bone-protecting agents (BPAs) became mandatory for all patients from March 2018. Final analysis of OS was triggered on 1 May 2025.

RESULTS

With a median follow-up of 58 months and 317 reported deaths, the hazard ratio (HR) was 0.76 [95% confidence interval (CI) 0.60-0.96, P = 0.0096] for OS in favor of the enzalutamide + Ra223 arm, reaching the predefined level of statistical significance of <0.0248. Median OS was 32.6 months (95% CI 29.3-38.2 months) in the enzalutamide arm (n = 224) and 38.2 months (95% CI 33.1-44.8 months) in the combination arm (n = 222). The HR for rPFS was 0.71 (95% CI 0.57-0.89). Grade ≥3 treatment-emergent adverse events (TEAEs) increased from 57.6% to 69.3% in the combination arm, as did treatment-related grade ≥3 TEAEs (18.8% versus 28.9%), with the most frequent being hypertension.

CONCLUSIONS

The final analysis of this study confirmed that the combination of enzalutamide with Ra223 significantly improved not only rPFS but also OS as first-line therapy for mCRPC versus enzalutamide alone. Co-administration of a BPA is required to reduce skeletal complications.