- Adding radium-223 to abiraterone acetate+prednisone/prednisolone (AAP) fails to improve symptomatic skeletal event-free survival in patients with castration-resistant prostate cancer (CRPC) and bone metastases vs placebo.
- Add-on radium-223 increases the frequency of bone fractures.
Why this matters
- Both AAP and radium-223 are approved in CRPC; based on these findings, a combination of both therapies is not recommended.
- Randomized, double-blind, placebo-controlled, phase 3 trial, ERA 223.
- 806 chemotherapy-naive patients with CRPC and bone metastases were randomly assigned to AAP+radium-223 (n=401) or AAP+placebo (n=405).
- Funding: Bayer.
- Median follow-up, 21.2 months
- 49% of patients in the AAP+radium-223 group and 47% in the placebo group had ≥1 symptomatic skeletal event or died.
- In the AAP+radium-223 vs placebo group:
- Median symptomatic skeletal event-free survival was 22.3 vs 26.0 months (HR, 1.122; P=.2636).
- Fracture rate (any grade) was 29% vs 11%.
- Most common grade 3-4 treatment-emergent adverse events (TEAEs) were hypertension (11% vs 13%), fractures (9% vs 3%), and increased alanine aminotransferase concentrations (9% vs 7%).
- Serious TEAE rate was 41% vs 39%.
- OS was not significantly different (HR, 1.195; P=.1280)
- Treatment-related deaths occurred in 2 vs 1 patient.
- Bone mineral density not evaluated.