Radium‐223 in Asian patients with castration‐resistant prostate cancer with symptomatic bone metastases: A single‐arm phase 3 study

Aim Radium‐223, a targeted alpha therapy, is approved widely for the treatment of patients with metastatic castrate‐resistant prostate cancer, based on a pivotal phase 3 study in predominantly white patients. We investigated the efficacy and safety of radium‐223 in Asian patients with castrate‐resistant prostate cancer and metastatic bone disease. Methods This multicenter, prospective, single‐arm, open‐label phase 3 trial evaluated the efficacy and safety of the standard radium‐223 regimen (55 kBq/kg every 4 weeks for six cycles) in patients from Asian countries. The primary endpoints were the safety and overall survival. Results A total of 226 patients were enrolled and received at least one dose of radium‐223. Median overall survival was 14.0 months (95% confidence interval [CI], 11.2–17.4). Median time to total alkaline phosphatase and prostate‐specific antigen progression were 7.5 (95% CI, 6.8–7.7) and 3.6 (95% CI, 3.1–3.7) months, respectively. Median skeletal‐related event‐free survival was 26.0 months (95% CI, 12.6–not reached). Grade ≥3 treatment‐emergent adverse events were reported in 103 (46%) of 226 patients, with anemia being the most common event (34 [15%] patients). Grade ≥3 drug‐related treatment‐emergent adverse events occurred in 39 (17%) of 226 patients. Serious treatment‐emergent adverse events were reported in 65 (29%) of 226 patients. Seven (3%) patients had an adverse event leading to death; none were considered to be related to radium‐223. Conclusion The results of this study support the use of the standard radium‐223 regimen for the treatment of Asian patients with castrate‐resistant prostate cancer and symptomatic bone metastases. This article reports the outcomes of a single‐arm, multicenter, phase 3 study, which investigated the efficacy and safety of radium‐223 in Asian patients with castrate‐resistant prostate cancer (CRPC) and symptomatic bone metastases. Radium‐223 is effective and safe in Asian patients, and results in a trend towards improved quality of life.