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.