The efficacy of abiraterone acetate in treating Taiwanese chemo-refractory metastatic castration-resistant prostate cancer patients

Objective: To evaluate the efficacy of abiraterone acetate in combination with prednisolone in Taiwanese men with metastatic castrate-resistant prostate cancer (mCRPC) who failed docetaxel-based chemotherapy. Materials and methods: In this single-arm, open label study, 30 mCRPC patients with prostate specific antigen (PSA) progression after docetaxel chemotherapy were enrolled. All patients were treated with abiraterone acetate 1000 mg once daily and prednisolone 5 mg twice daily. The primary end-point was PSA response rate (defined as proportion of patients achieving a PSA decline of ≥50%). Secondary end-points were overall survival and time-to-PSA progression. Results: Among 28 patients who received one or more cycles of treatment, 15 (53.6%) men achieved PSA response [95% confidence interval (CI) 33.9–72.5]. The median time-to-PSA progression was 5.5 months (95% CI 3.1–7.9). The median interval from stopping abiraterone to death was 3.4 months (95% CI 0.1–21.0), and the median overall survival was 19.2 months (95% CI 13.0–25.4). The PSA responders had better overall survival compared with PSA nonresponders, in both univariate (log rank test, p = 0.007) and multivariate (Cox regression, p = 0.001; relative risk: 0.31; 95% CI: 0.12–0.76) analysis. Both a high Gleason score (≥8) and viscera involvement did not have an unfavorable response to abiraterone treatment. Conclusion: A combination of abiraterone acetate and prednisolone can improve the overall survival in Taiwanese mCRPC patients who fail prior docetaxel chemotherapy