Abiraterone acetate and prednisolone for metastatic castration-resistant prostate cancer failing androgen deprivation and docetaxel-based chemotherapy: a phase II bridging study in Korean and Taiwanese patients.

Objectives: To evaluate the safety and efficacy of abiraterone acetate and prednisolone in Korean and Taiwanese patients with metastatic castration-resistant prostate cancer not responding to docetaxel-based chemotherapy.

Methods: In this single-arm study, 82 metastatic castration-resistant prostate cancer patients who failed docetaxel-based chemotherapy were treated with abiraterone (1000 mg, once daily) and prednisolone (5 mg, twice daily). Patients achieving a prostate-specific antigen decline ≥ 50% were considered as responding.

Results: A total of 35 patients (43%) achieved prostate-specific antigen response (95% confidence interval 32-54). The median time to prostate-specific antigen progression was 4.7 months (95% confidence interval 3.7-8.3); the median overall survival was 11.8 months. Two (4%) of 50 patients with measurable disease achieved partial response. The median testosterone concentration was in the castration range (1.21 nmol/L) throughout the treatment period. Median dehydroepiandrosterone sulfate decreased from 0.725 μmol/L (baseline) to 0.080 μmol/L (cycle 4). The most common adverse event was bone pain (20%); grade 3/4 adverse event of special interest were hypokalemia (7%), fluid retention and liver function abnormalities (5% each), hypertension (2%), and cardiac disorders (1%).

Conclusions: A combination of abiraterone acetate and prednisolone appears to be a favorable second-line treatment in Taiwanese and Korean patients with advanced metastatic castration-resistant prostate cancer after failed docetaxel-based chemotherapy.