Outcome of Patients with Metastatic Castration-resistant Prostate Cancer After PSA Progression with Abiraterone Acetate.

Background/Aim: The main purpose of this study was to evaluate the outcome of patients with prostate-specific antigen (PSA) progression after abiraterone acetate (AA) treatment for metastatic castration-resistant prostate cancer (mCRPC). Patients and Methods: Between 2012 and 2017, 83 patients with clinically-confirmed mCRPC previously treated with docetaxel with/without cabazitaxel followed by AA were included in this retrospective study. All patients received 1,000 mg AA with 5 or 10 mg prednisolone. Among them, 59 were eligible for this study based on PSA progression during the clinical course. Patients were divided into two groups, AA responders and AA non-responders according to previous PSA response to AA treatment. Overall survival and treatment response to subsequent therapy were analyzed. Results: The median overall survival of the 59 patients after AA-treated PSA progression was 12 (95% confidence interval(CI)=7.6-16.4) months and was longer in the AA-responding group compared to the non-responding group (25 vs. 8 months, p<0.001). The survival time after PSA progression on AA was longer in the AA-responsive group despite not being statistically different (13 vs. 7 months, p=0.126). Patients with AA treatment who received subsequent therapies after PSA progression had better overall survival than those without (18 vs. 4 months, p=0.003). In addition, there was a trend for better chemotherapy response in AA non-responders than AA responders, 62.5% (5/8) vs. 12.5% (1/8) respectively. Conclusion: In our small retrospective patient experience, effective sequential treatments for patients with mCRPC provided overall survival benefit. Previous treatment response can act as a clinical predictor for subsequent treatment.