(Objective) We retrospectively evaluated the clinical efficacy and safety of abiraterone acetate (AA) in patients with castration-resistant prostate cancer (CRPC). (Methods) We analyzed the clinical records of 50 patients who had received AA in Gunma Cancer Center between October 2014 and June 2017. We assessed the response of prostate-specific antigen (PSA) to AA, and analyzed the association between overall survival and various parameters, including the types of primary hormonal therapy, PSA level, Gleason score, time to CRPC, prior treatment with enzalutamide (Enz) and docetaxel, and sites of metastases. (Results) The median patient age was 74.5 years and median PSA level at baseline was 15.9 ng/ml; 39 (78%) patients had Gleason score ≥8. Eleven (45.8%) of the 24 docetaxel-naïve patients achieved >50% reduction in PSA level from baseline as opposed to one (4.5%) of the 22 patients previously treated with docetaxel.Eleven (55%) of the 20 Enz-naïve patients achieved >50% reduction in PSA level from baseline compared to one (3.8%) of the 26 patients previously treated with Enz. The overall survival of the group with time to CRPC >12 months was significantly longer than that of the group with time to CRPC <12 months (p=0.035). In general, AA was tolerated; the most frequently reported adverse events included liver dysfunction (22%) and fatigue (6%). (Conclusion) Our results suggest that AA is tolerated and may be suitable for patients with time to CRPC >12 months.
Keywords: abiraterone acetate; castration-resistant prostate cancer.