Abiraterone acetate versus enzalutamide against chemo-naïve castration resistant prostate cancer with full dose induction

Purpose We recently released the multi-institutional real-world analysis about the difference of survival outcome between abiraterone acetate and enzalutamide against chemo-naïve castration resistant prostate cancer as first line setting. Although reduced dose induction cases were included in that analysis, induction dose reduction might correlate reduced efficacy. In this study, we analyzed full dose induction subgroups from our overall cohort and investigated true difference of efficacy between these agents. Methods A total of 220 chemotherapy-naïve CRPC cases treated with full dose induction of first-line ARSI were analyzed. Outcome measures were PSA response, PSA progression-free survival (PSA-PFS), treatment failure free survival (TFF), cancer specific survival (CSS) and overall survival (OS). Results Abiraterone acetate (A) and enzalutamide (E) were administered to 58 and 162 patients, respectively. The median PSA response rate (− 65.4% [A] and − 81.5% [E], p = 0.0252), PSA decline ≥ 90% (22.4% [A] and 37.0% [E], p = 0.0478), PSA-PFS (median 4 months [A] and 7 months [E], p = 0.00833), TFF (median 6 months [A] and 15 months [E], p < 0.0001), CSS (median 45 months [A] and not reached [E], p < 0.0001) and OS (median 34 months [A] and 80 months [E], p < 0.001) were significantly better in the enzalutamide group. Conclusion This study showed that PSA response, PSA-PFS, TTF, CSS and OS were better with first-line enzalutamide administration. Direct inhibition of androgen receptor signaling by enzalutamide is associated with better clinical outcomes in full dose induction cohort.