Docetaxel followed by abiraterone in metastatic castration-resistant prostate cancer: efficacy and predictive parameters in a large single center cohort.

PURPOSE: To report the outcome and course of disease in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with first-line docetaxel followed by abiraterone acetate in a single center.
METHODS: In this retrospective observational study, we reviewed the course of disease of all applicable patients with mCRPC treated with docetaxel followed by abiraterone at our center. We analyzed progression-free survival (PFS) of docetaxel and abiraterone treatments. We further searched for predictive factors for the duration of treatment response.
RESULTS: Median PFS between initiation of androgen deprivation therapy and the diagnosis of mCRPC was 32 months. Median PFS on docetaxel treatment was 9 months. Median PFS on abiraterone treatment was 11 months. Patients with higher Gleason scores (GS) (8-10) at initial diagnosis had a significantly longer median PFS on docetaxel as compared to patients with GS 6-7, p = 0.01. We demonstrate a significant correlation between the PFS on docetaxel and PFS on abiraterone in the post-docetaxel setting (Kendall tau r = 0.32, p = 0.019) as well as a significant negative correlation between the PSA nadir under abiraterone treatment and the time to progression under abiraterone (Kendall tau r = -0.43, p = 0.007).
CONCLUSIONS: High Gleason score appears to be predictive of duration of response to docetaxel. Interestingly, progression-free survival with abiraterone appears to be correlated with the duration of response with docetaxel, whereas PSA decline and low nadir appear to be predictive of response to abiraterone.