Clinical trials have shown that there is an overall survival and radiographic progression-free survival benefit derived from abiraterone acetate (Zytiga) in the treatment of men with metastatic castration resistant prostate cancer (mCRPC). A new retrospective study published online, ahead of print, shows this trend is true regardless of a man’s Gleason score at diagnosis, despite if they have had prior chemotherapy or not.
To perform this retrospective study, researchers evaluated whether a Gleason score less than 8 or equal to or more than 8 at initial diagnosis is predictive of response to abiraterone acetate plus prednisone in men with mCRPC.
To do this they analyzed data from 1048 men who had received docetaxel (chemotherapy) and 996 who had not received chemotherapy. When treated with abiraterone acetate 1 g plus prednisone 5 mg orally twice daily or placebo plus prednisone the results showed that abiraterone acetate treatment significantly improved radiographic progression-free survival, overall survival, prostate-specific antigen (PSA) response, objective response, and time to PSA progression in post-docetaxel patients and chemotherapy-naïve men regardless of Gleason score at initial diagnosis.
This means that initial Gleason score should not be considered in men with mCRPC when deciding whether to treat with abiraterone acetate (Zytiga). This has been attributed to the possibility that metastases may have changed the tumor’s histology from the time of diagnosis.
- Fizazi K, Flaig TW, Stöckle M, et al. Does Gleason score at initial diagnosis predict efficacy of abiraterone acetate therapy in patients with metastatic castration-resistant prostate cancer? An analysis of abiraterone acetate phase III trials [published online ahead of print November 25, 2015]. Ann Oncol. doi: 10.1093/annonc/mdv545.