In a nutshell
This study examined whether abiraterone (Zytiga) or enzalutamide (Xtandi) should be administered first in the treatment of metastatic castration-resistant prostate cancer. Authors report preliminary evidence for reduced disease progression when administering abiraterone before enzalutamide compared to the reverse sequence. A significant difference in survival was not observed.
Some background
Treatment for metastatic (cancer that spreads to distant organs) prostate cancer often involves hormone therapy. Hormone therapy reduces male hormones, such as testosterone, active in cancer growth. Over time, however, many men become resistant to standard hormone therapy. This is known as metastatic castration-resistant prostate cancer (mCRPC).
Abiraterone and enzalutamide are two types of secondary hormone therapies used to treat mCRPC. It has been suggested that treatment response may be improved if abiraterone and enzalutamide are administered together, one after the other. The optimal timing of the two therapies for mCRPC has not been fully studied.
Methods & findings
The aim of this study was to examine whether abiraterone or enzalutamide should be administered first in mCRPC.
The records of 81 men with mCRPC were analyzed. All men were treated with both abiraterone and enzalutamide. Of these, 65 were treated with abiraterone first. 16 men were treated with enzalutamide first. Treatment outcomes were compared between the two groups.
The average time until disease progression was 19.5 months for men treated with abiraterone first. This was significantly longer compared to men treated with enzalutamide first (13 months). Overall, the risk of progression was 42% higher among men treated with enzalutamide first.
Overall survival (time from treatment until death from any cause) was 33.3 months for men treated with abiraterone first. This was similar among treated with enzalutamide first (29.9 months). However, the risk of a shorter overall survival was 2.12 times higher for men previously treated with chemotherapy.
Treatment response (based on blood tests) to both abiraterone and enzalutamide was significantly higher if abiraterone was administered first. 33.8% of men treated with abiraterone first responded to both therapies. In contrast, 6.3% of men treated with enzalutamide first responded to both therapies.
The bottom line
Authors concluded that administering abiraterone before enzalutamide may improve disease progression more than the reverse order. A significant difference in survival was not observed.
The fine print
Larger studies that randomly assign patients to treatment groups are needed to confirm these results.
Published By :
Prostate
Date :
Aug 16, 2016
