#AUA14 - Efficacy and long-term safety analysis of study COU-AA-302: Abiraterone acetate plus prednisone in chemotherapy-naïve metastatic castration-resistant prostate cancer - Session Highlights

ORLANDO, FL USA (UroToday.com) - Dr. Neal Shore presented an abstract on a multi-institutional study evaluating the safety and tolerability of long-term treatment (≥ 24 months) and also reported on the efficacy at 56% overall survival (OS) events of study COU-AA-302. In study COU-AA-302, 1 088 patients were randomized 1:1 to abiraterone (AA) 1000 mg + prednisone (P) 5 mg po BID vs placebo + P. “Co-primary” end points were radiographic progression-free survival (rPFS) and OS. Kaplan-Meier was used to estimate the 95% confidence interval (CI) of the end points and median times. Moreover, efficacy analysis and post hoc analysis of adverse events (AEs) was performed at the pre-specified third interim analysis (IA3).

auaAt IA3, the median follow-up was 27.1 months. rPFS, (HR=0.53 [95% CI], (0.45-0.62), p < 0.0001), and OS (HR=0.79 [95%CI], (0.66-0.96), p = 0.0151), were improved over P; the latter did not reach the pre-specified efficacy boundary (p = 0.0035). All reported secondary end points favored the AA arm of the study. In regards to adverse effects, grade 3/4 AEs (AA + P vs P) were reported as: hypokalemia (3% vs 2%); hypertension (4% vs 3%); increase in alanine aminotransferase (6% vs 1%); and also increase in aspartate aminotransferase (3% vs 1%). Dr. Shore showed the date illustrating that prolonged exposure to AA + P was safe and well tolerated vs P alone among most men. Moreover AA + P did not clinically show any relevant increase in the incidence rate of grade 3/4 AEs with ≥ 24 months drug exposure. The percentage of patients who came off the study due to an AE was reported as 8% (AA) vs 6% (P).

Abiraterone acetate is a selective androgen biosynthesis inhibitor that prolongs OS in patients with mCRPC and is approved for use in this population. This study shows that the updated IA3 of COU-AA-302 causes delay in progression and prolongation of life with a favorable safety profile, including patients who were treated for more than 24 months with AA + P or P.

Presented by Neal D. Shore, MD at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA

Myrtle Beach, SC USA

Written by Reza Mehrazin, MD, medical writer for UroToday.com