The U.S. Food and Drug Administration (FDA) has approved a label update for Zytiga (abiraterone acetate) plus prednisone based on the final analysis of the COU-AA-302 trial.

The randomized, double-blind, placebo-controlled study showed that Zytiga plus prednisone significantly prolonged median survival in chemotherapy-naive patients with metastatic castration-resistant prostate cancer (mCRPC).

After a median follow-up of 49.2 months, the study demonstrated a median overall survival of 34.7 months in the patients randomly assigned to Zytiga plus prednisone versus 30.3 months in the placebo plus prednisone arm (HR = 0.81; 95% CI: 0.70 – 0.93; = 0.0033).

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“The statistically significant improvement in overall survival demonstrated in the final analysis and resulting label update help affirm the established efficacy, safety and tolerability that physicians treating men with metastatic castration-resistant prostate cancer have seen with ZYTIGA,” said Charles Ryan, M.D., Professor of Clinical Medicine, Urology at the University of California, San Francisco, and lead investigator of the COU-AA-302 study. 

“Representing a median follow-up of four years, this analysis adds to the robust body of clinical data supporting ZYTIGA as an important treatment option for men with metastatic castration-resistant prostate cancer.”

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There were no notable changes in the safety profile of Zytiga since the previous interim analyses. The most common adverse reactions associated with Zytiga treatment are confusion, cough, diarrhea, dyspnea, edema, fatigue, hot flush, hypertension, joint swelling, urinary tract infection, and vomiting.

The U.S. FDA approval of Zytiga plus prednisone for the treatment of chemotherapy-naive men with mCRPC was based on the results from the second interim analysis of the COU-AA-302 study.


  1. FDA approves label update for Zytiga to include statistically significant overall survival results in chemotherapy-naiive men with metastatic castration-resistant prostate cancer [news release]. Horsham, PA: Janssen Research & Development, LLC; March 30, 2015. Accessed March 31, 2015.