(ChemotherapyAdvisor) – Abiraterone acetate significantly prolongs overall survival (OS) in patients with metastatic castration-resistant prostate cancer, according to a final analysis of the phase 3 randomized study results published in The Lancet Oncology online September 18.

The trial randomly assigned 1,195 patients with metastatic castration-resistant prostate cancer who had disease progression after treatment with docetaxel at a 2:1 ratio to oral abiraterone acetate 1000mg/day plus oral prednisone 5mg twice daily (n=797), or placebo plus prednisone (n=398), noted Karim Fizazi, MD, of the Institut Gustave Roussy, Villejuif, France, on behalf of the investigators.

At a median follow-up of 20.2 months, OS was 15.8 months (95% CI, 14.8–17.0) for the abiraterone acetate arm vs 11.2 months (95% CI 10.4–13.1) for the placebo arm( HR 0.74 [95% CI 0.64–0.86]; P<0.0001).

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The abiraterone acetate arm also had improved median time to PSA progression, 8.5 months (95% CI 8.3–11.1) vs 6.6 months (95% CI 5.6–8.3) in the placebo group (HR 0.63 [95% 0.52–0.78]; P<0.0001); median radiologic progression-free survival, 5.6 months (95% CI 5.6–6.5) vs 3.6 months (95% CI 2.9–5.5; HR 0.66 [95% CI 0.58–0.76]; P<0.0001), and increased proportion of patients who had a PSA response, 29.5% vs 5.5% (P<0.0001).

“No new safety signals were identified with increased follow-up,” the investigators reported. The most common grade 3 or 4 adverse events observed were fatigue (9% in the abiraterone acetate arm vs 10% in the placebo arm), anemia (8% vs 8%), back pain (7% vs 10%), and bone pain (6% vs 31%).

“Our work confirms that abiraterone acetate can be used as an effective and safe treatment for castration-resistant metastatic prostate cancer patients whose disease continues to progress after docetaxel treatment,” said Dr. Fizazi. “Furthermore, unlike current alternatives for this patient population, abiraterone plus prednisone therapy can be given orally in an outpatient setting, providing an additional benefit for both patients and clinicians.”

Dr Guru Sonpavde, of the University of Alabama, Birmingham, Comprehensive Cancer Center, wrote in a linked Comment, “[This trial] represents an important advance in the therapy of metastatic castration-resistant prostate cancer,” adding that, “[Further] clinical trials investigating novel drugs and combinations should be strongly encouraged since all available options are palliative in nature.”

The study was funded by Janssen Research & Development.


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