Abiraterone acetate may improve survival for patients with metastatic advanced prostate cancer

Patients with metastatic castration-resistant prostate cancer treated with the investigational agent abiraterone acetate plus low-dose prednisone/prednisolone showed a significant improvement in overall survival compared to patients treated with prednisone/prednisolone plus placebo, according to a phase 3 study published in the May 26 issue of the New England Journal of Medicine.

To evaluate whether abiraterone acetate, an inhibitor of androgen biosynthesis, prolongs overall survival, investigators conducted a randomized, placebo-controlled study including 1,195 patients with metastatic advanced prostate cancer who previously had been treated with 1 or 2 chemotherapy regimens, at least 1 of which contained docetaxel. Patients were randomly assigned in a 2:1 ratio to receive 5 mg of prednisone twice daily with either 1,000 mg of abiraterone acetate (797 patients) or placebo (398 patients).

Treatment with abiraterone acetate resulted in a 35% reduction in the risk of death (HR=0.65; 95% CI: 0.54, 0.77; P<.0001) and a 36% increase in median survival (14.8 months vs 10.9 months) compared with placebo. Significant improvements in secondary end points were also noted in the treatment group: time to PSA progression (10.2 vs 6.6 months; P<.001), progression-free survival (5.6 months vs 3.6 months; P<.001), and PSA response rate (29% vs 6%, P<.001), favored the treatment group.

"Abiraterone acetate has the potential to meet a significant unmet need, so this news will be incredibly important to prostate cancer patients and their families," said Johann S. de Bono, MD, FRCP, MSc, PhD, The Institute for Cancer Research, The Royal Marsden NHS Foundation Trust, one of the lead COU-AA-301 investigators. "We are very pleased with the definitive results of this rigorous study, which show that abiraterone acetate may extend survival for men with metastatic advanced prostate cancer that progressed after treatment with docetaxel."