The addition of Zytiga® (abiraterone acetate) to prednisone significantly improves survival of chemotherapy-naive patients whose prostate cancer has become resistant to hormone therapy. Final results of the COU-AA-302 were reported in The Lancet Oncology and clear the way for a new treatment option for men with hormone refractory prostate cancer (HRPC).1
Prostate cancer is a hormonally sensitive disease that can often be controlled for long periods with androgen-deprivation therapy (ADT). When prostate cancer stops responding to this treatment, it is referred to as HRPC. Metastatic HRPC is a challenging form of the disease to treat because the cancer has spread to distant sites in the body and does not respond to treatment with standard hormonal therapy.
Zytiga® is an oral targeted agent that blocks the production of androgens (male hormones such as testosterone) not only by the testes, but also by the adrenal glands and the tumor itself. The addition of Zytiga® to prednisone has previously been demonstrated to significantly delay patient-reported pain progression and health-related quality-of-life deterioration compared with prednisone alone in chemotherapy-naive men with metastatic castration-resistant prostate cancer.2
In this clinical trial, 1,088 asymptomatic or mildly symptomatic patients with HRPC that had not received prior treatment with chemotherapy were assigned treatment with Zytiga® plus prednisone or prednisone plus placebo and directly compared.
Patients have been followed approximately 4 years from treatment and the overall survival is 34.7 months in the Zytiga® group compared to 30.3 months in the control group. The study also found that Zytiga delayed the time to opiate use for cancer-related pain by 10 months (33.4 vs 23.4 months).
The investigators concluded that treatment with Zytiga® prolonged overall survival compared with prednisone alone by a margin that was both clinically and statistically significant. These results further support the favorable safety profile of Zytiga® in patients with chemotherapy-naive metastatic castration-resistant prostate cancer.
1. Ryan C, Smith M, Fizazi K, et al. Abiraterone acetate plus prednisone versus placebo plus prednisone in chemotherapy-naive men with metastatic castration-resistant prostate cancer (COU-AA-302): final overall survival analysis of a randomised, double-blind, placebo-controlled phase 3 study. The Lancet Oncology. Volume 16, No. 2, p152–160, February 2015.
2. Basch E, Autio K, Ryan CJ, et al: Abiraterone acetate plus prednisone versus prednisone alone in chemotherapy-naive men with metastatic castration-resistant prostate cancer: patient-reported outcome results of a randomized phase 3 trial. The Lancet Oncology. 2013; 14(12):1193-1199.
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