Phase 3 study of denosumab for the treatment of bone metastases associated with breast cancer

Amgen announced that its Phase 3 trial comparing denosumab to Zometa (zoledronic acid, from Novartis) in the treatment of bone metastases in patients with advanced breast cancer met its primary and secondary endpoints and demonstrated superior efficacy compared to Zometa. This trial was an international, randomized, double-blind study involving 2049 patients. These patients were randomized in a one-to-one ratio to receive either 120 mg of denosumab subcutaneously every four weeks or Zometa administered intravenously at a dose of 4 mg single, 15 minute infusion every four weeks. The primary endpoint was to evaluate if denosumab is non-inferior to Zometa with respect to the first on-study Skeletal Related Events (SREs). Secondary endpoints were to evaluate if denosumab was superior to Zometa with respect to the first on-study SRE, as well as first-and-subsequent on-study SREs, and to assess the safety and tolerability of denosumab compared with Zometa. Denosumab was superior to Zometa for both delaying the time to the first on-study SRE (fracture, radiation to bone, surgery to bone, or spinal cord compression) (hazard ratio 0.82, 95 percent CI: 0.71, 0.95), and delaying the time to the first-and-subsequent SREs (hazard ratio 0.77, 95 percent CI: 0.66, 0.89). Both results were statistically significant.

Denosumab is a fully human monoclonal antibody that targets RANK Ligand, the essential regulator of osteoclasts (the cells that break down bone).

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