Denosumab superior to zoledronic acid in delaying first skeletal-related side effect in breast cancer patients

A newly approved drug, denosumab (Xgeva, Amgen), delays skeletal-related side effects for 5 months longer compared to zoledronic acid (Zometa and Reclast, Novartis) in patients with breast cancer and bone metastases, according to phase 3 trial results presented at the 33rd Annual CTRC-AACR San Antonio Breast Cancer Symposium.

The research, headed by Alison T. Stopeck, MD, associate professor of medicine and director of the Clinical Breast Cancer Program at the University of Arizona’s Arizona Cancer Center, randomized 2,046 patients with advanced breast cancer to receive either 120 mg of subcutaneous denosumab or 4 mg of intravenous zoledronic acid every 4 weeks. Results showed that denosumab was better at delaying the time to first on-study, skeletal-related event by 18% and the time to first and subsequent event by 22%. The median time to first on-study, skeletal-related event was 5 months longer for the denosumab group compared to the zoledronic acid group. Denosumab is more efficacious and better tolerated by patients, Dr. Stopeck said. “Denosumab gives me a new option that is much more convenient, where the patient can have a more normal life, have more normal daily functioning, and spend less time at the cancer center,” she said. “Living with metastatic breast cancer is about quality of life. The less time patients spend with me and the more time they spend with their families and friends is better for everybody. This drug will allow that.” Overall survival and disease progression was similar for both groups. Rates of side effects were 96.2% for those taking denosumab and 97.4% for those taking zoledronic acid. Osteonecrosis of the jaw occurred in 2.5% of patients taking denosumab and 1.8% of those taking zoledronic acid.

FDA approved denosumab starting Nov. 18, 2010, for the prevention of skeletal-related events in patients with bone metastases from solid tumors.