In a study of women with bone metastases from breast cancer, Xgeva™ (denosumab) delayed bone complications for five months longer than Zometa® (zoledronic acid). These updated results from a Phase III clinical trial were presented at the 2010 San Antonio Breast Cancer Symposium.
Metastatic cancer refers to cancer that has spread to distant sites in the body. Several types of cancer—including breast cancer—have a tendency to spread to the bone. Bone metastases can lead to serious problems such as fracture and spinal cord compression and may require treatment with surgery or radiation therapy.
Bisphosphonate drugs such as Zometa are commonly used to reduce the risk of complications from bone metastases. Researchers continue, however, to explore new approaches to treatment.
Xgeva is a drug that targets a protein known as the RANK ligand. This protein regulates the activity of osteoclasts (cells that break down bone). Xgeva was recently approved for the prevention of bone complications such as fracture in patients with bone metastases from solid (not blood-related) cancers.
To directly compare Xgeva to Zometa among breast cancer patients with bone metastases, researchers conducted a Phase III clinical trial among more than 2,000 patients. Study participants were assigned to receive either Xgeva or Zometa. Zometa is given intravenously, and Xgeva is given as a subcutaneous (under-the-skin) injection.
The objective of the study was to determine whether the occurrence of bone complications (“skeletal related events”) differed between the two study groups. The bone complications that were evaluated were fracture, radiation to the bone, surgery to the bone, and spinal cord compression.
- Patients treated with Xgeva remained free of bone complications for a median of five months longer than patients treated with Zometa.
- Overall survival was similar in the two groups.
- Osteonecrosis of the jaw—an uncommon but serious side effect—occurred in 2.5% of patients treated with Xgeva and 1.8% of patients treated with Zometa.
The results of this study suggest that Xgeva is more effective than Zometa at delaying or preventing skeletal complications in breast cancer patients with bone metastases.
Reference: Stopeck A, Martin M, Ritchie D et al. Effect of denosumab versus zoledronic acid treatment in patients with breast cancer and bone metastases: results from the extended blinded treatment phase. Presented at the 33rd annual San Antonio Breast Cancer Symposium, December 8-12, 2010. Abstract P6-14-01.