Phase 3 clinical trial evaluating the safety and efficacy of 12-weekly zoledronic acid in breast cancer patients with bone metastases

This phase 3 clinical trial examined whether zoledronic acid (ZA) given at a lower frequency (every 12 weeks) has the same effects as the previous frequency (every 4 weeks) in breast cancer patients with bone metastases (cancer that has spread from the breast to the bones).  

Over half of patients with advanced breast cancer will develop metastases of the bone. This can cause multiple problems, including debilitating pain and bone resorption. Bone resorbtion means the loss of bone mass, with the release of calcium (one of the main components of the bone) into the blood. In time, this leads to osteoporosis, with a great risk of fratures (breaking of the bone). ZA (Zometa) is an antiresorbtive drug (prevents the loss of bone mass) approved by the U.S. FDA for the treatment of bone metastases for patients with breast cancer. ZA has been shown to work for at least 2 years, but it’s not clear whether a prolonged treatment is safe and effective at the dosage normally prescribed. The current study evaluated whether reducing the dose after one year is still an effective treatment.

This study included 425 women with advanced breast cancer and bone metastases. All of the patients had already taken ZA for one year before the study. They were randomly divided into two groups: one group (216 patients) received 4 mg ZA every 4 weeks (a normal dosage schedule) for one year, while the second group (209 patients) was given 4 mg ZA every 12 weeks (a reduced dosage schedule) for one year. The patients were followed up for approximately one year for any bone-related problems or other side effects. The authors of the study found that the reduced dosing schedule of ZA (every 12 weeks) was as effective and safe as the normal dosage schedule of ZA (every 4 weeks). 

In summary, this study showed that by reducing the dosage of ZA the efficacy of the drug was not decreased in breast cancer patients with bone metastases. This indicates that, after 1 year at the regular dosage, it may be possible for patients to decrease the number of treatments.

This study was partly funded by Novartis Farma, the manufacturer of Zometa.

Discuss with your doctor what might be the appropriate treatment for your situation.