SAN ANTONIO, Dec. 15 Denosumab is a new drug being studiedto prevent fractures in breast cancer patients receiving hormonal therapy.Results of a phase 3 clinical trial using denosumab were presented Fridayevening at the San Antonio Breast Cancer Symposium by Georgiana Ellis, MD,from the Seattle Cancer Care Alliance.
Denosumab is a highly specific antibody that interrupts the development ofosteoclasts -- specialized cells that break down bone. Because it is highlyspecific, the chance of systemic effects in other parts of the body is low, sopatients do not need routine laboratory monitoring.
A group of drugs called aromatase inhibitors is used to prevent therecurrence of breast cancer in postmenopausal women. These drugs are veryeffective, but commonly associated with loss of bone density and an increasedrisk of fractures.
To test the effectiveness of denosumab in preventing bone loss caused byaromatase inhibitors, a clinical trial recruited 252 patients who had beentreated for early stage breast cancer and for whom treatment with anastrozole,an aromatase inhibitor, was planned. Half of the patients were givendenosumab, while the other half was not. All patients were instructed to takedaily doses of calcium and vitamin D.
The study lasted for 2 years, with patients receiving an injection ofdenosumab every 6 months. All the women from both groups had their lumbarspine bone density measured at the end of the first and second years. By theend of the first year, the bone density of the women receiving denosumab hadincreased by nearly 5%, while the women who did not receive denosumab had bonedensity decreases of almost 1%. By the end of the second year, the differencewas even greater: in the women receiving denosumab, bone density had increasedby almost 6%, while the bone density of the women who did not receivedenosumab decreased by nearly 2%. Similar effects on bone density were seen atthe hip and the wrist. Side effects of denosumab were similar to thosereported in the control group.
Denosumab appears to be a safe and effective treatment for preventing boneloss in women taking aromatase inhibitors, offering an alternative to existingtherapies, such as oral or intravenous bisphosphonates.
SOURCE San Antonio Breast Cancer Symposium