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Treatment of Choice for Breast Cancer Patients With Bone Metastases

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For patients with breast cancer that spread to the bones, skeletal-related events were reduced when patients received treatment with denosumab compared to zoledronic acid during a phase 3 study. The data, published in Clinical Cancer Research, also shows that health-related quality of life was maintained with denosumab.

“Our data indicate that denosumab should be the treatment of choice for the prevention of skeletal-related events and hypercalcemia in patients with breast cancer that has metastasized to the bone,” said Miguel Martin, MD, PhD, professor of medicine and head of the Medical Oncology Service at Hospital General Universitario Gregorio Marañón in Madrid, Spain.

Bisphosphonates, such as zoledronic acid, delay the onset of skeletal-related events, including hypercalcemia, bone fractures, spinal cord compression, and more. However, treatment with these drugs is associated with acute reactions and kidney toxicity. Compared with zoledronic acid, denosumab has a mechanism of action that is more specific, and it does not cause these adverse events.

For the study, Martin and colleagues randomly assigned 2046 patients with breast cancer to receive subcutaneous denosumab and IV placebo, or IV zoledronic acid and subcutaneous placebo.

Only 31% of patients on denosumab experienced a skeletal-related event compared with 36% of patients treated with zoledronic acid. Among those who experienced a skeletal-related event, few patients receiving denosumab suffered a second event while enrolled in the study.

Quality of life also improved. Treatment with denosumab reduced the need for radiation therapy to the bone by 26%. Those patients also had an 18% lower risk for developing a skeletal-related event or hypercalcemia of malignancy. Compared with those receiving zoledronic acid, patients treated with denosumab had fewer acute-phase reactions associated with a flu-like syndrome and fewer adverse events related to kidney dysfunction.

“This analysis provides additional evidence of the superiority of denosumab over zoledronic acid,” Martin said. “The clinical implication of this analysis is clear: Denosumab offers an improved therapeutic index with respect to the prior standard.”

Source: AACR.