Cost-Effectiveness of Denosumab Compared With Zoledronic Acid in Patients With Breast Cancer and Bone Metastases

BackgroundResults from a phase III clinical trial showed that denosumab significantly reduced the risk of first on-study and subsequent skeletal-related events (SREs) compared with zoledronic acid. This study aims to assess the cost-effectiveness of denosumab vs. zoledronic acid in the prevention of SREs in patients with advanced breast cancer and bone metastases.Materials and MethodsA Markov model was developed with 4-week model cycles and a 1-year time horizon. The health states were defined by SRE status (no SRE, first on-study SRE, subsequent SRE, no SRE but history of SRE) and SRE type (pathologic fracture, radiation to the bone, surgery to the bone, spinal cord compression). Costs (in 2011 US dollars) included drug, SRE treatment, and adverse event (AE) costs and were assessed from a third-party payer perspective. The primary outcome was incremental total cost per SRE avoided; the secondary outcome was incremental total cost per pathologic fracture avoided. One-way and probabilistic sensitivity analyses were used to assess the robustness of the model.ResultsDuring the 1-year treatment period, denosumab incurred $7522 higher costs ($30,033 for denosumab and $23,511 for zoledronic acid), 0.06 fewer SREs, and 0.02 fewer pathologic fractures per patient, which led to an incremental total cost per SRE and pathologic fracture avoided of $114,628 and $290,136, respectively, compared with zoledronic acid. Results were robust to 1-way and probabilistic sensitivity analyses.ConclusionAlthough denosumab demonstrated superiority in preventing SREs in the phase III trial, it may not be cost-effective compared with zoledronic acid because of its high cost.