A comparison between Denosumab and Zoledronic acid in bone metastasis due to breast cancer

Breast cancer is the fifth cause of cancer – related death in Iran. Bone is themost common site of metastatic disease associated with breast cancer and it is asignificant cause of morbidity. Denosumab a fully human monoclonal antibody,binds to the receptor activator of nuclear factor – KB ligand (RANKL) andthereby inhibits RANKL-mediated bone resorption.Methods:There is a systematic review of 6 randomized, double-blind studies ofdenosumab versus zoledronic acid in the treatment of bone metastasis inpatients with metastatic breast cancer. In all of these studies patient wererandomly assigned to receive either subcutaneous denosumab (120mg) vs.intravenous zoledronic acid (4mg) adjusted for creatinine clearance every 4weeks. All patients were strongly recommended to take daily calcium andvitamin D supplements. Primary end points were time to first on –studySRE(defined as pathologic fracture, radiation or surgery to bone ,or spinal cordcompression),time to subsequent (multiple)SRE.Finding and Results:Denosumab was superior to Zoledronic Acid in delayingtime to first on-study SER and time to first and subsequent (multiple) on –studySRES .Reduction in bone turnover markers was greater with denosumab.Overall survival and disease progression were similar between groups.Osteonecrosis of the jaw occurred at similarly low rates in both groups.Conclusion:Denosumab was superior to Zoledronic Acid in delaying orprevention SREs in patients with breast cancer metastatic to bone and wasgenerally well tolerated and safely administered and no requirement for renalmonitoring, denosomab represent a potential treatment option for patients withbone metastases.