United Osteoporosis Centers, Gainesville, Georgia; Medical College Jagiellonian University, Krakow, Poland; Michigan Bone and Mineral Clinic, Detroit, Michigan; the Clinical Research Center of North Texas, Denton, Texas; the University of Wisconsin–Madison Osteoporosis Clinical Center and Research Program, Madison, Wisconsin; the Palacios Institute of Woman's Health, Madrid, Spain; OB-GYN Associates of Mid Florida, PA, Leesburg, Florida; Amgen Inc, Thousand Oaks, California; Amgen Ltd, Cambridge, United Kingdom; Ovatech Solutions Ltd, London, United Kingdom; The Bethesda Health Research Center, Bethesda, Maryland; and Institut National de la Santé et de la Recherche Médicale (INSERM) U658, CHR d'Orléans, Orléans, France.
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OBJECTIVE:To compare the efficacy and safety of denosumab to ibandronate in postmenopausal women with low bone mineral density (BMD) previously treated with a bisphosphonate.METHODS:In a randomized, open-label study, postmenopausal women received 60 mg denosumab subcutaneously every 6 months (n=417) or 150 mg ibandronate orally every month (n=416) for 12 months. End points included percentage change from baseline in total hip, femoral neck, and lumbar spine BMD at month 12 and percentage change from baseline in serum C-telopeptide at months 1 and 6 in a substudy.RESULTS:At month 12, significantly greater BMD gains from baseline were observed with denosumab compared with ibandronate at the total hip (2.3% compared with 1.1%), femoral neck (1.7% compared with 0.7%), and lumbar spine (4.1% compared with 2.0%; treatment difference P<.001 at all sites). At month 1, median change in serum C-telopeptide from baseline was −81.1% with denosumab and –35.0% with ibandronate (P<.001); the treatment difference remained significant at month 6 (P<.001). Adverse events occurred in 245 (59.6%) denosumab-treated women and 230 (56.1%) ibandronate-treated women (P=.635). The incidence of serious adverse events was 9.5% for denosumab-treated women and 5.4% for ibandronate-treated women (P=.046). No clustering of events in any organ system accounted for the preponderance of these reports. The incidence rates of serious adverse events involving infection and malignancy were similar between treatment groups.CONCLUSION:In postmenopausal women previously treated with a bisphosphonate and low BMD, denosumab treatment resulted in greater BMD increases than ibandronate at all measured sites. No new safety risks with denosumab treatment were identified.CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov, www.clinicaltrials.gov, NCT00936897.LEVEL OF EVIDENCE:I