Effects of denosumab on bone mineral density and bone turnover in postmenopausal women

CONTEXT: Denosumab is an investigational fully human monoclonal antibody against receptor activator of nuclear factor-kappaB ligand, a mediator of osteoclastogenesis and osteoclast survival. OBJECTIVE: This study evaluated the ability of denosumab to increase bone mineral density (BMD) and decrease bone turnover markers (BTMs) in early and later postmenopausal women with low BMD. DESIGN AND SETTING: This 2-yr randomized, double-blind, placebo-controlled study was conducted in North America. PARTICIPANTS: Subjects included 332 postmenopausal women with lumbar spine BMD T-scores between -1.0 and -2.5. Interventions: SUBJECTS were randomly assigned to receive denosumab sc, 60 mg every 6 months, or placebo. Randomization was stratified by time since onset of menopause (< or =5 yr or > 5 yr). MAIN OUTCOME MEASURES: The primary end point was the percent change in lumbar spine BMD by dual-energy x-ray absorptiometry at 24 months. Additional end points were percent change in volumetric BMD of the distal radius by quantitative computed tomography; percent change in BMD by dual-energy x-ray absorptiometry for the total hip, one-third radius, and total body; hip structural analysis; percent change in BTMs; and safety. RESULTS: Denosumab significantly increased lumbar spine BMD, compared with placebo at 24 months (6.5 vs. -0.6%; P<0.0001) with similar results for both strata. Denosumab also produced significant increases in BMD at the total hip, one-third radius, and total body (P < 0.0001 vs. placebo); increased distal radius volumetric BMD (P < 0.01); improved hip structural analysis parameters; and significantly suppressed serum C-telopeptide, tartrate-resistant acid phosphatase-5b, and intact N-terminal propeptide of type 1 procollagen. The overall incidence of adverse events was similar between both study groups. CONCLUSIONS: Twice-yearly denosumab increased BMD and decreased BTMs in early and later postmenopausal women.