The monoclonal antibody romosozumab binds to sclerostin and increases bone formation.METHODS: In a phase 2, multicenter, international, randomized, placebo-controlled, parallel-group, eight-group study, we evaluated the efficacy and safety of romosozumab over a 12-month period in 419 postmenopausal women, 55 to 85 years of age, who had low bone mineral density (a T score of -2.0 or less at the lumbar spine, total hip, or femoral neck and -3.5 or more at each of the three sites).