Romosozumab increases bone mineral density in postmenopausal Japanese women with osteoporosis: A phase 2 study

Romosozumab is a monoclonal antibody that inhibits sclerostin and rapidly increases bone mineral density (BMD) through a dual effect on bone by increasing bone formation and decreasing bone resorption, as shown in a global phase 2 study in postmenopausal women with low bone mass. Here, we report the key results of a phase 2, double-blind, placebo-controlled, dose-ranging study to assess the efficacy and safety of romosozumab in postmenopausal Japanese women with osteoporosis. Participants were postmenopausal Japanese women with osteoporosis aged 55–85years with a lumbar spine, total hip, or femoral neck dual-energy X-ray absorptiometry T-score≤−2.5. Women were randomized to receive placebo or romosozumab (70, 140, or 210mg) subcutaneously once monthly (QM) for 12months. The primary efficacy endpoint was the percentage change from baseline in lumbar spine BMD at month 12. Secondary efficacy endpoints included the percentage change from baseline in lumbar spine BMD at month 6, total hip and femoral neck BMD at months 6 and 12, and serum bone turnover markers procollagen type 1N-terminal propeptide (P1NP) and C-terminal telopeptide of type 1 collagen (CTX) at multiple visits. This study enrolled 252 women who had a mean age of 67.7years and mean T-scores of −2.7, −1.9, and −2.3 at the lumbar spine, total hip, and femoral neck, respectively. All romosozumab doses significantly increased BMD at month 12 compared with placebo (p