Study: Romosozumab Significantly Increases BMD

Amgen and UCB have announced results from a Phase 2 trial evaluating romosozumab, an investigational medicine, in postmenopausal women with low bone mineral density (BMD). Published in the New England Journal of Medicine (NEJM), the trial demonstrated that, compared with placebo, romosozumab treatment for 12 months significantly increased BMD at the lumbar spine, total hip and femoral neck. Significant increases were also observed in the first BMD assessment at three months. The researchers also observed at the lumbar spine and hip were significantly greater than those observed with current treatments FOSAMAXand FORTEO/FORSTEO.

“The results of the study demonstrate significantly increased BMD and stimulation of bone formation with romosozumab treatment in women with postmenopausal osteoporosis, ” said Michael McClung, M.D., director of the Oregon Osteoporosis Center and lead study investigator, in the January 1, 2014 news release. “Additionally, romosozumab treatment resulted in greater increases in bone mineral density than those seen with both placebo and the active comparators. These data provide important insight into this medicine being developed for women with postmenopausal osteoporosis at high risk for fractures.”

Romosozumab works by inhibiting the protein sclerostin, and is designed to increase bone formation and decrease bone breakdown.Romosozumab is being studied for its potential to reduce fracture risk in an extensive global Phase 3 program.

Asked what he was surprised to learn, Dr. McClung told OTW, “Compared to placebo, all doses of romosozumab significantly increased bone mineral density (BMD) in the spine and hip regions. With the largest dose of romosozumab (210 mg given each month) the increase in BMD was significantly greater (11.3%) than were the responses to either alendronate (4, 1%) or teriparatide (7.1%). Biochemical indices of bone formation increased during the first 6 months of treatment while markers of bone resorption were modestly decreased during the 12 months of romosozumab therapy. While these results cannot be described as surprising, two aspects of the results stand out: a) the magnitude of the BMD response to romosozumab and b) the fact that the effect on bone formation was transient, with markers of bone formation returning to baseline despite continued therapy with romosozumab.”

Regarding future research, Dr. McClung added, “The results of our study provide encouragement to continue to evaluate the potential of romosozumab as a treatment for osteoporosis. The Phase 2 study has been extended to evaluate the effect of longer term treatment with romosozumab, the effects of stopping treatment, of following treatment with denosumab therapy and of re-treatment. Larger Phase 3 studies will evaluate the effectiveness of romosozumab therapy on reducing fracture risk in women with postmenopausal osteoporosis.”

The study was a Phase 2, multicenter, international, randomized, placebo-controlled, parallel-group, eight-arm study of 419 postmenopausal women aged 55 to 85 years with BMD. Romosozumab is not currently approved by any regulatory authority.