UCB and Amgen have reported positive top-line data for romosozumab from a late-stage trial assessing its safety and efficacy in men with osteoporosis.

The Phase III BRIDGE trial met its primary endpoint in demonstrating a statistically significant increase in bone mineral density (BMD) at the lumbar spine in male osteoporosis patients treated with the drug compared with placebo after 12 months.

All secondary endpoints comparing romosozumab with placebo were also met, with patients taking the drug experiencing a significant increase in BMD at the femoral neck and total hip at 12 months and at the lumbar spine, femoral neck, and total hip at six months.

Safety signals were also positive, with the overall patient incidence of adverse events and serious adverse events (SAEs) “generally balanced between arms,” the firms noted. The most frequently reported adverse events were nasopharyngitis, back pain, hypertension, headache and constipation, while injection site reactions were reported in 5.5 percent of patients in the romosozumab treatment group and 3.7 percent in the placebo group, most of which were considered mild. 

The patient incidence of positively adjudicated cardiovascular (CV) SAEs was 4.9 percent (8/163) in the romosozumab group and 2.5 percent (2/81) in the placebo group, while that of positively adjudicated cardiovascular death was 0.6 percent (1/163) versus 1.2 percent (1/81), respectively. 

“While the focus of managing osteoporosis is often on women, osteoporosis in men is also a serious health issue that poses a significant health risk to millions of men worldwide,” noted Sean Harper, Research and Development lead at Amgen. “We are excited that these data showed romosozumab stimulates bone formation, leading to increases in bone mass, in this often overlooked and undertreated patient population.”

Further analysis of the Phase III BRIDGE study data is ongoing and will be submitted to a future medical conference and for publication, while UCB and Amgen also plan to discuss these results with global regulators.

Romosozumab is an investigational bone-forming monoclonal antibody designed to inhibit the protein sclerostin. It has a dual effect on bone, increasing bone formation and decreasing bone resorption.