Amgen and UCB’s application to market bone-boosting drug Evenity as a treatment for postmenopausal women with osteoporosis has hit a setback, having been turned down by US regulators.

The US Food and Drug Administration has issued a Complete Response Letter asking for new safety and efficacy data from the Phase III active-comparator ARCH study to be integrated into the drug’s submission, to build on that included in the original filing taken from the Phase III placebo-controlled FRAME study.

The resubmission will also include the efficacy and safety data from the BRIDGE study, a Phase III trial assessing Evenity (romosozumab) in men with osteoporosis, which has also been requested by the FDA.

"During our interactions with the FDA, we agreed that the ARCH data should be considered in the regulatory review prior to the initial marketing authorisation and, as a result, anticipated this request,” said Sean Harper, executive vice president of Research and Development at Amgen.

"We remain committed to helping patients with osteoporosis and will use the additional time to better understand the benefit:risk profile of Evenity.”

Evenity 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.

Women receiving once-monthly subcutaneous injections of Evenity in the FRAME trial experienced a 73 percent reduction in the relative risk of a vertebral fracture through 12 months compared to those receiving placebo, and this effect persisted after transitioning to treatment with denosumab through the second year.

The relative risk of a clinical fracture (non-vertebral and vertebral) through 12 months was reduced by 36 percent compared to patients taking a receiving placebo.

The Phase III BRIDGE trial also 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.

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.