Drug Development

Amgen’s expectations for romosozumab take a hit as Radius lines up its rival osteoporosis drug

Amgen has helped shore up expectations for its osteoporosis drug romosozumab, releasing updated Phase III data that underscore its straight shot at a marketing approval. But the big biotech, which is partnered on this program with UCB, may have to concede a big piece of this competitive market after spelling out its failure on a key secondary endpoint.

Romo — which targets the sclerostin protein — followed by Amgen’s Prolia (denosumab) clearly vaulted the bar in Phase III for reducing vertebral fractures, with a hefty 75% risk reduction compared to a placebo plus denosumab. Investigators also were able to show a better safety profile in its presentation at the annual confab of the American Society for Bone Mineral Research. And there was an increase in bone mineral density among the drug arm in the study, which recruited 7,180 high-prism postmenopausal women.

But the drug missed a key secondary endpoint, which may cost Amgen dearly. The drug did not significantly improve patients’ risk of non-vertebral fractures, leaving Radius Health — which has posted an 86% risk reduction in vertebral fractures — with a possible distinct advantage on that score.

Geoffrey Porges, Leerink

Geoffrey Porges, Leerink

As Leerink’s Geoffrey Porges has noted, payers are acutely aware of the cost of hip fractures in this patient population, a non-vertebral sector that appears to be a clear positive for Radius Health $RDUS. The fracture incidence rate in this group was 1.6% for Amgen’s drug group compared to 2.1% for the placebo plus denosumab.

Amgen tried to rationalize the shortfall in non-vertebral fractures, pointing to a particular data set as a possible culprit. But Porges wasn’t all that impressed. He noted:

Even in this post hoc analysis, at 12 months while the RRR for hip fractures fell 59%, the p value was only 0.12 – leaving us to question whether romosozumab has much clinical benefit at all in non-vertebral fractures.

Radius’s Phase III drug abaloparatide, in a group of parathyroid hormone analog drugs that includes Eli Lilly’s Forteo, may get to duke it out with the pharma giant, Porges adds. The sclerostin drugs, including Lilly’s experimental blosozumab, may have to settle for approvals restricted to reducing the risk of vertebral fractures.

Analysts’ peak sales projections for these drugs have been all over the map. Deutsche Bank last year pegged abalo’s peak at $1.1 billion, though they believed that romo would come out on top as the better drug with a bigger market share, depending on how the generics shake out.

While both Amgen and Radius stand a good chance of winning an approval, commercial success is a completely different issue. As The New York Times reported recently, patients are generally started on bisphosphanates like Fosamax, which are old and cheap. But they’re also limited, unable to build bone the way Forteo and the two new drugs are designed to do.

Lilly, meanwhile, has been rapidly jacking up the price of Forteo ahead of its loss of patent protection. The Times reports that the wholesale price has soared to $3,100 a month, more than three times its price in 2010. Lilly has been increasing the price twice a year, for six years.

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