WASHINGTON — A federal health panel on Thursday said a highly anticipated bone drug from Amgen benefits patients with osteoporosis but should not be used to prevent the disease because of long-term safety questions.
Food and Drug Administration experts unanimously voted that Amgen's injectable drug denosumab helps prevent bone fractures in women with postmenopausal osteoporosis. But panelists said the drug should only be used by patients who face the greatest risk of fractures.
In a separate 12-3 vote, the panel ruled against using the drug as a preventive measure for women with low bone density.
The FDA is not required to follow the group's advice, though it usually does.
Biotech drugmaker Amgen wants the FDA to approve the drug as a treatment and preventive measure against postmenopausal osteoporosis. The company also is seeking approval for osteoporosis in patients being treated for breast and prostate cancer.
But the mixed endorsement puts denosumab's multibillion-dollar sales potential in question, even as Wall Street has pegged the company's future growth to the medication.
While about 10 million Americans have osteoporosis, the larger opportunity is in preventing the disease in the nearly 45 million people with thinning bones.
Amgen's drug is a genetically engineered version of a protein that helps block a biological process that breaks down bone cells. While the FDA said the drug clearly works, regulators asked panelists to assess increased rates of skin infections and cancerous tumors seen in company trials.
Panelists said they wanted to see larger, more in-depth data on denosumab before recommending it to patients who don't yet have bone disease.
"I'm concerned we still don't have enough data at three years out that we can advocate for a preventive indication," said Dr. Clifford Rosen, of the Maine Center for Osteoporosis.
Panelists also voted overwhelmingly against using the drug in breast cancer patients with osteoporosis, because of questions about whether it could hasten tumor growth.
"We don't know how safe this molecule is to be given to patients with established cancer," said Dr. Gulbu Uzel of the National Institutes of Health.
Panelists voted 9-4 with one abstention that denosumab could be used in prostate cancer patients, saying the drug appeared safer for use in men.
Amgen representatives did not immediately respond to requests for comment Thursday evening.
Global sales of osteoporosis treatments reached $8.4 billion last year, including hundreds of vitamin brands and drugs like GlaxoSmithKline PLC's Boniva and Merck & Co. Inc.'s Fosamax, according to data from IMS Health.
Analysts have estimated peak denosumab sales between $1 billion and $2 billion.
With eight other pills and injectable medicines on the market, the drug's success likely will hinge on its price. Thousand Oaks, Calif.-based Amgen has not yet discussed pricing for denosumab, which would be marketed as Prolia. Its closest potential competitor, Novartis' injectable drug Zometa, sells for about $1,300 per year.
Denosumab also is under review in the European Union, Australia and Switzerland, where it would be marketed by British drugmaker GlaxoSmithKline.
Shares of Amgen dropped $1.30, or 2.1 percent, to $60.86 Thursday. The company's stock has traded between $44.96 and $66.51 in the past year.