Details of drug trial buoy biotech firm

Osteoporosis pill shown to reduce spinal fractures

NEW YORK - Amgen's experimental bone drug reduced the risk of spinal fractures in women with osteoporosis by 68 percent in a pivotal clinical trial, a robust result that raises the probability the drug can help restore the luster of the embattled biotechnology company.

The drug, called denosumab, also reduced the risk of hip fractures by 40 percent compared with a placebo and the risk of other fractures by 20 percent. The results were presented yesterday at the annual meeting of the American Society for Bone and Mineral Research in Montreal.

"Expectations were very high, but we believe the data have lived up to those expectations," Michael Aberman, an analyst at Credit Suisse, wrote in a note to clients.

Amgen needs denosumab, the first potentially major drug from its research lab in years, to be a big success. Sales of its flagship anemia drugs have been battered by safety concerns. Amgen's stock, which was trading at $75 in early 2007, had fallen below $40 by March of this year. But the stock has since rebounded to more than $60 on the prospects for denosumab.

Amgen's shares climbed $3.70, or 5 percent, to close at $65.89 yesterday.

Amgen had announced in late July that denosumab had succeeded in the clinical trial, which involved 7,800 postmenopausal women with osteoporosis, a disease marked by fragile bones. But the company did not say at that time how much the drug had reduced the risk of fractures, which could help determine whether denosumab will be a blockbuster or just another competitor in a crowded global market for bone-density drugs that is valued at about $8 billion. So Wall Street has been awaiting the results released yesterday.

The 68 percent reduction in vertebral fractures compares favorably with the 40 to 50 percent reductions achieved in clinical trials involving other pills now mainly used to treat osteoporosis. However, one drug, Reclast from Novartis, has achieved a 70 percent reduction in spinal fractures compared with a placebo. The hip fracture reduction of 40 percent achieved by denosumab was generally in line with the reduction achieved by other drugs.

Scientists cautioned that the best way to compare drugs is head-to-head in a clinical trial. Comparing across trials can be misleading because patients' characteristics can differ. Nevertheless, with little other data to go on, such comparisons were being made by Wall Street analysts and investors.

One possible concern was the number of serious infections among women treated with denosumab - 4.3 percent of the patients, compared with 3.4 percent of those getting the placebo.

This difference was not statistically significant. But some earlier trials had also shown an increased infection risk, so the issue could be a concern to regulators. Otherwise, denosumab looked to be as safe as the placebo.

Amgen has said it planned to apply for federal approval of denosumab, which could reach the market next year.

Analysts have been estimating sales of anywhere from $1 billion to several billion dollars just to treat osteoporosis. Amgen, which had revenue last year of $14.8 billion, is also testing denosumab as a treatment for bone complications arising from cancer or the treatment of cancer.

The main drugs now used for osteoporosis are a class known as bisphosphonates, which include Fosamax from Merck and its generic equivalents; Boniva from Roche and GlaxoSmithKline; Actonel from Procter & Gamble and Sanofi-Aventis; and Reclast.

The use of denosumab is likely to cost more than $1,000 a year.

About 10 million people in the United States, mainly postmenopausal women, suffer from osteoporosis and more than 30 million others have low bone mass that puts them at risk of the disease.