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Amgen's denosumab lowers fracture risk in study

Biotechnology company Amgen Inc. released widely anticipated data Tuesday showing its osteoporosis drug candidate denosumab dramatically cut the risk of spinal and hip fractures in postmenopausal women, compared with placebo.
/ Source: The Associated Press

Biotechnology company Amgen Inc. released widely anticipated data Tuesday showing its osteoporosis drug candidate denosumab dramatically cut the risk of spinal and hip fractures in postmenopausal women, compared with placebo.

Several analysts said Tuesday the latest data supports denosumab's position as a likely market blockbuster with annual sales of more than $1 billion, something Amgen sorely needs to offset declining sales of anemia drug Aranesp, which has been plagued with safety issues.

Shares of Thousand Oaks, Calif.-based Amgen rose $3.70, or 5.6 percent, to $65.89 Tuesday. They hit $66.51 earlier in the session, their highest point since February 2007.

In June, the company preannounced that denosumab reduced the rate of spinal fractures in postmenopausal women, starting Amgen shares on an upward trajectory as analysts and investors eagerly awaited the study's full results. Since that preannouncement, Amgen shares have climbed about 20 percent.

At the American Society of Bone and Mineral Research in Montreal Tuesday Amgen said data showed postmenopausal women taking denosumab cut their risk of spinal fractures by 68 percent and hip fractures by 40 percent. The late-stage clinical trial involved 7,808 women injected with denosumab every six months for three years.

Without head-to-head studies comparing denosumab to other osteoporosis drugs on the same patient population, there is no clinical way to determine the drugs' exact comparative effects. But Wall Street analysts said the latest denosumab data supports the drug stacking up well against rival treatments already on the market called bisphosponates.

Bisphosphonates are the most commonly prescribed treatments for osteoporosis, a condition characterized by weakening bones. Such drugs include Cincinnati-based Procter & Gamble's Actonel, Roche AG and GlaxoSmithKline PLC's Boniva, Fosamax from Whitehouse Station, N.J.-based Merck & Co. and Novartis AG's Reclast, which was approved by the FDA in 2007.

Reclast, which is administered annually via a 15-minute infusion, was shown to reduce risk of new spine fractures by 70 percent and of hip fractures by 41 percent.

Goldman Sachs analyst May-Kin Ho expects Amgen to file for Food and Drug Administration approval in late 2008 or early 2009 and said the drug has annual sales potential of $2 billion. In a note to clients she backed a "Buy" rating on Amgen shares.

Cowen and Co. analyst Eric Schmidt is a bit less bullish, seeing sales reaching $1 billion annually by 2012. He said it may be difficult for denosumab to dominate the osteoporosis market, but sees it becoming the drug of choice for the 20 percent of patients who can't tolerate bisphosphonates. He also reaffirmed an "Outperform" rating on shares.

A common complaint about oral bisphosphonates are side effects including heart-burn and upset stomach.

Amgen said patients taking denosumab had a slightly lower rate of minor infections and a slightly higher rate of serious infections than those taking placebo. Other potential side effects, including delayed fracture healing and stroke were similar with those seen in placebo patients.

Late Monday, the company also released results from a separate study, showing women who switched to denosumab from Merck's Fosamax had increased bone density. Wall Street has been viewing data from denosumab's head-to-head studies with Fosamax as crucial to the drug's market potential, since the once-weekly pill has a decade-long safety record and is now offered in cheap, generic versions.