Amgen drug increased bone density in trial
LOS ANGELES, Sept 19 (Reuters) - Amgen Inc's (AMGN.O) closely watched experimental osteoporosis drug significantly increased bone density in post-menopausal women through 48 months of treatment in a small mid-stage study, the head of a research team that studied the drug said on Wednesday.
The drug, denosumab, is considered to be by far the most important in Amgen's developmental pipeline. Its importance to Amgen's future has been heightened by safety concerns and new restrictions placed on the use of Amgen's top-selling anemia drugs that are expected to severely eat into the company's revenue and profits.
In the ongoing multi-center, Phase II study, denosumab demonstrated sustained bone mineral density gains from baseline levels after four years, according to data presented at the American Society for Bone and Mineral Research annual meeting in Honolulu.
Lumbar spine bone density of patients on the drug had increased 10.6 percent at 48 months, while there was a 2.7 percent decrease seen in individuals who received a placebo in the 229-patient study, said Dr. Paul Miller, medical director for the Colorado Center for Bone Research and the study's lead investigator.
"It continued to go up in a linear fashion," said Miller.
The results were considered to be highly statistically significant, Miller said.
Bone mineral density (BMD) is seen as a measure of the strength of bones and their resistance to fracture.
The Amgen-sponsored study also looked at BMD changes at other sites prone to fracture, such as the total hip and specific sections of the hip. All of those measures improved in the denosumab group, compared with the smaller placebo group, researchers said.
Total hip BMD increased 5.8 percent with denosumab, while the placebo group saw an average decrease of 2.9 percent, Miller said.
The Amgen drug, which has a different mechanism of action than widely used bisphosphonates, such as Merck & Co's (MRK.N) $3 billion a year Fosamax, may have fewer side effects than the older drugs.
Denosumab is a fully monoclonal antibody that mimics a naturally occurring protein that inhibits RANK Ligand, reducing the activity of bone-destroying cells called osteoclasts.
Bisphosphonates bind to the surface of the bone and inhibit those same bone-eroding cells.
Results from a large late-stage trial looking at fracture rates in denosumab recipients is expected in late 2008.
Amgen expects denosumab will be administered as an injection once every six months rather than a pill taken every week or once a month as with other commonly used osteoporosis medicines.
The world's biggest biotechnology company by sales is also testing denosumab as a potential treatment for cancer that has spread to the bones. (Additional reporting by Bill Berkrot)
