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【drug-news】阿尔茨海默病药物研发之争：谁将掌
By Elizabeth Lopatto and Michelle Fay Cortez
April 11 (Bloomberg) -- Eli Lilly & Co., Wyeth, Elan Corp. and Myriad Genetics Inc. are in a competition to develop drugs for delaying or halting Alzheimer's disease, the most common form of dementia that affects 18 million people worldwide.
Myriad plans to release in June the results from human tests of a medicine that scientists say may be the first therapy to counter the root cause of Alzheimer's, not just improve symptoms as do existing medicines. The report may indicate the potential for Wyeth, Elan and Lilly drugs.
Doctors say current medicines, with $5 billion a year in sales, only alleviate symptoms for a few months in patients who often suffer a progressive loss of memory and function for years before dying. The new drugs are the first designed to block damage to neurons from plaque in the brain. Critics say the new approaches may fail if they don't address the disease's underlying cause, which they say is still a mystery.
``There is a whole lot of skepticism about all of these drugs as they progress through clinical development,'' said David Heupel, a Minneapolis-based money manager with the $60 billion fund Thrivent Financial for Lutherans. ``It's a high- risk, high-reward business.''
The companies' treatment candidates could achieve annual sales of $20 billion or more after 2012 if proven useful, according to Cowen & Co. analyst Ian Sanderson in Boston. About 5.2 million people in the U.S. have Alzheimer's, a figure expected to reach 7.7 million by 2030 as the population ages, according to the Alzheimer's Association, an advocacy group based in Chicago.
History of Losses
The Alzheimer's-related revenue would be a boon to the drug developers. Myriad, a Salt Lake City biotechnology company with an accumulated deficit of $265.5 million as of Dec. 31, sees its drug, called Flurizan, as an opportunity to turn its first profit.
Elan, based in Dublin, now relies on the multiple sclerosis drug Tysabri for revenue growth. While the product generated $232 million for Elan in 2007, it's been linked to a rare, fatal brain condition and liver damage in some patients.
Wyeth, based in Madison, New Jersey, has had four drugs delayed by U.S. regulators in a year, and faces the loss of patent protection on the heartburn pill Protonix and the antidepressant Effexor.
Myriad fell 47 cents to $41.24 at 9:50 a.m. New York time in Nasdaq Stock Market composite trading. Elan fell 43 cents, or 1.8 percent, to $23.01 in New York Stock Exchange composite trading. Wyeth fell 23 cents to $45.32, and Lilly fell 46 cents to $51.93.
Experiments With Mice
While Alzheimer's was first identified in 1906, research into the disease accelerated 20 years ago when researchers identified a handful of genes that predispose people to the condition. A decade ago, scientists created mice that developed the so-called plaques and tangles that accumulate in the brains of people with the disease.
The mice gave investigators an animal model to use for testing new theories and treatments. Many scientists theorize that attacking the plaques that damage neurons in the brain will stem the disease. The plaques are made of a substance called beta amyloid, the target of the drugs being tested.
The approach represents a gamble because scientists have yet to demonstrate that inhibiting beta amyloid, or preventing its formation, will help slow or defeat Alzheimer's.
`It's Not Amyloid'
Alzheimer's may stem from a dysfunction in the way cells use energy, not from the plaques, according to Allen Roses, a professor of neurology at Duke University in Durham, North Carolina.
``I believe it's not amyloid that's the cause,'' said Roses, who discovered a gene that has been linked to early-onset Alzheimer's. ``It's a sign or symptom. Taking out the amyloid might be pathologically nice but clinically irrelevant.''
Myriad's drug, Flurizan, reduced production of beta amyloid in mouse studies, leaving 70 percent less of the substance to accumulate in the brain. Mice treated with the drug fared better in water mazes.
A subsequent 207-patient trial in humans with mild to moderate Alzheimer's showed that the drug wasn't better than a placebo at slowing the progression of dementia or improving ability to perform daily tasks. Patients with the mildest condition getting the highest dose of the drug did experience an improvement.
The company's 1,864-patient study involves only patients with mild forms of the disease who were given the highest 800 milligram dose. Patients will receive the drug for a longer period than in the earlier test to tease out any benefit.
Lilly's drug, called LY 450139, is the first of a class of medicines called gamma secretase inhibitors. The drugmaker began enrolling patients on March 31 in a late-stage trial required for regulatory approval, the company reported. Like Myriad's product, the drug works by preventing the formation of beta amyloid. The Lilly trial will last 21 months.
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作者:admin@医学,生命科学 2011-02-08 05:14
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