Elan and Wyeth Alzheimer drug results mixed

By Julie Steenhuysen

CHICAGO (Reuters)- Keenly awaited details on Elan (ELN.I) (ELN.N) and Wyeth's WYE.N new Alzheimer's drug bapineuzumab show it raised the risk of a potentially serious side effect, but may help people who do not have a common genetic risk of the disease, the companies said on Tuesday.

Shares of both companies plunged in after hours trade with Elan's New York shares falling more 18 percent and Wyeth's dropping more than 10 percent.

"I think the (drug's) side effects are going to be perhaps significant, but if they are temporary and tolerable and if the drug shows a benefit, the risk-benefit ratio will be worth the side effects," said Dr. Scott Turner, incoming director of the Memory Disorders Program at Georgetown University Medical Centre in Washington.

"This is potentially the first disease-modifying therapy."

The update on the antibody medicine, also known as AAB-001, has been closely watched by investors. If proven to work, the drug could be the first to modify the course of Alzheimer's disease, rather than just offering symptom relief.

Some analysts have forecast eventual annual sales of $13 billion (6.5 billion pounds).

Twelve people with mild-to-moderate Alzheimer's who were treated with the drug, developed a build-up of fluid in the brain called vasogenic edema, researchers told the Alzheimer's Association International Conference on Alzheimer's Disease in Chicago.

Ten of those cases were in people who have the ApoE4 gene, which significantly raises their risk of developing Alzheimer's disease.