Elan and Wyeth drug helps some Alzheimer's patients

By Ben Hirschler

LONDON (Reuters) - Elan (ELN.I) and Wyeth's (WYE.N) key new drug bapineuzumab worked for a substantial proportion of Alzheimer's disease patients in an intermediate clinical trial, supporting a prior decision to start final Phase III tests.

The two companies said on Tuesday that although the drug did not achieve overall statistically significant results in the Phase II study, its benefits over placebo were significant in important subgroups.

Shares in Irish drugmaker Elan rose 5.8 percent to 18.20 euros on the news by 1015 GMT, while Wyeth's stock gained 2.3 percent to 28.13 euros in Frankfurt (WYE.F).

The update on the antibody medicine, also known as AAB-001, is perhaps the year's most keenly awaited biotech trial result.

If successful in final-stage trials, the medicine could be the world's first drug to modify the course of Alzheimer's, the most common cause of dementia, rather than just relieving its symptoms.

Some analysts have forecast eventual annual sales of $13 billion (6.6 billion pounds), which would make it the biggest drug ever.

But the project remains high risk for Elan and its U.S. partner Wyeth, given past failures in the Alzheimer's treatment field and looming competition from others companies, such as Eli Lilly (LLY.N) and Myriad Genetics (MYGN.O).

Because of the design of the clinical study and the limited number of patients involved, the Phase II trial had not been expected to show overall statistical significance.