Wyeth Alzheimer's drug fails to meet goal in trial

According to the drug makers, bapineuzumab's ability to improve Alzheimer's symptoms was not significantly different from those on placebo.

However, in patients lacking a certain gene, bapineuzumab was shown to improve symptoms compared with placebo patients. About 40 to 70 percent of Alzheimer's patients lack the gene, known as the ApoE4 allele.

No benefit was seen with bapienzumab in patients with the gene.

Wyeth and Ireland-based Elan said the data supports their previous decision to continue late-stage studies, which were started last year.

The companies added that in the mid-stage trial, there were differences in patient characteristics and numbers in subgroups at the start of the trial which could have impacted the results.

Detailed results will be presented at an Alzheimer's disease conference in late July.

In premarket trading, Wyeth shares rose $1.02, or more than 2 percent, to $44.10. American Depositary Receipts of Elan rose $1.07, or 4 percent, to $28.15.