Wyeth Shares Rise on Promising Study of Alzheimer’s Drug

The drug maker Wyeth said on Tuesday that a potential product for treating Alzheimer’s showed promise in an intermediate clinical study.

The news of an advance in Wyeth’s program to develop Alzheimer’s treatments sent shares of the company up 4.83 percent, or $2.08, to close at $45.16.

The product, called Bapineuzumab, is one of 23 paths that Wyeth is exploring under its so-called war on Alzheimer’s.

The study data will not be fully disclosed until next month, but the company said on Tuesday in a release that bapineuzumab improved cognitive functioning in a subset of patients, those who did not carry a genetic variation called ApoE4. Noncarriers make up 40 to 70 percent of Alzheimer’s patients.

The results were important because on a test of cognitive functioning in Alzheimer’s patients, the average decline in scores over 18 months is 6.5 points. In the 18-month study of bapineuzumab, the patients lacking ApoE4 declined 2 to 2.5 points, according to an estimate by Ian Sanderson, senior research analyst for Cowen & Company.

“Anything north of a two-point spread would be considered clinically significant,” he said.

In a release, Wyeth said that M.R.I.’s of those patients showed less loss of brain volume among treated patients compared with those given a placebo.

Wyeth’s chief executive, Bernard J. Poussot, said the company was encouraged by the findings.

The results were considered positive, even though the study of 240 patients with Alzheimer’s did not meet its primary goals. That was because the drug did not appear to have the same effect on patients with the ApoE4 gene.

Wyeth and its partner in the project, the Elan Corporation, announced last year that they had moved to a Phase 3 study of the product based on an interim look at the results announced on Tuesday. Phase 3, which began enrolling patients in December, will involve 4,100 Alzheimer’s patients at 350 study sites.

Bapineuzumab is considered the most promising of the 23 Alzheimer’s products that Wyeth has in various stages of development. If bapineuzumab were to be approved, it could represent a significant advance over current Alzheimer’s treatments, which can temporarily improve symptoms, but do not attack the underlying process. Some analysts have said it could generate many billions of dollars in sales.

In a note to investors on Tuesday, Dr. Tim Anderson, a pharmaceutical analyst for Sanford C. Bernstein & Company, gave bapineuzumab a 30 percent chance of reaching the market.

STEPHANIE SAUL