In another setback for the idea that a vaccine might be able to fight Alzheimer’s, two clinical tests of an experimental vaccine known as ACC-001 from Wyeth and Elan have been halted for the investigation of a potential safety problem.

In March, one of 59 patients enrolled in studies in Europe and the U.S. was hospitalized after developing skin lesions on the fingers and toes. The patient received the first dose of the vaccine last July. The third — and most recent dose — was given in October. The patient developed side effects in March, was hospitalized and later released. A Wyeth spokesman told the Health Blog the patient is still being evaluated.

The FDA put a halt on the U.S. trial and and the companies voluntarily stopped the European trial, the Wyeth spokesman said. The companies are cooperating with the FDA, but don’t know when the agency may conclude its investigation, he added.

ACC-001 isn’t related to bapineuzumab, an antibody against Alzheimer’s plaques now in phase III testing. Work on an earlier vaccine, called AN-1792, was stopped by the companies years ago after some patients in a clinical trial developed encephalitis.

And what does this mean for Wyeth and Elan, both heavy bettors on Alzheimer’s research? “Certainly we?re working toward the resolution of this issue,” the Wyeth spokesman said. But the company remains optimistic about the vaccine approach.

Alzheimer’s brain by Associated Press

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