Generating concern and disappointment among Alzheimer’s disease researchers worldwide, a drug company in Ireland has halted tests of an experimental vaccine for the brain disorder. Citing evidence of inflammation in the central nervous system in four of the 97 patients in a French trial, Elan Corp. of Dublin announced the suspension in January and said it won’t provide more information until its scientists complete a detailed investigation.
The vaccine consists primarily of a protein fragment called beta-amyloid, the same substance that accumulates in the brains of people with Alzheimer’s. When mice with symptoms resembling those of Alzheimer’s disease were injected with beta-amyloid, the treatment limited and cleared deposits of the protein from their brains (SN: 7/15/00, p. 38: Possible Alzheimer’s vaccine seems safe).
An initial safety study in people with mild to moderate Alzheimer’s disease showed no serious side effects from the vaccine, so researchers at Elan expanded their trial and began evaluating the vaccine’s effectiveness. That’s apparently when brain inflammation was detected in several of the participants.
“Without details, it’s hard to speculate . . . . They had to see something that concerned them greatly” to have stopped the trial, says David Morgan of the University of South Florida in Tampa Bay.
Morgan, who has tested beta-amyloid vaccines in mice, notes that the inflammation may be just a temporary reaction–and one that indicates that the vaccine is having an effect. “These people could ultimately benefit from the vaccine,” he says.