TRIALS of a new Alzheimer鈥檚 vaccine could begin soon. Trials of the first were halted after several people developed signs of brain inflammation.
In Alzheimer鈥檚, plaques and tangles of a protein called beta-amyloid form in the brain. The vaccines aim to trigger production of antibodies that destroy these plaques, by injecting the protein into muscles. Elan Pharmaceuticals of Dublin, Ireland, stopped the first trials in January 2002 due to the problem with inflammation. But an autopsy of one patient showed that the vaccine cleared plaques (New Scientist, 22 March, p 25).
The latest version, patented by a team at New York University School of Medicine, is a shorter version of the beta-amyloid protein. Some amino acids have also been modified to alter the areas that seem to trigger the most severe inflammation and increase the protein鈥檚 solubility, so making it less toxic.
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The modified protein still stimulates antibody production in mice, although not as effectively as the full-length version, says team member Einar Sigurdsson. 鈥淲e also see some cognitive improvement,鈥� he says. 鈥淲hat we have is a gentle and safer vaccine treatment for Alzheimer鈥檚 disease.鈥� A final version for human trials will be selected in months, adds Daniel Chain, head of Mindset BioPharmaceuticals of Jerusalem, Israel, which is to develop the vaccine.
Other approaches are also close to human trials. Elan is gearing up to start human trials of synthetic antibodies that target plaques. And Cynthia Lemere of Harvard Medical School is developing products made of tiny fragments of beta-amyloid bound to synthetic proteins.
But we still don鈥檛 know if amyloid plaques are a cause or symptom of Alzheimer鈥檚. Getting rid of beta-amyloid may not be enough, says John Trojnowski of the University of Pennsylvania in Philadelphia.
