AN EXPERIMENTAL Alzheimer鈥檚 vaccine does destroy the plaques characteristic of the disease, post-mortem studies on the brain of a recipient have shown.
However, it is still not clear whether removing the plaques will prevent the slow mental decline that afflicts sufferers. And of the 200 or so people who have been given the vaccine, about 5 per cent suffered brain inflammation 鈥� a problem that was partly responsible for the death of the woman whose brain has now been examined. So the company developing the vaccine, Elan Pharmaceuticals of Dublin, is applying for permission to try out two potentially safer treatments.
The post-mortem showed that despite the inflammation the vaccine worked as expected, destroying brain deposits of the beta amyloid protein. 鈥淚鈥檝e seen nothing like it before,鈥� says James Nicoll, the pathologist at Britain鈥檚 Southampton General Hospital who did the autopsy.
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鈥淗er brain had all the features of Alzheimer鈥檚 disease, but with the plaques taken out. What鈥檚 left are the tangles, the abnormal structures of nerve fibres,鈥� Nicoll says.
The key unanswered question is whether this is enough to block the disease (see 快猫短视频, 1 February, p 34). 鈥淲ould it stop the rest of the symptoms, or would they develop anyway?鈥� asks Nicoll, whose results appear in Nature Medicine (DOI: 10.1038/nm840).
Elan could have some partial answers soon. Investigators in France and Britain are carrying out tests on the vaccine recipients who did not suffer inflammation to see if they have improved at all. 鈥淲e should have data for release in the second half of the year,鈥� says Ivan Lieberberg, Elan鈥檚 chief scientist.
One of the potentially safer treatments Elan wants to try is a modified version of the vaccine. The original consists of the beta amyloid protein along with an adjuvant that prompts an immune reaction and leads to the production of antibodies that destroy the protein. In the modified version, the company has stripped out a part of the protein called the carboxy terminus, which it blames for aggravating inflammation.
Another alternative would be to use ready-made antibodies, rather than using a vaccine to make the body produce its own. Nicoll thinks both approaches could prove safer than the original and hopes trials will begin later this year.