Sticky plaques in the brain are linked to Alzheimer's
A new drug which shows promise as a treatment for Alzheimer's disease has been developed by UK scientists.
The Proceedings of the National Academy of Sciences reports the drug, CPHPC, removes a protein thought to play a key role in Alzheimer's from the blood.
Tests at the University College London found the protein also disappeared from the brains of five Alzheimer's patients given the drug for three months.
Longer and larger scale clinical studies are now being planned.
The protein - serum amyloid P component (SAP) is always present in both the sticky clumps (plaques) and the tangles of nerve fibres that are found in the brains of people with Alzheimer's disease, and are thought to damage healthy cells.
It appears to prevent both structures from breaking up, and has also been shown - in lab experiments at least - to promote formation of the amyloid protein which forms the damaging plaques.
There is also some evidence that SAP itself can damage brain cells directly.
Two of the big potential advantages CPHPC are that it is not broken down once inside the body, and it has a very specific action, not interacting with cells at all, thus reducing the risk of side effects.
The researchers expected a depletion of SAP in the five patients' blood - but were taken aback at the drug's apparent effect on the brain.
By using laboratory tests they were also able to reveal both the molecular process underpinning the effect of the drug, and the way in which SAP accumulates in the brain in Alzheimer's disease.
The study also confirmed that use of the drug - and the removal of SAP from the brain - had no side effects on the patients.
CPHPC has already been given to patients with other diseases without any any adverse effects.
Although the three-month treatment period was too short to show any clinical benefit there was no obvious deterioration.
Longer and larger scale clinical studies are being planned to confirm safety and seek evidence of benefit to the patients.
Lead researcher Professor Mark Pepys said: "The complete disappearance of SAP from the brain during treatment with CPHPC could not have been confidently predicted, and the drug, also to our surprise, entered the brain.
"Coupled with the absence of any side effects, these new findings strongly support further clinical studies to see whether longer term treatment with CPHPC protects against the inexorable mental decline in patients with Alzheimer's disease."
Dr Susanne Sorensen, head of research at the Alzheimer's Society, said: "A key characteristic of Alzheimer's disease is the clumping together of proteins in the brain.
"It's very exciting that this drug could potentially interfere with this process, but it's too early to say how much it will benefit people with the disease."
Rebecca Wood, of the Alzheimer's Research Trust, said the study was small, but the results were cause for "cautious optimism".
"New treatments for Alzheimer's disease are desperately needed, and it's possible that this small molecule could be a future candidate."