German team finds new way to fight Alzheimer's

By Ben Hirschler

LONDON (Reuters) - A new kind of drug designed to "hitch-hike" into cells reversed signs of Alzheimer's disease when injected into the brains of mice and may become a potent new treatment for humans, German scientists said on Thursday.

The compound effectively blocks an enzyme responsible for the build-up of sticky deposits, or plaques, in the brain by attaching to exactly the right spot on the cell wall where the toxic activity takes place, they wrote in the journal Science.

The formation of plaque is thought to play a key role in the development of Alzheimer's disease.

If all goes well, a version could be available for use by patients in five to 10 years, said Kai Simons of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden.

"It's clear that when it is injected into the brain of mice it works," Simons told Reuters. "The next stage is to see if can cross the blood-brain barrier ... if we get it through, it has huge potential."

Medicines given by mouth or standard injection that target the brain must be able to cross the natural barrier protecting the brain from chemicals in the blood if they are to work.

Animal tests on this next step are now under way, following the success seen with the direct brain injections, which reduced plaque formation by 50 percent in mice within four hours.

Max Planck Institute scientists are collaborating with a startup biotech company, JADO Technologies, on the new treatment approach, which involves using a special compound to anchor an inhibitor of the enzyme beta-secretase to cell membranes.

Beta-secretase is responsible for forming damaging amyloid plaques and is partly blocked by some experimental Alzheimer's drugs, including one from private U.S. biotech group CoMentis. The new-style drugs should be much more potent, Simons believes.

Alzheimer's is a hot area for pharmaceutical research, since the incidence of the degenerative brain disease is rising rapidly as people live longer. But developing effective treatments has proved notoriously difficult.

Existing drugs such as Aricept from Pfizer and Eisai, Exelon by Novartis and Razadyne or Reminyl from Johnson & Johnson and Shire can ease symptoms but do not stop the disease.

One new drug that could make a real difference is an experimental antibody-based treatment called bapineuzumab from Wyeth and Elan, which is now in final Phase III clinical tests.

The World Health Organization estimates there are about 18 million people worldwide with Alzheimer's disease and this figure is projected to reach 34 million by 2025.

(Editing by Louise Ireland)