Scientists reverse effects of Alzheimer's in mice using skin cancer drug bexarotene

Scientists have reversed the effects of Alzheimer’s disease in mice using an already licensed skin cancer drug.

Destructive plaques commonly found in the brains of Alzheimer’s patients were broken down at an ‘unprecedented speed’ by cancer drug bexarotene, in a study on mice published in the journal Science.

The exact cause of Alzheimer’s disease remains unknown, but the leading theory involves the formation of clumps of a protein called beta-amyloid. These damage and kill brain cells, resulting in memory problems and the inability to think clearly.

Clearing these beta-amyloid plaques is a major focus of Alzheimer’s research.

In the body, the role of removing beta-amyloid falls to a protein called ApoE. People with the ApoE4 gene variant are at the biggest risk of developing the disease.

Scientists at the Case Western Reserve University in Ohio investigated ways of boosting levels of ApoE to reduce levels of beta-amyloid.

They tested licensed skin cancer drug bexarotene on mice with a similar illness to Alzheimer’s. After one dose in young mice, the levels of beta-amyloid plaques in the brain were ‘rapidly lowered’ within 6 hours, and a 25 per cent reduction was sustained for 70 hours.

In older mice with established amyloid plaques seven days of treatment halved the number of plaques in the brain.

In all ages  there was an improvement in brain function after treatment in maze performance, nest building and remembering electric shocks.

One of the major advantages of bexarotene is that it's already been approved by the Food and Drug Administration for use in humans, which means the researchers can move into human trials sooner than if it were a completely new drug.

However, Gary Landreth, the lead researcher at Case Western, cautioned that even though his results were impressive in mice, it may turn out not to work in people.

"I want to say as loudly and clearly as possible that this was a study in mice, not in humans," he said. "We've fixed Alzheimer's in mice lots of times, so we need to move forward expeditiously but cautiously."

The research is at a very early stage, and drugs often do not make the leap from animal experiment to human treatment. The next objective is to see if it acts similarly in humans.

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