Cancer drug improves Alzheimer's disease symptoms in mice

Cancer drugs available on the NHS could help reverse Alzheimer’s disease by boosting the immune system, according to new research published in the journal Nature Medicine.

The drug targets a protein called PD-1, which is found in certain immune cells and is responsible for suppressing their activity. By blocking the function of this protein, the immune system can be mobilised to respond to and destroy cancer cells.

Director of research and development at Alzheimer’s Society, Dr Doug Brown, said: "It’s clear that inflammation and the immune system play a highly important role in the development of Alzheimer’s disease, but just how that relationship works is incredibly complex and not fully understood."

The researchers treated mice that had been genetically altered to show the hallmarks of Alzheimer's disease - memory loss and toxic build-ups of amyloid - with the drug.

After regular injections over two months, the mice showed improved learning and memory and had fewer amyloid plaques in their brains compared to mice that did not receive treatment.

The researchers suggest that by stopping PD-1 from suppressing the immune cells, certain elements of the immune system can be used to remove toxic build-ups, such as amyloid plaques.

Lead author of the study, Professor Michal Schwartz of the Weizmann Institute of Science, added: "We are extremely excited about our new study, we believe it is a game changer both conceptually and therapeutically.

"There is currently no cure or disease-modifying treatment for Alzheimer’s disease, and the prospect of using PD-1 blockers, may suggest short translation to the clinic.

"Notably, since such immune therapy empowers the individual immune system to fight the disease, rather than directed against any single disease factor associated with Alzheimer’s disease, we believe that it targets multiple factors associated with the disease, and therefore will be applicable to the various forms of the disease, at different stages of progression, and potentially also to other neurodegenerative conditions."

Commenting on the findings, Mr Brown said: "It’s early days yet, but this study in mice gives us an indication that activating certain immune cells could be a potential way to clear the toxic build-ups of amyloid, one of the hallmarks of Alzheimer’s disease.

"However, previous treatments targeting the immune system that have shown promise in mice have failed to have the same effect in people. We’re still a few years away from knowing whether this will hold promise for people with dementia.

"Repurposing drugs that already work for other conditions could provide us with a shortcut to new dementia treatments, and is a key aspect of Alzheimer's Society's Drug Discovery programme."

Alzheimer’s Society research has revealed that 850,000 people in the UK have a form of dementia, which costs the UK economy over £26 bn per year. In less than ten years it is estimated that one million people will be living with dementia, which could soar to two million people by 2051.