Alzheimer's treatment hopes raised after drug that prevents toxic proteins from growing in brain enters final trials

A new drug that can virtually prevent the production of sticky, toxic proteins found in the brains of people with Alzheimer’s has entered the final stage of clinical trials, raising hopes that it could provide the first effective treatment of the disease.

Researchers reported that the drug was a “potent inhibitor” of production of amyloid plaques, as the tangle of proteins are known, and also appeared to have only “relatively benign” side-effects.

They now plan to test various doses of the drug, called verubecestat, on about 1,500 people with mild cognitive impairment caused by Alzheimer’s over two years.

This, they said, should finally settle the debate about whether amyloid plaques cause the disease or are merely a symptom of it.

In August, scientists reported they had developed a different drug that could clear amyloid plaques from the brains of Alzheimer’s patients, prompting one expert to suggest it could be a “game-changer” for treatment of the disease if it passed the last set of clinical trials.

But, commenting on that study, Professor Gordon Wilcock, of Oxford University, cautioned other anti-amyloid drugs had “failed to deliver” at the final hurdle.

Writing in the journal Science Translational Medicine, the researchers behind the verubecestat study said the drug “proved to be a potent and effective inhibitor of … production [of different kinds of amyloid plaques] in both rats and monkeys, achieving greater than 90 per cent reduction”.

And they added: “The potency and maximal effect … were similar in humans and animals.”

The drug also seemed to be reasonably safe to take compared to others designed to clear amyloid plaques.

“Many previously studied anti-amyloid mechanisms … are associated with serious side effects that limit the dose that can be administered to humans,” the researchers said.

“Thus, the relatively benign preclinical and clinical safety profile of verubecestat is noteworthy.”

They now plan to test the drug on people with the mild or “prodromal” form of the disease, which can last for up to 12 years.

“Because deposition of amyloid begins several years before Alzheimer’s disease is diagnosed, it is possible that administration of an anti-amyloid agent will be more effective if given early in the disease process,” they said.

“These trials will be able to determine whether verubecestat can be a much-needed disease-modifying treatment for Alzheimer’s disease.”

Dr Clare Walton, Research Manager at Alzheimer’s Society, said they were keen to see how the trial goes.

“Amyloid plaques are a key hallmark of Alzheimer’s disease and most recent efforts to find new dementia treatments focus on reducing the production of amyloid or clearing plaques out of the brain,” she said.

“This study describes a new drug that reduces the production of amyloid in people with dementia and, importantly, it appears to be safer than similar drugs that have come before.

“This finding has paved the way for much larger clinical trials that are currently underway, and we very much look forward to the results of these in the coming years.”