Alzheimer’s Research UK said the finding was a “historic moment for dementia research”, as this is the first later-stage trial of an Alzheimer’s drug “in a generation” to successfully slow cognitive decline.
The phase three clinical trial results have been reported by Eisai, a Tokyo-based pharmaceutical company that has partnered with US biotech firm Biogen to develop lecanemab.
Eisai reported results from a trial on 1,795 participants with early Alzheimer’s disease.
Lecanemab is designed to target and clear amyloid, one of the proteins that builds up in the brains of people with Alzheimer’s at an early stage of the disease.
Eisai examined the drug – an “anti-amyloid beta protofibril antibody” – for the treatment of mild cognitive impairment for patients with amyloid in the brain.
The pharmaceutical company reported “highly statistically significant” results.
It compared results of people taking the drug and those taking a placebo.
Scientists found that after 18 months the drug slowed the disease progression by 27 per cent compared with those taking the placebo.
Findings were evident as early as six months after participants started taking the drug.
The company also reported differences in the build-up of amyloid in the brain in scans of participants, with those taking the drug having lower levels compared to those taking the placebo.
Commenting on the findings, Dr Susan Kohlhaas, director of research at Alzheimer’s Research UK, said: “This is a historic moment for dementia research, as this is the first phase three trial of an Alzheimer’s drug in a generation to successfully slow cognitive decline.
“These results show that lecanemab slows the progression of memory and thinking problems in people with early Alzheimer’s, demonstrating a major breakthrough in dementia research.
“This is the first drug that’s been shown to not only remove the build-up of a protein called amyloid in the brain, but to have a small but statistically significant impact on cognitive decline in people with early-stage disease.
“The drug can also cause substantial side effects which will need to be considered.
“These top-line results, announced by the pharmaceutical company that make the drug, Eisai, offer new hope to people affected by this cruel and devastating disease.
“Before a drug is made available, regulators in different parts of the world, including the UK, will still need to assess the full data to determine whether lecanemab is safe and effective enough to be used in people with Alzheimer’s.
“If the drug is approved, it is essential that it gets to the people who may benefit from it as quickly as possible.”
Rob Howard, professor of old age psychiatry, University College London, added: “This is an unambiguously statistically positive result and represents something of an historic moment when we see the first convincing modification of Alzheimer’s disease. God knows, we’ve waited long enough for this.”
Dr Liz Coulthard, associate professor in dementia neurology at the University of Bristol, added: “Our health system moved impressively rapidly to deliver trials and therapies for Covid. Let’s hope we can apply the same efficiency for people with Alzheimer’s disease.”