Alzheimer’s drug lecanemab hailed as ‘momentous’ breakthrough in slowing memory decline

Doctors have hailed the “beginning of the end” in the search for effective Alzheimer’s treatments after a new drug reduced memory decline among patients.

The “momentous” research breakthrough ends decades of failure and shows a “new era” of drugs to treat the disease is possible.

Lecanemab is designed to target and clear a protein called amyloid - thought to be a key cause of the most common form of dementia - from patient’s brains, and was found to slow decline in patients’ memory and thinking.

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 initial results in September from a trial on 1,795 participants with early Alzheimer’s disease and found that after 18 months the drug slowed the disease progression by 27% compared with patients taking the placebo.

Full results from the study have since been published in The New England Journal of Medicine, with experts hailing it as long-awaited proof that Alzheimer’s disease can be treated.

Professor John Hardy, group leader at the UK Dementia Research Institute at University College London, said: “This trial is an important first step, and I truly believe it represents the beginning of the end.

“The amyloid theory has been around for 30 years so this has been a long time coming. It’s fantastic to receive this confirmation that we’ve been on the right track all along, as these results convincingly demonstrate, for the first time, the link between removing amyloid and slowing the progress of Alzheimer’s disease.

“The first step is the hardest, and we now know exactly what we need to do to develop effective drugs. It’s exciting to think that future work will build on this, and we will soon have life-changing treatments to tackle this disease.”

Prof Bart De Strooper, director at the UK Dementia Research Institute, described the results of the study as “extremely positive”, adding that the trial “proves that Alzheimer’s disease can be treated.”

Prof Nick Fox, director of the Dementia Research Centre, agreed and said it brings an era of “many disappointments” to an end, while Dr Richard Oakley, associate director of research at Alzheimer’s Society, said the results had the potential to be “game-changing”. He said: “They give us hope that in the future people with early Alzheimer’s disease could have more time with their loved ones.”

Call for changes in diagnostic services

Experts have warned that UK officials have much to do to prepare to deliver the drug, provided it gets regulatory approval.

There are two ways to tell whether there is amyloid on the brain – a brain scan or biomarker test which is currently done through lumbar puncture. While a blood test is on the horizon, dementia services must rely on current tests which are expensive and can have big waiting lists.

Private patients and those living near to big dementia services can access these diagnostic tests, but the vast majority of the public cannot, experts said. They warned that unless there are big changes in diagnostic services, people could become ineligible for lecanemab treatment while on the waiting list for diagnosis because it can only be given to patients with mild disease. If their disease progresses to a moderate stage while on the waiting list, they will no longer be eligible for treatment.

Prof De Strooper said: “The participants of this trial were all people with very early-stage Alzheimer’s disease, which raises the question of how we ensure that people can access these drugs at the right stage in their disease course.

“In parallel, we must focus on making early diagnosis easier and more accessible, so that treatments can be administered when they are most likely to have a positive impact, before amyloid levels are too high and start to cause damage to the brain.”

Experts also stressed that more work still needed to be done to investigate the drug’s side effects. Prof Hardy said: “The trial results have shown us that there is a risk of side effects, including brain bleeds in a small number of cases.

“This doesn’t mean the drug can’t be administered, but that will be important to have rigorous safety monitoring in place for people receiving lecanemab, and further trials to fully understand and mitigate this risk.”