Alzheimer’s: what is new drug Lecanemab and is it an effective treatment against cognitive decline?

A new drug could be used as an effective treatment against Alzheimer’s disease in the future, according to researchers. But what is the Lecanemab drug and how could it help those with Alzheimer’s? Here’s what you need to know.

What is Lecanemab?

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. 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. A lumbar puncture is where a thin needle is inserted between the bones in your lower spine. While a blood test is on the horizon, dementia services must rely on current tests which are expensive and can have big waiting lists.

The phase three clinical trial results for the use of lecanemab have been reported by Eisai, a Tokyo-based pharmaceutical company that has partnered with US biotech firm Biogen to develop the drug. 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. Experts have hailed it as long-awaited proof that Alzheimer’s disease can be treated.

Private patients and those living near to big dementia services can currently access diagnostic tests for amyloid, 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.

What have experts said?

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.”

He added: “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.”

However, he noted that UK officials have much to do to prepare to deliver the drug, provided it gets regulatory approval. 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.”

Who are Eisai and Biogen?

Eisai is a global leading research-based pharmaceutical company with operations in Asia, Europe, the Middle East and the United States. Biogen is an American multinational biotechnology company based in Cambridge, Massachusetts. It specialises in the discovery, development and delivery of therapies for the treatment of neurological diseases - such as Alzheimer’s - to patients worldwide.