At long last, it seems a drug has been found to treat Alzheimer’s disease.
Lecanemab has been shown in trials to slow the progress of early-stage Alzheimer’s – scientists found that after 18 months, the drug slowed disease progression by 27% compared with patients taking a placebo.
Tokyo-based pharmaceutical Eisai, who has partnered with US biotech firm Biogen to develop lecanemab, reported the phase three clinical trial results – which have been hailed by dementia researchers as a major step forward in the treatment of Alzheimer’s.
Professor John Hardy, group leader at the UK Dementia Research Institute (UKDRI) at University College London, says: “This trial is an important first step, and I truly believe it represents the beginning of the end.”
Considering Alzheimer’s is the most common cause of dementia, affecting hundreds of thousands of people in the UK, this is big news.
So, what does the drug do, who will it help, and when is it likely to be available?
We asked Sian Gregory, research information manager at the Alzheimer’s Society (alzheimers.org.uk), to explain…
What does lecanemab do?
“This drug is a disease-modifying treatment, which targets the amyloid protein build-up in the brain in Alzheimer’s disease. It sticks to these amyloid protein build-ups and essentially marks them for clearance and the brain’s immune system will clear them away.
“Research we funded 30 years ago with Professor Hardy showed amyloid was the key player in the causes of Alzheimer’s disease, and the theory is that removing the amount of amyloid in the brain reduces the toxic effect it’s having on brain cells, which will slow down the damage done to those cells and how quickly they die,” Gregory explains.
“It’s the first treatment that targets this root cause and is of benefit to how quickly Alzheimer’s progresses and gets worse. We’ve not seen that before from previous clinical trials. It’s slowing down how quickly the symptoms get worse, and giving people longer with a quality of life.
“It’s not a cure, but it’s a fantastic first step in our development of new treatments, because the treatments we have at the moment just improve the daily symptoms, but don’t do anything about the root causes.”
Has there ever been anything like this before?
“This is the first time we’ve really seen a drug that can clear amyloid. We’ve never had this clear evidence showing the slowing down of progression – that’s why everyone’s so excited. It’s a first step that shows this is possible, and the hope is we’ll have drugs in the future that do this even more effectively.”
Who will the drug help?
“Because this drug targets amyloids, it’s just for people who have Alzheimer’s disease, not everyone who has dementia, unfortunately. There are lots of different types of dementia, although Alzheimer’s disease is what affects the majority,” says Gregory.
“It has only been tested on people in the early stages. If it was to be approved and become available, it would only benefit people in the early stages of Alzheimer’s disease specifically. This is when you first start to see symptoms like memory loss or problems with cognition and thinking skills.
“These protein build-ups and brain changes happen years before a person first shows symptoms. We want to intervene with treatment before cells have been damaged and too many brain cells have died, because that’s what causes the symptoms.
“That opens up challenges in terms of diagnosis, because we need to make sure we’re accurately diagnosing people with Alzheimer’s really early. That’s something the NHS needs to be ready for.”
When is lecanemab likely to be available?
“It needs to be approved before it can be available, and it would have to be approved in Europe by the European Commission, and by the Medicines and Healthcare products Regulatory Agency (MHRA)in the UK. The producers have said they’ll submit an application for it to be approved in March 2023, and we’re expecting a decision on it in Europe by 2024, so we should hear then whether it’s been approved and will therefore be available.
“And if it’s approved in the UK, there’s the question of whether it’ll be available on the NHS – and in all honesty it’s too soon to say. Until it’s approved, we won’t know how much it’s going to cost either. NHS England are anticipating these drugs by 2026, but NHS availability is really hard to guess.”
What about side-effects?
The UKDRI says these type of drugs can have a side-effect called ARIA, which can involve a bleed in the brain.
Gregory says: “Safety is something the regulatory bodies will look at. The majority of side-effects with drugs in this category are asymptomatic, so you can see them on a brain scan but people don’t have any symptoms of them. The main focus of the regulation is to make sure any side-effects are safe, if you can call them that. That’s why it’s such a long process to get these drugs approved.”
