Alzheimer’s drug lecanemab approved in the UK

The drug, given via intravenous drip every two weeks, is the first disease-modifying treatment that can both slow cognitive decline and reduce plaques associated with the disease.

Clinical trials found that it slowed the decline of memory and functional thinking in participants.

The treatment was approved by the U.S. Food and Drug Administration last year.

Risk of side effects

The European Medicines Agency, however, has been far more cautious, rejecting the drug’s licence last month, saying its potential side effects, including “brain swelling and potential bleeding”, outweighed its potential to slow the progression of Alzheimer’s.

When the MHRA approves lecanemab, it is expected to list a number of exclusions to minimise the risk of side effects.

These include patients who carry the APOE gene, which is carried by about one in four people. Studies have found that patients with this gene have a greater risk of developing Alzheimer’s disease and amyloid-associated imaging abnormality (ARIA), which is characterized by swelling and bleeding in the brain.

Patients taking certain types of blood-thinning medications will also be excluded because of an increased risk of bleeding.

An MHRA spokesperson said: “We are currently conducting a rigorous review of the evidence supporting lecanemab for the treatment of Alzheimer’s disease. We will provide more information in due course.”

Although major trials have found that lecanemab, made by Japanese pharmaceutical company Eisai, can slow the early stages of Alzheimer’s disease, its effectiveness depends on early diagnosis and the use of specialist scans and tests.

Last year’s trial results were the first positive treatment breakthrough in nearly 30 years, showing that lecanemab could slow the progression of the disease, rather than just masking symptoms.

But the treatment requires greater diagnostic capabilities, with MRI scans, lumbar punctures and PET scans needed to determine which cases may benefit from the drug.

Lecanemab is designed to target and clear amyloid, one of the proteins that accumulates in the brains of people with early-stage Alzheimer’s disease.

The study, called Clarity AD, is the largest to date to test a long-debated theory: that clearing toxic brain plaques called amyloid may slow the progression of Alzheimer’s disease.

Scientists compared the results of people who took the drug with those who took a placebo (or fake medicine). After 18 months, they found that the drug slowed the progression of the disease by 27%.

The trial showed differences in the accumulation of amyloid in the brains of participants’ scans, with those taking the drug having lower levels than those taking a placebo.

The study found that the most common side effects were headache and swelling.

NHS roll-out requires expansion of diagnostic capacity

In January 2023, lecanemab was approved for use in the United States under an “accelerated approval” process at a cost of $US45,000 ($75,000) per year.

Rolling out the technology across the NHS would require a massive expansion of diagnostic capacity to identify who could benefit, and widespread use of genetic testing.

An audit published earlier this month found that only 2.1 per cent of people with dementia received the specialist checks they needed.

Experts also say the effectiveness of such treatments depends on early diagnosis.

The National Dementia Audit also found that the average waiting time from referral to diagnosis was up to five months.

According to the Alzheimer’s Society, around 982,000 people in the UK are living with dementia. This number is expected to reach 1.4 million by 2040.

Professor John Hardy, one of the world’s leading researchers in the field, said the drug was a “game changer” and called it “the biggest breakthrough in Alzheimer’s disease in decades”.

Professor Hardy, chair of the molecular biology of neurological diseases at the Institute of Neurology at University College London, said: “This is without a doubt the biggest advance in 30 years.”

When the trial results are announced in November 2022, he described lecanemab as the “beginning of the end” for Alzheimer’s disease.

“It slows the progression of the disease. It slows it down by about 25 to 30 percent,” he said. “So, you know, if before you were five years before you were going to a nursing home, now you’re seven years before you’re going to a nursing home.”

Alzheimer’s Research UK said the same finding was a “historic moment” for dementia research.