Next steps for new Alzheimer’s treatment

A potential treatment for Alzheimer’s disease has gained approval for use in the United States this month – but it is likely to be some time before it becomes available in Australia.

Lecanemab, also known by its brand name Leqembi, was approved by the US’ Food and Drug Administration (FDA) on 6 January following a trial involving treatment of 856 patients.
 
The treatment is a monoclonal antibody delivered by infusions every two weeks, with trial results showing it slowed progression of cognitive decline in those with mild cognitive impairment or at the mild dementia stage of the disease by 27% compared to a placebo control group.
 
However, the companies that helped develop the treatment, Eisai and Biogen, have not started the regulatory process for approval in Australia.
 
The Therapeutic Goods Administration (TGA) confirmed on Friday it is yet to receive any application for the treatment’s use in Australia following a newsGP inquiry.
 
The FDA described the approval as ‘an important advancement in the ongoing fight’ against Alzheimer’s disease.
 
The treatment targets amyloid-beta protein fragments and aims to reduce amyloid plaques from gathering around neurons – a process scientists believe may form part of the onset of the disease.
 
It is the second drug approved by the FDA for treatment of the disease’s underlying causes, rather than its symptoms.
 
The first was a drug called aducanumab, which was approved by the FDA in 2021 but subsequently failed to gain approval in Europe due to doubts about its clinical benefits.
 
Professor Ashley Bush, Director of the Melbourne Dementia Research Centre at the Florey Institute of Neuroscience and Mental Health, argued against the approval of that drug.
 
However, Professor Bush told newsGP he has a separate opinion about the FDA’s lecanemab decision.
 
‘I have a very different – much more positive – view on lecanemab,’ he said. ‘Firstly, the data indicate a clear efficacy signal.’
 
He said the incidence of amyloid related imaging artifact (ARIA), a common side effect of the aducanumab treatment associated with a range of neurological complications, is more encouraging.
 
‘[Lecanemab] significantly slowed cognitive decline in the treatment cohort and the benefit cannot be possibly explained by unblinding caused by ARIA,’ he said.
 
‘The incidence of ARIA was substantially lower with lecanemab so I think approval of lecanemab is justified.’
 
However, Professor Bush said the fact the treatment did not stop deterioration altogether indicates there may be other mechanisms of brain damage apart from amyloid at play.
 
Lecanemab was approved under the FDA’s Accelerated Approval process, which is designed to fast-track treatments for a ‘serious condition’ where there is ‘an unmet medical need’.
 
Under the process, which has been controversial in instances such as for the aducanumab treatment, the regulatory authority can base approval on measures that ‘predict clinical benefit’ rather than those that confirm clinical benefits.
 
The approval was based on Phase 2 clinical trial results.
 
Phase 3 clinical trial results were also published this month in the New England Journal of Medicine (NEJM).
 
‘Lecanemab reduced markers of amyloid in early Alzheimer’s disease and resulted in moderately less decline on measures of cognition and function than placebo at 18 months but was associated with adverse events,’ the authors wrote.
 
‘Longer trials are warranted to determine the efficacy and safety of lecanemab in early Alzheimer’s disease.’
 
A letter also published this month in NEJM raised concerns about the death of a participant of the trial, while the US Science journal has reported three people who were participating in further trials have died.
 
Nevertheless, the developers have said they will file for traditional approval in the US as well as for marketing authorisation applications in Japan and Europe by the end of March this year. Australia is not mentioned in the strategy.
 
Professor Bush said that he hopes lecanemab will eventually become available in Australia ‘at a sensible price point’.
 
‘The benefit is not dramatic, but possibly the benefit (difference from placebo) increases with time,’ he said.
 
‘It takes 18 months to see a clear benefit.’
 
A TGA spokesperson said that if an application to register lecanemab is accepted for evaluation, it will be published under its ‘prescription medicines undergoing evaluation’ web page.
 
There are between 386,200 and 472,000 Australians living with dementia, according to the Australian Institute of Health and Welfare (AIHW), with Alzheimer’s disease the most common form.
 
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