TOKYO, Nov 30, 2022 (BSS/AFP) - Experts hailed full data Wednesday showing 
a new drug can slow cognitive decline in Alzheimer's patients, but warned 
improvements were comparatively small and the treatment can have serious side 
effects.

Preliminary data from a trial of lecanemab was released in September and 
found it slowed cognitive decline by 27 percent across an 18-month period.

The complete trial data, published in the New England Journal of Medicine, 
fleshes out those findings but also raises concern about the incidence of 
"adverse effects" including brain bleeds and swelling.

The results showed 17.3 percent of patients administered the drug experienced 
brain bleeds, compared with nine percent of those receiving a placebo.

And 12.6 percent of those taking the drug experienced brain swelling, 
compared with just 1.7 percent of those in the placebo group.

Deaths were reported at approximately the same rate in both arms of the trial 
of the drug, which was developed by firms Biogen and Eisai.

The results were broadly welcomed by researchers and campaigners for patients 
with the disease, including Bart De Strooper, director of the UK Dementia 
Research Institute.

"This is the first drug that provides a real treatment option for people with 
Alzheimer's," he said.

"While the clinical benefits appear somewhat limited, it can be expected that 
they will become more apparent if the drug is administered over a longer time 
period."

- Longer trials needed -

In Alzheimer's disease, two key proteins, tau and amyloid beta, build up into 
tangles and plaques, known together as aggregates, which cause brain cells to 
die and lead to brain shrinkage.

Lecanemab works by targeting amyloid, and De Strooper said the drug proved 
effective at clearing it but also had "beneficial effects on other hallmarks 
of Alzheimer's, including tau".

The phase 3 trial involved nearly 1,800 people, divided between those given 
the drug and given a placebo, and ran over 18 months.

They were assessed on a clinical scale for Alzheimer's patients that measures 
cognition and function, as well as for changes in amyloid levels and other 
indicators.

But Tara Spires-Jones, programme lead at the UK Dementia Research Institute, 
noted that "there is not an accepted definition of clinically meaningful 
effects in the cognitive test they used".

"It is not clear yet whether the modest reduction in decline will make a big 
difference to people living with dementia. Longer trials will be needed to be 
sure that the benefits of this treatment outweigh the risks," she added.

The drug also only targets those in the early stages of the disease with a 
certain level of amyloid build-up, limiting the number of people who could 
potentially use the treatment.

And as Alzheimer's is not always caught quickly, some experts said an 
overhaul in early diagnosis would be needed to ensure more people could 
benefit.

"This isn't the end of the journey for lecanemab -- it's being explored in 
further trials to see how well it works over a longer period of time," said 
Richard Oakley, associate director of research at the Alzheimer's Society.

"The safety of drugs is crucial and lecanemab did have side effects, but they 
will be closely looked at when decisions are made about whether or not to 
approve lecanemab, to see if the benefits outweigh the risks," he said.

Biogen and Eisai previously brought the Alzheimer's drug Aduhelm to market, 
but there was significant controversy over the evidence that it worked, and 
its approval led to three high-level resignations in the US Food and Drug 
Administration.