Alzheimer's: significant side effects for a hopeful drug

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Alzheimer's: significant side effects for a drug that brings hope

Neurons showing amyloid plaques (right) compared to healthy neurons (left). Amyloid plaques accumulate on the outside of neurons and lead to their degeneration.

The drug lecanemab reduces cognitive decline in people with Alzheimer's, but it causes also sometimes severe adverse effects, shows an important study conducted on this treatment published on Wednesday.

The full results of this advanced clinical study (phase III) conducted on nearly 1800 people followed for 18 months confirmed a 27% reduction in cognitive decline in patients treated with lecanemab, a drug developed by the Japanese pharmaceutical group Eisai and l& #x27;American Biogen.

This statistically significant proportion, according to the two groups, had already been announced at the end of September.

But the x27; full study, published Wednesday in the New England Journal of Medicine (in English), also specifies the incidence rates of side effects of lecanemab, sometimes serious and notably more frequent than in the group of patients on placebo.

Thus, 17.3% of patients treated with lecanemab suffered from cerebral hemorrhages, compared to 9% in the placebo group.

And 12.6% of people with received this experimental drug suffered from cerebral edema, compared to just 1.7% in the placebo group.

However, the overall mortality rate is almost the same in the two groups of patients in the study (0.7% in those treated with lecanemab, 0.8% for those on placebo).

This is the first drug to deliver a real treatment option for people with Alzheimer's, said Bart De Strooper, director of the UK Institute for Alzheimer's Research. dementia.

Although the clinical benefits appear somewhat limited, they can be expected to become more apparent if the drug is administered over a longer period, the professor said.

In Alzheimer's disease, two proteins (tau protein and another called beta-amyloid) gradually accumulate abnormally in the brain, causing brain cell death as well as x27; brain shrinkage.

This causes, among other things, memory loss and a growing inability to perform daily tasks. This disease is a major public health problem, affecting tens of millions of people worldwide.

Lecanemab targets beta-amyloid protein deposits, but only at early stages of Alzheimer's, which may limit its use, as this disease is often diagnosed late.

Another anti-Alzheimer's treatment from Biogen and Eisai, named Aduhelm (aducanumab) and also targeting amyloid plaques, had already raised a lot of hopes in 2021 by being the first drug approved in the United States against the disease since 2003.

But Aduhelm has also caused controversy, the American drug agency FDA having gone against the opinion of a committee of #x27;experts, who had judged that the treatment had not sufficiently demonstrated its effectiveness in clinical trials. The FDA later restricted its use.

Countless pharmaceutical companies, such as the Swiss giant Roche recently, have so far broken their teeth on Alzheimer's disease, which remains incurable for the time being and whose causes and precise mechanisms still remain largely uncertain.

Eisai and Biogen's new treatment is also not curative and there is no accepted definition of the clinically significant effects in the cognitive test that the study authors used, warned Tara Spires-Jones, deputy director of the Center for Discovery Brain Sciences at the University of Edinburgh (Scotland). /p>

It is not yet certain that the modest reduction (in the rate of cognitive decline, editor's note) will make a big difference for patients, and longer trials will be necessary to ensure that the benefits of this treatment outweigh the risks, added this neuroscientist ific.

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