Scientists on Wednesday welcomed the detailed results of a clinical study on a new drug confirming its effectiveness in slowing the cognitive decline of patients with neurodegenerative Alzheimer’s disease, but also noted its sometimes severe adverse effects.
The complete results of this advanced clinical study (phase III) conducted on nearly 1,800 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 American Biogen.
This “statistically significant” proportion according to the two groups had already been announced at the end of September.
But the full study, published Wednesday in the New England Journal of Medicinealso specifies the incidence rates of adverse effects of lecanemab, which are 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 who 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 people treated with lecanemab, 0.8% for those on placebo).
“It’s the first drug that delivers a real treatment option for people with Alzheimer’s,” said Bart De Strooper, director of the UK Dementia Research Institute.
“Although the clinical benefits appear somewhat limited, they can be expected to become more apparent if the drug is administered over a longer period of time,” said the professor.
An incurable disease
In Alzheimer’s disease, two key proteins — tau and another called amyloid beta — gradually build up abnormally in the brain, causing brain cell death and brain shrinkage.
This causes, among other things, memory loss and a growing inability to perform daily tasks. This disease is one of the main public health problems, affecting tens of millions of people worldwide.
Lecanemab targets deposits of amyloid beta protein, but only at the early stages of Alzheimer’s, which could limit its use because this disease is often diagnosed late.
Another anti-Alzheimer’s treatment from Biogen and Eisai, called Aduhelm (adacanumab) and also targeting amyloid plaques, had already raised many 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 experts, who had judged that the treatment had not sufficiently demonstrated its effectiveness during clinical trials. The FDA later restricted its use.
Countless pharmaceutical laboratories, 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 precise causes and mechanisms are still largely uncertain.
Eisai and Biogen’s new treatment is also not curative and “there is no accepted definition of clinically significant effects in the cognitive test” that the study authors used, Tara Spires-Jones warned. , Deputy Director of the Center for Discovery Brain Sciences at the University of Edinburgh (Scotland).
“It is not yet certain that the modest reduction (in the speed 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 l ‘outweigh the risks,’ added the neuroscientist.