A monoclonal antibody obtained the green light from the American authorities. It has proven its effectiveness to reduce cognitive disorders, but the benefit-risk balance in view of the undesirable effects raises questions.
by Pascale Santi
A new drug against Alzheimer’s disease was approved on January 6 by the American health authorities (Food and Drug Administration, FDA) , Lecanemab, marketed by the Eisai and Biogen laboratories, under the name of Leqembi. This monoclonal antibody, which aims to reduce cognitive decline, is aimed at patients with a light form of this neurodegenerative disease. It affects around 55 million people worldwide. No treatment for braking it exists to date. There have been many disappointments over the past twenty years, the last concerning the ADUHELM (ADUCANUMAB), also developed by EISAI and BIOGEN.
If the causes of Alzheimer’s disease remain poorly known, it is characterized on the pathophysiological level by changes in the brain. Beta-amyloid plates, formed by the abnormal accumulation of a so-called beta-amyloid protein, are deposited between the nerve cells located in the gray substance of the cerebral cortex, causing a dysfunction of connections between neurons. There is also a neurofibrillar degeneration, an abnormal accumulation of filaments within neurons, linked to the deleterious effect of the Tau protein. “These two lesions correspond to piles of protein that form during the normal aging process. However, in Alzheimer’s diseases, these proteins accumulate in much larger quantity”, specifies The site of the Alzheimer Research Foundation .
Now the LecaneMab aims at the so-called beta-amyloid protein. Published in New England of Medicine on November 29 , the results of the study conducted on 1,795 participants (898 of whom received the molecule) showed that LecaneMab, administered by intravenous infusion every two weeks, reduced the markers of the amyloid by more than 50 % . They also highlighted a 27 % drop in cognitive disorders after eighteen months of treatment compared to placebo.
The researchers used the dementia assessment scale (Clinical Dementia Rating) to assess cognitive (memory, orientation, judgment) and social (acts of everyday, etc.). The questions are asked to patients and their loved ones, and a severity score is attributed to each factor. In the end, the total scores range from 0 to 18, the score from 0 to 6 indicating an early stage of the disease. The average score at the start for the two groups was 3.2. At the end of the eighteen months, it was 1.21 for those who had taken LecaneMab, against 1.66 for the placebo group, a difference of 27 %.
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