Alzheimer’s, whose incidence is growing year after year, is one of the great evils of our time. Fortunately, the first drug that successfully achieves slow down your course: lecanemab, developed by the companies Eisai and Biogen.
What effects does lecanemab have?
As explained by the magazine specialized in scientific dissemination Scientific Americanthe lecanemab is not a cure for disease. It can have serious side effects for some people. Its benefits are more modest than one might think judging by the media coverage it has received, and its price is very high (and it is not covered by public services in all countries. However, it is still a milestone in a sisyphean task as the race for Alzheimer’s drugs seemed, which had met with dismal failure time and time again over the years.
In the aforementioned medium, the neurologist specializing in Alzheimer’s Samuel Gandy, details that what lecanemab achieves is that “patients treated with the drug deteriorate at a slower rate than those receiving a placebo. This slowdown was statistically significant across five pre-specified goals [‘objetivos’ a medir en un ensayo clínico, el tipo de experimento en el que se testan los fármacos] many different”.
In fact, the expert points out that “patients and their families they should not expect to see improvements. Neither the patient nor their relatives are likely to see any effect from the drug.”
Does it have side effects?
Regarding the side effects of the drug, Gandy states that “there was some brain swelling in about 15% of patients in one of the clinical studies. And patients who have a genetic risk for Alzheimer’s called APOE4 tended to show less response to treatment while being more prone to side effects.”
“Brain inflammation,” he argues, “can sometimes, but not always, be detected on brain scans before any symptoms occur. In some patients, this inflammation can also lead to small amount of bleeding which normally does not cause any problems. There is some concern that three patients receiving the drug suffered severe bleeding and died. Of course, at least two of these patients were taking anticoagulants, which can cause cerebral hemorrhages even without the presence of lecanemab.”
Based on this, he points out, he estimates that “close to 20% of the population of patients with mild cognitive impairment will be eligible for this medication. Patients with a history of stroke or coagulants will be warned that they are more likely to experience side effects than those who have not had a stroke and are not taking anticoagulant medication.”
How does lecanemab work?
Lecanemab has a rather unique mechanism of action: “What is unusual about this drug is that it not only targets the amyloid plaques that are a hallmark of Alzheimer’s, but also the amyloid aggregates, called oligomers, that float within and between brain cells, along with the protofibrils they share.” properties with both oligomers and plaques. Because oligomers are invisible in amyloid brain scans, we currently have no way of knowing when we have gotten rid of them. This is important, because oligomers are even more toxic to neurons than plaques.
How important is the approval of the drug?
“This is the first drug targeting amyloid“, argues this expert, “which has shown a statistically significant benefit for patients. This gives us strong evidence that amyloid is part of the story, but also makes it clear that it’s not the whole story. There are other factors that contribute to cognitive decline in Alzheimer’s patients related to inflammation and aggregations of another protein, called tau, that accumulate inside the cell. And experts believe that a cocktail of drugs will be necessary to achieve a more robust effect; and by ‘more robust’ I mean ‘completely halt the decline’. This is important to note, because we currently have methods to detect the pathology before any symptoms appear; if we manage to stop the progression of the pathology, we could even prevent them from suffering from the disease.”
References
Gary Stix. A Neurologist Answers Questions Patients Might Have about the New Alzheimer’s Drug Lecanemab. Scientific American (2023). Consulted online at https://www.scientificamerican.com/article/a-neurologist-answers-questions-patients-might-have-about-the-new-alzheimers-drug-lecanemab/ on 02/02/2023