The study offers patients new hope — but not everyone’s convinced.
The experimental drug lecanemab shows promise as an Alzheimer’s treatment according to new Phase 3 trial results published on November 29, but longer trials are still needed to determine its efficacy and safety in the long term.
It’s been pointed out that because the drug works in the early stages of the disease, which often go unnoticed, advances in spotting it are also needed. The news will nevertheless be encouraging for many who’ve felt disheartened after a rocky year in Alzheimer’s research.
The Alzheimer’s Association has expressed renewed hope in a statement, saying: “These peer-reviewed, published results show lecanemab will provide patients more time to participate in daily life and live independently. It could mean many months more of recognizing their spouse, children and grandchildren.
Treatments that deliver tangible benefits to those living with mild cognitive impairment (MCI) due to Alzheimer’s and early Alzheimer’s dementia are as valuable as treatments that extend the lives of those with other terminal diseases.”
A turbulent time for Alzheimer’s research
The pharmaceutical companies Biogen and Eisai announced in September that a drug they are developing to treat Alzheimer’s disease had slowed the rate of cognitive decline in a large clinical trial.
The late-stage trial, which tested 1,800 subjects with mild cognitive impairment, showed that lecanemab reduced clinical decline by 27% over 18 months compared with a placebo. Patients who were taking lecanemab performed 0.45 points better on the test, passing the threshold of statistical significance.
In a press briefing, Ivan Cheung, the chairman and chief executive of Eisai, said the results represented “the first definitively positive large clinical trial to show that you can indeed slow down Alzheimer’s disease at this very early symptomatic stage.”
According to the New York Times, Dr. Lon Schneider, director of the California Alzheimer’s Disease Center at the University of Southern California, took a more cautious line, pointing out that the effect of the new drug “is small and would not be considered by many as a minimally clinically important difference.” However, he added, “others would strongly disagree and say it’s clinically meaningful.”
He added that it looks likely that lecanemab will be approved by the Food and Drug Administration.
A shot at redemption for Biogen
The study offers patients new hope after years of disappointing results, and last year’s disastrous Aduhelm rollout from Biogen. Aduhelm, which was approved in June 2021, was touted as a major breakthrough — with manufacturers claiming that it not only alleviated Alzheimer’s symptoms, but actually slowed the progression of the disease.
Aduhelm, like lecanemab, aims to reduce the buildup of harmful plaque in patients’ brains. Crucially however, the assumption that plaque is the cause of cognitive deterioration in Alzheimer’s patients has come under serious scrutiny. Some experts have argued that the whole idea behind Aduhelm — and many other drugs that aim to target the same plaque — may be invalid.
A controversial theory
The notion that a harmful buildup of plaque in the brains of Alzheimer’s patients leads to cognitive decline is largely based on a paper published in Nature in 2006. In July this year, Science magazine published a six-month investigation that showed that the results of the 2006 study had been fabricated. This seemed to explain the poor efficacy of the vast majority of Alzheimer’s drugs made under the premise that “amyloids” (proteins) found in plaque that builds up in the brains of Alzheimer’s patients are the cause of memory loss and dementia.
The findings of the Science investigation only added to the controversy surrounding Aduhelm’s release. The drug is so expensive that it was expected to inflate premiums for 60 million Medicare enrollees — and after a massive furor, Medicare decided to limit its availability to patients in clinical trials.
Cause for hope
At this stage, lecanemab appears to be more effective than Aduhelm. In a trial comparable to that carried out using lecanemab, Aduhelm slowed cognitive decline in patients by 22%, outperforming a placebo by 0.39 points. A second study using identical methodology failed.
