Well-Being Longevity

Alzheimer’s drug slowed cognitive decline in clinical trial

In nearly 1,800 participants, a treatment from Eisai and Biogen slowed the rate of cognitive decline by 27 percent.
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Story at a glance


  • Several pharmaceutical companies are developing treatments for Alzheimer’s disease that target brain plaques, or amyloids.

  • Eisai and Biogen announced results from a phase 3 clinical trial.

  • The findings suggest that their treatment reduced the rate of cognitive decline by 27 percent compared to a placebo group.

Preliminary results are in for a promising new drug to prevent cognitive decline among Alzheimer’s patients. 

Lecanemab, developed in a joint effort by the Japanese company Eisai and its American partner Biogen, slowed the rate of cognitive decline by 27 percent in a phase 3 clinical trial, according to a press release, increasing the drug’s chances of getting approved by early next year. 

The trial included 1,795 participants who had early stage Alzheimer’s disease. On a biweekly basis, one group was administered the drug intravenously and another group was given a placebo for 18 months. 

The researchers saw “highly statistically significant” slowing of deterioration compared to the placebo group. The findings renew hope for Alzheimer’s patients.  

There were some side effects for some participants; about 21 percent experienced brain swelling or bleeding. 

The announcement stands in stark contrast to the rollout of another Alzheimer’s drug from the same company, called Aduhelm. Both Aduhelm and lecanemab target brain plaque buildup, or amyloids. But the data for Aduhelm was not convincing, raising questions about whether the drug actually worked. 

Despite the lack of evidence, Aduhelm received regulatory approval.  

Haruo Naito, the CEO of Eisai says in the press release that these results “prove the amyloid hypothesis, in which the abnormal accumulation of [beta amyloid] in the brain is one of the main causes of Alzheimer’s disease.” 

This clinical trial, while promising, is not a guarantee that this drug will become widely available. Eisai had already applied for accelerated approval from the Food and Drug Administration, the type of approval given to Aduhelm. 

“Ideally, we need to wait for data to be presented or published in a peer-reviewed journal. But the prospect of moving closer to finding treatments for Alzheimer’s Disease, even if that progress is incremental, is promising,” said physician Riddhi Patira, an assistant professor of neurology at the University of Pittsburgh and an investigator at the school’s Alzheimer’s Disease Research Center, to Changing America in an email. 

The companies have not yet released that data from the trials, which would also need to be thoroughly examined by the U.S. Food and Drug Administration before approval. 

There are two ways to think about these results: how much of this benefit is due to chance and how good of an advantage does it give to a patient, says Constantine G. Lyketsos at the Alzheimer’s Disease Research Center at Johns Hopkins University. These results tell us that the difference in outcomes from the drug or placebo is not due to chance, but the potential benefit of the drug to the patient is very small. The metric used in the trial is a Clinical Dementia Rating (CDR), and the benefit of 0.4 of a CDR point is very small, says Lyketsos.

“We’re going to have some real questions about how long do we treat people with this drug, if we get to treating them,” says Lyketsos. He continues, if everyone is getting worse anyway, giving them the treatment becomes a moral question. During treatment, the patient has limited life quality, is very dependent, and it costs a lot to take care of them. Lyketsos notes that the drug companies could look at their data to determine what subset of Alzheimer’s patients could benefit the most from this treatment.

A few other companies are also developing similar treatments that attack amyloids, including Roche and Eli Lilly.  

“As pioneers in neuroscience, we believe defeating this disease will require multiple approaches and treatment options, and we look forward to continuing the discussion about the significance of these findings with the patient, scientific, and medical communities,” Biogen’s CEO Michel Vounatsos said in the press release.