The upbeat news contrasted sharply with the calamitous deployment last year of another drug, marketed as Aduhelm, sponsored by the two companies.
Like Aduhelm, lecanemab reduces abnormal beta-amyloid clumps, a hallmark of Alzheimer’s disease. But unlike Aduhelm, for whom the data was confused and contradictory, the trial results for canemab told a simple and encouraging story, some experts said. Aduhelm has been approved by the Food and Drug Administration, but Health insurance refused to cover it extensively, and the drug collapsed in the market.
“A 27% slowing of deterioration seems like a modest effect, but for patients with Alzheimer’s disease it could be very significant,” said Gil Rabinovici, a neurologist at the University of California, San Francisco.
Aduhelm’s trials were stopped before they were complete and a post-hoc analysis raised a series of questions. But the canemab trial, called Clarity AD, was “completed according to protocol” and shows that “reducing amyloid at this stage can translate into slower clinical decline,” Rabinovici said. “It’s a huge breakthrough.”
Some other experts warned that the drug’s benefits were likely to be small and said they wanted to see the full data before drawing conclusions.
The companies have already applied to the FDA for expedited approval for lecanemab, based on past data. The FDA decision deadline is January 6. The companies said the FDA agreed that the results of the Clarity AD trial could serve as a confirmatory study to verify the clinical benefits of lecanemab. This process will continue to move forward.
But Eisai officials said Tuesday they would also seek full FDA approval for the drug after securing fast-track approval. Full approval would make the treatment much more likely to be covered by Medicare and other insurers.
The trial included nearly 1,800 patients with mild cognitive impairment caused by Alzheimer’s disease or early-stage Alzheimer’s disease.
Eisai, who is leading the drug’s development and working with regulatory authorities, said he will present the full study results in late November at an Alzheimer’s disease conference in San Francisco. The results will also be published in a medical journal, the company said.
Officials said participants in the clinical trials were tested in several areas to gauge the rate of their decline, including memory, orientation and problem solving. From six months, the companies said, the group that received the treatment did better than the placebo group. The treatment was administered intravenously twice a month.
The lecanemab group experienced side effects including brain swelling and bleeding – complications of anti-amyloid therapies – but the rates were in line with expectations, the companies said in the statement.
Eisai officials also said the results showed the “amyloid hypothesis” – which argues that removing amyloid plaques can slow the progression of neurodegenerative disease – is valid. Critics have expressed skepticism about this approach due to multiple failures involving drugs targeting amyloid.
The results of the trial “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,” said Haruo Naito, CEO of Eisai.