Experimental Alzheimer’s Drug Slows Cognitive Decline in Trial, Firms Say

An experimental Alzheimer’s drug reduced cognitive and functional decline by 27 percent in a closely watched clinical trial, the drug’s sponsors said Tuesday, raising the chances of the therapy’s approval early next year.

Japanese drugmaker Eisai and its US partner, Biogen, said in a news release that the slowing of decline, compared with a placebo, was “highly statistically significant.” They said the drug, called lecanemab, had met the primary and secondary endpoints of the 18-month late-stage study. The results of the trial have not been subjected to peer review.

The upbeat news served as a stark contrast to the dire deployment last year from another drug, marketed as Aduhelm, sponsored by the two companies.

Like Aduhelm, lecanemab reduces abnormal accumulations of amyloid beta, a hallmark of Alzheimer’s disease. But unlike Aduhelm, for whom the data was confused and conflicted, the results of the lecanemab trial told a simple and encouraging story, some experts said. Aduhelm was approved by the Food and Drug Administration, but Medicare declined to cover it widely, and the drug crashed on the market.

“A 27 percent decrease in impairment seems like a modest effect, but for Alzheimer’s patients, this could be very significant,” he said. Gil Rabinovici, a neurologist at the University of California, San Francisco.

The Aduhelm trials were closed before they were completed, and a post-hoc analysis raised a number of questions. But the lecanemab trial, called Clarity AD, “was completed according to protocol” and shows that “reducing amyloid at this stage can translate to a slowing of clinical deterioration,” Rabinovici said. “That’s a big breakthrough.”

Other experts cautioned that the drug’s benefits are 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 accelerated approval of lecanemab, based on data from earlier stages. The FDA’s deadline to make a decision is January 6. The firms said the FDA has agreed that the results of the Clarity AD trial can serve as a confirmatory study to verify the clinical benefit of lecanemab. That process will continue.

But Eisai officials said Tuesday they will also seek full FDA approval for the drug after gaining accelerated approval. Full approval would make it much more likely that the treatment would 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 results of the study in late November at an Alzheimer’s conference in San Francisco. The results will also be published in a medical journal, the company said.

Officials said the clinical trial participants were tested in several areas to gauge the rate of their decline, including memory, orientation and problem solving. Starting at six months, the companies said, the treatment group fared 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 from anti-amyloid therapies, but the rates were within expectations, the companies said in the statement.

Eisai officials also said the results showed the “amyloid hypothesis” —which maintains that the removal of amyloid plaques can delay the progression of neurodegenerative disease— is valid. Critics have expressed skepticism about that approach because of the multiple failures associated with anti-amyloid drugs.

The trial results “prove the amyloid hypothesis, in which abnormal accumulation of [beta amyloid] in the brain is one of the main causes of Alzheimer’s disease,” said Haruo Naito, CEO of Eisai.

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