Alzheimer's drug succeeds in 'slowing' cognitive decline

An experimental Alzheimer's drug developed by Eisai Co Ltd and Biogen Inc significantly slowed the cognitive and functional decline in a large trial of patients in the early stages of the disease, the companies have said. 

The injected drug, lecanemab, slowed the progress of the brain-wasting disease by 27 percent compared to a placebo, meeting the study's main goal, and offering an apparent win for the companies and potentially for patients and their families desperate for an effective treatment.

Eisai, on Tuesday, said the results from the 1,800-patient trial prove the longstanding theory that the removal of sticky deposits of a protein called amyloid beta from the brains of people with early Alzheimer's can delay advance of the debilitating disease.

Analysts, such as Salim Syed at Mizuho Securities, have said the results would be considered a "win" if lecanemab slowed the rate of decline by around 25 percent, and that shares of both companies could jump on the news.

Lecanemab, like the companies' previous drug Aduhelm, is an antibody designed to remove those amyloid deposits. Unlike Aduhelm, lecanemab targets forms of amyloid that have not yet clumped together.

The so-called amyloid hypothesis has been challenged by some scientists, particularly after the US Food and Drug Administration's controversial approval of Aduhelm in 2021 based on its plaque-clearing ability rather than proof that it helped slow cognitive decline. The decision came after the FDA's own panel of outside experts had advised against approval.

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Pending FDA approval

Aduhelm was the first new Alzheimer's drug approved in 20 years after a long list of high-profile failures for the industry.

Eisai, leader of the 50-50 partnership's lecanemab programme, is seeking FDA approval under the same accelerated pathway as Aduhelm, with a decision expected in early January. But on Tuesday the Japanese drugmaker said it will use the new efficacy results to submit lecanemab for traditional FDA review.

The company said it will also seek authorisation in Japan and Europe during its current fiscal year, ending March 31.

The Phase III trial evaluated the drug's ability to reduce cognitive and functional decline based on the Clinical Dementia Rating-Sum of Boxes (CDR-SB), a numerical scale used to quantify the severity of dementia in patients in areas such as memory, orientation, judgment and problem solving and personal care.

Aduhelm's approval was a rare bright spot for Alzheimer's patients, but critics have called for more evidence that amyloid-targeting drugs are worth the cost.

But Medicare, the US government health plan for people 65 and older, this year said it would only pay for Aduhelm if patients were enrolled in a valid clinical trial, which sharply curtailed the medication's use. Since Alzheimer's is a disease of aging, an estimated 85 percent of patients eligible for the drug are covered by the government plan.

The number of Americans living with Alzheimer's is expected to rise to around 13 million by 2050 from more than 6 million currently, according to the Alzheimer's Association. Globally, that figure could rise to 139 million by 2050 without an effective treatment, according to Alzheimer's Disease International.

Other plaque-targeting antibodies in late-stage development for Alzheimer's patients include Roche Holding AG's gantenerumab and Eli Lilly and Co's donanemab.

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