Promising Alzheimer’s drug needs to be studied just to be safe, researchers say


An experimental Alzheimer’s drug moderately reduced the effects of the disease but was associated with patient safety risks that warrant longer clinical trials, according to a study published late Tuesday.

The study, in the New England Journal of Medicine, found that a drug developed by Tokyo-based Eisai and Cambridge, Mass.-based Biogen reduced a key marker of Alzheimer’s disease, the amyloid beta protein, and that patients given the drug performed better on cognitive and physical measures than a placebo group.

But the detailed results also concluded that the drug, lecanemab, was associated with “adverse events” and warranted more studies.

Marwan Sabbagh, a neurologist at the Barrow Neurological Institute and a co-author of the study, described two patient deaths that had raised concerns about the safety of the drug before Tuesday’s presentation. “Causality with lecanemab is a bit difficult,” he said, noting that both patients, a 65-year-old woman and an 87-year-old man, had underlying health problems. Although the rate of brain bleeding was low, he said, the risk increases with medications to prevent blood clots.

“There may be a relative risk that needs to be addressed,” he said at the Clinical Trials in Alzheimer’s Disease conference late Tuesday.

Eisai confirmed the two deaths on Tuesday night and denied they were related to the drug.

The new details have been the subject of intense anticipation by doctors and Wall Street since Eisai and Biogen announced in September that lecanemab had slowed cognitive decline by 27 percent compared with a placebo.

Lecanemab has emerged as the front runner among one class of drugs that seek to remove clumps of a protein in the brain called amyloid beta, which scientists have long suspected plays a role in Alzheimer’s. The Food and Drug Administration will make a decision to approve the drug as early as January. That could translate into a multibillion-dollar prize for treating a progressively debilitating disease that affects 6 million Americans and have get approved therapies.

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“It’s the best data we’ve seen in Alzheimer’s in a pivotal study,” Myles Minter, a biotechnology analyst at William Blair, said of the initial results released in September.

Lecanemab’s positive results followed a controversy over another drug developed by Eisai and Biogen, aducanumab. This drug, known by the brand name Aduhelm, was approved by the FDA last year despite conflicting data on its effectiveness. Aduhelm failed commercially after Medicare refused to reimburse largely for it.

Lecanemab is designed to work by removing clumps of tiny proteins known as amyloids from the brain. Still, despite the drug’s early success, some experts remain skeptical that targeting these amyloids is the key to treating Alzheimer’s. This month, Roche announced disappointing results from its anti-amyloid drug.

Matthew Schrag, a neurology professor at Vanderbilt University Medical School, said the lecanemab study was well designed and showed strong statistical results on a cognitive measure. But he doubted that the drug would lead to a noticeable improvement for many sufferers, noting that the drug can cause significant side effects.

“I worry that any minor benefit could be washed out by the practical difficulties of living with the drug and the significant risks associated with taking the drug,” he said in an interview.

Eisai and Biogen reported that patients in the trial experienced brain swelling and bleeding, which are known to be complications of anti-amyloid drugs, but the companies said the rates were within expectations. However, concerns about the drug’s safety were heightened by the two patient deaths.

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On Sunday, Science magazine reported that a patient taking lecanemab died after suffering a stroke and receiving an anti-clotting medication. It followed a report last month by Stat News that another patient in the trial had died while on blood thinners. Both deaths reportedly stemmed from a condition where amyloid binds to blood vessels in the brain and makes them more prone to rupture.

Research analysts at investment bank UBS questioned whether the deaths would lead to FDA restrictions on patients taking blood thinners, which it estimated could make up as many as 20 percent of Alzheimer’s patients.

Libby Holman, a spokeswoman for Eisai, said the patients who died had underlying medical conditions and risks, including taking medications that prevent blood clots, that contributed to their deaths. “It is Eisai’s judgment that the deaths are not attributable to lecanemab,” she said, adding that the number of brain hemorrhage deaths was 0.1 percent for patients in both the placebo and treatment groups.

Despite the unknowns about lecanemab’s risks and benefits, it remains a draw for Alzheimer’s patients who are eager for any option to slow its degenerative effects and help find a cure.

Hugh Courtney, a 59-year-old economist diagnosed with early-onset Alzheimer’s, said he feels lucky to have participated in the clinical trial even though he is not sure how much he has benefited.

“It’s hard to say how much has changed, quite frankly,” he said of the lecanemab infusions he receives about twice a month. Still, he said, “it has given me a sense of purpose, a concrete way to help.”

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