FDA Approves Controversial New Alzheimer’s Drug

Lecanemab shows clinical benefits — but do they justify the risks?

By Kenneth MillerDec 12, 2023 5:00 PM
GettyImages-1296945064 (1)
More than 6 million Americans are living with Alzheimer’s disease. By 2050, that figure may surge to nearly 13 million. (Credit: PamelaJoeMcFarlane/E+ VIA Getty Images)


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Few ailments are as fearsome as Alzheimer’s disease, the most common form of dementia, which robs patients of their minds and memories before it takes their lives. So, when the U.S. Food and Drug Administration approved a new treatment for Alzheimer’s in July, the event made front-page news. But it also generated heated arguments.

What Is the New Alzheimer's Drug?

Lecanemab, branded as Leqembi by pharma companies Esiai and Biogen, is the first drug targeting the disease’s underlying mechanisms to receive full approval from the FDA. The medication — an engineered molecule known as a monoclonal antibody — works by removing the sticky plaques of amyloid beta protein that gum up the brain as Alzheimer’s progresses.

In that respect, it resembles an earlier drug: aducanumab (marketed by Biogen as Aduhelm), which in 2021 was granted “accelerated” approval based on biomarkers rather than results. While that drug was effective at busting amyloid, its benefits to patients’ cognitive health were never clearly demonstrated, and side effects were substantial. The FDA’s decision drew near-universal criticism.

What Does the New Alzheimer's Drug Do?

Lecanemab, by contrast, was approved last summer on the basis of a large clinical trial showing that patients with early-stage Alzheimer’s who received the medication declined 27 percent more slowly over 18 months than patients receiving a placebo.

“This gives people more months of recognizing their spouse, children and grandchildren,” Joanne Pike, president and CEO of the Alzheimer’s Association, said in a statement.

So why the controversy? For starters, that reduction in disease progression represents less than half a point on an 18-point scale measuring functions such as memory and problem-solving, a difference that some experts suggest is too small to be clinically meaningful.

And the drug’s potential side effects raise the question of whether the rewards justify the risks: Nearly 13 percent of trial patients receiving lecanemab experienced brain swelling and 17 percent had brain bleeds. Although these symptoms were mostly mild or moderate, three of the affected patients died (though not during the randomized course of study).

How Much Does the New Alzheimer's Drug Cost?

Then there’s the cost: a hefty $26,500 a year. Patients must also undergo regular brain scans, potentially raising the tab to $90,000 — and adding to the inconvenience posed by biweekly, hour-long infusions of the medication.

Patients and physicians may soon have other options to choose from. Days after lecanemab got the nod, a large study of a similar drug, donanemab, reported marginally better efficacy numbers. Meanwhile, more amyloid antibodies are in development and researchers are investigating an array of alternative approaches, including preventive vaccines and anti-inflammatory medications.

“What we can all agree on,” says Lon Schneider, director of the California Alzheimer’s Disease Center at the University of Southern California, “is that we need much better treatments.”

This story was originally published in our January February 2024 issue. Click here to subscribe to read more stories like this one.

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