New drug slows Alzheimer’s but comes with caveats

Washington: A new Alzheimer’s drug is hitting the market — the first with clear-cut evidence that it can slow, by several months, the mind-robbing disease.

It’s a long-needed new treatment, but experts also are voicing a lot of caution: The drug isn’t a cure, it’s only intended for early-stage patients, requires IV doses every two weeks, and comes with some safety concerns.

It’s not even clear just how noticeable that modest benefit will be in people’s everyday lives.

Still, “it’s a landmark,” said Dr. Richard Hodes, director of the National Institute on Aging. “It’s not enough, but it’s encouraging that there’s something we can do.”

Here are some things to know about the Food and Drug Administration’s approval of lecanemab, to be sold under the brand name Leqembi:

How does the new drug work? 

The drug, made by Japan’s Eisai and its U.S. partner Biogen, is designed to target and clear away a sticky protein called beta-amyloid that builds up into brain-clogging plaques — one key hallmark of Alzheimer’s disease.

It targets a slightly different form of that amyloid, possibly explaining why it proved successful in a rigorous study while a long list of prior amyloid-targeting drugs have failed, said Dr. Sam Gandy, an Alzheimer’s expert at New York’s Mount Sinai Hospital.

What are the risks? 

Like other amyloid-targeting medications, Leqembi can cause brain swelling or small brain bleeds. In Eisai’s study, 13 percent of drug recipients had swelling and 17 percent has small brain bleeds.

The likely reason: Amyloid plaques usually form around nerve cells in the brain but sometimes the gunk gets inside blood vessels, too. Pulling amyloid out of those blood vessels can weaken them, making them leaky, Gandy explained.

While the brain swelling and bleeds may cause only minimal symptoms such as dizziness and vision problems, they occasionally can be severe — and several Leqembi users have died while taking the drug, including two who were on blood-thinning medications.

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