ROB SCHMITZ, HOST:
A new drug for Alzheimer's disease goes before an FDA advisory committee today, and it's expected to be approved - but the way the drugmaker wants to market it is raising questions. NPR's Jon Hamilton reports.
JON HAMILTON, BYLINE: The committee of outside experts will discuss donanemab, a drug that appears to slow down the progression of Alzheimer's. Dr. Lon Schneider, of the University of Southern California, expects members to agree that donanemab is effective and reasonably safe.
LON SCHNEIDER: I don't see the actual approval of this in any doubt.
HAMILTON: One reason is that a similar drug called - lecanemab and sold under the brand name Leqembi - was approved more than a year ago. Schneider says both drugs are lab-made antibodies that target amyloid, a substance that forms plaques in the brains of Alzheimer's patients.
SCHNEIDER: These particular amyloid-targeting antibodies really do what they were designed to do. They reduce plaque to absent-to-normal levels in a certain period of time.
HAMILTON: Both drugs also appear to slow the progression of Alzheimer's by one-third or more. But donanemab's maker, Eli Lilly, wants to describe its drug in ways that would differentiate it from the competition. Schneider says that seems to have caused some concern at the FDA.
SCHNEIDER: They and Lilly have a dispute over what should be in the labeling and how the labeling should be phrased.
HAMILTON: For example, Leqembi's label says patients should get an infusion every other week indefinitely, but Eli Lilly wants donanemab's label to say doctors can consider discontinuing the drug once a PET scan or other test shows that a patient's amyloid plaques are mostly gone. Schneider says that raises several questions for the advisory committee.
SCHNEIDER: Should this be used until plaques are reduced? Should PET scans be gotten at six and/or 12 months, and should the medication be stopped?
HAMILTON: Because it's not clear if the plaques will return. Other issues on today's agenda include whether donanemab is more effective for patients who have less amyloid plaque in the brain and how often the drug causes serious swelling or bleeding. Dr. Howard Fillit, of the Alzheimer's Drug Discovery Foundation, says at the end of the day, though, the committee is likely to support putting donanemab on the market.
HOWARD FILLIT: They approved, you know, lecanemab, and this drug seems to be at least as efficacious, with a reasonable safety profile, so I can't really think of any reason why they wouldn't.
HAMILTON: Fillit says amyloid drugs like lecanemab and donanemab are the first to change the course of Alzheimer's. But removing amyloid doesn't halt the disease. Patients get worse, just more slowly. Fillit says that's why so many drug companies are trying other approaches, like protecting vulnerable brain cells from damage or reducing inflammation.
FILLIT: There's over 120 drugs now in development, and 75% of those drugs in development - they're addressing these other pathways.
HAMILTON: Fillit says there's growing evidence that Alzheimer's is the result of several different mechanisms, all related to aging, so he says treatment is likely to require several different drugs.
FILLIT: I imagine 10 years from now, people will be on three or four different disease-modifying agents and that we'll be able to get people into treatment even before they develop symptoms.
HAMILTON: Fillit, and many other scientists, think amyloid drugs will be more effective if they're started sooner. A large study to test this idea is already underway.
Jon Hamilton, NPR News.
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