Nov 29, 2022 - Health

Safety concerns hang over new Alzheimer's treatment

Illustration of a person with a cane near a hole shaped like a red cross symbol.

Illustration: Shoshana Gordon/Axios

Within hours, the world will have a better idea about the prospects of a new Alzheimer's treatment when Japanese drugmaker Eisai releases late-stage clinical trial results.

The big picture: News of a second patient death linked to the drug has dampened expectations and potentially created a more complicated path for the drug hitting the market.

Driving the news: Researchers will present the clinical trial results for Eisai and its partner Biogen's drug lecanemab this evening at the Clinical Trials on Alzheimer’s Disease conference in San Francisco.

  • Eisai shares fell by 6% on Tuesday after Science reported that a woman who was enrolled in a clinical trial for the drug died from a brain hemorrhage that researchers linked to the experimental treatment.
  • It was the second death reported among patients who are part of the lecanemab trial. A patient who took Eliquis, a blood thinner, died in June after experiencing bleeding in the brain, according to an investigative report from STAT.

State of play: In September, Eisai and Biogen said in a press release that lecanemab slowed the progression of Alzheimer's disease by 27% in phase III trials, offering renewed hope for an effective treatment for the disease after past efforts were mired in controversy.

  • Biogen's Aduhelm was approved by the FDA in 2021 over strong objections by the agency's own advisory panel. Scientists say clinical trials for the drug were poorly conducted and that it's unclear whether it even works.
  • Medicare refused to cover the $56,000 drug except when patients are enrolled in clinical trials, making Aduhelm a commercial failure.

Between the lines: Both patient deaths within the lecanemab trial involved people that took blood thinners to treat other ailments.

  • Trial participants were warned that blood thinners and lecanemab "are both associated with a slight risk of bleeding in the brain," according to the trial's patient consent form, which was obtained by Science.
  • Both patients also had cerebral amyloid angiopathy, per STAT and Science, a condition that experts told Science likely makes the blood vessels more vulnerable to weakening during the treatment.

What we're watching: The deaths, at the very least, could prompt regulators to limit approval of the drug for narrow patient populations.

  • Many Alzheimer's patients take blood thinners, and nearly half have CAA, according to Science. That suggests potential lecanemab patients may need to be carefully screened.
  • “If lots of people [on lecanemab] who go into the hospital with garden-variety strokes end up dying, that sets the field back decades," University of Kentucky neuroscientist Donna Wilcock told Science.
  • A narrower patient population would subsequently mean a smaller revenue pool for Eisai and Biogen. Eisai previously said the potential "annual value-based price" of lecanemab was estimated at $9,249 to $35,605.

What's next: Eisai has already submitted and application with the FDA for accelerated approval, and the company expects a decision by Jan. 6, 2023.

  • The company plans to file for full approval by the end of March.
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