Shares of Eisai Co. and partner Biogen Inc. have soared since reporting that their drug lecanemab slowed Alzheimer’s, the first to unambiguously impede the progression of the disease in a final-stage trial. But many questions linger.
Doubts still remain over the magnitude of the benefits, side effects, and what kind of insurance coverage it will receive if approved. At the moment, all that’s known is the drug slowed early Alzheimer’s by 27% over 18 months when compared to a placebo in a giant trial. The companies said Tuesday that just over 21% of the people who received the drug in the trial experienced brain swelling or brain bleeding, a major side effect of antibodies that target amyloid, a toxic protein that clutters the brains of Alzheimer’s patients.