Eisai, Biogen stock shows promise of lecanemab after a year and half

A new study found that Eisai and Biogen's experimental Alzheimer's drug moderately reduced cognitive decline after a year and a half.

The stock of Eisai's 4523 was up 1.7% in Wednesday morning trading in Japan, while the shares of Biogen Inc. BIIB gained 0.9% in after-hours trading on Tuesday in the U.S.

The study assessing lecanemab as a treatment for people with early Alzheimer's disease published Tuesday night in the New England Journal of Medicine.

Eisai also presented the full findings from the trial at the annual Clinical Trials on Alzheimer s Disease in San Francisco on Tuesday night. A Biogen spokesman said in a statement that the randomized, placebo-controlled, double-blind Phase 3 clinical trial shows the promise of lecanemab as a new treatment option. The full dataset is aligned with the preliminary data that the companies shared in October that the drug slowed cognitive decline by 27% in the 1,795 people enrolled in the trial.

The deaths of participants in the lecanemab and placebo groups occurred in 0.7% and 0.8%, though none were related to lecanemab, according to the companies. There have been two deaths in the trial.

The study's researchers said lecanemab was associated with adverse events, and longer trials are warranted to determine the efficacy and safety of lecanemab in early Alzheimer's disease. Eisai is taking a lead on commercializing lecanemab after the failure of Aduhelm, the other Alzheimer s treatment that the companies developed together.