Biogen, Eisai stock up on Alzheimer's drug success

Shares in Biogen and Eisai went up on Wednesday due to the surprise trial success of their experimental Alzheimer's drug, which has also lifted the stocks of rival drugmakers Roche and Eli Lilly.

Nearly all drugs tested to treat Alzheimer's disease, a fatal brain disease that affects an estimated 55 million worldwide, have stumbled in clinical trials.

In a large trial of patients in the early stages of Alzheimer's, Biogen and Eisai said on Tuesday that their experimental drug, lecanemab, slowed progress of the brain-wasting disease by 27% compared to a placebo.

Biogen's stock went up 50% in early premarket trading. Eisai's shares went up 17% to the daily limit in Tokyo.

In early trading, Roche's shares rose by 6% to a two-month high, as it is expected to report results on a rival Alzheimer's drug gantenerumab later this year.

By the end of 2023, data on Eli Lilly's rival drug, donanemab, is expected to be available. The stock of the U.S. drugmaker was up 7.8% before the bell on Wednesday.