Biogen, Eisai’s Milestone Spurs Hope for Alzheimer’s Research

Biogen Inc. and partner Eisai Co. surged and led other drugmakers’ shares higher amid optimism about their breakthrough trial results on Alzheimer’s disease.

The two partners said their experimental drug lecanemab significantly slowed the disease, making it the first medicine to blunt progression of the most common dementia in a large definitive study.

Biogen climbed 43% in trading before US exchanges opened, adding more than $12 billion in market capitalization. Eisai closed up 17% in Tokyo, reaching the highest level in nine months, after remaining untraded earlier in the day as bids outweighed offers by more than 19 times. Eli ...