Eisai shares surged the most in more than three months Tuesday after winning initial U.S. regulatory clearance for its lecanemab medication, the first treatment seen to slow the advance of Alzheimer’s disease.

The drug, to be sold under the brand name Leqembi, was approved by the Food and Drug Administration under an accelerated pathway late Friday. While Eisai and partner Biogen are submitting more data to gain full approval, the decision expands treatment options for the millions of patients living with the debilitating condition. The drug will cost $26,500 (¥3.5 million) a year for a person of average weight, Eisai said.

Eisai shares jumped as much as 9.2% in Tokyo trading Tuesday, the most since Sept. 29 on an intraday basis. The stock had dropped 19% through Friday from a peak of ¥10,050 on Dec. 5.