Shares of Biogen Inc.
BIIB,
-1.71%
were up 0.8% in premarket trading on Wednesday after the company and Eisai Inc. said they plan to speed up the completion of what is called a "confirmatory" clinical trial for its recently approved Alzheimer's disease treatment. In the weeks since the drug's approval in the U.S., Aduhelm has faced criticism over how it was priced and whether or not the clinical data were strong enough to support the approval. In the new statement, the companies said they they now plan to complete the confirmatory study in advance of the 2029 deadline. They also said they do not plan to raise Aduhelm's price for four years. The drug currently has an annual cost of $56,000. Up to 2 million people with mild Alzheimer's disease are considered potential patients for this drug. Biogen's stock is up 52.9% so far this year, while the broader S&P 500
SPX,
+0.51%
is up 13.0%.