Biogen and Japan's Eisai said on Friday the U.S. Food and Drug Administration has granted an expedited review for the marketing application of their potential blockbuster Alzheimer's drug aducanumab.
Biogen's shares were up 10% at $306 before the bell.
If approved, aducanumab would be the first treatment designed to delay progression of the fatal, mind-robbing disease, which is expected to affect 13.9 million Americans or 3.3% of the country's population by 2060, according to the U.S. Centers for Disease Control and Prevention.
It has been several years since the FDA reviewed an application for a new Alzheimer's treatment, as drugs that were tested failed trials. The agency is expected to take a decision by March 7, but intends to act early on it if possible, the companies said.
Biogen in October revived plans to seek approval for the treatment, months after scrapping the development of the drug following disappointing study results.
Wall Street analysts have been divided about the data from the clinical studies.
"There still are a ton of questions surrounding the aducanumab dataset," Stifel analyst Paul Matteis said.
The drug regulator would consult a panel of outside experts on a yet-to-be-determined date for the approval of the drug, the companies said. The agency is not required to follow the panel's recommendation, but often does.
"We largely view an advisory committee as one of the big 'clearing events' and predict it will be 'mixed,' leaving the Street in limbo," Jefferies analyst Michael Yee said.
The FDA has granted a priority review, which allows it to accelerate the review of an application for drugs aimed to treat an unmet medical need.
Biogen said it did not use its priority review voucher for the aducanumab application.