The Food and Drug Administration (FDA) has extended the review period for the Biologics License Application (BLA) for aducanumab (Biogen and Eisai), an investigational treatment for Alzheimer disease, by 3 months. The new Prescription Drug User Fee Act (PDUFA) target date is now June 7, 2021.

Aducanumab, a human monoclonal antibody, binds to aggregated β-amyloid and promotes removal of amyloid from the brain; it is administered as a monthly intravenous infusion. The BLA submission was supported by data from 3 clinical trials: EMERGE (phase 3), ENGAGE (phase 3), and PRIME (phase 1b). While the EMERGE study met its primary end point (change from baseline in Clinical Dementia Rating-Sum of Boxes score), the ENGAGE trial did not.

Following a meeting with the FDA’s Peripheral and Central Nervous System Drugs Advisory Committee, in which the panel voted against approval, Biogen submitted additional analyses and clinical data that were requested by the Agency. According to the Company, the FDA considered this a “major amendment” to the application that would require more time for review; the original PDUFA date had been March 7, 2021.


Biogen and Eisai announce FDA’s 3-Month extension of review period for the Biologics License Application for aducanumab. [press release]. Cambridge, MA and Tokyo, Japan; Biogen and Eisai: January 29, 2021.