> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Biogen to File Alzheimer’s Confirmatory Trial Protocol
- URL: https://www.fdaweb.com/biogen-to-file-alzheimers-confirmatory-trial-protocol/
- Published: 2021-12-16T12:00:00.000Z
- Updated: 2026-09-14T17:26:09.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5150791

Biogen says it will submit to FDA in 3/2022 a final clinical trial protocol for a required post-marketing trial of its controversial Alzheimer’s drug Aduhelm (aducanumab). Aduhelm was granted accelerated approval earlier this year amid a firestorm of criticism over the agency’s use of the pathway for an Alzheimer’s indication ([see earlier story](https://www.fdaweb.com/uproar-greets-fdas-aduhelm-ok-for-alzheimers/)). Three FDA advisory committee members who were on a panel that voted 10-0-1 last November not to recommend the drug’s approval have resigned their agency posts in protest.

As part of its approval, FDA is requiring a post-marketing confirmatory trial that will assess the therapy’s safety and effectiveness. Biogen says it is planning a global, placebo-controlled trial that aims to enroll more than 1,300 early Alzheimer’s disease patients, with a primary clinical endpoint at 18 months after treatment initiation. Based on enrollment rates from the previous Phase 3 trials, the primary completion date is expected to be about four years after the study begins, targeted for 5/2022\. The trial will also include a long-term extension to collect longer-term treatment data for up to 48 months.

Aduhelm is a monoclonal antibody directed against amyloid beta. “The accumulation of amyloid beta plaques in the brain is a defining pathophysiological feature of Alzheimer’s disease,” Biogen says. The accelerated approval was granted on data from clinical trials showing the drug’s effectiveness in reducing amyloid beta plaque, a surrogate biomarker that is reasonably likely to predict clinical decline.