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# FDA Approves Biogen’s Alzheimer’s Drug
- URL: https://www.fdaweb.com/fda-approves-biogens-alzheimers-drug/
- Published: 2021-06-07T12:00:00.000Z
- Updated: 2026-09-14T17:02:03.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5149477

FDA has granted accelerated approval for Biogen’s Aduhelm (aducanumab), the first drug since 2003 approved for treating Alzheimer’s. Approval was based on the drug’s effect on a surrogate endpoint — reducing amyloid beta plaque— and a post-approval trial is required to verify that the drug provides the expected clinical benefit. Patients on the drug had significant dose-and time-dependent reduction of amyloid beta plaque compared to patients in the studies’ control arm who had no reduction, FDA said in a [news release](https://www.fda.gov/news-events/press-announcements/fda-grants-accelerated-approval-alzheimers-drug?ref=fdaweb.com). “As we have learned from the fight against cancer, the accelerated approval pathway can bring therapies to patients faster while spurring more research and innovation,” said CDER director **Patrizia Cavazzoni**.

The drug’s prescribing information includes a warning for amyloid-related imaging abnormalities (ARIA), “which most commonly presents as temporary swelling in areas of the brain that usually resolves over time and does not cause symptoms, though some people may have symptoms such as headache, confusion, dizziness, vision changes, or nausea,” the agency said. Another warning is for hypersensitivity risk, and the most common side effects reported are ARIA, headache, fall, diarrhea, and confusion/delirium/altered mental status/disorientation. 

The approval is faced with some controversy. In 11/2020, FDA’s Peripheral and Central Nervous System Drugs Advisory Committee voted 8 to 1 that an aducanumab study did not provide strong evidence to support its effectiveness. The panel also voted 7 to 0 (4 votes uncertain) that a second study did not provide evidence of the aducanumab’s effectiveness for treating Alzheimer’s.

Panel members also were concerned about FDA’s statistical reviewer, **Tristan Massie**, who wrote in a briefing paper that the one positive trial of aducanumab could not overcome the negative one ([see earlier story](https://www.fdaweb.com/panel-thumbs-down-on-biogen-alzheimers-drug/)). “There is no compelling evidence of treatment effect or disease slowing and … another study is needed to confirm or deny the positive study and the negative study,” she wrote. FDA Office of Neuroscience director **Billy Dunn** told the panel that issues with the negative trial don’t “meaningfully detract from the persuasiveness” of the positive trial. He suggested the drug might still have a clear path to approval.  

In a [6/7 letter](https://www.fda.gov/media/149903/download?ref=fdaweb.com) to advisory committee members, Dunn thanked them for their input and explained how the agency decided to consider an accelerated approval for aducanumab. “Following the advisory committee meeting, further discussion within FDA considered the uncertainty introduced by the conflicting results of Study 302 and Study 301 and the committee’s discussion of that uncertainty,” Dunn wrote. “Our discussions raised further consideration of the accelerated approval pathway; a topic discussed earlier in the development program but not directly discussed during the advisory committee meeting given the focus at that meeting on the evidence of clinical benefit... We concluded that \[accelerated approval\] requirements were met for aducanumab, with substantial evidence that the drug reduces amyloid beta plaque, and that this reduction is reasonably likely to predict clinical benefit.”

In April, Public Citizen called on HHS secretary **Xavier Becerra** to have the department Office of Inspector General immediately investigate the “unprecedented and inappropriate close collaboration between FDA and Biogen regarding the company’s application for approval of the Alzheimer’s disease drug aducanumab.” In a 4/1 [letter](https://www.citizen.org/news/letter-becerra-must-take-immediate-action-to-address-fdas-inappropriate-collaboration-with-biogen-on-alzheimers-disease-drug/?ref=fdaweb.com), the consumer advocacy group warned Becerra of the adverse consequences if the agency were to approve aducanumab despite the lack of evidence of effectiveness.