From the U.S. Food & Drug Administration

Aducanumab Information (marketed as Aduhelm)

Aduhelm is an amyloid beta-directed antibody indicated to treat Alzheimer’s disease. Aduhelm is approved under the accelerated approval pathway, which provides patients with a serious disease earlier access to drugs when there is an expectation of clinical benefit despite some uncertainty about the clinical benefit. Accelerated approval is based upon the drug’s effect on a surrogate endpoint — an endpoint that reflects the effect of the drug on an important aspect of the disease — where the drug’s effect on the surrogate endpoint is expected, but not established, to predict clinical benefit. In the case of Aduhelm, the surrogate endpoint is the reduction of amyloid beta plaque. The accelerated approval pathway requires the company to verify clinical benefit in a post-approval trial. If the sponsor cannot verify clinical benefit, FDA may initiate proceedings to withdraw approval of the drug.

https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/aducanumab-marketed-aduhelm-information

FDA Grants Accelerated Approval for Alzheimer’s Drug (June 7, 2021)

https://www.fda.gov/drugs/news-events-human-drugs/fdas-decision-approve-new-treatment-alzheimers-disease

From AARP

First Drug That Could Slow Alzheimer's Disease Gets FDA Approval

https://www.aarp.org/health/brain-health/info-2021/fda-biogen-alzheimers-drug.html