How did Aduhelm switch to the accelerated approval pathway?
After a November 2020 advisory meeting went badly, the FDA pivoted to accelerated approval on amyloid reduction — contrary to its own Alzheimer's guidance — a move the congressional investigation called abrupt and irregular.
Biogen originally sought traditional approval based on clinical benefit. After the November 2020 advisory committee meeting went badly, the FDA pivoted. The congressional report found Aduhelm "abruptly" gained accelerated approval after unfavourable feedback from the advisory committee through the traditional process, and that this was contrary to the FDA's own guidance for Alzheimer's drugs. Accelerated approval allows the FDA to approve drugs for serious conditions based on a surrogate endpoint "reasonably likely" to predict clinical benefit, on condition that confirmatory trials follow. Critics argued amyloid reduction had not been shown to predict benefit, since previous amyloid drugs had failed despite reducing plaques. The FDA said it would continue to use accelerated approval whenever appropriate, and the pathway remains in use.