On November 6, 2020, a US Food and Drug Administration (FDA) advisory committee reviewed issues related to the efficacy and safety of aducanumab, a human IgG1 anti-Aβ monoclonal antibody specific for β-amyloid oligomers and fibrils implicated in the pathogenesis of Alzheimer disease.1 Given the importance of drug innovation for this common and often devastating disease, the abandonment of prior monoclonal antibodies targeting β-amyloid, and the clinical, regulatory, and market effects that approval of aducanumab could have, there has been significant interest in the development and regulatory review of aducanumab.