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Clinical Efficacy, Drug Safety, and Surrogate Endpoints

We recently learned that aducanumab has been approved by the US Food and Drug Administration (FDA) for the treatment of Alzheimer disease. As neurologists, we need to carefully review the evidence from the phase 1B and III randomized controlled clinical trials concerning the clinical efficacy and safety of this drug in symptomatic persons with mild cognitive impairment or mild dementia who have elevated cerebral levels of β-amyloid (Aβ). We should also gain an appreciation for how this drug acquired accelerated approval from the FDA on the basis of the surrogate endpoint of Aβ plaque reduction as measured by PET imaging. We owe this to our patients and to their caregivers.