Clinical Practice Outcomes With Lecanemab for Alzheimer Disease

Background and Objectives: Lecanemab, an antiamyloid monoclonal antibody, received US Food and Drug Administration approval in July 2023 to treat amyloid-positive early stages of Alzheimer disease (AD) and has since been adopted in many countries. The primary objective was to assess amyloid-related imaging abnormality (ARIA) incidence and serious adverse events. Secondary objectives included identifying ARIA predictors and evaluating its effect on 12-month cognitive change. Methods: We performed a retrospective, single-site observational study in patients treated with lecanemab at the Duke University (May 2023-June 2025). Eligible patients met National Institute on Aging-Alzheimer's Association criteria for mild cognitive impairment or mild AD with confirmed amyloid pathology. Treatment protocols and MRI interpretations were standardized. Results: ε4 noncarriers and those with lower baseline amyloid burden. Discussion: Despite the limitations of a single-site cohort, these findings inform real-world lecanemab safety and efficacy. Dual ARIA-E peaks at ~10 and ~25 weeks underscore the need for ongoing MRI monitoring. Although several markers showed modest negative predictive value, none reliably predicted ARIA. Improved markers to predict and monitor ARIA are needed to optimize cognitive outcomes.