Neurological and systemic adverse event reporting patterns for lecanemab: A global WHO VigiAccess analysis

Lecanemab is an anti-amyloid monoclonal antibody approved for early Alzheimer disease. Evaluation of spontaneous reports may complement clinical-trial evidence by identifying real-world adverse-event reporting patterns. This study aimed to characterize lecanemab-associated adverse drug reaction reports in the World Health Organization VigiAccess database at the System Organ Class (SOC) and Preferred term (PT) levels. A retrospective descriptive pharmacovigilance analysis was conducted using VigiAccess data from database inception through 13 September 2026. Frequencies and percentages were calculated for SOCs, PTs, demographic characteristics, geographic regions, and reporting years. Wilson 95% confidence intervals were calculated for principal reporting proportions. VigiAccess contained 3212 individual safety reports comprising 5358 adverse drug reaction events. Nervous system disorders constituted the largest SOC (n = 1827; 34.10%; 95% confidence interval: 32.84-35.38), followed by general disorders and administration-site conditions (n = 1015; 18.94%; 95% confidence interval: 17.92-20.01). The most frequently reported PTs were headache (n = 512; 9.56%), amyloid-related imaging abnormality-edema/effusion (n = 360; 6.72%), amyloid-related imaging abnormality-microhemorrhages and hemosiderin deposits (n = 326; 6.08%), chills (n = 281; 5.24%), pyrexia (n = 272; 5.08%), and infusion-related reaction (n = 235; 4.39%). Females accounted for 52.21% of reports, patients aged ≥ 65 years for 62.95%, and the Americas for 80.23%. Most reports (95.73%) were recorded during 2024 to 2026. Neurological, amyloid-related imaging abnormality, systemic, and infusion-associated events were prominent in spontaneous reporting for lecanemab. These findings describe reporting patterns and should not be interpreted as incidence rates or causal associations. Continued patient-level and exposure-adjusted surveillance is required to further characterize lecanemab safety.