Eligibility for lecanemab therapy in a biomarker defined memory clinic cohort: A five-year analysis.

We assessed cross-sectional lecanemab eligibility (January 2026) in 479 patients with mild cognitive impairment or dementia who underwent Alzheimer's disease (AD) biomarker testing at a tertiary memory clinic (2021-2025). Overall eligibility was 16%, with exclusions due to negative biomarkers (41%), advanced disease stage (31%), APOE ε4/ε4 homozygosity (6%), and other safety reasons (6%). In the 2025 subgroup (n = 100), eligibility increased to 32%, reflecting fewer exclusions for disease progression and a targeted evaluation of patients likely to meet criteria. These findings highlight a narrow post-diagnosis therapeutic window and suggest an upper eligibility limit under the current appropriate use recommendations for anti-amyloid therapies.