Biogen and Eisai's Leqembi study shows nearly 83% of early Alzheimer's patients remained stable or improved

Biogen and Eisai reported real-world results from the LEADER Study showing that nearly 83% of patients with early Alzheimer’s disease remained stable or improved while receiving Leqembi. The companies said that, over an average of 17 months, 75.9% of participants stayed stable and 6.6% improved. The interim analysis included 432 patients who received at least seven Leqembi infusions as of May 2026, and staging could be evaluated in 427. Across those early AD patients, 82.5% remained stable or improved, with consistency across gender, race, ethnicity, and APOE genotype groups. Stable meant patients stayed in the same disease stage from baseline; improvement reflected a shift from mild AD dementia to MCI due to AD. Nearly 87% chose to continue Leqembi, and mean treatment lasted 520 days with 26 doses. Data were presented at AAIC 2026 in London and online, supporting the rationale for ongoing therapy. The release attributed potential benefit to continuous Leqembi targeting amyloid beta pathology.