AAIC 2026: Eisai and Biogen report LEADER real-world study findings showing 82.5% of early Alzheimer’s patients remained stable or improved during LEQEMBI treatment.
Written By: Anamika Koshti, Pharm D
Reviewed By: Pharmacally Editorial Team
On July 14, 2026, Eisai and Biogen announced results from the real-world Lecanemab in Early Alzheimer’s Disease (LEADER) study at the Alzheimer’s Association International Conference (AAIC) 2026 in London. The interim analysis found that nearly 83% of early Alzheimer’s disease (AD) patients remained stable (75.9%) or improved (6.6%) during an average of 17 months of LEQEMBI (lecanemab) therapy, with findings consistent across sex, race, ethnicity, and APOE genotype.
How LEQEMBI Works?
LEQEMBI is a humanized IgG1 monoclonal antibody that targets aggregated amyloid-beta (Aβ) in two forms: insoluble plaques and soluble protofibrils, which are thought to be among the most toxic forms of Aβ contributing to neuronal damage and cognitive decline in AD. By removing both forms, LEQEMBI is designed to address the underlying pathology of Alzheimer’s disease rather than only managing symptoms. It is currently approved for early AD in 53 countries and regions, including the US, Japan, China, and Europe.
LEADER Study Design
LEADER is a three-year, multicenter, retrospective real-world study designed to examine LEQEMBI utilization, treatment persistence, safety, and cognitive and functional outcomes in diverse U.S. clinical settings. It integrated deidentified chart and electronic medical record (EMR) data from 13 U.S. sites along with healthcare professional surveys and interviews. As a retrospective study using deidentified records, it received central IRB exemption rather than a ClinicalTrials.gov registration. This interim analysis included 432 patients with early AD who received at least seven LEQEMBI infusions as of May 2026, with a mean age of 74 years and 55.8% female patients. At baseline, 63.9% had mild cognitive impairment (MCI) due to AD and 36.1% had mild AD dementia. The mean treatment duration was 520 days, with a mean of 26 doses administered.
Disease Stage Outcomes
Of the 427 patients with evaluable disease stage data, 82.5% remained stable or showed improvement during LEQEMBI treatment. Specifically, 75.9% were stable, maintaining the same disease stage from baseline throughout treatment, and 6.6% improved, transitioning from mild AD dementia at baseline to MCI due to AD. These results were consistent across sex, race, ethnicity, and APOE genotype. Among APOE ε4 heterozygotes, 81.7% remained stable or improved, and among APOE ε4 homozygotes, 81.0% did. Nearly 87% of patients chose to remain on LEQEMBI treatment throughout the observation period.
Maintenance Dosing Findings
Of the 432 participants, 155 transitioned to once-every-four-weeks intravenous (IV) maintenance therapy, and 14 transitioned to once-weekly subcutaneous (SC) maintenance treatment. Among those on IV maintenance, 81% remained stable (72.3%) or improved (8.4%). Of the 14 on SC maintenance, 12 (85.7%) maintained their disease stage. No new ARIA-E events, macrohemorrhages, or intracerebral hemorrhages greater than 1 cm were reported during once-every-four-weeks IV maintenance therapy.
Real-World Safety
Overall safety observations were consistent with the FDA-approved label. Amyloid-related imaging abnormalities (ARIA) were observed in 12.3% of patients overall (ARIA-E: 6.3%; ARIA-H: 7.9%), and the majority of ARIA cases were asymptomatic and mild in radiographic severity. In APOE ε4 homozygotes, all graded ARIA cases were mild to moderate and no severe ARIA was reported. Among the 24.5% of patients receiving antithrombotic therapy (anticoagulants or antiplatelets), the incidence of ARIA was not meaningfully different from those not receiving such therapy.
Study Limitations
As with all retrospective real-world studies, the LEADER study carries inherent limitations. The absence of a control or placebo group means that the observed disease stability and improvement cannot be attributed exclusively to LEQEMBI. Potential biases, incomplete or inconsistent data across sites, and confounding variables are also considerations when interpreting these findings alongside data from randomised controlled trials.
What This Means to Patient?
Clinical trial data demonstrate that LEQEMBI slows disease progression, and the LEADER study adds a real-world dimension to that picture, showing that patients receiving the drug outside of controlled trial conditions also experienced disease stability or improvement over more than a year of continuous treatment. For clinicians and patients making long-term treatment decisions, real-world evidence on treatment persistence, safety in broader populations including antithrombotic users, and outcomes during maintenance dosing provides practical context that randomised trials alone cannot offer.
Reference
LEQEMBI Real-World LEADER Study Presented at AAIC 2026. Eisai Inc. and Biogen Inc. July 14, 2026.
About the Writer
Anamika Koshti (LinkedIn) is a PharmD professional and healthcare writer with interests in clinical research, pharmacovigilance, and evidence-based medicine. She has authored peer-reviewed publications on Alzheimer’s disease and PCOS, presented research at national conferences, and gained hands-on experience in medical content development and clinical data interpretation. She is committed to translating complex medical research into accurate, accessible content for healthcare professionals and patients.