Announcement • Jul 15
Eisai Co., Ltd. and Biogen Inc. Present Real-World LEADER Study Results For LEQEMBI At AAIC 2026
Eisai Co., Ltd. and Biogen Inc. announced that results from the real-world Lecanemab in Early Alzheimer's Disease (LEADER) Study show that nearly 83% of early Alzheimer's disease (AD) patients enrolled in the study remained stable (75.9%) or improved (6.6%) while receiving LEQEMBI therapy over an average of 17 months. The results were consistent across sex, race, ethnicity and APOE genotype. The data was presented during the "Developing Topics Session #3-33-DEV-A: Lecanemab Three Years Post-Approval: A Comprehensive Multicenter, Real-World, Retrospective Study (LEADER) in Diverse US Clinical Settings" at the Alzheimer's Association International Conference (AAIC) 2026 in London and online. LEQEMBI targets the underlying pathology of the disease and works in two ways throughout treatment - by removing insoluble (plaque) and soluble amyloid beta (protofibrils), helping to slow cognitive decline and loss of daily functioning. Data show continued treatment with LEQEMBI may be able to help keep patients in early AD for longer. Early AD includes mild cognitive impairment (MCI) due to AD and mild AD dementia. The three-year LEADER Study is a multicenter, retrospective real-world study designed to examine LEQEMBI utilization, treatment persistence, transition to maintenance therapy, safety, cognitive and functional assessments, and healthcare professional (HCP) implementation learnings in diverse U.S. clinical settings for patients with early Alzheimer's disease (AD). The study integrated deidentified chart and electronic medical record (EMR) data from 13 U.S. sites, HCP surveys and HCP interviews. This interim analysis included 432 patients with early AD who received at least seven LEQEMBI infusions as of May 2026. The mean age was 74 years and 55.8% were female. Disease stage at baseline was mild cognitive impairment (MCI) due to AD for 63.9% and mild AD dementia for 36.1%. The mean duration of LEQEMBI treatment was 520 days and the mean number of LEQEMBI doses was 26. Change in disease stage was defined as stable (patient remaining in the same disease stage from baseline throughout the course of LEQEMBI treatment), improvement (patient transitioning from mild AD dementia at baseline to MCI due to AD over the course of LEQEMBI treatment), and progression (patient advancing from MCI at baseline to mild/moderate AD dementia or from mild AD dementia at baseline to moderate AD dementia throughout the course of LEQEMBI treatment). Of the 432 participants enrolled in the LEADER Study, disease stage could be evaluated in 427. Among these patients with early Alzheimer's disease, 82.5% remained stable or improved while receiving LEQEMBI, with consistent results across sex, race, ethnicity, and APOE genotype groups. 75.9% remained stable compared with baseline, meaning they remained in the same disease stage throughout treatment. 6.6% improved from baseline, moving from mild AD dementia to MCI due to AD. Nearly 87% of patients chose to remain on LEQEMBI treatment. In analyses by APOE e4 status, clinician-evaluated stable or improved disease stage was observed in 81.7% of APOE e4 heterozygotes (stable: 73.8%; improved: 7.9%) and 81.0% of APOE e4 homozygotes (stable: 75.9%; improved: 5.2%). Of the 432 participants in the LEADER Study, 155 transitioned to once-every-four-weeks intravenous (IV) maintenance treatment, and 14 transitioned to once-weekly subcutaneous (SC) maintenance treatment. Among the 155 participants who transitioned to IV maintenance therapy, nearly 81% remained stable (72.3%) or improved (8.4%). Of the 14 patients who transitioned to SC maintenance treatment, 12 (85.7%) maintained their disease stage. Overall safety observations in this real-world study were consistent with the U.S. FDA-approved label. ARIA (amyloid-related imaging abnormalities) was observed in 12.3% of patients overall; ARIA-E was observed in 6.3% and ARIA-H in 7.9% and isolated ARIA-H in 6.0%. Most ARIA cases were asymptomatic and mild in radiographic severity. No new ARIA-E events, macrohemorrhages or intracerebral hemorrhages greater than 1 cm were reported during once-every-four-weeks IV maintenance therapy. APOE e4 status safety observations were consistent with the overall cohort and the U.S. FDA-approved label. ARIA-E was observed in 5.3% of APOE e4 noncarriers, 6.1% of APOE e4 heterozygotes and 10.3% of APOE e4 homozygotes. ARIA-H was observed in 12.1%, 4.8% and 12.1%, respectively. In APOE e4 homozygotes, no severe ARIA was reported, and all graded ARIA cases were mild to moderate in radiographic severity. Antithrombotic therapy, including anticoagulants or antiplatelet medications, was used by 106 patients, representing 24.5% of the study population. Of these, 11 patients were receiving an anticoagulant, either alone or with an antiplatelet medication, and 95 patients were receiving antiplatelet therapy only. Among patients receiving antithrombotic therapy, the incidence of ARIA was not meaningfully different from that observed in patients not receiving antithrombotic therapy. Lecanemab is the result of a strategic research alliance between Eisai and BioArctic. It is a humanized immunoglobulin gamma (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of amyloid-beta (Aß). Lecanemab has been approved in 53 countries and regions including Japan, the United States, China, Europe, South Korea, Taiwan, and Saudi Arabia, and is under regulatory review in 6 countries. Following the initial phase with treatment every two weeks for 18 months, intravenous (IV) maintenance dosing with treatment every four weeks was approved in 8 countries including the U.S., China, the UK, and others, and applications have been filed in 12 countries and regions. The U.S. FDA approved LEQEMBI IQLIK, the subcutaneous autoinjector formulation of lecanemab, for use as maintenance treatment in August 2025 and as initiation treatment on July 13, 2026. In November 2025, an application for a subcutaneous injectable formulation in Japan was submitted. In January 2026, the Biologics License Application (BLA) for the subcutaneous formulation was accepted in China. Since December 2025, lecanemab (IV) has been included in the "Commercial Insurance Innovative Drug List", recently introduced by the National Healthcare Security Administration (NHSA) of China. Since July 2020, the Phase 3 clinical study (AHEAD 3-45) for individuals with preclinical AD, meaning they are clinically normal and have intermediate or elevated levels of amyloid in their brains, is ongoing.
