Biogen and Eisai have 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 three-year LEADER Study is designed to examine Leqembi in diverse US clinical settings for patients with early Alzheimer’s disease (AD). The interim analysis included 432 patients with early AD who received at least seven Leqembi infusions as of May 2026.
Of the 432 participants enrolled in the 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 gender, 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.
Of the 432 participants, 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.
At baseline, 63.9% of the patients had mild cognitive impairment (MCI) due to AD, and 36.1% had mild AD dementia. The average age of the patients was 74 years and 55.8% of the patients were female. The average Leqembi treatment was 520 days, with an average of 26 doses.
Change in disease stage was defined as:
- Stable: Patient remaining in the same disease stage (MCI due to AD or mild AD dementia) 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
- 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.
AD is a chronic, progressive disease that requires ongoing treatment. 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.
Early AD includes mild cognitive impairment (MCI) due to AD and mild AD dementia. The data shows continued treatment with Leqembi may be able to help keep patients in early AD for longer.
The data was presented at the Alzheimer’s Association International Conference (AAIC) 2026 in London and online.