Eisai Co., Ltd. (TSE: 4523) and Biogen Inc. (NASDAQ: BIIB) announced results from a real-world analysis showing that patients receiving LEQEMBI (lecanemab) maintain treatment adherence beyond the initial 18-month period. The findings were presented at the International Conference on Alzheimer's and Parkinson's Diseases in Copenhagen.

The retrospective study analyzed data from the PurpleLab CLEAR Claims database, examining 10,763 individuals who received at least one intravenous lecanemab treatment between January 6, 2023, and November 30, 2025. The analysis population had a mean age of 73.8 years, with 56.5% being female.

In a subgroup of 371 patients who initiated treatment in 2023 and had 20 months of continuous follow-up, 78.4% continued lecanemab treatment at 18 months, 71.7% at 20 months, and 67.3% at 24 months. The mean dosing interval was 16.4 days, consistent with the recommended bi-weekly dosing schedule.

The study represents the first time real-world lecanemab persistence data beyond 18 months has been reported. Patient characteristics and dosing patterns observed in the claims-based analysis were similar to those reported in the Phase III Clarity AD study.

LEQEMBI is approved in 53 countries and regions for treating Alzheimer's disease. The drug targets aggregated soluble and insoluble forms of amyloid-beta, with Eisai leading development and regulatory submissions globally while both companies co-commercialize the treatment.

The analysis was based on information from a company press release.