Eisai Co., Ltd. and Biogen Inc. have announced promising real-world findings on the long-term treatment persistence of their Alzheimer's drug, lecanemab. The analysis, presented at the 20th International Conference on Alzheimer’s and Parkinson’s Diseases in Copenhagen, revealed that most patients continue treatment beyond the initial 18 months.
The study, utilizing the PurpleLab CLEAR Claims database, assessed 10,763 individuals in the U.S. who received intravenous lecanemab between January 2023 and November 2025. The findings showed that 78.4% of patients remained on treatment at 18 months, with persistence rates of 71.7% at 20 months and 67.3% at 24 months.
These results align with the Phase III Clarity AD study, where 94% of patients opted to continue with a long-term extension study after completing 18 months of treatment. The analysis suggests that potential delays due to MRI monitoring and other factors did not significantly impact dosing adherence.
Lecanemab, developed through a collaboration between Eisai and BioArctic, targets amyloid-beta protofibrils, believed to contribute to Alzheimer's progression. The drug has been approved in 53 countries, with maintenance dosing sanctioned in seven nations, including the U.S. and China.
In clinical trials, lecanemab demonstrated a notable reduction in cognitive decline, with a 1.01-point decrease on the Clinical Dementia Rating-Sum of Boxes scale over three years, compared to the Alzheimer’s Disease Neuroimaging Initiative cohort. This benefit increased to a 1.75-point reduction after four years.
The ongoing Phase 3 AHEAD 3-45 study and the Tau NexGen clinical study continue to explore lecanemab's potential in preclinical and dominantly inherited Alzheimer's disease, respectively.