Swedish research-based biopharma company BioArctic AB (STO:BIOA-B) reported on Friday that its Japanese partner Eisai Co Ltd (TYO:4523) generated preliminary global Leqembi (lecanemab) sales of JPY20.7bn in the fourth quarter of 2025.

This translates into a royalty payment of SEK127m to BioArctic, representing an increase of approximately 31% year over year. BioArctic noted that the strong appreciation of the Swedish krona during 2025 materially affected reported growth, and at constant exchange rates the royalty increase would have been about 50%.

Leqembi is the outcome of a strategic research alliance between BioArctic and Eisai and is approved in 53 countries, with regulatory reviews ongoing in six additional markets. Maintenance dosing regimens are approved in several major markets, including the United States, Japan, the UK, and China, with further applications submitted. Under existing agreements, Eisai leads development and commercialisation globally, while BioArctic holds Nordic commercialisation rights.

BioArctic has no development costs for lecanemab in Alzheimer's disease and is entitled to payments in connection with sales milestones as well as royalties on global sales.