Swedish research-based biopharma company BioArctic AB (STO:BIOA-B) and its partner Eisai Co Ltd (TYO:4523) announced on Monday the approval of LEQEMBI Intravenous Infusion (200 mg, 500mg, lecanemab) in Japan as a treatment for slowing progression of mild cognitive impairment (MCI) and mild dementia due to Alzheimer's disease (AD).

This regulatory milestone in Japan entitles BioArctic to a milestone payment of EUR17m.

LEQEMBI, a humanised immunoglobulin gamma 1 (IgG1) monoclonal antibody targeting aggregated soluble (protofibril) and insoluble forms of amyloid beta, is the first approved treatment proven to reduce the rate of disease progression and to slow cognitive and functional decline by selectively binding to and eliminating the most toxic amyloid beta aggregates (protofibrils) that contribute to neurotoxicity in AD. The approval in Japan follows traditional approval in the United States in July 2023.

The decision was based on Phase 3 data from Eisai's large, global Clarity AD clinical trial, in which LEQEMBI met its primary endpoint and all key secondary endpoints and confirmed the clinical benefit of LEQEMBI.

Post-approval, Eisai will conduct a special use results survey (all-case surveillance) for all patients who are administered LEQEMBI, as mandated by the Japanese Ministry of Health, Labour and Welfare.

Eisai leads the global development and regulatory submissions for LEQEMBI, with both Eisai and Biogen co-commercialising and co-promoting the product. In Japan, Eisai and Biogen Japan will co-promote LEQEMBI, with Eisai distributing the product. BioArctic has the right to commercialise lecanemab in the Nordic region and currently Eisai and BioArctic are preparing for a joint commercialisation in the region.