Canada has conditionally approved Leqembi (lecanemab), the first treatment that targets an underlying cause of early Alzheimer’s disease by removing toxic amyloid beta proteins from the brain.
Health Canada issued the Notice of Compliance with Conditions on 27 October for adults with mild cognitive impairment or mild dementia due to Alzheimer’s disease who have confirmed amyloid build-up and carry one or no copies of the ApoE ε4 gene variant.
Leqembi works by binding to and removing amyloid beta aggregates, including soluble forms known as protofibrils and insoluble fibrils, which form amyloid plaques in the brain.
These are believed to damage neurons and disrupt communication between brain cells, driving cognitive decline.
The conditional authorisation is based on the Phase 3 Clarity AD trial, which enrolled 1,795 patients with early Alzheimer’s.
In the 18-month study, Leqembi met its primary and all key secondary endpoints, showing a statistically significant slowing of cognitive and functional decline compared to placebo.
Eisai must submit real-world data to verify the drug’s benefit to maintain the authorisation.
Leqembi, co-developed by Swedish biotech BioArctic and Japan’s Eisai, is now approved in 51 countries and regions, including Japan, the US, Europe, China, South Korea, Taiwan and Saudi Arabia, with regulatory reviews ongoing in nine others.
The antibody is given intravenously every two weeks for 18 months, with four-weekly maintenance dosing approved in some markets.
Patients are tested for the ApoE ε4 gene before treatment, as those with two copies of the variant face a higher risk of ARIA (amyloid-related imaging abnormalities) — a side effect that can cause brain swelling or small bleeds.
Professor Lars Lannfelt at BioArctic discovered the Arctic mutation linked to Alzheimer’s disease that led to Leqembi’s development.
Eisai manages global clinical development, regulatory submissions and commercialisation, while BioArctic retains co-commercialisation rights in the Nordic region.
A subcutaneous version, Leqembi Iqlik, is approved in the US for maintenance dosing. Eisai also began a rolling submission to the FDA in September 2025 for subcutaneous initiation dosing.
A long-term study, AHEAD 3-45, is testing the drug in individuals with preclinical Alzheimer’s — those with amyloid build-up but no symptoms — and is expected to continue until 2028.
