Eisai Co., Ltd. (Tokyo, CEO: Haruo Naito) and Biogen Inc. (Cambridge, Massachusetts, CEO: Christopher A. Viehbacher) have announced that the Medicines and Healthcare products Regulatory Agency (MHRA) in Great Britain has granted Marketing Authorization for their humanized amyloid-beta (Aβ) monoclonal antibody, Leqembi® (lecanemab). This authorization allows lecanemab to be used for treating mild cognitive impairment (MCI) and mild dementia caused by Alzheimer’s disease (AD) in adult patients who are apolipoprotein E ε4 (ApoE ε4) heterozygotes or non-carriers. Leqembi® is the first treatment in Europe to target an underlying cause of early AD.
Lecanemab specifically binds to Aβ aggregate species, including toxic Aβ protofibrils and fibrils, which are significant components of Aβ plaques. This binding action helps neutralize and remove these aggregates from the brain.
The approval is based on Phase 3 results from Eisai’s global Clarity AD clinical trial, which demonstrated that lecanemab met its primary endpoint—change in Clinical Dementia Rating Sum of Boxes (CDR-SB) at 18 months—along with all key secondary endpoints with statistically significant outcomes. Common adverse reactions in Great Britain include infusion-related reactions, amyloid-related imaging abnormalities with hemorrhage (ARIA-H), falls, headaches, and amyloid-related imaging abnormalities with cerebral edema (ARIA-E).
With approximately 982,000 people in the UK living with dementia—60-70% of whom have AD—this number is expected to grow as the population ages. Eisai is working with the National Institute for Health and Care Excellence (NICE), the Scottish Medicines Consortium (SMC), and the National Health Service (NHS) to make lecanemab available to eligible patients as soon as possible.
Eisai leads the global development and regulatory submissions for lecanemab, while Biogen co-commercializes and co-promotes the product. In Great Britain, the two companies will co-promote lecanemab, with Eisai serving as the Marketing Authorization holder.
