MHRA Approves Eisai And Biogen’s LEQEMBI® For Once-Monthly Maintenance Dosing in Early Alzheimer’s Disease

Eisai Co., Ltd. and Biogen Inc. announced that the UK Medicines and Healthcare products Regulatory Agency (MHRA) has approved LEQEMBI® (lecanemab) for once-every-four-weeks intravenous (IV) maintenance dosing. LEQEMBI is a humanized monoclonal antibody that targets soluble aggregated amyloid-beta (Aβ), and represents one of the first disease-modifying therapies for early Alzheimer’s disease (AD).

The latest approval builds on the MHRA’s August 2024 authorization, which allowed LEQEMBI for the treatment of mild cognitive impairment (MCI) and mild dementia due to Alzheimer’s disease in ApoE ε4 heterozygotes or non-carriers. Under the new regimen, patients who complete the initial 18-month therapy at 10 mg/kg every two weeks may either continue with the same dosing frequency or transition to the extended maintenance regimen of 10 mg/kg every four weeks, offering greater flexibility and convenience for long-term disease management.

Alzheimer’s disease is marked by the accumulation of amyloid-beta plaques and tau tangles, driven by a long-standing neurotoxic process that begins before plaque formation and persists even after plaques are cleared. Research has shown that amyloid-beta protofibrils and tau pathology contribute significantly to neurodegeneration, and LEQEMBI is the only approved therapy that addresses both amyloid plaques and protofibrils, potentially modifying downstream tau activity. Evidence also indicates that halting therapy leads to the reaccumulation of AD biomarkers and a return to placebo-level rates of cognitive decline, supporting the importance of continuous maintenance treatment beyond the initial 18-month course.

In the UK, an estimated 982,000 people are currently living with dementia, with Alzheimer’s disease accounting for 60–70% of these cases—a number expected to rise as the population ages. Eisai is leading the global development and regulatory strategy for lecanemab, while Eisai and Biogen jointly commercialize and promote the therapy, with Eisai retaining final decision-making authority.