Eisai and Biogen's LEQEMBI® Receives Approval for Once Every Four Weeks IV Maintenance Dosing in the UK

TOKYO and CAMBRIDGE, Mass., Nov. 13, 2025 (GLOBE NEWSWIRE) -- Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) and Biogen Inc. (Nasdaq: BIIB, Corporate headquarters: Cambridge, Massachusetts, CEO: Christopher A. Viehbacher, “Biogen”) announced today that humanized anti- soluble aggregated amyloid-beta (Aβ) monoclonal antibody “LEQEMBI ^® ” (generic name: lecanemab) has been approved for once every four weeks intravenous (IV) maintenance dosing by the Medicines and Healthcare products Regulatory Agency (MHRA) in the United Kingdom.

In August 2024, LEQEMBI was approved for the treatment of mild cognitive impairment (MCI) and mild dementia due to Alzheimer’s disease (AD) in adult patients that are apolipoprotein E ε4 (ApoE ε4)* heterozygotes or non-carriers in the United Kingdom. With this latest approval for IV maintenance dosing, after 18 months of a dosing regimen of 10 mg/kg once every two weeks patients may be transitioned to the maintenance dosing regimen of 10 mg/kg once every four weeks, or the regimen of 10 mg/kg once every two weeks may be continued.

AD is a progressive, relentless disease characterized by formation of protein deposits known as plaques made of amyloid-beta aggregates and neurofibrillary tangles made of tau protein in the brains of people living with AD. It is caused by a continuous underlying neurotoxic process that begins before amyloid plaque accumulation and continues after plaque removal. ^1,2 The data show that amyloid-beta protofibrils and tau tangles play roles in the neurodegeneration process, ^2,3 and only LEQEMBI fights AD in two ways – targeting both amyloid plaque and protofibrils**, which can impact tau downstream. Due to the reaccumulation of AD biomarkers and return to placebo rate of decline after therapy is stopped, ^3-5 continuing maintenance treatment after the initial 18-month therapy is essential to slow the progression of AD and extend the therapeutic benefits, helping patients maintain who they are for longer.

In the United Kingdom, it is estimated that 982,000 people are living with dementia, ⁶ and AD is the cause in 60-70% of people with dementia. ⁷ These numbers are expected to rise, as the population ages. ^6,7

Eisai serves as the lead for lecanemab’s development and regulatory submissions globally with Eisai and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making authority.

* Apolipoprotein E is a protein involved in the metabolism of lipid in humans. It is implicated in AD. People with only one (heterozygous) or no copy (non-carriers) of the ApoE ε4 gene are less likely to experience ARIA than people with two ApoE ε4 copies (homozygous). ⁸
** Protofibrils are thought to be the most toxic Aβ species that contribute to brain damage in AD and play a major role in the cognitive decline of this progressive and devastating disease. Protofibrils can cause neuronal and synaptic damage in the brain, which can subsequently adversely affect cognitive function through multiple mechanisms. ³ The mechanism by which this occurs has been reported not only by increasing the formation of insoluble Aβ plaques, but also by directly damaging signaling between neurons and other cells. It is believed that reducing protofibrils may reduce neuronal damage and cognitive impairment, potentially slowing the progression of AD. ⁴

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References

1. Eisai presents full results of lecanemab Phase 3 confirmatory Clarity AD study for early Alzheimer's disease at Clinical Trials on Alzheimer's Disease (CTAD) conference. Available at: https://www.eisai.co.jp/news/2022/news202285.html
2. Hampel H, Hardy J, Blennow K, et al. The amyloid pathway in Alzheimer's disease. Mol Psychiatry. 2021;26(10):5481-5503.
3. Amin L, Harris DA. Aβ receptors specifically recognize molecular features displayed by fibril ends and neurotoxic oligomers. Nat Commun . 2021;12:3451. doi:10.1038/s41467-021-23507-z
4. Ono K, Tsuji M. Protofibrils of Amyloid-β are Important Targets of a Disease-Modifying Approach for Alzheimer's Disease. Int J Mol Sci. 2020;21(3):952. doi: 10.3390/ijms21030952. PMID: 32023927; PMCID: PMC7037706.
5. Eisai presents long-term administration data of lecanemab at the Alzheimer's Association International Conference (AAIC) 2024. Available at: https://www.eisai.co.jp/ir/library/presentations/pdf/4523_240731_1.pdf
6. Alzheimer’s Society. 2024. The economic impact of dementia. Available at: https://www.alzheimers.org.uk/about-us/policy-and-influencing/dementia-scale-impact-numbers . Last accessed: August 2024.
7. World Health Organization. 2023. Dementia. Available at: https://www.who.int/news-room/fact-sheets/detail/dementia . Last accessed: August 2024
8. van Dyck, C.H., et al. Lecanemab in Early Alzheimer’s Disease. New England Journal of Medicine. 2023;388:9-21. https://www.nejm.org/doi/full/10.1056/NEJMoa2212948.