Eisai To Present Four-Year Efficacy And Safety Data On Continuous Treatment With Lecanemab At The Alzheimer’s Association International Conference 2025Latest findings from Eisai's robust Alzheimer's disease (AD) pipeline include results from lecanemab long-term data, an immunoassay for measuring amyloid-β protofibrils in cerebrospinal fluid, and a subcutaneous form of lecanemab for continued treatment of AD
AD is a progressive, relentless disease caused by a continuous underlying neurotoxic process that begins before and continues after plaque deposition

• For Print
• July 22, 2025

Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) announced today that the company will present the latest findings from its robust Alzheimer's disease (AD) pipeline and research, including our dual-acting, anti-amyloid beta (Aβ) protofibril antibody for the treatment of AD, lecanemab (generic name, U.S. brand name: LEQEMBI^®), and anti-MTBR (microtubule binding region) tau antibody, etalanetug (E2814), at the Alzheimer's Association International Conference (AAIC), being held in Toronto and virtually from July 27-31. Eisai will present 21 oral presentations, 24 posters, three (3) symposia and two (2) lecanemab product theaters.

Key Oral Lecanemab Presentations

• ・Four-year Data: On Wednesday July 30 (8:00 – 8:45 AM EDT), as part of the “Developing Topics Session: Innovative Therapeutic Approaches”, initial four-year findings will be presented on lecanemab from the Phase III Clarity AD Open-Label Extension in Early Alzheimer's Disease trial.
• ・Subcutaneous Maintenance Dosing: A Featured Research Session on Wednesday, July 30 (9:00 – 10:30 AM EDT) will include data on the potential of a new and convenient option for ongoing lecanemab treatment, the subcutaneous formulation for maintenance dosing.
• ・Real World Case Studies: A Developing Topics Session on Sunday, July 27 (9:00 – 10:30 AM EDT) will include data on real-world case studies and patient pathway learnings from diverse U.S. clinical settings two years post-approval of lecanemab.

Key Lecanemab Poster Presentation

• ・A Poster Presentation on Monday, July 28 (viewing available from 7:30 AM – 4:15 PM EDT) will share findings on cerebrospinal fluid (CSF) samples collected from the Clarity AD trial and analyzed using the novel, sensitive immunoassay developed to measure amyloid-β protofibrils in CSF.

Key Oral E2814 Presentation

• ・A Featured Research Session on Wednesday, July 30 (4:15 PM – 5:45 PM EDT) will include findings from “Anti-Tau Etalanetug (E2814) with Lecanemab Therapy in Individuals with Dominantly Inherited Alzheimer’s Disease: A First Look at Baseline Characteristics and Impact of 6-Month Lecanemab Treatment on Amyloid PET and Safety in the DIAN-TU-001 NexGen Trial.”

“The data presented at AAIC 2025 will highlight long-term findings from lecanemab’s open-label extension trial, real-world lecanemab case studies as well as results on a subcutaneous formulation and dosing regimen that may offer patients more flexibility to continue treatment to fight Alzhierm’s disease,” said Lynn D. Kramer, M.D., FAAN, Chief Clinical Officer, Deep Human Biology Learning (DHBL), Eisai. “Eisai will also share preliminary results from the DIAN-TU-001 NexGen Trial, exploring etalanetug with background lecanemab therapy to slow or prevent the progression of Alzhierm’s disease. As we gain more experience using dual-acting lecanemab in different clinical settings and continue to explore new avenues to improve the diagnosis and treatment of Alzhierm’s disease, we are hopeful about the future. We remain committed to patients and their loved ones who are impacted by this progressive, relentless disease, caused by a continuous underlying neurotoxic process that begins before and continues after plaque is removed from the brain.”

Featured Research Session (FRS) #1-31-FRS-A:

Anti-Amyloid Therapies in Clinical Practice: Real World Evidence and Implementation Consideration (Abstract ID 103048)

4:15 - 5:45 PM EDT, Sunday, July 27

Featured Research Session, #4-13-FRS-C:

Lecanemab Subcutaneous Formulation for Maintenance Dosing: The Potential of a New and Convenient Option for Ongoing Treatment in Early Alzheimer’s Disease

9:00 – 10:30 AM EDT, Wednesday, July 30

Featured Research Session, #4-31-FRS-B:

Anti-Tau Etalanetug (E2814) with Lecanemab Therapy in Individuals with Dominantly Inherited Alzheimer’s Disease: A First Look at Baseline Characteristics and Impact of 6-Month Lecanemab Treatment on Amyloid PET and Safety in the DIAN-TU-001 NexGen Trial

4:15 - 5:45 PM EDT, Wednesday, July 30

Key Developing Topics Sessions

Real-World Data (Abstract ID 108809)

8:00 - 8:45 AM EDT on Sunday, July 27

Lecanemab Two Years Post-Approval: Real-World Case Series and Patient Pathway Learnings from Diverse US Clinical Settings (Abstract ID 108605)

9:00 - 10:30 AM EDT on Sunday, July 27

Innovative Therapeutic Approaches (Abstract ID 108905)

8:00 - 8:45 AM EDT, Wednesday, July 30

Additional Featured Research and Developing Topics Sessions

Poster Presentations

Eisai-Sponsored Symposia

Eisai-Sponsored Product Theaters

Product theaters will feature presentations based on real-world clinical experience with lecanemab - providing attendees with an opportunity to hear best practices and expert guidance on using this therapy.

This release discusses investigational uses of agents in development and is not intended to convey conclusions about efficacy or safety. There is no guarantee that such investigational agents will successfully complete clinical development or gain health authority approval.

[Notes to Editors]

1. 1. About lecanemab  (generic name, brand name: Leqembi^®)

Lecanemab is the result of a strategic research alliance between Eisai and BioArctic. It is a humanized immunoglobulin gamma (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of amyloid-beta (Aβ). Protofibrils are believed to contribute to the brain injury that occurs with AD and are considered to be the most toxic form of Aβ, having a primary role in the cognitive decline associated with this progressive, debilitating condition.¹ Protofibrils cause injury to neurons in the brain, which in turn, can negatively impact cognitive function via multiple mechanisms, not only increasing the development of insoluble Aβ plaques but also increasing direct damage to brain cell membranes and the connections that transmit signals between nerve cells or nerve cells and other cells. It is believed the reduction of protofibrils may prevent the progression of AD by reducing damage to neurons in the brain and cognitive dysfunction.²

Lecanemab has been approved in 45 countries, including Japan, the United States, China, the European Union, South Korea, and Taiwan, and been under regulatory review in 11 countries. In January 2025, the supplemental Biologics License Application (sBLA) for intravenous (IV) maintenance dosing of the treatment was approved in the U.S. After an 18 months initiation phase with once every two weeks of dosing, a transition to the maintenance dosing regimen of 10 mg/kg once every four weeks or continuing 10 mg/kg once every two weeks may be considered. Additionally, the U.S. Food and Drug Administration (FDA) accepted Eisai’s Biologics License Application (BLA) for the LEQEMBI subcutaneous autoinjector for weekly maintenance dosing in January 2025 and set a PDUFA action date for August 31, 2025.

Since July 2020 the Phase 3 clinical study (AHEAD 3-45) for individuals with preclinical AD, meaning they are clinically normal and have intermediate or elevated levels of amyloid in their brains, is ongoing. AHEAD 3-45 is conducted as a public-private partnership between the Alzheimer's Clinical Trial Consortium that provides the infrastructure for academic clinical trials in AD and related dementias in the U.S, funded by the National Institute on Aging, part of the National Institutes of Health, Eisai and Biogen. Since January 2022, the Tau NexGen clinical study for Dominantly Inherited AD (DIAD), that is conducted by Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU), led by Washington University School of Medicine in St. Louis, is ongoing and includes lecanemab as the backbone anti-amyloid therapy.

1. 2. About the Collaboration between Eisai and BioArctic for AD

Since 2005, Eisai and BioArctic have had a long-term collaboration regarding the development and commercialization of AD treatments. Eisai obtained the global rights to study, develop, manufacture and market lecanemab for the treatment of AD pursuant to an agreement with BioArctic in December 2007. The development and commercialization agreement on the antibody lecanemab back-up was signed in May 2015.

1. 3. About the Collaboration between Eisai and Biogen for AD

Eisai and Biogen have been collaborating on the joint development and commercialization of AD treatments since 2014. Eisai serves as the lead of lecanemab development and regulatory submissions globally with both companies co-commercializing and co-promoting the product and Eisai having final decision-making authority.

References

1. 1. 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
2. 2. 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.

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