Eisai announced new data showcasing the long-term efficacy and safety of lecanemab (LEQEMBI®), its anti-amyloid beta antibody, for the treatment of early Alzheimer's disease (AD). These updates, presented at the 2025 Alzheimer's Association International Conference (AAIC), include four-year trial results, real-world patient data, and a new subcutaneous formulation. Eisai also shared progress on its tau-targeting antibody etalanetug (E2814), reinforcing its ongoing commitment to developing innovative therapies for AD.

Long-Term Data and Subcutaneous Formulation

At AAIC 2025, Eisai presented four-year results from the open-label extension of the Phase 3 Clarity AD trial, showing sustained benefit and safety of lecanemab in early AD. Additionally, Eisai introduced findings on a subcutaneous version of lecanemab designed for maintenance therapy. This alternative delivery method may offer a more convenient option for ongoing treatment, potentially improving adherence and access.

Real-World Experience and Biomarker Research

Eisai also shared real-world case studies from U.S. clinics, highlighting patient outcomes and clinical pathways two years after lecanemab's approval. Another key poster presentation featured a novel immunoassay that detects amyloid-β protofibrils in cerebrospinal fluid, aiding early diagnosis and monitoring of treatment response.

Progress with Etalanetug and Combination Trials

Eisai reported early results from the DIAN-TU-001 NexGen Trial, which evaluates etalanetug (E2814), an anti-tau antibody, in combination with lecanemab in genetically inherited AD. This dual-acting approach targets both amyloid and tau pathology, aiming to slow or prevent disease progression.

Global Access and Research Partnerships

Lecanemab is already approved in over 15 regions, including the U.S., Japan, China, and the EU, for patients with mild cognitive impairment or early-stage AD. Ongoing trials such as AHEAD 3-45 and Tau NexGen continue to assess lecanemab's effects in preclinical and inherited forms of AD. Eisai leads the development and global regulatory work, in collaboration with Biogen and BioArctic.

Conclusion

With four-year data, new delivery options, and insights from real-world settings, Eisai's presentations at AAIC 2025 reflect steady progress in AD research. Through strategic alliances and a focus on dual-target approaches, the company continues to expand its Alzheimer's pipeline and global reach.