TOKYO and CAMBRIDGE, Mass., July 13, 2026 - (JCN Newswire) - Eisai Co., Ltd. and Biogen Inc. (Nasdaq: BIIB)announced today that new data presented at the Alzheimer’s Association International Conference®(AAIC®) 2026 in London support that the LEQEMBI® (lecanemab) subcutaneous autoinjector (SC-AI)formulation offers efficacy and safety comparable to intravenous (IV) administration for people with early Alzheimer’s disease (AD). The data was featured during the “Lecanemab Subcutaneous Formulation in Early Alzheimer’s Disease: Emerging Clinical Evidence and Practical Use Considerations” Developing Topics Session #1-32-FRS-C.

AD is a chronic, progressive disease that requires ongoing treatment. LEQEMBI is an early AD treatment that targets the underlying pathology of the disease, helping to slow cognitive decline and loss of daily functioning. The lecanemab subcutaneous auto-injector (SC-AI) was developed to provide a more convenient alternative to intravenous (IV) dosing from the initiation of treatment.

Key Findings

This session presented data from the lecanemab SC-AI development program in early Alzheimer’s disease, including pharmacokinetic (PK), pharmacodynamic (PD), efficacy, safety and real-world patient and care partner experience findings. Results showed that once-weekly 500 mg SC-AI achieved drug exposure similar to the approved intravenous (IV) initiation regimen (10 mg/kg every two weeks), supporting the expectation of similar clinical efficacy and safety, independent of the route of administration. 

The subcutaneous dosing option may offer a convenient at-home alternative to IV infusion which could support access and delivery of care across healthcare settings.

Data Showed

• Bioequivalence Achieved: Once-weekly 500 mg SC-AI demonstrated bioequivalence to the IV initiation regimen (10 mg/kg every two weeks), with an exposure ratio of 104% (90% confidence interval [CI]: 99.1%–109%). Exposure remained consistent across body weight quartiles, demonstrating a stable pharmacokinetic profile in a broad patient population.
• Efficacy Driven by Exposure, Not Route of Administration: Amyloid removal measured by amyloid PET, clinical efficacy measured by CDR-SB, and the incidence of ARIA-E were driven by lecanemab exposure rather than route of administration. The 500 mg SC-AI initiation regimen achieved exposure comparable to the IV initiation regimen, supporting the expectation of acomparable efficacy and safety profile despite the different route of administration.
• Consistent Results Across Patient Populations: The 500 mg SC-AI initiation regimen demonstrated consistent exposure, amyloid clearance as measured by amyloid PET, clinical efficacy and safety across body weight groups. In addition, amyloid clearance and clinical outcomes were not meaningfully affected by body weight, supporting the appropriateness of a fixed-dose regimen.
• Flexible switching between IV and SC administration: Patients may also switch from IV to SC administration, or vice versa, and if a dose is missed patients can take it the next day or up to day six providing greater convenience and flexibility in LEQEMBI administration.

Safety Profile Aligned of SC LEQEMBI

• Overall safety profile of SC-AI was generally consistent with that observed for the IV formulation.
• Incidence of ARIA-E with the 500 mg SC-AI initiation regimen was predicted to be similar to that observed with the IV initiation regimen. 
• Injection-related reactions were observed with subcutaneous LEQEMBI, most of which were localized, while systemic reactions were less frequently observed.
• The incidence of anti-drug antibodies (ADA) was low, at 1.4% in the 500 mg SC-AI group. No neutralizing antibodies were observed, confirming that the low immunogenicity profile was maintained with the SC-AI formulation.

Clinical Trial Perspectives and Real-World Evidence: Sustained Clinical Benefit with SC-AI

• Data from two U.S. Alzheimer’s treatment centers (Alzheimer’s Research and Treatment Center,and First Choice Neurology and Visionary Investigators Network) provide early insight into clinical trial and real-world use of subcutaneous LEQEMBI:
  • At Alzheimer’s Research and Treatment Center, 28 patients receiving SC administration demonstrated slower cognitive decline as measured by CDR-SB over 36 months relative to a matched Alzheimer’s Disease Neuroimaging Initiative (ADNI) natural history cohort. The cohort included 25 patients newly initiated on SC administration and 3 patients who transitioned from IV administration.
  • In a separate case series from First Choice Neurology and Visionary Investigators Network, 10 of 11 evaluable patients (91%) showed improvement or remained stable on MMSE compared with baseline before maintenance therapy. At this center, patients who had received maintenance therapy with SC administration for at least 6 months were included in the analysis.
  • Patient and care partner surveys in these two sites demonstrated high satisfaction with subcutaneous LEQEMBI administration, with satisfaction rates ranging from 75% to 97%, convenience ratings from 83% to 97%, and willingness to recommend treatment ranging from 92% to 100%.

Results presented in this session further reinforce the importance of early and continuous treatment, highlighting how LEQEMBI SC initiation and maintenance administration provides greater optionality for long-term disease management. 

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

MEDIA CONTACTS

Eisai Co., Ltd.
Public Relations Department
TEL: +81 (0)3-3817-5120

Eisai Europe, Ltd.
EMEA Communications Department
+44 (0) 797 487 9419
Emea-comms@eisai.net

Eisai Inc. (U.S.)
Libby Holman
+1201-753-1945
Libby_Holman@eisai.com

Biogen Inc.
Madeleine Shin
+1-781-464-3260
public.affairs@biogen.com

INVESTOR CONTACTS

Eisai Co., Ltd.
Investor Relations Department
TEL: +81 (0) 3-3817-5122

Biogen Inc.
Tim Power
+1-781-464-2442
IR@biogen.com

For more information: https://www.eisai.com/news/2026/pdf/enews202638pdf.pdf 

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