TOKYO and CAMBRIDGE, Mass., Jan 26, 2026 - (JCN 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 the U.S. Food and Drug Administration (FDA) has accepted for review Eisai’s Supplemental Biologics License Application (sBLA) for lecanemab-irmb (U.S. brand name: LEQEMBI®) subcutaneous autoinjector (SC-AI), LEQEMBI IQLIK, as a weekly starting dose. LEQEMBI is indicated for the treatment of Alzheimer’s disease (AD) in patients with Mild Cognitive Impairment (MCI) or mild dementia stage of disease (collectively referred to as early AD). The sBLA has been granted Priority Review, with a Prescription Drug User Fee Act (PDUFA) action date of May 24, 2026.

Should the FDA approve the LEQEMBI IQLIK 500 mg SC dosing regimen (two 250 mg injections), the autoinjector could be used to administer a once-weekly starting dose, as an alternative to the current bi-weekly intravenous (IV) dosing. This would enable patients and care partners to choose SC administration at home for both treatment initiation and the currently approved maintenance therapy (360 mg), offering the option of SC or IV administration throughout the entire treatment journey. The injection time for LEQEMBI IQLIK autoinjector takes approximately 15 seconds per each 250 mg injection. The SC formulation also has the potential to reduce healthcare resources associated with IV dosing, such as infusion preparation and nurse monitoring, while streamlining the overall AD treatment pathway.

The sBLA is supported by data evaluating SC administration of lecanemab across a range of doses and as part of sub-studies within the Phase 3 Clarity AD open-label extension (OLE) following the 18- month core study in individuals with early AD. Data show that once-weekly administration of the 500 mg of SC-AI achieved equivalent exposure to once every two weeks IV administration and similar clinical and biomarker benefits. SC administration demonstrated a safety profile similar to IV administration, with less than 2% incidence of systemic injection or infusion-related reactions.

AD is a progressive, relentless disease, with amyloid beta (Aβ) and tau as hallmarks, that is caused by a continuous underlying neurotoxic process driven by protofibrils* (PF) that begins before amyloid plaque removal and continues afterward. 1,2,3 Only LEQEMBI fights AD in two ways – targeting both PF and amyloid plaque, which can impact tau downstream.

LEQEMBI is currently approved in 53 countries and regions and is under regulatory review in 7 countries. In August 2025, the US FDA approved LEQEMBI IQLIK 360 mg for weekly subcutaneous maintenance dosing after 18 months of IV treatment every two weeks.

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.

*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. 1 The mechanism by which this occurs as 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 preventing the progression of AD.2

For more details, please visit: https://www.eisai.com/news/2026/pdf/enews202605pdf.pdf

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