Food and Drug Administration (FDA) for lecanemab-irmb (U.S. brand name: LEQEMBI®) subcutaneous autoinjector (SC-AI), LEQEMBI IQLIK, as a weekly starting dose after the FDA granted Fast Track Status.
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). Upon acceptance of the sBLA, the FDA will set a Prescription Drug User Fee Act (PDUFA) action date (target date for review completion).
The sBLA is supported by data evaluating subcutaneous (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 intravenous (IV) administration and similar clinical and biomarker benefits. Subcutaneous administration demonstrated a safety profile similar to IV administration, with less than 2% incidence of systemic injection/infusion-related reactions.
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 (every two weeks) intravenous (IV) dosing.
This would enable patients and care partners to choose SC administration at home for both initial treatment and the currently approved maintenance therapy, offering the option of SC or IV administration throughout the entire treatment journey. The injection time for each LEQEMBI IQLIK autoinjector takes approximately 15 seconds. The SC formulation also has the potential to reduce healthcare resources associated with IV dosing, such as preparation for infusion and nurse monitoring, while streamlining the overall AD treatment pathway.
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* that begins before amyloid plaque accumulation and continues after plaque removal.1,2,3 Only LEQEMBI fights AD in two ways – targeting both protofibrils and amyloid plaque, which can impact tau downstream.
LEQEMBI is currently approved in 51 countries and regions and is under regulatory review in 9 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 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 condition1. 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
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).
Lecanemab has been approved in 51 countries and regions including Japan, the United States, Europe, China, South Korea, Taiwan, and Saudi Arabia, and is under regulatory review in 9 countries. Following the initial phase with treatment every two weeks for 18 months, intravenous (IV) maintenance dosing with treatment every four weeks was approved in the U.S., China, the United Kingdom, and others, and applications have been filed in 4 countries and regions. The U.S. FDA approved Eisai's Biologics License Application (BLA) for subcutaneous maintenance dosing with LEQEMBI IQLIK in August 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.
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.
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.
About Eisai Co., Ltd.
Eisai's Corporate Concept is "to give first thought to patients and people in the daily living domain, and to increase the benefits that health care provides." Under this Concept (also known as human health care (hhc) Concept), we aim to effectively achieve social good in the form of relieving anxiety over health and reducing health disparities. With a global network of R&D facilities, manufacturing sites and marketing subsidiaries, we strive to create and deliver innovative products to target diseases with high unmet medical needs, with a particular focus in our strategic areas of Neurology and Oncology.
