TOKYO and CAMBRIDGE, Mass., Aug. 24, 2026 (GLOBE NEWSWIRE) -- Eisai Co., Ltd. and Biogen Inc. (Nasdaq: BIIB), announced today that once weekly lecanemab-irmb subcutaneous injection (brand name: LEQEMBI IQLIK®) is now available in the U.S. for initiation therapy for early Alzheimer’s disease (AD) in adults with mild cognitive impairment (MCI) or mild dementia due to AD, collectively referred to as early AD. MCI due to AD is the earliest symptomatic stage of AD and can appear with subtle symptoms such as forgetfulness, confusion, or feeling at a loss for words.1
LEQEMBI IQLIK is administered via an autoinjector, introducing a convenient alternative to intravenous (IV) dosing from the start of treatment. For initiation, the approved regimen is 500 mg given once weekly as two consecutive 250 mg injections, each delivered in approximately 15 seconds. LEQEMBI IQLIK may also be used for maintenance dosing at 360 mg once weekly after 18 months of IV or subcutaneous (SC) treatment. Throughout the entire treatment course – from initiation through maintenance – patients may receive LEQEMBI either as IV infusion or as SC injection with LEQEMBI IQLIK. Patients may also switch from IV to SC administration, or vice versa, providing greater convenience and flexibility in LEQEMBI administration.
Expanding Treatment Convenience and Flexibility Across the Alzheimer’s Disease Care Pathway
The availability of LEQEMBI IQLIK for both initiation and maintenance therapy in the U.S. enhances treatment convenience and flexibility, offering early AD patients and their care partners more control in managing their care while lowering barriers to initiating and continuing treatment with LEQEMBI. LEQEMBI IQLIK may reduce the time spent receiving anti-amyloid therapy via IV infusions. In addition, at-home administration allows patients and their care partners to continue treatment without the burden of clinic visits, making it easier to go out and travel. LEQEMBI IQLIK also has the potential to reduce healthcare resources associated with IV dosing, such as infusion preparation and nurse monitoring. These features may help streamline the overall AD treatment pathway. For ARIA monitoring, as with IV administration, brain magnetic resonance imaging (MRI) is performed prior to initiating treatment and at specified time points after treatment initiation.
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 53 countries and regions including Japan, the U.S., China, Europe, South Korea, Taiwan, and Saudi Arabia, and is under regulatory review in 6 countries. Following the initial phase with treatment every two weeks for 18 months, intravenous (IV) maintenance dosing with treatment every four weeks is approved in 8 countries including the U.S., China, the UK, and others, and applications have been filed in 12 countries and regions. The U.S. FDA approved Eisai’s Biologics License Application (BLA) for subcutaneous maintenance dosing with LEQEMBI IQLIK in August 2025. For subcutaneous initiation treatment (500 mg), approval was obtained in the United States in July 2026, and applications are under review in four countries, including Japan and China. In China, the application has been granted Priority Review designation. Since December 2025, lecanemab (IV) has been included in the “Commercial Insurance Innovative Drug List,” recently introduced by the National Healthcare Security Administration (NHSA) of China.
LEQEMBI's approvals in these countries were based on Phase 3 data from Eisai's global placebo-controlled, double-blind, parallel-group, randomized Clarity AD clinical trial, in which it met its primary endpoint and all key secondary endpoints with statistically significant results. The primary endpoint was the global cognitive and functional scale, Clinical Dementia Rating Sum of Boxes (CDR-SB). Clarity AD evaluated lecanemab 10 mg/kg bi-weekly IV treatment of early Alzheimer's disease, which involved 1,795 patients (treatment group: 898, placebo group: 897). 95% of patients who completed the core study (18 months) chose to continue in the long-term extension study (LTE), with 478 patients still receiving treatment for four years. In the Clarity AD core clinical study, data showed LEQEMBI IV significantly slowed disease progression at 18 months (27% vs placebo), and the mean change from baseline between the lecanemab treated group and the placebo group after 18 months was -0.45 (P=0.00005) on the primary endpoint of CDR-SB global cognitive and functional scale.
To provide context, a change from 0.5 to 1 on the Clinical Dementia Rating (CDR) score domains of Memory, Community Affairs and Home/Hobbies reflects a shift from mild impairment to loss of independence. This can affect a person’s ability to be left alone safely, recall recent events, participate in daily activities, manage household tasks, and engage in hobbies and intellectual interests.
LEQEMBI also rapidly reduced plaque as early as three months (−59.1 CL difference vs placebo in amyloid level at 18 months; P<0.00001).* Additionally, LEQEMBI continued to show benefit over a four-year LTE treatment period; in a subgroup analysis, 81 percent of LEQEMBI patients who stayed on treatment remained in the early AD stages at four years.**
Over three years of treatment, including both the core study and the LTE, data showed lecanemab demonstrated a reduction in cognitive decline—measured by CDR-SB—of 1.01 points compared to the expected decline observed in the Alzheimer’s Disease Neuroimaging Initiative (ADNI)** cohort. This benefit grew more pronounced after four years, with a reduction of 1.75 points. Similarly, when benchmarked against the expected decline in the BioFINDER cohort, lecanemab showed a reduction of 1.40 points at three years and an even greater reduction of 2.17 points at the four-year mark. In Clarity AD, the most common adverse events (>10%) in the lecanemab group were infusion reactions, ARIA-H (combined cerebral microhemorrhages, cerebral macrohemorrhages, and superficial siderosis), ARIA-E (edema/effusion), headache, and fall.
*The Centiloid scale is used for amyloid PET, where 0 CL is anchored as the average amyloid in young people without amyloid plaques, and 100 is anchored as the average amyloid level in moderate AD. The baseline centiloid level in CLARITY AD was approximately 78 CL. Plaque negativity is defined as conversion to amyloid PET negative (<30 centiloid, or CL).
**Prespecified subgroup analysis of reduced risk of progression: Progression was defined as CDR-SB score progressing to moderate or severe dementia (≥9.5), based on Kaplan-Meier plots.
About Protofibrils
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.2 The mechanism by which this occurs has 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.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.
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.
In addition, we demonstrate our commitment to the elimination of neglected tropical diseases (NTDs), which is a target (3.3) of the United Nations Sustainable Development Goals (SDGs), by working on various activities together with global partners.
For more information about Eisai, please visit www.eisai.com (for global headquarters: Eisai Co., Ltd.), and connect with us on X, LinkedIn and Facebook. The website and social media channels are intended for audiences outside of the UK and Europe. For audiences based in the UK and Europe, please visit www.eisai.eu and Eisai EMEA LinkedIn.
About Biogen
Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science to deliver new medicines to transform patient’s lives and to create value for shareholders and our communities. We apply deep understanding of human biology and leverage different modalities to advance first-in-class treatments or therapies that deliver superior outcomes. Our approach is to take bold risks, balanced with return on investment to deliver long-term growth.
References
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National Institute on Aging (NIA), National Institutes of Health. What Is Mild Cognitive Impairment? Available at: https://www.nia.nih.gov/health/memory-loss-and-forgetfulness/what-mild-cognitive-impairment. Accessed July 22, 2026.
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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.
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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.