LEQEMBI® Pen (Subcutaneous Formulation of LEQEMBI®) Approved in Japan for the Treatment of Early Alzheimer’s Disease

TOKYO and CAMBRIDGE, Mass., Sept. 16, 2026 (GLOBE NEWSWIRE) -- Eisai Co., Ltd. and Biogen Inc. (Nasdaq: BIIB), announced today that “LEQEMBI ® Pen”, the subcutaneous (SC) formulation of the anti-amyloid beta (Aβ) protofibril antibody “LEQEMBI ®” (brand name, generic name: lecanemab) has been approved in Japan as a new route of administration.

LEQEMBI Pen is an autoinjector formulation that enables administration by a care partner or patient self-administration, with two pens (totaling 500 mg) administered once weekly. With this approval, LEQEMBI treatment now offers a new option of once-weekly SC administration at home*, in addition to intravenous (IV) administration every two weeks in a hospital setting.

LEQEMBI Pen may reduce the time required for anti-amyloid therapy administration compared with IV infusions (approximate injection time of 15 seconds per injection). In addition, at-home administration may reduce the burden of clinic visits for patients and their care partners and provide greater flexibility in treatment, allowing patients to make treatment choices that better fit their lifestyles, including fewer constraints on going out and traveling. The improved convenience and flexibility of treatment with LEQEMBI is expected to lower barriers to initiating and continuing treatment with LEQEMBI. Furthermore, LEQEMBI Pen also has the potential to reduce healthcare resources associated with IV dosing, such as nurse monitoring, as well as maintaining infusion capacity. These features are expected to contribute to further streamlining the overall Alzheimer’s disease (AD) treatment pathway. For amyloid-related imaging abnormalities (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.

AD is a progressive, relentless disease with 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.

This marks the third country globally to approve LEQEMBI SC formulation. This approval is based on the integrated results of data and associated modeling and simulation from the 18-month core study of the Phase 3 Clarity AD study of LEQEMBI in patients with mild cognitive impairment (MCI) due to AD or mild AD dementia (collectively referred to as early AD), as well as multiple SC administration sub-studies in its subsequent long-term extension study (LTE). Once-weekly administration of SC formulation 500 mg demonstrated similar exposure to IV administration once every two weeks and supported the expectation that the SC formulation provides efficacy comparable to that of the IV formulation. The overall safety profile of SC administration was generally similar to that of IV administration, while systemic injection/infusion-related reactions were observed less frequently with SC administration (1.4%)** than with IV administration.

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.

* At-home, self-administration using LEQEMBI Pen will be possible after it is listed in the injectable drug list designated by the Minister of Health, Labour and Welfare that health insurance doctor can administer (or prescribe), following deliberation and approval by the Central Social Insurance Medical Council, in principle within 60 days after approval. In addition, the following points are stipulated to be observed when self-administering.

** Incidence in participants newly initiated on lecanemab treatment via SC administration, based on clinical data obtained from once-weekly subcutaneous administration of lecanemab 720 mg using vial formulations.

Notes to Editors

References