Eisai Co., Ltd. and Biogen Inc. (NASDAQ:BIIB) announced today that the National Medical Products Administration (NMPA) of China has approved the subcutaneous formulation (subcutaneous autoinjector: SC-AI), the anti-amyloid beta (Aβ) protofibril antibody LEQEMBI® (Chinese trademark: 乐意保®; generic name: lecanemab) as an initiation treatment for mild cognitive impairment (MCI) due to Alzheimer’s disease (AD) or mild AD dementia (collectively referred to as early AD). The application was accepted by the NMPA in January 2026 and was subsequently granted Priority Review designation. Launch is planned during Eisai’s FY 2026, ending March 31, 2027.

LEQEMBI SC-AI is a self-administered autoinjector formulation. The approved regimen is 500 mg given once weekly as two consecutive 250 mg injections. 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. Patients may also switch from IV to SC administration, or vice versa, during treatment.

LEQEMBI SC-AI may significantly reduce the time required 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 enable treatment options that better fit their lifestyles, providing greater flexibility for 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 SC-AI 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 AD treatment pathway. For ARIA (amyloid-related imaging abnormalities) 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 relentless disease with Aβ and tau as hallmarks, 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 second country globally to approve LEQEMBI SC-AI. 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 early AD, as well as multiple subcutaneous (SC) administration sub-studies (including the Chinese cohort) in its subsequent long-term extension (LTE). Once-weekly administration of SC-AI 500mg demonstrated exposure equivalent to once every two weeks IV administration, with similar clinical and biomarker benefits. The overall safety profile of SC administration was generally similar to that of IV administration. Injection-related reactions were observed with subcutaneous LEQEMBI, most of which were localized, while systemic reactions were less frequently observed.

Eisai estimates that there were 17 million patients with MCI or mild dementia due to AD in China in 2024, which is expected to increase as the population ages. LEQEMBI was launched in China in June 2024 and is leading the establishment of anti-amyloid therapy in AD management, expanding its contribution to patients with early AD.

Eisai serves as the lead of LEQEMBI development and regulatory submissions globally with Eisai and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making authority. Eisai will distribute the product in China and will conduct information provision activities through specialized medical representatives.