Eisai and Biogen Win China Approval for LEQEMBI SC

Tokyo, Japan and Cambridge, Massachusetts, USA, September 3, 2026

LEQEMBI SC Enables Weekly At-Home Treatment

The newly approved LEQEMBI SC-AI is a self-administered autoinjector designed to deliver 500 mg once weekly, administered as two consecutive 250 mg injections. This provides an alternative to the currently available intravenous administration every two weeks in a hospital environment. Patients receiving LEQEMBI may also have the option to switch between intravenous and subcutaneous administration during treatment, providing additional flexibility as their treatment needs and circumstances change. Each 250 mg autoinjector injection takes approximately 15 seconds, potentially substantially reducing the time associated with conventional infusion-based administration. The at-home option could also reduce the frequency of clinic visits for patients and care partners and may help streamline healthcare resources associated with intravenous treatment.The development of a subcutaneous formulation addresses an important practical consideration in long-term Alzheimer’s disease treatment. Anti-amyloid therapies require repeated administration and monitoring, meaning treatment logistics can influence the experience of patients and their care partners. By enabling administration outside a hospital setting, LEQEMBI SC-AI is intended to provide greater flexibility while maintaining a treatment schedule designed to deliver consistent exposure. However, brain MRI monitoring remains required before treatment initiation and at specified time points following initiation to monitor for amyloid-related imaging abnormalities (ARIA), an established safety consideration associated with anti-amyloid antibody therapy.

Lecanemab Targets Amyloid-Beta in Early Alzheimer’s

Lecanemab is a humanized IgG1 monoclonal antibody directed against aggregated soluble amyloid-beta (Aβ) protofibrils and insoluble forms of Aβ, including amyloid plaques. The therapy is designed to remove amyloid pathology associated with Alzheimer’s disease and is intended for patients in the early stages of disease, when intervention may have greater potential to influence the course of cognitive and functional decline. The regulatory foundation for LEQEMBI includes data from the global Phase 3 Clarity AD study, a randomized, double-blind, placebo-controlled trial involving 1,795 patients with early Alzheimer’s disease. The study met its primary endpoint and all key secondary endpoints with statistically significant results. The Chinese approval of the subcutaneous initiation formulation was based on integrated evidence from the 18-month Clarity AD study, additional subcutaneous administration studies, including a Chinese cohort, and associated pharmacokinetic modeling and simulation. According to the companies, the once-weekly 500 mg SC-AI regimen produced exposure equivalent to intravenous administration every two weeks, while demonstrating similar clinical and biomarker benefits. The overall safety profile of subcutaneous administration was generally consistent with the established intravenous formulation, although injection-related reactions were observed, most commonly localized reactions.

China Expands Access to Anti-Amyloid Therapy

The NMPA decision represents the second global approval of LEQEMBI SC-AI as an initiation treatment, according to Eisai and Biogen. LEQEMBI itself was launched in China in June 2024, establishing an anti-amyloid treatment option for eligible patients with early Alzheimer’s disease. Eisai estimates that approximately 17 million people in China had MCI or mild dementia due to Alzheimer’s disease in 2024, with the number expected to increase as the population ages. The new formulation could therefore provide an additional treatment pathway for a substantial patient population requiring repeated disease-modifying therapy. The companies are continuing to expand the availability and flexibility of lecanemab treatment globally. LEQEMBI has been approved in numerous countries and regions, while additional formulations and dosing approaches remain under regulatory review in other markets. In the United States, the FDA approved LEQEMBI IQLIK for subcutaneous maintenance dosing in August 2025, while approval for subcutaneous initiation treatment was obtained in July 2026. These developments reflect the broader evolution of anti-amyloid therapy from hospital-based infusion toward more flexible administration models. For Alzheimer’s disease drug development, the China approval highlights the importance of not only demonstrating clinical efficacy and safety, but also developing practical administration options that can support long-term treatment. LEQEMBI SC-AI provides a new route for initiating anti-amyloid therapy while retaining the ability to transition between subcutaneous and intravenous treatment. As Eisai and Biogen prepare the Chinese launch, the new formulation could further shape how early Alzheimer’s disease treatment is delivered in routine care.

Source: Eisai, Biogen press release