Eisai and Biogen Inc. have announced that China’s National Medical Products Administration (NMPA) has approved the Subcutaneous Autoinjector (SC-AI) formulation of Leqembi (lecanemab) as an initiation treatment for patients with mild cognitive impairment due to Alzheimer’s disease or mild Alzheimer’s dementia.

The approval provides a new once-weekly, self-administered treatment option alongside the existing intravenous (IV) administration every two weeks in a hospital setting. The approved SC-AI regimen is 500 mg once weekly, administered as two consecutive 250 mg injections. Patients can also switch between IV and subcutaneous administration during treatment.

The SC-AI formulation is designed to reduce administration time and the burden of hospital visits for patients and care partners. Each injection takes approximately 15 seconds, while at-home administration could provide greater flexibility and potentially reduce healthcare resources associated with IV infusion.

The approval is based on integrated data from the Phase 3 Clarity AD study and multiple subcutaneous administration studies. Once-weekly 500 mg SC administration demonstrated exposure comparable to biweekly IV treatment, with similar clinical and biomarker benefits. The overall safety profile was generally consistent with IV administration, although injection-related reactions were observed with subcutaneous dosing.

Leqembi targets amyloid-beta (Aβ) protofibrils and plaques and is designed to slow disease progression in early Alzheimer’s disease. In the Clarity AD study, IV lecanemab slowed clinical decline by 27 percent compared with placebo at 18 months.

China represents a significant market for Alzheimer’s treatment, with Eisai estimating approximately 17 million people with MCI or mild dementia due to Alzheimer’s disease in 2024. Leqembi was launched in China in June 2024.

The Chinese approval marks the second country globally to approve the Leqembi SC-AI initiation regimen. Eisai leads global development and regulatory submissions, while Eisai and Biogen jointly commercialise and promote the medicine, with Eisai retaining final decision-making authority.