Eisai has submitted a supplemental Biologics License Application (sBLA) for monthly lecanemab-irmb intravenous (IV) maintenance dosing to the US Food and Drug Administration (FDA).

Leqembi is indicated for the treatment of Alzheimer's disease (AD) in patients with mild cognitive impairment or mild dementia stage of disease (collectively referred to as early AD). 

As part of the monthly IV maintenance regimen, the patients who have completed the biweekly IV initiation phase, the exact period under discussion with the FDA, would receive a monthly IV dose that maintains effective drug concentration to sustain the clearance of highly toxic protofibrils which can continue to cause neuronal injury even after the amyloid-beta (Aβ) plaque has been cleared from the brain.

The sBLA is based on the modeling of observed data from the Phase 2b study (Study 201) and its open-label extension (OLE) as well as the Clarity AD study (Study 301) and its OLE study. 

Eisai had aimed to submit a Biologics License Application (BLA) for weekly maintenance therapy using subcutaneous (SC) administration in March 2024. To respond to the FDA's recent requirement of additional three-month immunogenicity data at the proposed maintenance dose of 360 mg weekly, Eisai planned to initiate a rolling BLA for lecanemab SC maintenance in the first quarter 2024, under lecanemab's existing Fast Track and Breakthrough Therapy designations.

However, Eisai was recently informed by the FDA that a Fast Track designation specific to the SC formulation is needed to receive rolling review. Following the guidance, Eisai submitted a request for Fast Track designation for the SC formulation and will initiate a rolling submission should the FDA grant this designation. The Fast Track designation will be determined within 60 days from the March 2024 submission.

AD is an ongoing neurotoxic process that begins before and continues after plaque deposition. There is an urgency to treat early AD because early and ongoing treatment can slow the progression of AD and continuing treatment may prolong the benefit even after plaque is cleared from the brain. The earlier Mild Cognitive Impairment (MCI) due to AD and mild AD dementia are diagnosed and treated, the greater the opportunity for the patient to benefit. Continued maintenance dosing is intended to maintain the clinical and biomarker benefits with a dosing regimen that may be more convenient for some patients and their care partners.

Leqembi is now approved in the US, Japan and China, and applications have been submitted for review in the European Union, Australia, Brazil, Canada, Hong Kong, Great Britain, India, Israel, Russia, Saudi Arabia, South Korea, Taiwan, Singapore, and Switzerland.

The drug is the result of a long-standing collaboration between BioArctic and Eisai, and the antibody was originally developed by BioArctic based on the work of Professor Lars Lannfelt and his discovery of the Arctic mutation in Alzheimer's disease.

Eisai serves as the lead of lecanemab development and regulatory submissions globally with both Eisai and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making authority. BioArctic has the right to commercialize lecanemab in the Nordic region, pending European approval, and currently, Eisai and BioArctic are preparing for joint commercialization in the region.