Eisai Co.,  and Biogen announced that the U.S. Food and Drug Administration (FDA) has accepted Eisai’s Supplemental Biologics License Application (sBLA) for monthly lecanemab-irmb (U.S. brand name: LEQEMBI^®) intravenous (IV) maintenance dosing. A Prescription Drug User Fee Act (PDUFA) action date is set for January 25, 2025. 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 proposed monthly IV maintenance regimen, the patients who have completed the biweekly IV initiation phase, 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. The sBLA is based on modeling of observed data from the Phase 2 study (Study 201) and its open-label extension (OLE) as well as the Clarity AD study (Study 301) and its OLE study.

AD is a progressive disease caused by toxic amyloid proteins. Once established, this pathophysiological process continues through the patient’s life and therefore sustained treatment may be necessary. In those who are eligible, treatment should be initiated after diagnosis as early as possible to maximize patient outcomes. Data from Studies 201, 301 and their OLEs show that continued treatment with LEQEMBI beyond the 18-month core phase prolongs the benefit as highly toxic protofibrils are continuously removed. If the sBLA is approved, the clinical and biomarker benefits may be maintained through the once-monthly dosing regimen that is less burdensome and easier for patients and care partners to continue long-term.

Additionally, Eisai initiated the rolling submission of a BLA to the FDA for the LEQEMBI subcutaneous autoinjector for weekly maintenance dosing after it was granted Fast Track designation by the FDA in May 2024.

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

Eisai serves as the lead for lecanemab’s development and regulatory submissions globally with both Eisai and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making authority.

* Protofibrils are believed to contribute to the brain injury that occurs with AD and are considered to be the most toxic form of Aβ, having a primary role in the cognitive decline associated with this progressive, debilitating condition.¹ Protofibrils cause injury to neurons in the brain, which in turn, can negatively impact cognitive function via multiple mechanisms, not only increasing the development of insoluble Aβ plaques but also increasing direct damage to brain cell membranes and the connections that transmit signals between nerve cells or nerve cells and other cells. It is believed the reduction of protofibrils may prevent the progression of AD by reducing damage to neurons in the brain and cognitive dysfunction.²