Eisai Co., Ltd. and Biogen Inc. have announced a key regulatory milestone for their Alzheimer’s disease therapy lecanemab-irmb, marketed in the United States as LEQEMBI®. The U.S. Food and Drug Administration (FDA) has accepted Eisai’s Supplemental Biologics License Application (sBLA) for review, covering a new subcutaneous autoinjector formulation known as LEQEMBI IQLIK. The application has been granted Priority Review, with a Prescription Drug User Fee Act (PDUFA) decision date set for May 24, 2026.
The submission seeks approval of a 500 mg subcutaneous dosing regimen—administered as two 250 mg injections—designed to be used as a once-weekly starting dose for patients. If approved, this option would provide an alternative to the current bi-weekly intravenous (IV) infusion used at treatment initiation. Importantly, it would allow patients with early Alzheimer’s disease, including those with mild cognitive impairment or mild dementia, to begin and continue treatment using subcutaneous injections at home, rather than relying exclusively on clinic-based IV infusions.
According to the companies, the LEQEMBI IQLIK autoinjector delivers each 250 mg injection in approximately 15 seconds, potentially improving convenience for patients and caregivers. The subcutaneous option could also reduce healthcare resource demands associated with IV administration, such as infusion preparation, chair time, and nurse monitoring, while simplifying the overall treatment pathway for Alzheimer’s disease.
The sBLA is supported by clinical data from studies evaluating subcutaneous administration of lecanemab across multiple doses, including sub-studies within the Phase 3 Clarity AD open-label extension following the 18-month core trial. Results showed that once-weekly 500 mg subcutaneous dosing achieved drug exposure comparable to bi-weekly IV dosing, with similar clinical and biomarker outcomes. Safety findings were also consistent with the IV formulation, with systemic injection- or infusion-related reactions occurring in fewer than 2% of patients.
LEQEMBI targets Alzheimer’s disease by addressing both amyloid beta protofibrils and amyloid plaques—key pathological features of the disease that are linked to downstream tau pathology and cognitive decline. Protofibrils are believed to be among the most neurotoxic forms of amyloid beta, contributing directly to neuronal and synaptic damage.
The therapy is currently approved in 53 countries and regions and remains under regulatory review in seven additional markets. In August 2025, the FDA approved LEQEMBI IQLIK 360 mg for weekly subcutaneous maintenance dosing following 18 months of bi-weekly IV treatment.
Eisai leads global development and regulatory submissions for lecanemab, while Eisai and Biogen jointly commercialize and promote the product. The companies say the potential approval of a weekly subcutaneous starting dose could represent a meaningful step forward in expanding treatment flexibility and access for patients living with early Alzheimer’s disease.