Alzheimer's Drug LEQEMBI Subcutaneous Data Shows Similar Efficacy to IV Formulation

Eisai and Biogen announced new data at the Alzheimer's Association International Conference (AAIC) 2026 in London, suggesting the LEQEMBI® (lecanemab) subcutaneous autoinjector (SC-AI) formulation achieves comparable efficacy and safety to intravenous (IV) administration for patients with early Alzheimer's disease (AD).

The subcutaneous formulation was developed to provide a more convenient treatment option than IV infusions. Key findings from the development program showed that a once-weekly 500 mg SC-AI achieved drug exposure similar to the approved IV initiation regimen (10 mg/kg every two weeks). This supports the expectation of similar clinical efficacy and safety, regardless of the route of administration.

Data indicated that amyloid removal, clinical efficacy measured by CDR-SB, and the incidence of ARIA-E (amyloid-related imaging abnormalities with edema or lobar hemorrhage) were driven by lecanemab exposure rather than administration route. The overall safety profile of the SC-AI was found to be consistent with that observed for the IV formulation, with predicted similar rates of ARIA-E.

If approved by the U.S. Food and Drug Administration (FDA), the subcutaneous dosing for initiation could offer a convenient at-home alternative to IV infusion, potentially improving access and delivery of care across healthcare settings. The autoinjector system may also provide greater flexibility for patients and care partners, including the ability to switch between IV and SC administration and manage missed doses.