Eisai shares rise as much as 4.4% FDA approves lecanemab-irmb

Eisai shares rise as much as 4.4% FDA approves lecanemab-irmb

Eisai Co., Ltd. and Biogen Inc. announced on August 29, 2025, that the U.S. Food and Drug Administration (FDA) has approved the Biologics License Application (BLA) for once-weekly lecanemab-irmb subcutaneous injection (U.S. brand name: LEQEMBI® IQLIK™) for maintenance dosing to treat early Alzheimer's disease (AD). This approval marks a significant milestone for Eisai and Biogen, as LEQEMBI IQLIK is the first and only anti-amyloid treatment to offer an at-home injection for patients and care partners.

The approval is based on the results of LEQEMBI subcutaneous (SC) sub-studies of the Phase 3 Clarity AD open-label extension (OLE) trial, which evaluated various subcutaneous doses. The trial demonstrated that transitioning to weekly LEQEMBI IQLIK autoinjector after 18 months of 10 mg/kg IV every two weeks maintained clinical and biomarker benefits comparable to continued IV dosing. Importantly, none of the 49 patients who received a weekly 360 mg subcutaneous maintenance dose experienced local or systemic injection-related adverse events (AEs) [1].

The safety profile of LEQEMBI IQLIK autoinjector was similar to that of the IV maintenance treatment, with systemic reactions much less common (less than 1% compared to approximately 26% with IV infusions). Approximately 11% of patients experienced mild-to-moderate local reactions, which did not interfere with continued administration, and less than 1% had mild systemic symptoms such as headache, fever, or fatigue. ARIA rates in patients who received the weekly 360 mg subcutaneous maintenance dose were similar to ARIA rates reported in patients who continued with the IV dose after 18 months and are similar to the background rates of ARIA in patients without treatment [1].

The approval of LEQEMBI IQLIK offers patients and care partners a new option for maintenance treatment, allowing them to administer the drug at home and continue slowing the progression of AD. This development also has the potential to reduce healthcare resources associated with IV maintenance dosing and increase infusion capacity for new eligible patients to begin initiation treatment.

Following the FDA approval, Eisai shares rose by as much as 4.4% on August 29, 2025, reflecting investor confidence in the company's Alzheimer's disease pipeline and the market potential for LEQEMBI IQLIK.

References:

[1] https://investors.biogen.com/news-releases/news-release-details/fda-approves-leqembir-iqliktm-lecanemab-irmb-subcutaneous