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FDA Approves Once-Monthly Lecanemab-irmb Dosing for Early Alzheimer Disease

FDA buildingThe US Food and Drug Administration (FDA) has approved a supplemental biologics license application for lecanemab-irmb (Leqembi, Eisai Co., Ltd.; Biogen Inc.), an intravenous treatment (IV) for early Alzheimer disease (AD). Lecanemab-irmb is indicated for patients with mild cognitive impairment (MCI) or mild dementia due to AD.

The new approval introduces a once-monthly (every 4 week) maintenance dosing regimen as an alternative to the biweekly 10-mg/kg dosing regimen following an 18-month initiation phase.

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Lecanemab-irmb targets beta-amyloid protofibrils and plaques, toxic contributors to AD-related neuronal damage. Data from the Clarity AD study (phase 3) and Study 201 (phase 2) demonstrated slowed disease progression and maintenance of clinical benefits during extended treatment. In the Clarity AD trial, lecanemab-irmb reduced cognitive decline, with a mean difference of −0.45 (P<.0001) in the Clinical Dementia Rating–Sum of Boxes (CDR-SB) score compared with placebo after 18 months. Over 3 years of bi-weekly treatment, lecanemab-irmb reduced cognitive decline by −0.95 compared with a matched natural history cohort.

Contraindications and Warnings

Lecanemab-irmb IV is contraindicated in patients with hypersensitivity to lecanemab-irmb or its excipients. A boxed warning highlights the risk of amyloid-related imaging abnormalities (ARIA), including ARIA with edema (ARIA-E) and ARIA with hemosiderin deposition (ARIA-H). Symptomatic ARIA occurred in 3% of patients and serious ARIA symptoms in 0.7% with lecanemab-irmb IV. Clinical ARIA symptoms resolved in 79% of patients during the period of observation. ApoE ε4 homozygous individuals, representing approximately 15% of patients with AD, have an increased risk of ARIA. Baseline and periodic MRI monitoring are recommended to detect ARIA.

Adverse Reactions

Adverse reactions reported in at least 5% of patients receiving lecanemab-irmb include infusion-related reactions (26%), ARIA-H (14%), ARIA-E (13%), headache (11%), and rash (6%). Infusion-related reactions, primarily mild to moderate, occurred predominantly during the first infusion.

Reference

FDA approves IV maintenance dosing of LEQEMBI (lecanemab-irmb) for the treatment of early Alzheimer’s disease in the US. News release. PR Newswire. January 26, 2025. Accessed January 28, 2025.