Subcutaneous Leqembi Autoinjector Gains FDA Approval for Maintenance Use in Early Alzheimer Disease: Daily Dose

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On September 1, 2025, we reported on the US approval of Leqembi Iqlik (lecanemab-irmb) as a once-weekly 360 mg subcutaneous autoinjector for maintenance dosing in patients with early Alzheimer disease (AD) following an initial 18-month course of intravenous (IV) therapy.

The approval

The new formulation will launch in the US on October 6, 2025, as the first antiamyloid treatment to provide an at-home injection option for patients with mild cognitive impairment or mild dementia due to AD.

The approval is based on substudies of the phase 3 Clarity AD open-label extension study, which evaluated a range of subcutaneous dosing regimens in more than 600 study participants. In 49 adults who transitioned to the weekly autoinjector after at least 18 months of biweekly 10 mg/kg IV therapy, safety and biomarker outcomes were comparable to continued IV dosing. None of these participants experienced local or systemic injection-related adverse events. Systemic reactions occurred in less than 1% of participants receiving subcutaneous treatment, compared with approximately 26% with IV infusions. About 11% experienced mild-to-moderate local injection site reactions, and less than 1% reported mild systemic symptoms such as headache, fever, or fatigue. Amyloid-related imaging abnormality rates were consistent between IV and subcutaneous regimens and aligned with background rates observed in untreated populations, with most events occurring during the first six months of IV initiation therapy.

Lecanemab is indicated for the treatment of AD disease and should be initiated only in persons with MCI or mild dementia, reflecting the populations enrolled in pivotal clinical trials.

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