FDA Approves Subcutaneous Leqembi Autoinjector for Maintenance Therapy in Early Alzheimer Disease

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The FDA has approved 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.¹

Eisai and Biogen announced that 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.¹

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.²

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 (ARIA) 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.¹

“We believe LEQEMBI IQLIK provides a practical and patient-friendly option for those living with Alzheimer’s disease who have already benefited from therapy," Eisai CEO Haruo Naito said in a press statement. By enabling at-home treatment, we hope to lessen the burden of care and expand access to this important therapy.”¹

Clinical data from the Clarity AD core study demonstrated a mean difference of -0.45 points (P =.00005) on the Clinical Dementia Rating–Sum of Boxes (CDR-SB) after 18 months of IV therapy compared with placebo. At 4 years, participants treated with lecanemab had a reduction in cognitive decline of -1.75 points on CDR-SB relative to the expected trajectory from the Alzheimer’s Disease Neuroimaging Initiative cohort and -2.17 points compared with the BioFINDER cohort. These findings underscore the need for ongoing therapy, as discontinuation has been associated with biomarker reaccumulation and a return to the placebo rate of decline.¹

ADNI, launched in 2005, is a long-term observational study tracking healthy elderly participants, individuals with mild cognitive impairment, and patients with early-stage AD to improve prediction of disease onset and progression and to assess treatment effectiveness. BioFINDER, a large-scale longitudinal study led by Lund University in Sweden, similarly tracks biomarker and imaging changes in neurodegenerative disease but focuses on participants with MCI, excluding those with mild AD, and also studies Parkinson’s disease. Both cohorts provide real-world benchmarks for the rate of decline in untreated or minimally treated populations, helping contextualize the clinical outcomes reported in Clarity AD.¹

The device underwent additional human factors and tolerability testing to confirm safety and usability in a home setting. Eisai noted that the new option may reduce healthcare resource demands related to infusion center visits, potentially increasing capacity for new patients to initiate treatment. Support services will include dedicated patient navigators and injection training.¹

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, Eisai and Biogen stated.¹

References:

1. Eisai Co, Ltd; Biogen Inc. FDA approves LEQEMBI® IQLIK™ (lecanemab-irmb) subcutaneous injection for maintenance dosing for the treatment of early Alzheimer’s disease [news release]. August 30, 2025. Accessed August 30, 2025. https://investors.biogen.com/news-releases/news-release-details/fda-approves-leqembir-iqliktm-lecanemab-irmb-subcutaneous
2. Jennings S. Lecanemab Shows Sustained Benefit at 4 Years in Early Alzheimer Disease: AAIC 2025. Patient Care®. August 1, 2025. https://www.patientcareonline.com/view/lecanemab-shows-sustained-benefit-at-4-years-in-early-alzheimer-disease-aaic-2025