FDA Approves Subcutaneous Lecanemab Injection for Maintenance Dosing in Early Alzheimer Disease

Key Takeaways

The FDA approved a subcutaneous form of lecanemab for maintenance dosing in early Alzheimer's disease, enhancing treatment accessibility.
Lecanemab targets beta-amyloid, reducing cognitive decline without reversing memory loss, and is administered via a 15-second injection.
The Clarity AD study confirmed the safety and efficacy of subcutaneous lecanemab, with common adverse events including infusion-related reactions and amyloid-related imaging abnormalities.
The treatment was generally well-tolerated, with no deaths in the core study and a few potentially treatment-related deaths in the open-label extension.

The subcutaneous injection for maintenance treatment enhances accessibility and reduces infusion time for patients.

The FDA approved the biologics license application for once-weekly lecanemab irmb subcutaneous injection (Leqembi Iqlik; Eisai, Co., Ltd.) for maintenance dosing to treat Alzheimer disease in patients with mild cognitive impairment or mild dementia stage of the disease. Following 18 months of lecanemab intravenous (IV) treatment at 10 mg/kg every 2 weeks, patients may continue IV infusions at 10/mg once every 4 weeks, or this weekly 360 mg subcutaneous injection administered via an autoinjector.¹

Image credit: HalynaRom | stock.adobe.com

About the Trial

Trial Name: A Study to Confirm Safety and Efficacy of Lecanemab in Participants With Early Alzheimer's Disease (Clarity AD)

ClinicalTrials.gov ID: NCT03887455

Sponsor: Eisai Inc.

Completion Date (Estimated): May 26, 2027

Lecanemab is an antibody IV infusion therapy that targets and removes beta-amyloid from the brain. There is no evidence that lecanemab restores or reverses lost memories or cognitive function; rather, it reduces cognitive and functional decline in patients, according to the Alzheimer’s Association. It previously received approval for the treatment of early Alzheimer disease, including those with mild cognitive impairment (MCI) or mild dementia due to Alzheimer disease who have confirmation of elevated beta-amyloid in the brain. On January 26, 2025, the FDA approved maintenance dosing of lecanemab once every 4 weeks for early Alzheimer disease.^1-3

Initially, treatment was administered via an IV, lasting an hour for each infusion. This new administration method allows for the agent to be injected in approximately 15 seconds, addressing a crucial need for accessibility and reducing the time burden surrounding IV infusions.^1,3

For the subcutaneous maintenance dosing, the initial biologics license application is based on data from the Clarity AD (study 301) open-label extension (OLE; NCT03887455)⁴ and modeling of observed data. The placebo-controlled, double-blind, parallel-group trial confirmed the efficacy and safety of subcutaneous lecanemab in patients with early Alzheimer disease, and the OLE portion evaluated whether the long-term safety and tolerability as measured by the Clinical Dementia Rating-Sum of Boxes (CD-RSB) at the end of the core study is maintained throughout the OLE’s duration.

The OLE’s primary end points were the frequency of treatment-emergent adverse events (TEAEs) and change from core study baseline in CDR-SB. Updated safety results were published in Alzheimer’s Research & Therapy.^4,5

A total of 1795 patients from the core study and 1612 patients with at least 1 dose of lecanemab (both core study and OLE) were included. Generally, lecanemab was well-tolerated throughout Clarity AD’s duration, with no deaths in the core study and 9 deaths in the OLE; however, only 4 of these were considered to be potentially related to treatment with lecanemab.

Further, in the core and OLE portions, the most common AEs in the lecanemab group (> 10%) were infusion-related reactions (24.5%), amyloid-related imaging abnormalities (ARIA) with hemosiderin deposits (ARIA-H) microhemorrhages (16.0%), COVID-19 (14.7%), ARIA with edema (ARIA-E; 13.6%), and headache (10.3%). Both ARIA-E and ARIA-H were largely radiographically mild to moderate, wrote the investigators. Additionally, ARIA-E generally occurred within 3 to 6 months of treatment, was more common in ApoE e4 carriers (16.8%), and was most common in ApoE ε4 homozygous participants (34.5%).⁵

"Eisai's continued work to support and simplify patient and health care administration and treatment is an important work to help remove potential bottlenecks in health care and broaden patient population while supporting a sustainable long-term cost of treatment," Gunilla Osswald, CEO at BioArctic, said in the news release.¹

REFERENCES

1. PR Newswire. US FDA approves Leqembi® IQKLIK™ (lecanemab-irmb) subcutaneous injection for maintenance dosing for the treatment of early Alzheimer's disease. News release. August 29, 2025. Accessed September 2, 2025. https://www.prnewswire.com/news-releases/us-fda-approves-leqembi-iqklik-lecanemab-irmb-subcutaneous-injection-for-maintenance-dosing-for-the-treatment-of-early-alzheimers-disease-302542433.html

2. Eisai Global. FDA Accepts LEQEMBI® (lecanemab-irmb) Biologics License Application for Subcutaneous Maintenance Dosing for the Treatment of Early Alzheimer’s Disease. News release. January 15, 2025. Accessed August 28, 2025. https://www.eisai.com/news/2025/news202502.html

3. Alzheimer’s Association. Lecanemab Approved for Treatment of Early Alzheimer's Disease. News release. Accessed August 28, 2025. https://www.alz.org/alzheimers-dementia/treatments/lecanemab-leqembi

4. A Study to Confirm Safety and Efficacy of Lecanemab in Participants With Early Alzheimer's Disease (Clarity AD). ClinicalTrials.gov identifier: NCT03887455. Updated July 3, 2025. Accessed August 29, 2025. https://clinicaltrials.gov/study/NCT03887455

5. Honig LS, Sabbagh MN, van Dyck CH, et al. Updated safety results from phase 3 lecanemab study in early Alzheimer's disease. Alzheimers Res Ther. 2024;16(1):105. Published 2024 May 10. doi:10.1186/s13195-024-01441-8

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