FDA Approves Lecanemab Subcutaneous Formulation as Maintenance Dose for Alzheimer Disease

The FDA approved lecanemab (Leqembi; Leqembi Iqlik) as a subcutaneous formulation as a weekly maintenance dose after the 18-month intravenous (IV) phase to treat Alzheimer disease (AD) for patients with mild cognitive impairment or the mild dementia stage of the disease. The autoinjector is expected to launch October 6, 2025.^1,2

"This shift to subcutaneous maintenance dosing is a crucial step toward making Leqembi more accessible for patients, similar to how diabetes and GLP-1 [glucagon-like peptide-1] medications are delivered, and represents the first step toward the day when patients can bypass infusions altogether," Howard Fillit, MD, cofounder and chief science officer at the Alzheimer’s Drug Discovery Foundation, said in a news release.¹ "This milestone lessens the burden on patients and caregivers by reducing the logistical challenges of receiving Alzheimer treatment, while also bringing us closer to the day when patients can more easily receive a combination of drugs, potentially administered from home."

After 18 months of IV treatment at 10 mg/kg every 2 weeks, patients have the option to continue the infusion at 10 mg/kg every 4 weeks or use the weekly
360-mg subcutaneous injection. The approval was based on data from substudies to the phase 3 Clarity AD (NCT03887455), an open-label extension trial for individuals with early-stage AD. Investigators evaluated a range of doses, and data showed the transition to the weekly autoinjector after 18 months maintained clinical and biomarker benefits compared with continued IV dosing. There were 49 patients who received the weekly 360-mg subcutaneous maintenance dose, and no patient experienced local or systemic injection-related adverse events (AEs).^2,3

The safety of the autoinjector was studied in approximately 600 patients, and investigators found that the safety profile was similar to maintenance IV treatment. However, the data showed that systemic reactions were less common with subcutaneous dosing, with less than 1% of patients experiencing systemic AEs compared with 26% for the IV infusion. Further, 11% of patients experienced mild-to-moderate local reactions, including redness, swelling, and itching at the injection site, and the AEs did not interfere with administration. Less than 1% of patients had mild systemic symptoms, including headache, fever, or fatigue.³

Additionally, investigators reported on amyloid-related imaging abnormalities (ARIA) rates for the 360-mg injection. They found that the ARIA rates were similar to the rates for patients who continued the IV dose after 18 months. The investigators also reported that the background rates of ARIA were also similar to those of patients without treatment.³

"We've long known that Alzheimer is not a 1-target disease, and the future lies in precision combination therapies tailored to each patient based on their individual biomarker profiles," Fillit said in the news release.¹ "Subcutaneous delivery is more than an upgrade—it's a gateway to the next generation of Alzheimer care, accelerating our ability to bring effective, multimodal treatment regimens to the millions of patients who need them."

READ MORE: Neurology Resource Center

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REFERENCES

1. FDA approval of Leqembi subcutaneous formulation charts path to combination therapies for Alzheimer's disease. News release. Alzheimer’s Drug Discovery Foundation. August 29, 2025. Accessed September 2, 2025. https://prnmedia.prnewswire.com/news-releases/fda-approval-of-leqembi-subcutaneous-formulation-charts-path-to-combination-therapies-for-alzheimers-disease-302542469.html

2. US FDA approves Leqembi Iqlik (lecanemab-irmb) subcutaneous injection for maintenance dosing for the treatment of early Alzheimer's disease. News release. Eisai Inc. August 29, 2025. Accessed September 2, 2025. https://prnmedia.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

3. FDA approves Leqembi Iqklik (lecanemab-irmb) subcutaneous injection for maintenance dosing for the treatment of early Alzheimer's disease. News release. Biogen. August 29, 2025. Accessed September 2, 2025. https://investors.biogen.com/news-releases/news-release-details/fda-approves-leqembir-iqliktm-lecanemab-irmb-subcutaneous