FDA Priority Review of Subcutaneous Lecanemab Signals Shift in Alzheimer’s Treatment Delivery

FDA has accepted a supplemental biologics license application (sBLA) for lecanemab-irmb (US brand name Leqembi) as a subcutaneous starting dose for treating early Alzheimer’s disease, granting the sBLA priority review. The application covers use of a subcutaneous autoinjector, branded as Leqembi Iqlik, with an FDA action date set for May 24, 2026.

If approved, the new dosing option could represent a shift in how disease-modifying Alzheimer’s therapies are initiated and maintained in clinical practice (1). Lecanemab is indicated for patients with mild cognitive impairment or mild dementia due to Alzheimer’s disease.

The supplemental application seeks approval of a 500 mg weekly subcutaneous (SC) starting regimen, administered as two 250 mg injections, as an alternative to the currently approved biweekly intravenous dosing used during treatment initiation. The proposed approach would allow patients to use SC administration at home for both starting and maintenance therapy, which is currently approved at a 360 mg weekly SC dose following an initial intravenous (IV) phase (1).

Priority review status is intended for therapies that could offer significant improvements in safety or effectiveness. In this case, regulatory acceptance reflects growing attention to delivery methods that may reduce treatment burden for patients and caregivers while maintaining clinical benefit.

What evidence supports subcutaneous initiation of lecanemab therapy?

The sBLA is supported by data evaluating SC administration of lecanemab across multiple dose levels, including analyses from sub-studies within the Phase III Clarity AD open-label extension that followed the 18-month core study in individuals with early Alzheimer’s disease. According to the data submitted, once weekly SC administration of 500 mg achieved exposure comparable to biweekly IV dosing, with similar clinical and biomarker outcomes, according to the company (1).

Eisai reported that safety findings from these evaluations showed a profile consistent with IV administration. According to the company, less than 2% of patients experienced systemic injection- or infusion-related reactions, and overall tolerability was comparable between routes of administration.

These findings are notable as anti-amyloid therapies have required close monitoring during IV infusions, which can limit flexibility in treatment delivery (2). The autoinjector for the SC format is designed for rapid administration, with each 250 mg injection taking approximately 15 seconds, Eisai stated in a company press release (1).

From a development and manufacturing perspective, SC delivery also has the potential to reduce reliance on infusion infrastructure, including preparation time and nursing oversight, factors that have influenced real-world uptake of infused biologics in neurodegenerative disease (3).

Why does at-home administration matter for Alzheimer’s drug development?

Alzheimer’s disease is characterized by a continuous neurotoxic process involving amyloid beta and tau pathology. Lecanemab targets amyloid beta protofibrils as well as amyloid plaque, a mechanism intended to intervene earlier in the disease cascade.

While efficacy and safety remain central considerations, route of administration is increasingly viewed as a determinant of scalability as disease-modifying therapies move into broader patient populations (1). From an industry standpoint, the ability to initiate and maintain treatment outside of infusion centers could lower healthcare resource utilization and expand access, particularly as health systems prepare for increased demand for Alzheimer’s therapies.

SC options may also influence how future biologics for neurodegenerative diseases are designed, with delivery convenience considered earlier in development (4). Lecanemab is currently approved in more than 50 countries and regions, with additional regulatory reviews ongoing globally.

In August 2025, FDA approved the SC autoinjector for weekly maintenance dosing following 18 months of IV therapy, establishing a regulatory precedent for expanded use of this delivery format (1).

As regulators evaluate the supplemental application, the decision may signal how receptive agencies are to alternative dosing strategies that preserve clinical performance while addressing real-world implementation challenges. For developers of central nervous system biologics, the outcome could shape future investment in device-enabled formulations and patient-centered administration models (1,4).

References

1. Eisai. FDA Accepts LEQEMBI IQLIKTM (lecanemab-irmb) Supplemental Biologics License Application as a Subcutaneous Starting Dose for the Treatment of Early Alzheimer's Disease under Priority Review. Press Release. Jan. 25, 2026.
2. Penner, N.; Rawal, S.; Aluri, J.; et al. Development of Subcutaneous Lecanemab: Establishing the Comparability of Subcutaneous and Intravenous Lecanemab Formulations. Alzheimer's Dementia 2025, 21 (Suppl 5), e104694. DOI: 10.1002/alz70859_104694
3. Chen, J.; Lin, B.; Seow, E.; et al. Prediction of Infusion Capacity to Deliver Alzheimer's Disease Treatments in the United States Relative to Expected Demand. J Alzheimers Dis. 2025, 107 (4), 1567–1574. DOI: 10.1177/13872877251372129
4. Tahami Monfared, A. A.; Barrows, S.; Fox, L.; et al. Societal Costs and Efficiency of Subcutaneous versus Intravenous Lecanemab in Early Alzheimer's Disease: A US Cost Comparison Model. Neurol Ther. 2025, 14 (5), 1863–1888. DOI: 10.1007/s40120-025-00790-2