New Findings on LEQEMBI® as a Subcutaneous Treatment for Early Alzheimer's Disease

The Alzheimer’s Association International Conference (AAIC) 2025, held in Toronto and virtually, recently showcased significant new data from Eisai Co., Ltd. and Biogen Inc. regarding LEQEMBI® (lecanemab-irmb), aimed at transforming treatment methodologies for early-stage Alzheimer's disease.

The investigational treatment evaluated focused on a 360 mg subcutaneous (SC) maintenance dosing via an autoinjector. This treatment is being positioned as a promising alternative to intravenous (IV) therapy, with early data suggesting comparable efficacy and safety profiles to established intravenous formulations, highlighting a significant step in Alzheimer’s care innovation.

The Transition from IV to SC Dosing

The importance of ongoing treatment for Alzheimer's disease (AD) cannot be overstated, given that biomarkers related to the disease may reemerge once therapy is halted. Therefore, Eisai is proactively exploring this new SC maintenance option following an initial 18 months of IV therapy, enabling patients to potentially maintain their quality of life longer against this relentless condition.

Evidences supporting this transition were drawn from sub-studies of an open-label extension following the Phase 3 Clarity AD study. This investigational SC option permits flexibility in administration—an aspect crucial for patients and caregivers. The study utilized evaluations of various doses conducted through both SC vials and autoinjectors, reflecting a comprehensive approach to determine optimal dosing strategies.

Efficacy and Safety Highlights

The findings indicate that transitioning to a 360 mg SC autoinjector (AI) after an IV initiation dose of 10 mg/kg biweekly maintains clinical and biomarker benefits that align closely with ongoing IV dosing routines. Specific outcomes from the research indicated that both amyloid-positive and negative patients exhibited similar responses after 48 months into the treatment, reinforcing the versatility of the lecanemab AI in effectively managing early Alzheimer’s disease symptoms.

A particularly striking finding is the demonstrated safety profile of the SC 360 mg weekly maintenance dosing, revealing that adverse reactions occurred in less than 1% of cases—an impressive reduction compared to the 26% encounter rates associated with IV deliveries. Additionally, no occurrences of ARIA-E (amyloid-related imaging abnormalities) were reported, showcasing the potential safety advantages of the SC formulation.

User-Friendliness of the SC-AI Device

To optimize the use of the SC autoinjector, extensive studies culminated in positive user feedback. The human factors study involved 110 participants, including early AD patients, care partners, and healthcare professionals. An overwhelming 95% of participants successfully self-administered the maintenance dose, highlighting the promising ease of use and accessibility that could greatly enhance treatment adherence.

An acceptability study involving 126 participants echoed these sentiments, where the majority reported satisfaction with the device's convenience, ease of administration, and its ability to lessen the burden of frequent clinical visits. The autonomous use of the device within home settings allowed patients to maintain their treatment without the stress of invasive procedures—an embrace of self-management that resonates well with modern health care philosophies.

Future Directions for Lecanemab

This remarkable data underscores the transformative potential of the lecanemab investigational SC-AI, suggesting a significant paradigm shift in how Alzheimer’s disease may be managed going forward. Easier administration, lower risk of adverse effects, and the ability to engage more regularly at home could contribute substantially to the patient experience, providing healthcare professionals with a powerful tool to support their ongoing treatment plans.

Eisai continues to lead the charge in developing lecanemab, working collaboratively with Biogen to ensure broad accessibility of this potentially life-altering therapy. As evolving studies seek to refine and perfect the formulation and its delivery, hope remains high for countless patients and their families grappling with the consequences of early-stage Alzheimer’s disease.