In a significant development at the 2023 Clinical Trials on Alzheimer’s Disease (CTAD) conference, Eisai revealed promising results from an open-label extension (OLE) of the pivotal phase 3 Clarity AD study. The study highlighted the efficacy of a novel subcutaneous form of lecanemab (Leqembi), demonstrating a 14% increase in amyloid plaque removal compared to the biweekly intravenous (IV) administration method. This advancement has prompted Eisai to plan the submission of a biologics license application (BLA) for the subcutaneous formulation to the FDA by March 31, 2024.
The preliminary 6-month analysis of the OLE involved a subgroup of patients, including 72 who received lecanemab subcutaneously for the first time and 322 who transitioned from IV to subcutaneous administration. The findings showed reductions of –40.3 centiloids at 6 months for newly treated patients on subcutaneous lecanemab, compared to reductions of –35.4 centiloids for those on IV administration. Additionally, the weekly subcutaneous pharmacokinetic area under the curve (AUC) was 11% higher than the biweekly IV formulation.
Adverse events such as ARIA-edema and ARIA-H were observed in both administration methods, with slightly higher incidence rates in the subcutaneous group. However, Eisai noted that these comparisons were not exact due to the sample size. The company also highlighted that steady-state exposure was a better predictor of ARIA-E rates in subcutaneously delivered lecanemab, based on pharmacokinetic data.
Further findings from the Clarity AD study's open-label extension, involving patients treated for 24 months, indicated a potential disease-modifying effect of lecanemab. Changes in prominent biomarkers were observed as early as 3 months in newly treated participants, suggesting the treatment's efficacy in altering the course of Alzheimer’s disease.
