Lecanemab in early Alzheimer’s disease: extended efficacy results from the CLARITY AD study

<h3>Background</h3> In the CLARITY AD study, lecanemab was shown to reduce markers of amyloid and slow cognitive decline at 18 months in early Alzheimer’s disease (AD). Here, we report the initial findings from the open-label extension (OLE), including lecanemab’s efficacy over 24 months and the impact of baseline tau levels on the long-term treatment response. <h3>Methods</h3> Patients who completed 18 months of treatment during Clarity AD were eligible to enrol in the OLE. Assessments included Clinical Dementia Rating-Sum-of-Boxes (CDR-SB), AD Assessment Scale-Cognitive Subscale 14 (ADAS-Cog14), and amyloid positron emission tomography (PET). OLE results were analysed to evaluate clinical and biomarker outcomes. Tau sub-study participants’ OLE treatment response was assessed based on baseline tau levels. <h3>Results</h3> Differences between lecanemab and placebo across clinical endpoints were maintained with ongoing lecanemab through 24 months, relative to newly-treated lecanemab patients. Biomarker changes were seen as early as 3 months in newly-treated lecanemab patients in the OLE. Patients with low tau at core baseline continued to show benefits of lecanemab treatment beyond 18 months. <h3>Conclusions</h3> Efficacy of lecanemab treatment was extended through 24 months. The results of the delayed start and lower pathology group are consistent with disease modification and support early initiation of lecanemab.