Lecanemab, an antibody directed at Aβ-protofibrils and plaque, showed meaningful delay in disease progression and biological effects consistent with disease modification in the phase 3 Clarity AD trial.

The objective of this paper is to present efficacy and safety results in ApoE ε4 non-carriers or heterozygotes population of Clarity AD.

Clarity AD is an 18-month, randomized study (core) in participants with early AD, with an open-label extension phase (OLE) phase.

Academic and clinical centers.

All eligible ApoE ε4 participants were randomized 1:1 across 2 treatment groups (placebo and lecanemab 10 mg/kg biweekly); the results presented herein are for the ApoE4 heterozygote or non-carrier participants.

Endpoints included change from baseline at 18 months in the global cognitive and functional scale, CDR-SB, amyloid positron emission tomography (PET), Alzheimer’s Disease Assessment Scale-Cognitive Subscale 14 (ADAS-Cog14), Alzheimer's Disease Cooperative Study-Activities of Daily Living Scale for Mild Cognitive Impairment (ADCS-MCI-ADL), and health-related quality-of-life (HRQoL) assessments. Amyloid imaging related abnormalities (ARIA) occurrence was monitored throughout the study by central reading of magnetic resonance imaging. Following 18 months treatment in the Core, eligible participants transitioned to the OLE where they received open-label lecanemab. Clinical outcomes (CDR-SB, ADAS-Cog14, and ADCS-MCI-ADL) were evaluated by examining ‘delayed start’ (core:placebo followed by OLE:lecanemab) and ‘early start’ (core:lecanemab followed by OLE:lecanemab) cohorts as well as natural history cohorts. Time to progression to next stage of AD was also evaluated through 36 months.

1,795 participants with early AD were enrolled in Clarity AD, of which 1,521 were ApoE ε4 heterozygotes or non-carriers (85%). Lecanemab significantly reduced clinical decline on CDR-SB at 18 months compared to placebo in the ApoEε4 heterozygotes or non-carriers subgroup. Amyloid PET, ADAS-Cog14, ADCS-MCI-ADL, and HRQoL results were consistent with the CDR-SB findings. In the analysis subgroup, the most common adverse reactions for lecanemab were infusion-related reactions (26%), ARIA-H (13%), fall (11%), headache (11%), and ARIA-E (9%). In the OLE, lecanemab-treated participants continued to accrue benefit in CDR-SB through 36 months, with continued separation through 36 months relative to the ADNI natural history cohort. Delayed start results follow a parallel trajectory relative to early start results, but do not catch up, confirming a disease modifying effect and reflecting importance of early treatment initiation. Results were similar for ADAS-Cog14 and ADCS-MCI-ADL. Lecanemab reduced the risk of progression to next stage of AD by 28% on lecanemab as compared to the ADNI natural history cohort.

In the ApoE ε4 heterozygotes or non-carrier subgroup of Clarity AD, lecanemab slowed decline in disease progression and reduced markers of amyloid, with expanding benefit over time.

Clarity AD NCT03887455