At the AD/PD 2023 International Conference on Alzheimer’s disease (AD) and Parkinson’s disease (PD), Eisai and Biogen presented new data from their Leqembi (lecanemab) clinical programme taken during a March 30 session on amyloid beta (Aβ) and tau targeting therapies in AD. As part of this session, new data was presented from the Phase III Clarity AD study (NCT03887455) on quality of life (QoL) for both patients and caregivers.

Leqembi received accelerated approval from the FDA for the treatment of early AD in January 2023, and the companies have also submitted an application for full approval based on data from its Phase III Clarity AD study. In that study, treatment with lecanemab resulted in a reduction in clinical decline of 27% compared with placebo at 18 months of treatment, as measured by the primary endpoint Clinical Dementia Rating-Sum of Boxes (CDR-SB). Although an important step forward in treatment for AD, a 27% reduction in clinical decline is still considered only a modest improvement by many. However, QoL data presented at AD/PD 2023 enhances the demonstration of benefits of the therapy as felt by both patients and caregivers, adding value to the drug.

Three different health related QoL exploratory endpoints were used in the Clarity AD trial: European Quality of Life-5 Dimensions (EQ-5D-5L) with input from the patient alone on their QoL; Quality of Life in AD (QoL-AD), a 13-item questionnaire designed to give the patient’s perspective on their own QoL and the caregivers perspective on the patient’s QoL; and the Zarit Burden Interview (ZBI), which focuses on caregiver burden.

Looking at the patients’ own perspective of their QoL, 18 months of lecanemab treatment showed 49% and 56% less decline in QoL as measured by EQ-5D-5L and QoL-AD, respectively, compared with the placebo. Both results were consistent across all subdomains within the endpoints, and across apolipoprotein E (APOE) genotypes. APOE plays an important role in Aβ metabolism and the different APOE genotypes are thought to affect Aβ plaque formation, with AD of the APOE ε4 phenotype observed to be caused by a reduced ability to clear Aβ. Therefore, it is significant that patients with the APOE ε4 genotype demonstrated less decline in QoL consistent with the other APOE genotypes. When the patients’ QoL was measured by the caregiver using QoL-AD, the decline in QoL over 18 months was reduced by 23% for the lecanemab group compared to the placebo group. Although this is less decline than the patient’s own QoL-AD measure (56% less decline), the caregiver’s assessment at this early stage of AD has lower significance compared to the caregiver’s assessment at later stages of the disease, so more emphasis can be placed on the patient QoL-AD scores. Lastly, lecanemab treatment resulted in 38% less decline in caregiver burden compared with placebo as measured by ZBI. On this measure, a significant separation between the lecanemab and placebo treatment arms was seen as early as six months, and was consistent across all 22 domains within the ZBI score.

In AD, a disease with a particularly high burden for both patients and caregivers, measures of QoL and patient-reported outcomes as a result of therapy are of particularly high value. These results demonstrate the meaningful benefit of lecanemab treatment in early AD for patients, and provide context for what clinical benefit means for patients and caregivers beyond clinically significant clinical trial endpoints.