Leqembi intravenous infusion (lecanemab) approved for the treatment of Alzheimer’s disease in Japan

Leqembi is a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble (protofibril- protofibrils are large A aggregated soluble species of 75-5000 Kd) and insoluble forms of Abeta. Leqembi is the first and only approved treatment shown to reduce the rate of disease progression and to slow cognitive and functional decline by selectively binding to and eliminating the most toxic Abeta aggregates (protofibrils) that contribute to neurotoxicity in AD.

In Japan, an application for marketing approval was filed and was designated for priority review in January 2023. Japan is the second country to grant approval, following the traditional approval in the U.S. in July 2023.

Leqembi met its primary endpoint and all key secondary endpoints with statistically significant results and confirmed the clinical benefit of Leqembi. The primary endpoint was the global cognitive and functional scale, Clinical Dementia Rating Sum of Boxes (CDR-SB). In the Clarity AD clinical trial, treatment with Leqembi reduced clinical decline on CDR-SB by 27% at 18 months compared to placebo.

Eisai will conduct a post-marketing special use results survey (all-case surveillance) in all patients who are administered Leqembi until data from a certain number of patients are accumulated after market launch, in accordance with an approval condition imposed by the Ministry of Health, Labour and Welfare. In addition, the appropriate use of Leqembi will be promoted in accordance with the package insert and training materials will be developed for healthcare professionals to assist the management and monitoring of amyloid-related imaging abnormalities (ARIA).