Eisai and Biogen’s humanized anti-soluble aggregated amyloid-beta (Aβ) monoclonal antibody “LEQEMBI Intravenous Infusion” (200 mg, 500mg, lecanemab) has been approved in Japan as a treatment for slowing progression of mild cognitive impairment (MCI) and mild dementia due to Alzheimer’s disease (AD).
LEQEMBI is a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of Aβ. 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 Aβ 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’s approval is based on Phase 3 data from Eisai’s large, global Clarity AD clinical trial, in which 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. In addition, the secondary endpoint from the AD Cooperative Study-Activities of Daily Living Scale for Mild Cognitive Impairment (ADCS MCI-ADL), which measures information provided by people caring for patients with AD, noted a statistically significant benefit of 37% compared to placebo. The ADCS MCI-ADL assesses the ability of patients to function independently, including being able to dress, feed themselves and participate in community activities.
The most common adverse events (>10%) in the LEQEMBI group were infusion reactions, ARIA-H (combined cerebral microhemorrhages, cerebral macrohemorrhages, and superficial siderosis), ARIA-E (edema/effusion), headache, and fall. Full results of the Clarity AD study were presented at the Clinical Trials on Alzheimer’s Disease (CTAD) 2022 conference and simultaneously published in the peer-reviewed medical journal The New England Journal of Medicine on November 29, 2022.
“Today LEQEMBI received approval, making it the first approved anti-amyloid Alzheimer’s disease treatment shown to reduce the rate of disease progression and to slow cognitive impairment in the early and mild dementia stages of the disease in Japan. We believe that we have turned a new page in the history of Alzheimer’s disease treatment. Alzheimer’s disease is a progressive and serious disease that not only causes significant impairment and burden for the people living with it and their care partners, but also has a tremendous impact on society as a whole,” said Haruo Naito, Chief Executive Officer at Eisai.
“For around 40 years since we began research on dementia at our Tsukuba Research Laboratories, Eisai has interacted with people with dementia and their care partners, and made efforts to understand their sincere feelings. In response, we have been taking on the challenge to develop therapeutic agents that act on the underlying pathology of Alzheimer’s disease. We are committed to delivering LEQEMBI to the people with early Alzheimer’s disease who need it and their families as a new treatment that removes the cause of the disease. Through these efforts, we aim to create impact on issues surrounding dementia in Japanese society.”
“With this approval, alongside Eisai, we will be able to help address the devastating impact Alzheimer’s has on people living with the condition as well the emotional, social and financial burden it places on care partners,” said Christopher A. Viehbacher, President and Chief Executive Officer of Biogen. “This is a significant step in the work of Biogen and Eisai to usher in a new era of treatments for this disease which impacts millions. We look forward to working alongside Eisai to build on the approvals in the U.S. and now Japan to bring this option to patients and their families worldwide.”
Eisai serves as the lead of LEQEMBI development and regulatory submissions globally with both Eisai and Biogen co-commercializing and co-promoting the product and Eisai having final decision-making authority. In Japan, Eisai and Biogen Japan will co-promote LEQEMBI, with Eisai distributing the product as the Marketing Authorization Holder.
