LEQEMBI (lecanemab) Approved for the Treatment of Alzheimer’s Disease in South Korea

TOKYO and CAMBRIDGE, Mass., May 28, 2024 – (JCN Newswire) – Eisai Co., Ltd. and Biogen Inc. announced today that the Ministry of Food and Drug Safety (MFDS) in South Korea has approved humanized anti-soluble aggregated amyloid-beta (Aβ) monoclonal antibody “LEQEMBI” (lecanemab) for treatment in adult patients with mild cognitive impairment due to Alzheimer’s disease (AD) or mild AD (early AD).

LEQEMBI selectively binds to soluble Aβ aggregates (protofibrils*), as well as insoluble Aβ aggregates (fibrils) which are a major component of Aβ plaques in AD, thereby reducing both Aβ protofibrils and Aβ plaques in the brain. LEQEMBI is the first and only approved treatment shown to reduce the rate of disease progression and to slow cognitive and functional decline through this mechanism. South Korea is the fourth country to grant approval, following approvals in the U.S., Japan, and China.

It is estimated there were approximately 900,000 dementia patients in South Korea in 2021,(1) with one in ten people over the age of 65 suffering from dementia,1 and one in five from mild cognitive impairment (MCI).(2) The average annual nursing care and medical costs per dementia patient is estimated to be 21.1 million KRW, while the cost for patients with severe dementia reaches 33.1 million KRW.(1)

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 South Korea, Eisai Korea Inc. will distribute the product and conduct information provision activities. Eisai is committed to working together with healthcare professionals and other stakeholders to realize the early diagnosis and treatment of AD.

* Protofibrils are believed to contribute to the brain injury that occurs with AD and are considered to be the most toxic form of Aβ, having a primary role in the cognitive decline associated with this progressive, debilitating condition.(3) Protofibrils cause injury to neurons in the brain, which in turn, can negatively impact cognitive function via multiple mechanisms, not only increasing the development of insoluble Aβ plaques but also increasing direct damage to brain cell membranes and the connections that transmit signals between nerve cells or nerve cells and other cells. It is believed the reduction of protofibrils may prevent the progression of AD by reducing damage to neurons in the brain and cognitive dysfunction.(4)

About lecanemab (LEQEMBI®)

Lecanemab is the result of a strategic research alliance between Eisai and BioArctic. It is a humanized immunoglobulin gamma 1 (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of amyloid-beta (Aβ).(5) Lecanemab is approved in the U.S.,(6) Japan,(7) and China.8 In the U.S., Japan and China, the indications are as follows:

U.S.: For the treatment of Alzheimer’s disease (AD). It should be initiated in patients with mild cognitive impairment (MCI) or mild dementia stage of disease.6 Japan: For slowing progression of MCI and mild dementia due to AD.7China: For the treatment of MCI due to AD and mild AD dementia.(8)

LEQEMBI’s FDA approval was based on Phase 3 data from Eisai’s, global Clarity AD clinical trial, in which it met its primary endpoint and all key secondary endpoints with statistically significant results.(9) 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 lecanemab reduced clinical decline on CDR-SB by 27% at 18 months compared to placebo.9 The mean CDR-SB score at baseline was approximately 3.2 in both groups. The adjusted least-squares mean change from baseline at 18 months was 1.21 with lecanemab and 1.66 with placebo (difference, −0.45; 95% confidence interval [CI], −0.67 to −0.23; P