Leqembi: Japan approves Alzheimer treatment

Japan’s Eisai said on Monday the country’s health ministry had approved its Alzheimer treatment Leqembi, co-developed with US-based Biogen.

The development comes after a health ministry panel recommended the drug’s approval in August, followed by standard approval from the U.S. Food and Drug Administration (FDA) in July.

The drug is the first treatment shown to slow progression of the disease for people in the earlier stages of Alzheimer’s.

The U.S. health regulators, though, placed warning on the drug’s label, flagging the risk of potentially dangerous brain swelling for Alzheimer’s drugs in the same class.

An Eisai executive said in August the company expected to begin marketing Leqembi in Japan within about 60 days of receiving insurance reimbursement approval from the country’s national health system.

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. 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, 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(New Window) on November 29, 2022.