Following the news that Japan’s health ministry has approved Eisai’s intravenous formulation of lecanemab, branded as Leqembi, for use in Alzheimer’s disease;

Barbora Salcman, Neurology Analyst at GlobalData, offers her view:

“The approval of Leqembi in Japan comes nearly 10 months after the drug was filled for the priority review in January 2023, making it the first approved anti-amyloid Alzheimer’s disease treatment entering the Japanese market. The agent is already in use at the US, where the FDA provided accelerated approval in January 2023 and full approval in July 2023.

“The Phase 3 Clarity AD study (NCT03887455) demonstrated positive efficacy and clinically significant improvements for Leqembi, as the treatment reduced the disease progression rate and slowed cognitive impairment in early and mild dementia stages by overall 27% in comparison to placebo over the course of 18 months. The most common side effects were infusion-related reactions (26.4% Leqembi vs 7.4% placebo) and amyloid-related imaging abnormalities with edema or effusion (12.6% Leqembi vs 1.7% placebo).

“While this approval is great for a country like Japan, with a large aging population, the 27% reduction in clinical decline is still a very modest number, leaving uncertainty among some physicians if the reduction is large enough for patients to notice a real difference, particularly to outweigh potential health risks. Eisai is still awaiting response from the European Medicines Agency (EMA) about the use of Leqembi in the Europe after submitting the application in January 2023.

“Despite these uncertainties, Leqembi is the first disease-modifying therapy in the Japanese market and thus is expected to garner significant sales. According to GlobalData’s ‘Alzheimer’s Disease: Eight-Market Drug Forecast and Market Analysis report,’ Leqembi is expected to perform well in the Japanese market, generating sales of around $204 million in 2030, making it the most profitable treatment in the country ahead of its competition. These sales mean that Eisai will retain a dominant position over the Japanese market, especially as the company is already a large key player in the AD market with its drug Aricept, widely considered the gold standard symptomatic therapy for AD.”