After doubling sales of Requenby, its Alzheimer’s disease drug partnered with Biogen, in fiscal 2025, Eisai expects annual sales of the drug to reach $900 million in 2026, with the drug well on its way to becoming a blockbuster.
In the three years since amyloid beta-directed antibodies have been on the market, sales have gotten off to a relatively slow start. After being approved by the FDA in 2023, the drug generated 44.3 billion yen ($279 million) for Eisai in its 2024 fiscal year and 88 billion yen ($554.6 million) last year. Eisai’s fiscal year runs from the beginning of April to the end of March each year.
Eisai is now counting on Leqembi’s revenue of 143.5 billion yen ($904.6 million) in fiscal 2026, the company said in its full-year results briefing (PDF) on May 15.
Most of the growth is expected to come from the North American market, with sales reaching 44.6 billion yen ($281 million) in 2025. In the U.S. and other regions, Requembi is the “leading brand” for early treatment of Alzheimer’s disease, CEO Haruo Naito emphasized in an earnings call with investors. Referring to Eli Lilly’s rival drug Kisunra, Naito explained that sales of Requembi are surging in both Japan and the United States, outpacing sales of the “second brand.”
Naito said that since the launch of Rekenbi in 2023, Eisai has been “committed” to raising awareness of the importance of early initiation and long-term continuation of treatment. In the U.S., 72% of patients are still taking Requemby after 18 months, and 67% are still on it after two years, the executive said, pointing to actual U.S. long-term follow-up data.
The two major bottlenecks that the company has long believed are inhibiting Rekenbi’s further growth appear in the confirmatory diagnosis of amyloid beta required to administer the drug and the burden associated with infusion-based treatment. To overcome these challenges, Eisai is building a “fundamental transformation” based on two technological innovations that the company calls “game-changing.”
For one, the company is looking to simplify the diagnostic process by relying on blood-based biomarker (BBM) tests. According to Eisai, approximately 15% of confirmed diagnoses will be performed using this index in 2025, a 12-fold increase compared to the beginning of 2024. More BBM-based diagnostics are expected to be approved in 2026, and the company predicts that this test will account for more than half of all confirmed amyloid beta diagnoses in 2028.
Meanwhile, the August approval of Eisai and Biogen’s Leqembi Iqlik auto-injector for weekly maintenance dosing led to an increase in new patients for both the IV and Iqlik versions, Eisai explained in a presentation.
FDA action on auto-injectors as a starting treatment is expected this summer, with additional approvals expected in Japan and China this year. The company believes that having the option to start treatment using a more convenient auto-injector for home use could potentially expand Rechemevi’s reach to people who have previously refused treatment.
Eisai has already set high goals for Requembi’s growth path, predicting last year that it would become a blockbuster hit worth 250 billion to 280 billion yen ($1.6 billion to $1.8 billion) in Japanese yen by fiscal year 2027. As for fiscal 2026, Rekenbi will enter a “true expansion period,” Eisai said in a recent earnings call.
Driven by three products: the kinase inhibitor “Lenvima” and the insomnia treatment drugs “Davigo” and “Rekenbi,” Eisai’s sales by pharmaceutical category reached 810.8 billion yen ($5.1 billion) in fiscal 2025, recording an 8% year-on-year growth. The company achieved 5% growth to 825.4 billion yen ($5.2 billion), achieving a “record-high” revenue across its businesses, despite a decline in operating profit.
