Eisai's Leqembi Sales Forecast: A Turning Point?

Eisai's latest projections suggest the anti-amyloid antibody is finally gaining commercial traction after a rocky launch, but the path to blockbuster status remains fraught with logistical hurdles and lingering physician skepticism that BD teams and investors must weigh carefully.

Key Takeaways

Eisai now projects Leqembi global sales of ¥76.5 billion for fiscal 2025, a 73% year-over-year increase, driven by accelerating uptake in the US and Japan after a slow start that forced the company to slash earlier blockbuster forecasts.
The FDA's traditional approval in July 2023 was a pivotal catalyst, but reimbursement bottlenecks and infusion center capacity constraints continue to cap the drug's ceiling, while the EMA has blocked European market access entirely.
For pharma BD teams, Leqembi's trajectory offers a real-world case study on the commercial viability of anti-amyloid therapies and the infrastructure investments needed to support them, with clear implications for pipeline valuation and M&A targeting.

What Happened? Eisai Doubles Down on Leqembi Sales Projections

Eisai has significantly revised its Leqembi sales forecast upward, now targeting ¥76.5 billion in global revenue for its fiscal year ending March 2026. The updated projection, disclosed during the company's third-quarter earnings call in February 2025, represents a 73% jump from the ¥44.2 billion Eisai reported for fiscal 2024. The company reported that Leqembi generated roughly ¥56.5 billion in fiscal 2024, meaning the new forecast implies sustained acceleration rather than a one-off spike.

The momentum is being driven primarily by the US market, where the drug received traditional FDA approval in July 2023 following the confirmatory Clarity AD Phase III trial. Eisai noted that US sales grew 153% from the first half of fiscal 2024 to the second half, while Japan saw a 184% increase over the same period. The company expects selling, general and administrative expenses to rise roughly 2.2% year-over-year as it scales its field force alongside partner Biogen.

Still, the road has been anything but smooth. In early 2024, Eisai was forced to slash its fiscal 2027 sales forecast by roughly 50% compared to earlier projections, citing slower-than-expected US physician adoption and reimbursement delays. The company had initially projected Leqembi would hit blockbuster status by 2027, but those ambitions were dialed back as commercial realities set in. A Biogen proxy filing from April 2024 detailed the partners' joint efforts to expand the sales force by 30% and improve physician education on ARIA management, signaling that even with improving numbers, the commercial engine still requires significant tuning.

What Does This Mean for Pharma BD and Regulatory Teams?

The Leqembi story is a masterclass in the gap between clinical promise and commercial execution. For business development teams evaluating Alzheimer's pipeline assets, the key question is not whether anti-amyloid antibodies work — the FDA's traditional approval settled that debate — but whether the healthcare system can absorb them at scale.

The biggest bottleneck remains infusion capacity. Leqembi requires biweekly intravenous administration, and many community hospitals and neurology clinics lack the infrastructure to handle the volume of patients who might qualify. Eisai and Biogen have been working to expand access through partnerships with infusion center operators, but the ramp has been slower than anticipated. A July 2024 FDA advisory committee briefing document noted that ARIA monitoring also requires regular MRI scans, adding another layer of logistical complexity that can deter smaller practices from adopting the drug. For BD teams modeling peak sales for similar assets, assuming rapid infusion center buildout is a dangerous bet.

On the regulatory front, the FDA's accelerated approval pathway — which Leqembi used to get to market in January 2023 — remains a viable route for neurodegenerative disease therapies, but the agency is demanding increasingly strong confirmatory data. The EMA, meanwhile, has taken a more cautious stance. Eisai submitted Leqembi for European approval in early 2023, but the EMA's Committee for Medicinal Products for Human Use (CHMP) issued a negative opinion in July 2024, citing concerns about the drug's risk-benefit profile, particularly the incidence of amyloid-related imaging abnormalities (ARIA). A re-examination request is pending, but the EMA's skepticism has effectively blocked access to a major market.

For regulatory teams, the Leqembi saga underscores the importance of early and frequent dialogue with European regulators on ARIA management protocols. Companies developing next-generation anti-amyloid therapies — particularly those with subcutaneous formulations or reduced ARIA rates — should view the EMA's skepticism as both a warning and an opportunity. The annual report from another anti-amyloid developer, filed with the SEC in early 2024, highlighted that the entire class faces heightened regulatory scrutiny in Europe, making trial design and patient selection critical differentiators.

On the M&A front, Leqembi's improving commercial trajectory could spur increased dealmaking in the Alzheimer's space. If Eisai demonstrates that an anti-amyloid drug can generate meaningful revenue, it validates the entire therapeutic class and makes pipeline assets — particularly those with better safety profiles or more convenient dosing — more attractive acquisition targets. Biotech companies developing oral or subcutaneous anti-amyloid agents should expect heightened interest from big pharma looking to capture the next wave of Alzheimer's treatments.

Frequently Asked Questions

What is Leqembi's current FDA approval status?

Leqembi (lecanemab) received traditional FDA approval in July 2023 for the treatment of Alzheimer's disease in patients with mild cognitive impairment or mild dementia. The approval was based on the confirmatory Clarity AD Phase III trial, which showed a statistically significant reduction in cognitive decline.

Why is the EMA reluctant to approve Leqembi?

The EMA's CHMP issued a negative opinion in July 2024, citing concerns about the incidence of amyloid-related imaging abnormalities (ARIA), including brain swelling and microhemorrhages. The committee determined that the benefits of treatment did not outweigh the risks for the broad patient population studied. Eisai has requested a re-examination of the opinion, but no decision has been announced as of early 2025.

How does Leqembi's sales trajectory compare to other Alzheimer's therapies?

Leqembi's launch has been slower than many analysts initially projected, but the drug is now showing signs of acceleration. The forecasted ¥76.5 billion in fiscal 2025 revenue would put it well ahead of Biogen's Aduhelm, which was effectively withdrawn from the market after its controversial accelerated approval. However, it still trails behind the blockbuster expectations that many had for the anti-amyloid class. The ramp in sales is being driven by improved reimbursement coverage from Medicare and expanding physician familiarity with the drug's administration protocols, according to Eisai's investor materials.

What are the biggest logistical barriers to Leqembi's widespread adoption?

The primary bottleneck is infusion center capacity. Leqembi requires biweekly intravenous infusions, and many community neurology practices lack the infrastructure to administer them. Eisai and Biogen have been working to expand access through partnerships with hospital systems and standalone infusion centers, but scaling these networks takes time. A July 2024 FDA advisory committee briefing document noted that ARIA monitoring also requires regular MRI scans, adding another layer of logistical complexity that can deter smaller practices from adopting the drug.

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