Eisai
Japanese pharma co-developing Leqembi, an approved Alzheimer's drug, with Biogen.
On the record
Checkpoint: US launch of Leqembi IQLIK subcutaneous autoinjector, testing whether easier dosing defends share against Kisunla
The call
Eisai's near-term story rests on whether Leqembi's approvals, dosing convenience, and prescriber relationships hold share as Lilly's Kisunla competes for the same patients.
Eisai makes prescription medicines, including LEQEMBI, a drug that slows memory loss in early Alzheimer's patients. The company has decades of regulatory approvals and partnerships that make it hard to replace quickly, but Eli Lilly just shipped donanemab (Kisunla), which does basically the same thing and is winning patients in the market. The key question over the next few years is whether LEQEMBI can hold onto customers or if Eli Lilly's drug takes over, since that will determine whether Eisai's profits actually grow as promised.
Why
01
AI pressure: None apparent. No AI product currently displaces Leqembi; AI-aided diagnostics could someday speed patient identification for any Alzheimer's drug, including rivals' Could AI do the core job? Unlikely.
02
Bigger players: Eli Lilly (donanemab/Kisunla). Lilly's Kisunla is on the market as a competing amyloid antibody, giving prescribers and payers a second option to Leqembi. Could a giant copy it? No, they are blocked.
03
What protects it. Leqembi holds approvals in more than 50 markets, an established prescriber and infusion network, and Biogen shares commercial costs and risk.
What would change this call
LEQEMBI FY2026 revenue vs Eisai's own ¥143.5B (+63%) guidance at May 2027 earnings. Whether LEQEMBI is holding growth trajectory or losing ground to donanemab.
Kisunla vs LEQEMBI relative US prescription share reported over next 12 months. Whether Eli Lilly is actually taking Alzheimer's-drug patients from Eisai.
Canada CDA-AMC final reimbursement decision on LEQEMBI (originally negative draft Feb 2026). Whether a major market formally restricts LEQEMBI access, cutting future revenue.
Kisunla vs LEQEMBI relative US prescription share reported over next 12 months. Whether Eli Lilly is actually taking Alzheimer's-drug patients from Eisai.
Canada CDA-AMC final reimbursement decision on LEQEMBI (originally negative draft Feb 2026). Whether a major market formally restricts LEQEMBI access, cutting future revenue.
Key numbers
- FY2025 revenue ¥825.4 billion, up 4.6% YoY
- FY2025 operating profit fell 18.8% to ¥44.1 billion
- Leqembi FY2026 sales guided at ¥143.5 billion, +63% YoY
Named risks
- Eli Lilly's donanemab gaining share and projected to overtake lecanemab sales.
- Canada and Sweden reimbursement bodies issuing non-recommendation decisions for LEQEMBI.
- Product-liability litigation over LEQEMBI-linked brain injury and deaths.
- Operating profit decline of 18.8% in FY2025 despite record revenue.
- Consolidated headcount contraction of 3.4% YoY as of March 2026.
Rivals, as read in July 2026
| Rival | Direction | Evidence |
|---|---|---|
| Eli Lilly (donanemab/Kisunla) | gaining on | EU approved Sept 2025; analysts project it could overtake lecanemab sales by 2026-2027 |
| Roche/Genentech | contesting | Has its own anti-amyloid programs competing in the Alzheimer's disease-modifying therapy class |
| Biogen | contesting | Co-commercial partner sharing LEQEMBI upside and downside rather than a pure rival |
Questions people ask
- Is Eisai profitable in 2026?
- Yes but under pressure. FY2025 (ended March 31, 2026) revenue hit a record ¥825.4 billion, up 4.6% YoY, but operating profit fell 18.8% to ¥44.1 billion and net profit fell 17% to ¥38.6 billion, per Eisai's May 2026 earnings report.
- Who owns Eisai?
- Eisai is an independent public company listed on the Tokyo Stock Exchange (4523) and OTC in the US as ESALF, with no controlling parent. Major holders include Japan's Government Pension Investment Fund (~7.3%) and Vanguard Health Care Fund (~5.1%).
- Could AI replace Eisai?
- No. AI tools like the Elix Discovery platform, adopted July 2025, speed up compound screening, but cannot replicate Eisai's 50+ market regulatory approvals, Clarity AD trial data, or its exclusive Biogen co-commercialization deal for LEQEMBI, all core to its moat.
- Is Eisai's LEQEMBI losing to Eli Lilly's donanemab?
- Eisai's LEQEMBI still posted 109% YoY sales growth in Q3 FY2025, but analysts cited in a May 27, 2026 competitive landscape report project Lilly's donanemab (Kisunla, EU-approved September 2025) could overtake lecanemab sales within 12 months of approval.
- What is Eisai's biggest competitor?
- Eli Lilly's donanemab (brand Kisunla), FDA-approved July 2024 and EU-approved September 2025, is Eisai's closest direct rival in anti-amyloid Alzheimer's therapy, with analysts projecting it could surpass lecanemab sales by 2026-2027.
- Is Eisai facing lawsuits over LEQEMBI safety?
- Yes. A Bloomberg investigation reported at least seven US deaths linked to LEQEMBI over two years, and plaintiffs' firms including Seeger Weiss were actively litigating product-liability brain injury claims as of April 2026.
Timeline
- 2026-07-13FDA approves LEQEMBI IQLIK subcutaneous autoinjector as initiation dose
- 2026-07-12Eisai presents SC autoinjector and LEADER real-world data at AAIC 2026
- 2026-06-30UCL and Eisai renew tau antibody research partnership through 2030
- 2026-05-20BioArctic reports LEQEMBI Q1 FY2026 quarterly sales of ¥26.2 billion
- 2026-05-15Eisai reports FY2025 record revenue ¥825.4B but 18.8% operating profit decline
- 2026-05-15Eisai projects LEQEMBI FY2026 sales of ¥143.5 billion, +63% YoY
- 2026-02-19Canada's CDA-AMC issues draft non-reimbursement recommendation for LEQEMBI
- 2026-01-01Eisai acquires EMEA rights to taletrectinib from Nuvation Bio
- 2025-08-01LEQEMBI subcutaneous maintenance dosing approved in US
- 2025-07-17Eisai adopts Elix Discovery AI drug-discovery platform
Revision history
24 July 2026
First assessed. Defensible for now. The text above is fixed as of this date and is not edited afterwards.
In the same band
Sources
- Corporate Information (2026-03-30)
- Eisai Q4 2025 reports record revenue but profit declines (2026-05-15)
- LEQEMBI drives revenue growth, EPS misses expectations (2025-11-05)
- Eisai Q3 FY2025 slides reveal 109% growth in LEQEMBI sales (2026-02-09)
- Eisai projects Leqembi revenue to total JPY 143.5 billion for FY2026 (2026-05-15)
- BioArctic Interim Report for the period January-March 2026 (2026-05-20)
- Update on FDA Priority Review of LEQEMBI IQLIK
- FDA Approves LEQEMBI IQLIK (2026-07-13)
- LEQEMBI Presents Subcutaneous Autoinjector Data (2026-07-12)
- Eisai Maintains Commitment... (2026-02-19)
- UCL and Eisai renew partnership (2026-06-30)
- Eisai Deepens Body of Clinical Evidence for LENVIMA at ASCO 2026