Eisai
Corporate brand
UnclaimedJapanese multinational pharmaceutical company focused on neurology, oncology, and other specialty medicines.
Last updated November 4, 2026
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Overview
Eisai Co., Ltd. is a Japanese multinational pharmaceutical company headquartered in Tokyo. Its principal research and commercial interests are concentrated in neurology, oncology, and selected specialty-care areas, with additional products in gastroenterology, epilepsy, sleep medicine, supportive cancer care, and diagnostic imaging. The company operates as an innovative-drug developer and also commercializes medicines through alliances with larger pharmaceutical companies and regional partners. The business traces its origins to Nihon Eisai Co., Ltd., established in 1941. In 1944, a merger with Sakuragaoka Research Laboratory led to the formation of Eisai Co., Ltd. Over subsequent decades, Eisai developed from a primarily Japanese pharmaceutical business into an international company with research, manufacturing, regulatory, and marketing operations across North America, Europe, and Asia. Its American subsidiary, Eisai Inc., was established in 1995 and became an important base for the company’s international research and commercial activities. Eisai’s best-known historical product is Aricept, the donepezil brand for Alzheimer’s disease. The medicine was discovered in Eisai laboratories and received United States approval in 1996; it was commercialized in a partnership with Pfizer. Aricept became a major source of revenue and established Eisai’s long-term strategic emphasis on neurological disorders and dementia. The company later expanded its central nervous system portfolio through products such as Banzel or Inovelon for seizures associated with Lennox-Gastaut syndrome, Fycompa for partial-onset seizures, Zonegran for epilepsy, and Dayvigo for insomnia. Oncology became another major pillar of the company. Eisai strengthened this area through acquisitions and licensing transactions, including the purchase of oncology products from Ligand Pharmaceuticals in 2006, the acquisition of antibody developer Morphotek in 2007, and the acquisition of MGI Pharma later in 2007. These transactions added or reinforced products including Halaven, Dacogen, Aloxi, Hexalen, and Gliadel Wafer. Eisai subsequently developed and commercialized Lenvima, a multikinase inhibitor used in several cancer indications, in collaboration with Merck in certain markets, as well as Halaven, an eribulin-based treatment for advanced or metastatic breast cancer and other indications. The company’s most prominent recent development is Leqembi, the brand name for lecanemab, an anti-amyloid treatment for Alzheimer’s disease developed with Biogen. The United States Food and Drug Administration granted accelerated approval in January 2023 and converted that authorization to traditional approval in July 2023 after confirmatory evidence. The product represents Eisai’s continuing focus on disease-modifying approaches to dementia, while also exposing the company and its partners to the clinical, regulatory, reimbursement, and safety challenges associated with Alzheimer’s treatments. Eisai maintains research capabilities in Japan, the United States, the United Kingdom, and other locations. Its United States operations include research and corporate facilities in New Jersey and research activities in Massachusetts and North Carolina. Manufacturing sites and commercial operations extend across Japan, the United States, China, Indonesia, Taiwan, India, the United Kingdom, Europe, and the Asia-Pacific region. The company is listed on the Tokyo Stock Exchange and is included in major Japanese equity indices. In June 2023, a ransomware incident disrupted some logistics systems, highlighting operational and cybersecurity risks affecting the pharmaceutical supply chain.
History
Eisai's corporate history begins in Japan during the early 1940s. Nihon Eisai Co., Ltd. was established in 1941. In 1944, the company merged with Sakuragaoka Research Laboratory, creating Eisai Co., Ltd. The organization developed within Japan's pharmaceutical industry before expanding its research, manufacturing, and commercial footprint internationally. A major turning point came with the development of donepezil, an acetylcholinesterase inhibitor discovered in Eisai laboratories. The medicine was approved by the United States FDA in 1996 under the Aricept brand and was commercialized with Pfizer. Aricept became one of Eisai's most important products and gave the company a durable position in the Alzheimer's disease market. In 1999, the FDA approved rabeprazole, marketed as Aciphex in the United States and Pariet in several other markets, through a commercial arrangement involving Johnson & Johnson. These products broadened Eisai's international presence beyond Japan and demonstrated its reliance on strategic commercialization partnerships. During the 2000s, Eisai increased its emphasis on oncology. In 2006, it acquired four oncology products from Ligand Pharmaceuticals. In 2007, it acquired Morphotek, a Pennsylvania-based biotechnology company working on therapeutic monoclonal antibodies for cancer, rheumatoid arthritis, and infectious diseases. Later in 2007, Eisai acquired MGI Pharma for approximately US$3.9 billion, adding a portfolio of oncology and supportive-care products. The transaction brought products such as Dacogen, Aloxi, Hexalen, and Gliadel Wafer into the Eisai portfolio and significantly strengthened the company's presence in the United States. Eisai continued to build specialty franchises in oncology and neurology. Halaven, based on eribulin mesylate, was approved in the United States in 2010 for advanced or metastatic breast cancer, with approvals in the European Union, Japan, and Canada following in 2011. Other products in the broader portfolio included Lenvima for selected thyroid and kidney cancers, antiepileptic medicines such as Fycompa, Banzel or Inovelon, and Zonegran, as well as Dayvigo for insomnia and medicines for gastrointestinal and supportive-care indications. The company's research strategy increasingly centered on neurological diseases, especially Alzheimer's disease. Eisai worked with Biogen on lecanemab, an anti-amyloid antibody marketed as Leqembi. The FDA granted accelerated approval in January 2023 and converted that authorization to traditional approval in July 2023. Leqembi became a central example of Eisai's attempt to move beyond symptomatic treatment and develop therapies intended to affect the course of Alzheimer's disease. The product also brought scrutiny concerning clinical benefit, safety monitoring, treatment logistics, and access. Eisai's international network includes Japanese facilities and operations in North America, Europe, and Asia-Pacific. Its United States subsidiary, Eisai Inc., is headquartered in Nutley, New Jersey, and the company maintains research activities in New Jersey, Massachusetts, North Carolina, the United Kingdom, and Japan. Manufacturing facilities have operated in Japan, the United States, Indonesia, China, Taiwan, India, and the United Kingdom. In June 2023, a ransomware attack disrupted some logistical systems, adding a cybersecurity and business-continuity event to the company's recent corporate history. Today, Eisai remains an active, Tokyo-listed pharmaceutical company. Its identity is anchored in specialty medicines rather than consumer branding, with neurology and oncology serving as its principal strategic areas. The company combines internal discovery and development with acquisitions, licensing, co-development, and regional commercialization alliances.
- 2023
Leqembi regulatory approvals
[1]Leqembi received accelerated FDA approval in January and traditional FDA approval in July for Alzheimer's disease.
- 2023
Ransomware incident
[1]A ransomware attack disrupted some of Eisai's logistical systems.
- 2010
United States approval of Halaven
[1]Halaven received United States approval for advanced or metastatic breast cancer; approvals in additional markets followed in 2011.
- 2007
Acquisition of Morphotek
[1]Eisai acquired Morphotek, a biotechnology company developing therapeutic monoclonal antibodies for cancer and other diseases.
- 2007
Acquisition of MGI Pharma
[1]The acquisition of MGI Pharma substantially expanded Eisai's United States oncology and supportive-care business.
- 2006
Acquisition of oncology products from Ligand
[1]Eisai acquired four oncology products from Ligand Pharmaceuticals, expanding its cancer portfolio.
- 1999
FDA approval of Aciphex
[1]Rabeprazole, marketed as Aciphex in the United States, received FDA approval in a partnership involving Johnson & Johnson.
- 1996
FDA approval of Aricept
[1]Donepezil, marketed as Aricept and discovered in Eisai laboratories, received United States approval and was co-marketed with Pfizer.
- 1995
Eisai Inc. established
[1]Eisai established its American subsidiary, which later became a major base for United States research and commercial operations.
- 1944
Formation of Eisai Co., Ltd.
[1]A merger with Sakuragaoka Research Laboratory resulted in the formation of Eisai Co., Ltd.
Products and positioning
Research-driven specialty pharmaceutical company positioned around human health care, with particular emphasis on neurological diseases, dementia, oncology, and medicines addressing areas of substantial unmet medical need.
Neurology / Alzheimer's disease · 2023
Leqembi
Leqembi is the brand name for lecanemab, an anti-amyloid antibody developed by Eisai with Biogen for Alzheimer's disease. Its United States regulatory history includes accelerated approval in January 2023 followed by traditional approval in July 2023. The product represents Eisai's strategic effort to develop disease-modifying Alzheimer's treatments rather than only symptomatic therapies.
Neurology / Alzheimer's disease · 1996
Aricept
Aricept is the brand name for donepezil, an acetylcholinesterase inhibitor used in the treatment of symptoms associated with Alzheimer's disease. Discovered in Eisai laboratories, it received United States approval in 1996 and was co-marketed with Pfizer. It became one of Eisai's most important historical products and helped define the company's neurological focus.
Oncology
Lenvima
Lenvima is the brand name for lenvatinib, a multikinase inhibitor used in selected thyroid and kidney cancer indications and other approved oncology settings depending on jurisdiction. It is one of Eisai's major modern oncology products and has been commercialized through strategic collaboration in certain markets.
Oncology · 2010
Halaven
Halaven contains eribulin mesylate and was developed for advanced or metastatic breast cancer. It received United States approval in 2010, followed by approvals in the European Union, Japan, and Canada in 2011. The medicine strengthened Eisai's position in oncology and became a recognized product in its cancer portfolio.
Neurology / epilepsy
Fycompa
Fycompa is the brand name for perampanel, an antiepileptic medicine used for partial-onset seizures and, in some jurisdictions, additional seizure types. It is part of Eisai's neurology portfolio and reflects the company's continuing focus on treatments for seizure disorders.
Neurology / epilepsy
Banzel/Inovelon
Banzel in the United States and Inovelon in several other markets are brands for rufinamide, a medicine used for seizures associated with Lennox-Gastaut syndrome. Eisai received recognition from the National Organization for Rare Disorders for the development of Banzel.
Sleep medicine
Dayvigo
Dayvigo is the brand name for lemborexant, a sleep medicine used for insomnia. It extends Eisai's central nervous system portfolio beyond dementia and epilepsy into sleep-related disorders.
Gastroenterology · 1999
Aciphex/Pariet
Aciphex, known as Pariet in several markets, is a rabeprazole-based proton-pump inhibitor used for acid-related gastrointestinal conditions, including gastroesophageal reflux disease. It received United States approval in 1999 through a commercial relationship involving Johnson & Johnson.
Oncology supportive care
Aloxi
Aloxi is the brand name for palonosetron, a medicine used to prevent chemotherapy-induced nausea and vomiting. It entered Eisai's portfolio through the acquisition of MGI Pharma in 2007 and supports the company's broader oncology-care offering.
Oncology
Dacogen
Dacogen is the brand name for decitabine, an oncology medicine that was added to Eisai's portfolio through the acquisition of MGI Pharma. Its inclusion strengthened the company's presence in hematologic and cancer treatment markets.
Oncology
Gliadel Wafer
Gliadel Wafer is a carmustine-containing implant used in certain brain-tumor treatment settings. It became part of Eisai's oncology portfolio through the MGI Pharma acquisition and illustrates the company's participation in specialized cancer therapies.
Neurology / epilepsy
Zonegran
Zonegran is a brand for zonisamide, an antiepileptic medicine used for seizure disorders. It is among Eisai's established neurological products and complements its other epilepsy treatments.
Controversies
2023
Ransomware attack and logistics disruption
Eisai experienced a ransomware attack in June 2023 that caused the shutdown or disruption of some logistical systems. The incident was a cybersecurity and business-continuity event affecting company operations.
2021
Eisai and Arena Pharmaceuticals sued over Belviq
In 2021, a plaintiff and his deceased wife sued Eisai and Arena Pharmaceuticals in the District of New Jersey, alleging that the companies knew or should have known that Belviq could pose a cancer risk. The complaint included product-liability and other claims. The allegations are presented as claims in the lawsuit and are not presented as a court determination.
2020
Eisai voluntarily withdraws Belviq
Eisai said it agreed to voluntarily withdraw Belviq and Belviq XR from the U.S. market at the FDA’s request after study data showed a higher cancer rate among participants taking Belviq. Eisai said it disagreed with the FDA’s interpretation of the safety data.
Marketing campaigns
- Human Health Care mission
Global
Eisai's corporate positioning emphasizes a human health care mission and the development of medicines for patients and families affected by serious disease, particularly in neurology and oncology.
Outcome. This mission has guided Eisai's strategic focus, particularly in neurology and oncology, and has shaped its corporate identity.
Brand decisions
2023
Advance Leqembi through United States regulatory reviewProduct launchBackground
Eisai and Biogen pursued regulatory authorization for lecanemab as a potential disease-modifying Alzheimer's treatment.
Action taken
The FDA granted accelerated approval in January 2023 and later converted it to traditional approval in July 2023.
Aftermath
Leqembi became a central product in Eisai's neurology strategy and entered the highly scrutinized Alzheimer's treatment market.
2007
Acquire MorphotekM&ABackground
Eisai aimed to strengthen its biotechnology and therapeutic-antibody capabilities.
Action taken
Eisai acquired Morphotek, a company developing therapeutic monoclonal antibodies.
Aftermath
The acquisition expanded Eisai's research capabilities in oncology and other disease areas.
2007
Acquire MGI PharmaM&ABackground
Eisai pursued a larger United States presence and additional oncology and supportive-care products.
Action taken
Eisai acquired MGI Pharma.
Aftermath
The deal added Dacogen, Aloxi, Hexalen, and Gliadel Wafer to the company's portfolio and strengthened its United States business.
Acquisition value. US$3.9 billion (2007)
2006
Acquire oncology products from Ligand PharmaceuticalsM&ABackground
Eisai sought to expand its oncology portfolio and strengthen its specialty-pharmaceutical position.
Action taken
The company acquired four oncology products from Ligand Pharmaceuticals.
Aftermath
The transaction broadened Eisai's cancer-product portfolio.
Recent events
Reported
Eisai receives Tokyo Governor Prize for Corporate Governance[5]
Eisai was selected as the winner of the Tokyo Governor Prize for Corporate Governance of the Year 2021. The award ceremony was held on January 31, 2022.
Reported
Eisai and Arena Pharmaceuticals sued over Belviq[3]
A plaintiff and his deceased wife sued Eisai and Arena Pharmaceuticals in the District of New Jersey, alleging that the companies knew or should have known that Belviq could pose a cancer risk. The complaint included product-liability and other claims; the allegations are not presented as a court determination.
Reported
FDA approves Keytruda and Lenvima combination for advanced kidney cancer[6]
The FDA approved MSD's Keytruda and Eisai's Lenvima combination as first-line treatment for adults with advanced renal cell carcinoma.
- Unconfirmed
Reported
FDA approves Keytruda–Lenvima combination for advanced endometrial carcinoma[7]
The U.S. Food and Drug Administration approved Keytruda in combination with Lenvima for certain patients with advanced endometrial carcinoma following prior systemic therapy who are not candidates for curative surgery or radiation.
Eisai receives Japan Corporate Philanthropy Award[8]
Eisai received the 18th Corporate Philanthropy Award (FY 2020) from the Japan Philanthropic Association. The presentation ceremony took place on February 19, 2021.
Reported
Eisai launches Equfina in South Korea[9]
Eisai launched Equfina, a treatment for Parkinson’s disease, in South Korea. The article describes it as the first launch of Equfina in Asia outside Japan.
Reported
Eisai launches DAYVIGO in the United States[10]
Eisai's U.S. subsidiary launched DAYVIGO (lemborexant), a treatment for adults with insomnia, in the United States on June 1, 2020.
Reported
Eisai applies to withdraw Belviq in the United States[11]
Eisai applied to voluntarily withdraw Belviq and its extended-release form in the United States after the FDA requested withdrawal, concluding that potential risks outweighed benefits based on long-term trial data. Eisai said it interpreted the data differently, respected the FDA's decision, and was working on the withdrawal process.
Reported
Eisai voluntarily withdraws Belviq[4]
Eisai said it agreed to voluntarily withdraw Belviq and Belviq XR from the U.S. market at the FDA’s request after study data showed a higher cancer rate among participants taking Belviq. Eisai said it disagreed with the FDA’s interpretation of the safety data.
Reported
BioArctic and Eisai initiate BAN2401 research collaboration[12]
BioArctic announced that it had initiated a research collaboration with Eisai to further study the profile of the investigational drug candidate BAN2401. The program was planned to continue through the end of June 2021.
Sources15 sources
- 1Eisaien.wikipedia.org
- 2Eisai official websiteeisai.com
- 3Eisai and Arena Pharmaceuticals sued over Belviqlawstreetmedia.com
- 4Eisai voluntarily withdraws Belviqfoxbusiness.com
- 5Eisai获得东京知事企业治理奖finanznachrichten.de
- 6FDA 批准 Keytruda 与 Lenvima 联合治疗晚期肾癌pharmatimes.com
- 7FDA批准Keytruda与Lenvima联合治疗晚期子宫内膜癌finanznachrichten.de
- 8卫材获得日本企业慈善奖jcnnewswire.com
- 9卫材在韩国推出 Equfinathepharmaletter.com
- 10卫材在美国推出失眠治疗药物DAYVIGOfinanznachrichten.de
- 11Eisai申请在美国撤回Belviqpharmacytimes.com
- 12BioArctic与卫材启动BAN2401研究合作prnewswire.co.uk
- 13Eisai Receives Award for Excellence in Corporate Communications at the 37th Corporate Communications Awardsitbusinessnet.com
- 14Eisai: FDA Approves LENVIMA (lenvatinib) Plus KEYTRUDA (pembrolizumab) Combination for Patients With Certain Types of Advanced Endometrial Carcinomafinanznachrichten.de
- 15FDA approves Keytruda and Lenvima combination for endometrial cancerpharmaceutical-business-review.com
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