Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) announced today that it has entered into an agreement to transfer the United States (U.S.) commercial rights for the anti-epileptic drug (AED) Fycompa^® (generic name: perampanel) CIII to Catalyst Pharmaceuticals, Inc. (Headquarters: the United States, “Catalyst Pharmaceuticals”), as well as to provide Catalyst Pharmaceuticals with an exclusive negotiation period for an asset in Eisai’s epilepsy pipeline. Eisai will maintain its rights to Fycompa in countries and regions outside the U.S. and continue to contribute to patients with epilepsy. Closing of the transaction is contingent on completion of review under antitrust laws in the U.S.

The agreement will provide the opportunity for Eisai’s neuroscience team to focus on its long-term strategic priorities on the research, development, and commercialization of its Alzheimer’s disease portfolio. Eisai remains committed to drug discovery and research for anti-epileptogenesis through the modulation of neuroinflammation or lipid metabolism in glia cells, as well as the application of new technologies including spatial RNA-sequence. Research is a crucial aspect of Eisai’s aim to gain a deeper understanding of human brain biology and technologies that may also ultimately lead to broader neuroscience discoveries.

In the U.S., Fycompa was approved in 2012 and has been prescribed to more than 50,000 patients. Catalyst Pharmaceuticals is a company focused on developing therapies for rare neuromuscular as well as neurological disorders, and is increasing its presence in neurology in the U.S. The agreement is expected to maximize the patient value of Fycompa in the U.S. due to its strong commitment to patients living with epilepsy.

Under the terms of the agreement, Eisai will receive a contractual up-front payment of $160 million (USD) upon closing of the transaction. In addition, milestone payments and royalties may be received in the future. Eisai will continue to be responsible for the manufacture and supply of Fycompa to global markets including the U.S. Eisai’s U.S. subsidiary Eisai Inc. will provide transition services for a period to ensure patients continue to have access to this important medicine.

As a result of this transaction, Eisai anticipates no changes to its consolidated financial forecast for the period ended March 31, 2023.

Driven by our hhc concept, Eisai strives to create and deliver innovative products to target diseases with high unmet medical needs, with a particular focus in our strategic areas: Neurology, Oncology and Global Health. As an hhceco company, Eisai aims to effectively achieve social good in the form of relieving anxiety over health and reducing health disparities by creating solutions through building an ecosystem in collaboration with other industries.

Media Inquiries:

Public Relations Department,

Eisai Co., Ltd.

+81-(0)3-3817-5120

Media Inquiries:

Eisai Inc. (U.S.)

Christopher Vancheri

Christopher_vancheri@eisai.com

551-305-0050

[Notes to Editors]

1. 1.  About Catalyst Pharmaceuticals, Inc.

Catalyst Pharmaceuticals, Inc. (Catalyst Pharmaceuticals) is a commercial-stage biopharmaceutical company focused on in-licensing, developing, and commercializing novel medicines for patients living with rare diseases. With exceptional patient focus, Catalyst Pharmaceuticals is committed to developing a robust pipeline of cutting-edge, best-in-class medicines for rare diseases. Catalyst Pharmaceuticals’ New Drug Application for FIRDAPSE^® (amifampridine) Tablets 10 mg for the treatment of adults with Lambert-Eaton myasthenic syndrome ("LEMS") was approved in 2018 by the U.S. Food & Drug Administration ("FDA") and FIRDAPSE is commercially available in the U.S. as a treatment for adults and children ages six to seventeen with LEMS. Further, Canada's national healthcare regulatory agency, Health Canada, has approved the use of FIRDAPSE for the treatment of adult patients in Canada with LEMS.