Woodcliff Lake, NJ, July 29, 2011 - Eisai Inc. announced today that the U.S. Food and Drug Administration (FDA) has issued a Refusal to File letter in response to the company's New Drug Application (NDA) for perampanel (E2007), an investigational drug, for the treatment of partial-onset seizures associated with epilepsy which was submitted in May 2011. Perampanel is a highly selective non-competitive AMPA-type glutamate receptor antagonist, discovered and being developed by Eisai.

Upon preliminary review, the FDA requested reformatting and reanalyses of some datasets in the dossier to assist with a substantive review. Eisai believes that no new non-clinical or clinical studies are required to support this filing. This letter does not comment on the approvability of the drug, and no determination has been made with regard to the efficacy or safety of perampanel as part of the letter.

Eisai will work closely with the FDA to provide the information requested for resubmission of this application as quickly as possible. Eisai remains committed to research and development in the area of epilepsy as well as to our patients and their families as part of our corporate hhc (human health care) mission.

About Eisai Inc.

Eisai Inc. was established in 1995 and is ranked among the top-20 U.S. pharmaceutical companies (based on retail sales). The company began marketing its first product in the United States in 1997 and has rapidly grown to become a fully integrated pharmaceutical business. Eisai's areas of commercial focus include neurology, gastrointestinal disorders and oncology/critical care. The company serves as the U.S. pharmaceutical operation of Eisai Co., Ltd., a research-based human health care (hhc) company that discovers, develops and markets products throughout the world.

Eisai has a global product creation organization that includes U.S.-based R&D facilities in Massachusetts, New Jersey, North Carolina and Pennsylvania as well as manufacturing facilities in Maryland and North Carolina. The company's areas of R&D focus include neuroscience; oncology; vascular, inflammatory and immunological reaction; and antibody-based programs. For more information about Eisai, please visit www.eisai.com/US.

About Eisai Co., Ltd.

Eisai Co., Ltd. is a research-based human health care (hhc) company that discovers, develops and markets products throughout the world. Through a global network of research facilities, manufacturing sites and marketing subsidiaries, Eisai actively participates in all aspects of the worldwide healthcare system. Eisai employs approximately 11,000 employees worldwide.