Eisai Phase III Study for Eritoran Does Not Meet Primary Endpoint

Eisai Does Not Plan to Submit Marketing Authorization Applications to Regulatory Authorities
by Fiscal Year-End 2010

Woodcliff Lake, NJ, January 25, 2011 - Based on the preliminary findings from the ACCESS (A Controlled Comparison of Eritoran and Placebo in Patients with Severe Sepsis) trial, Eisai Inc. announced today that the company will not submit marketing authorization applications to regulatory authorities in the United States, the European Union and Japan by the end of the fiscal year (March 31, 2011), as previously planned. The decision was based on the fact that the study did not meet its primary endpoint of reduction in 28-day all-cause mortality in patients with severe sepsis.

Eisai will continue an analysis of the data and determine next steps. Eisai remains committed to addressing critical areas of unmet need, such as sepsis.

The ACCESS trial was a global, randomized, double-blind, placebo-controlled trial that evaluated the efficacy and safety of eritoran as a potential treatment for severe sepsis. The population studied had a moderate-to-high risk of mortality as determined by baseline APACHE II (Acute Physiology and Chronic Health Evaluation II) scores from 21 to 37. APACHE II is a severity of illness scoring system commonly used in sepsis research. This scoring system and other severity of illness scoring systems are also used in intensive care units (ICU).

Each year, severe sepsis causes approximately 215,000 deaths in the United States - as many as heart attacks, and nearly as many as lung, colorectal and breast cancers combined -- with a mortality rate of approximately 30 percent (depending on the population studied). Worldwide, sepsis affects 18 million people every year. The incidence of severe sepsis in the European Union has been estimated at 90.4 cases per 100,000 population, with a mortality of 36 percent. The incidence of severe sepsis in Japan is estimated at more than 380,000 cases per year.

Eisai's research and development efforts regarding eritoran and severe sepsis illustrate the company's human health care (hhc) mission, which is to address unmet medical needs and increase benefits to patients and their families.

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 with fiscal year 2009 (year ended March 31, 2010) sales of approximately $3.9 billion. 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.

Eisai has a global product creation organization that includes U.S.-based R&D facilities in Maryland, 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.

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 health care system. Eisai employs approximately 11,000 employees worldwide.

For more information regarding eritoran or ongoing clinical trials, please contact Eisai Medical Services at 1-888-274-2378.