EISAI INC. EXPANDS MARKETING AND SUPPLY AGREEMENT WITH ARENA FOR ANTI-OBESITY AGENT LORCASERIN

Eisai Co., Ltd. (Headquarters: Tokyo, President & CEO: Haruo Naito, “Eisai”) announced today that its U.S. subsidiary Eisai Inc. has expanded the marketing and supply agreement it concluded with Arena Pharmaceuticals GmbH, the Swiss subsidiary of U.S.-based Arena Pharmaceuticals Inc. (Headquarters: California, President & CEO: Jack Lief, “Arena”), in July 2010 for the anti-obesity agent lorcaserin. While the original agreement granted Eisai the exclusive rights to market and distribute lorcaserin in the United States, subject to U.S. Food and Drug Administration (FDA) approval, the expanded agreement now includes 20 countries throughout the Americas, including Mexico, Brazil, and Canada.

Lorcaserin, originally discovered by Arena, is an investigational drug candidate being developed for weight management, including weight loss and maintenance of weight loss, in patients who are obese (BMI>30) or patients who are overweight (BMI>27) and have at least one weight-related co-morbid condition. The lorcaserin New Drug Application (NDA) is currently under review by the FDA, with an assigned Prescription Drug User Fee Act (PDUFA) date of June 27, 2012, which is the target date for the agency to complete its review.

In recent years, obesity has become a major global health problem. With the expansion of the license agreement, Eisai seeks to deliver lorcaserin as a new treatment option to overweight and obese patients across the Americas who need a way to medically manage their weight.

[ Please refer to the following notes for further information on Eisai's presence in the Americas, lorcaserin and Arena Pharmaceuticals, Inc. ]

Aiming to enter the world's top 20 largest pharmaceutical markets, one of the objectives stipulated in its mid-term strategic plan “HAYABUSA,” Eisai manages its operations in new markets under an organizational structure comprising four regions: East Asia (Japan, China, South Korea, Taiwan and Hong Kong), the Americas (North, Central and South America), EMEA (Europe/the Middle East/Africa), and Indo-Pacific (South Asia, ASEAN countries, and Oceania). In the Americas region, Eisai has already established pharmaceutical sales subsidiaries in Canada (April 2010), Brazil (April 2011) and Mexico (August 2011). In Canada, Eisai has commenced sales of the antiepileptic agent Banzel® as well as the chemotherapeutic implant Gliadel® Wafer for the treatment of certain malignant brain tumors and the anticancer agent Halaven®.

Lorcaserin, discovered and developed by Arena, is a new chemical entity that is believed to act as a selective serotonin 2C (5-HT2C) receptor agonist. The serotonin 2C receptor is expressed in the brain, including the hypothalamus, an area believed to be involved in the control of appetite and metabolism. Stimulation of this receptor is strongly associated with reducing hunger and increasing satiety.

Arena Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing oral drugs that target G protein-coupled receptors, an important class of validated drug targets, in four major therapeutic areas: cardiovascular, central nervous system, inflammatory and metabolic diseases.
Arena Pharmaceuticals® and Arena® are registered service marks of the company.