For Immediate Release

Company name: DAIICHI SANKYO COMPANY, LIMITED
Representative: Takashi Shoda, President and Representative Director
(Code no.: 4568, First Section, Tokyo, Osaka and Nagoya Stock Exchanges)
Please address inquiries to Toshiaki Sai, General Manager,
Corporate Communications Department
Telephone: +81-3-6225-1126
http://www.daiichisankyo.com/

Daiichi Sankyo Launches New Phase 3 Trial with CS-8958 for Flu Prevention

Tokyo, November 05, 2009 - Daiichi Sankyo Co., Ltd. today announced that it has launched a new Phase 3 trial of its anti-influenza agent, CS-8958. The goal is to gain an influenza prevention indication in Japan.

The trial is placebo-controlled, double-blind and will evaluate preventive effect and safety of CS-8958 in families of influenza A and B sufferers. Daiichi Sankyo will measure influenza transmission among those receiving CS-8958 or placebo. We expect to observe that inhaled CS-8958 administered once weekly shows the prophylaxis effect.

CS-8958, a novel neuraminidase inhibitor discovered by Daiichi Sankyo for the treatment of influenza is co-owned with Biota Holdings Limited, and is a laninamivir prodrug. This inhaled formulation will be single-administered, acting directly on the trachea and lungs to inhibit influenza.

Daiichi Sankyo is pressing ahead with the development program of CS-8958 in Japan. We are preparing to submit an application for manufacturing and marketing approval by March 2010 to the Japanese Ministry of Health, Labour and Welfare for CS-8958 to treat adult and pediatric patients.

The trial is named SHIELD (a Study of Household Influenza prophylaxis Effect of Long-acting anti-influenza Drug).