For immediate release
April 17, 2009

Company Name: Dainippon Sumitomo Pharma Co., Ltd.
President: Masayo Tada
Stock Exchange: Listings: Tokyo, Osaka
Security Code Number: 4506
Discontinuation of development of AC-3933, a therapeutic agent for dementia
Dainippon Sumitomo Pharma Co., Ltd. (Head Office: Osaka, Japan; President: Masayo Tada) announces the discontinuation of clinical development in Japan and abroad of its investigational compound AC-3933, a treatment for dementia, which was under development (Phase II stage) in Japan, the United States and Europe. This time, the Company obtained its Phase II clinical study results in the United States, but the compound did not meet the criteria that the Company has envisaged. In the light of such study results, the Company has decided to abandon continuation of clinical development of this compound both in Japan and abroad.