Mr. Hamanaka joined Sepracor as a Member of the Board in October 2009 following the acquisition of the company by Dainippon Sumitomo Pharma Co., Ltd. (DSP). In February 2010, Mr. Hamanaka was appointed Chairman of Sepracor and in April 2010 was appointed Chairman and Chief Executive Officer.  Mr. Hamanaka has been a part of the DSP organization since July 2006 and also serves as Executive Officer of DSP.

Prior to joining DSP, Mr. Hamanaka was Corporate Officer and General Manager of U.S. Operations for Takeda Pharmaceuticals.  From 1998 to 2002, Mr. Hamanaka was President of Takeda Pharmaceutical North America based in Chicago and served in various roles at TAP Pharmaceuticals from 1983 to 1990.  Mr. Hamanaka began his career in the pharmaceutical industry in 1967 when he joined Takeda’s pharmaceutical operations in Japan.