SAN DIEGO & TOKYO, JAPAN, March 29, 2012—Optimer Pharmaceuticals, Inc. (NASDAQ: OPTR) and Tokyo-based Astellas Pharma Inc. (Tokyo: 4503) announced today the execution of an exclusive collaboration and license agreement to develop and commercialize fidaxomicin tablets in Japan for the treatment of Clostridium difficile Infection (CDI).

In return for the exclusive license to fidaxomicin in Japan, Optimer is entitled to receive a one-time, up-front cash payment of U.S. $20 million from Astellas. Optimer is also eligible to receive additional cash payments of up to U.S. $70 million upon the achievement of certain regulatory and commercial milestones. Optimer is further entitled to receive payments from Astellas that provide a return resulting in a double digit percent of Astellas net sales in the territory. Astellas is responsible for all future costs associated with the development and commercialization of fidaxomicin in Japan.

“We are pleased to have entered a collaboration with Optimer to introduce fidaxomicin to Japan for the treatment of Clostridium difficile infections,” said Mr. Yoshihiko Hatanaka, President and CEO of Astellas Pharma Inc. “We believe that fidaxomicin’s highly differentiated clinical profile, which has been confirmed by clinical studies conducted in the U.S. and EU, has the potential to provide a new and unique treatment option for patients in Japan. Astellas is committed to a focus on infectious diseases, and this collaboration is an important milestone for our franchise.”

“Astellas is a leader in the anti-infective market in Japan. Leveraging their expertise efficiently helps realize the potential of fidaxomicin to meet the serious unmet needs of CDI patients in Japan, helping to address the risk of recurrence inherent in the disease, while optimizing the market opportunity for our shareholders,” said Optimer’s President and CEO, Pedro Lichtinger. “Japan is a key territory we have prioritized for geographic market expansion and complements nearer term market opportunities in the U.S., Canada and the European Union as we continue to pursue additional international market opportunities.”

In 2011, Optimer entered into a commercial partnership with Astellas Pharma Europe Ltd. to develop and market fidaxomicin under the trade name DIFICLIR™ in Europe and certain other countries in the Middle East, Africa and the Commonwealth of Independent States. The European Medicines Agency granted marketing authorization to DIFICLIR in December 2011, and Astellas Pharma Europe Ltd. expects to begin selling DIFICLIR in the first of its territories starting in 2012.

Fidaxomicin is approved by the U.S. Food and Drug Administration (FDA) for the treatment of Clostridium difficile-associated diarrhea (CDAD) in adults 18 years of age or older in the United States under the trade name DIFICID.

Contact the Media Relations team
Communications & Investor Relations
Main phone line for Media: +81-3244-3201 
Business hours (JST)
From Monday to Thursday: 8:45 am to 5:45 pm, Friday: 8:45 am to 4:00 pm
(closed on Saturdays, Sundays, national holidays and company holidays)