Optimer Pharmaceuticals, Inc. and Astellas Pharma Inc. Enter Collaboration to Commercialize Fidaxomicin for Clostridium difficile Infection in Japan

Optimer Pharmaceuticals, Inc. and Astellas Pharma Inc. Enter Collaboration to Commercialize Fidaxomicin for Clostridium difficile Infection in Japan
Optimer Eligible to Receive up to $90 Million US Dollars, Including a $20 Million Upfront Cash Payment.

SAN DIEGO and TOKYO, March 29, 2012 /PRNewswire via COMTEX/ -- Optimer Pharmaceuticals, Inc. OPTR +0.14% 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(TM) 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®.

About CDI

CDI has become a significant medical problem in hospitals, long-term care facilities and in the community. CDI is a serious illness resulting from infection of the inner lining of the colon by C. difficile bacteria, which produce toxins that cause inflammation of the colon, severe diarrhea and, in the most serious cases, death. Patients typically develop CDI from the use of broad-spectrum antibiotics that disrupt normal gastrointestinal (gut) flora, possibly allowing C. difficile bacteria to flourish. Older patients in particular are at risk for CDI, potentially because of a weakened immune system or the presence of underlying disease

Important Safety Information for DIFICID® (fidaxomicin) tablets

DIFICID should not be used for systemic infections. Only use DIFICID for infection proven or strongly suspected to be caused by C. difficile. Prescribing DIFICID in the absence of a proven or strongly suspected C. difficile infection is unlikely to provide benefit to the patient and increases the risk of the development of drug resistant bacteria. The most common adverse reactions are nausea (11%), vomiting (7%), abdominal pain (6%), gastrointestinal hemorrhage (4%), anemia (2%), and neutropenia (2%).

About Astellas Pharma Inc.

Astellas Pharma Inc., located in Tokyo, Japan, is a pharmaceutical company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceutical products. Astellas has approximately 17,000 employees worldwide. The organization is committed to becoming a global category leader in Urology, Immunology including Transplantation and Infectious Diseases, Oncology, Neuroscience and Diabetes Mellitus (DM) Complications and Metabolic Diseases. For more information on Astellas Pharma Inc., please visit the company Website at www.astellas.com/en .

About Optimer Pharmaceuticals, Inc.

Optimer Pharmaceuticals, Inc. is a global biopharmaceutical company focused on discovering, developing and commercializing innovative hospital specialty products that have a positive impact on society. Optimer developed and commercialized DIFICID® (fidaxomicin) tablets, an FDA-approved antibacterial drug for the treatment of adults 18 years of age or older with Clostridium difficile-associated diarrhea (CDAD). Optimer has also received marketing authorization for fidaxomicin tablets in the European Union under the trade name DIFICLIR. The company is seeking marketing authorization for fidaxomicin in Canada and is exploring marketing authorization in other parts of the world where C. difficile has emerged as a serious health problem, including Asia. Additional information can be found at http://www.optimerpharma.com .

Forward Looking Statements

Statements included in this press release that are not a description of historical facts are forward-looking statements, including without limitation all statements related to the future filing of a Marketing Authorization Application in Japan, the potential regulatory approval and commercialization of fidaxomicin, future activities conducted under the collaboration and license agreement, the potential benefits of the collaboration and license agreement, Optimer's potential receipt of up-front, milestone and other payments, and the timing of a commercial launch of DIFICLIR in Europe. Words such as "believes," "would," "anticipates," "plans," "expects," "may," "intend," "will," and similar expressions are intended to identify forward-looking statements. The inclusion of forward-looking statements should not be regarded as a representation by Optimer that any of its plans will be achieved. These forward-looking statements are based on management's expectations on the date of this release. Actual results may differ materially from those set forth in this release due to the risks and uncertainties inherent in Optimer's and Astellas' respective businesses, including, without limitation, risks relating to: the implementation and continuation of the collaboration and license agreement, each party's performance of its respective obligations under the collaboration and license agreement, Optimer's and Astellas' ability to commercialize fidaxomicin in Japan and Europe, Optimer's and its third party manufacturers' ability to provide an adequate supply of fidaxomicin to Astellas, the ability to maintain market exclusivity for fidaxomicin, Astellas' ability to terminate the collaboration and license agreement, the development of alternative treatments for or means of preventing CDI, whether and when Astellas will file applications for regulatory approval and whether and when regulatory authorities will review or approve those applications, the timing and receipt of payments and fees, if any, from Astellas and other risks detailed in Optimer's filings with the Securities and Exchange Commission.


Optimer Pharmaceuticals, Inc.David Walsey, Vice President, Investor Relations and Corporate Communications858-909-0736

Canale Communications, Inc.Jason I. Spark, Senior Vice President619-849-6005

Astellas Pharma Inc.Corporate CommunicationsTel: +81-3-3244-3201 Fax: +81-3-5201-7473 http://www.astellas.com/en

SOURCE Optimer Pharmaceuticals, Inc.