Optimer Pharmaceuticals to Accelerate European Filing of Fidaxomicin (OPT-80)

SAN DIEGO--(BUSINESS WIRE)--Optimer Pharmaceuticals, Inc. (Nasdaq: OPTR - News) today announced that it plans to begin preparations to file a Marketing Authorization Application (MAA) with the European Medicines Agency (EMEA) for approval of fidaxomicin as an oral treatment for Clostridium difficile infection (CDI) based on the results from the company’s first Phase 3 CDI trial. The company reported positive top-line results from the first of two Phase 3 trials in November 2008, showing that fidaxomicin met its primary endpoint of clinical cure and showed a significantly lower recurrence rate versus Vancocin® (p=0.004). This trial is the largest single comparative study ever conducted against Vancocin.

“After further analysis of our North American clinical trial results and discussion with consultants and external advisors, we believe the data from this Phase 3 study sufficiently support our plan to prepare and file an MAA for fidaxomicin,” said Michael N. Chang, Ph.D., Optimer’s Chief Executive Officer. "We still intend to complete the second Phase 3 study of fidaxomicin before submitting a New Drug Application to the FDA for U.S. market approval.”

Dr. Chang added, "CDI is a global health concern and I believe that, if approved, fidaxomicin will be an important therapeutic option for CDI, an infection that currently has limited treatment options.”

About Fidaxomicin

Fidaxomicin, formerly known as OPT-80, is the first in a new class of antibiotics called macrocyclics, which inhibit the bacterial enzyme RNA polymerase, resulting in the death of Clostridium difficile. The narrow spectrum profile of OPT-80 may eradicate Clostridium difficile selectively with minimal disruption to the normal intestinal flora. This may facilitate the return of the normal physiological conditions in the colon and reduce the probability of CDI recurrence.

About Clostridium Difficile Infection

CDI has become a growing problem in hospitals, long-term care facilities and in the community. It is a serious illness caused by 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. CDI typically develops from the use of broad-spectrum antibiotics that disrupt normal gastrointestinal (gut) flora, allowing C. difficile bacteria to flourish.

Current therapeutic options for CDI include metronidazole and oral vancomycin. However, approximately 20% to 30% of CDI patients who initially respond to these treatments experience a clinical recurrence following cessation of antibiotic administration.

About Optimer Pharmaceuticals

Optimer Pharmaceuticals, Inc. is a biopharmaceutical company focused on discovering, developing and commercializing innovative anti-infective products to treat serious infections and address unmet medical needs. Optimer has two late-stage anti-infective product candidates under development. Fidaxomicin, formerly known as OPT-80, PAR-101, and Difimicin, is the only antibiotic therapy currently in Phase 3 worldwide clinical development for Clostridium difficile infection. Prulifloxacin is an antibiotic which has completed two Phase 3 clinical trials for the treatment of travelers’ diarrhea, a form of infectious diarrhea. 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 fidaxomicin, the incidence and anticipated effects of CDI, the efficacy of current CDI treatments and fidaxomicin and plans related to regulatory filings, including a potential MAA for fidaxomicin. Words such as "believes", "anticipates", "plans", "expects", “may”, "intend", "will", "goal" 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. Actual results may differ materially from those set forth in this release due to the risks and uncertainties inherent in Optimer's business including, without limitation, risks relating to: the cost and time required to submit filings for regulatory approval, the uncertainty regarding whether such filings will be accepted or approved, the timing, progress and likelihood of success of Optimer’s research and development and clinical trial programs, the timing and status of Optimer’s preclinical and clinical development of potential drugs, the development of alternative treatments for CDI, and other risks detailed in Optimer's filings with the Securities and Exchange Commission.

Optimer Pharmaceuticals, Inc.
Christina Donaghy, Corporate Communications Manager
John D. Prunty, Chief Financial Officer & VP Finance
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