The New England Journal of Medicine Publishes Results of Fidaxomicin Phase 3 Trial Showing Significantly Lower Recurrence Rates and Improved Global Cure Rates Compared to Vancomycin in Patients with Clostridium difficile Infection (CDI)

SAN DIEGO, Feb. 2, 2011 /PRNewswire/ -- Optimer Pharmaceuticals, Inc. (Nasdaq: OPTR) announced The New England Journal of Medicine has published results from the North American Phase 3 trial evaluating the safety and efficacy of the Company's novel antibiotic fidaxomicin as a treatment for patients with Clostridium difficile infection (CDI). The Phase 3 trial showed that fidaxomicin significantly reduced recurrence rates and increased global cure rates when compared to vancomycin, the only treatment approved by the U.S. Food and Drug Administration for CDI. The article titled, "Fidaxomicin versus Vancomycin for Clostridium difficile Infection," appears in the February 3, 2011 issue of The New England Journal of Medicine.

A multi-media news release containing video is available at the following link:  http://multivu.prnewswire.com/mnr/optimerpharma/47526/

"C. difficile has surpassed MRSA as a source for hospital acquired infection, and is associated with severe illness and death. More alarming, 20-30% of patients treated with current antibiotics will relapse," said Sherwood L. Gorbach, M.D., co-author and Optimer's Chief Medical Officer. "Data published in The New England Journal of Medicine shows that fidaxomicin not only maintained the high cure rate expected of vancomycin, but also demonstrated a 45% reduction in recurrences. Reduction in the rate of recurrence is a critical advancement for one of the most problematic aspects of CDI.  Fidaxomicin may represent a significant advance for physicians and hospitals to provide an effective treatment for patients with CDI.  At a time when our population is aging --the first of the baby boomers turned 65 in January – we welcome this innovation to treat CDI, in which the elderly are at particular risk."

The results published in The New England Journal of Medicine showed that patients treated with fidaxomicin experienced a significant reduction in rate of recurrence of CDI compared with patients treated with vancomycin (13.3% vs. 24.0%, p=0.004), which is equivalent to a 45 percent relative reduction in recurrences. In addition, patients treated with fidaxomicin demonstrated significantly improved global cure rates (cure with no recurrence) compared to those treated with vancomycin (77.7% vs. 67.1%, p=0.006).  The primary endpoint of non-inferiority for clinical cure was met in both the per protocol (92.1% for fidaxomicin vs. 89.8% for vancomycin) and modified intent-to-treat (mITT) (88.2% for fidaxomicin vs. 85.8% for vancomycin) patient populations.  The overall safety profile was similar between the fidaxomicin and vancomycin treatment groups. This Phase 3 trial is the largest comparative CDI study ever conducted versus vancomycin.

"These results showed that recurrence of CDI is significantly less likely to occur following treatment with fidaxomicin versus vancomycin. By lowering recurrences, fidaxomicin would eliminate the costs of treating additional CDI episodes and potentially reduce the spread of the disease, which may result in a lower cost burden to the healthcare system," said lead author, Thomas J. Louie, M.D., Medical Director, Infection Prevention and Control for the Calgary Health Region and professor in the Departments of Medicine and Microbiology-Infectious Diseases, University of Calgary.

"Fidaxomicin is minimally absorbed in the intestinal tract, which means it stays in the gut where C. difficile resides. Fidaxomicin is also a narrow spectrum antibiotic, meaning that it acts selectively on C. difficile with minimal disruption to the healthy, protective bacteria in the gut," said Mark Miller, M.D., FRCPC, a co-author on the paper and Chief of the Department of Microbiology, Head of Infectious Diseases Division and Chair of Infection Prevention and Control Committee, Jewish General Hospital in Montreal. "The ability of this antibiotic to stay in the gut and act primarily on the bacteria inflicting damage may be key reasons why we saw a significant reduction in the rate of CDI recurrences in the clinical trial."

Fidaxomicin Clinical Study Design

The Phase 3 trial was a multi-center, randomized, double-blind clinical trial, which enrolled 629 adult subjects. Subjects with confirmed CDI received either 200 mg fidaxomicin dosed orally twice daily or 125 mg Vancocin® (vancomycin hydrochloride capsules, USP) dosed orally four times daily.  This study was conducted in approximately 100 clinical sites throughout North America.  The objective of the study was to show that a 10-day course of fidaxomicin was at least as efficacious (non-inferior) and safe as a 10-day course of Vancocin for the treatment of CDI.  Non-inferiority in clinical cure (defined as patients requiring no further CDI therapy two days after completion of study medication) compared to Vancocin was the primary endpoint.  If cured, subjects were monitored for a subsequent four-week period to evaluate recurrence, which was a secondary endpoint.  Global cure, an exploratory endpoint, was defined as patients who were cured and did not have a recurrence during this subsequent four-week period.  The modified Intent-to-Treat Population (mITT) is the patient group with CDI confirmed by diarrhea with a positive toxin assay and received at least one dose of study medication.  The per protocol Population is the patient group with CDI confirmed by diarrhea with a positive toxin assay, that met all inclusion and exclusion criteria, and that received at least 3 days of therapy if deemed a failure or at least 8 days of therapy if deemed a cure.

About Fidaxomicin

Fidaxomicin is the first in a new class of antibiotics called macrocycles, which inhibit the bacterial enzyme RNA polymerase, resulting in the rapid killing of C. difficile. The narrow-spectrum profile of fidaxomicin eradicates C. difficile selectively with minimal disruption to the normal intestinal flora, while the alternative antibiotics used to treat CDI, metronidazole and vancomycin, have been shown to disrupt the gut flora. Fidaxomicin facilitates the return of normal physiological conditions in the colon which may be responsible for reducing CDI recurrence rates. Optimer has filed applications in the U.S. and the EU for marketing authorization for fidaxomicin for the treatment of CDI and reducing risk of recurrence when used for treatment of initial CDI.

About Clostridium difficile Infection (CDI)

Clostridium difficile infection (CDI), commonly referred to as "C. difficile" or "c-diff", has become a significant medical problem in hospitals, long-term care facilities, and in the community and is estimated to afflict more than 700,000 people each year in the U.S.  It 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, thus allowing C. difficile bacteria to flourish and produce toxins.

Current therapeutic options for CDI include the off-label use of metronidazole and oral vancomycin, the latter being the only FDA-approved treatment.  However, approximately 20% to 30% of CDI patients who initially respond to these treatments experience a clinical recurrence following cessation of the CDI treatment.

Primary risk factors for CDI include broad-spectrum antibiotic use (such as cephalosporins and fluoroquinolones), older age (over 65) and exposure to emerging hyper-virulent strains (BI/NAP1/027, 078, 001) of C. difficile. The increasing incidence of CDI, along with higher rates of both treatment failures and recurrences with current therapies have resulted in greater awareness and concern about CDI among medical professionals and public health officials. Learn more about CDI at www.cdiinfo.org.

About Optimer Pharmaceuticals

Optimer Pharmaceuticals, Inc. is a biopharmaceutical company focused on discovering, developing and commercializing hospital specialty products to treat serious infections and address unmet medical needs. Optimer has two anti-infective product candidates in development, fidaxomicin and Pruvel™ (prulifloxacin).  Fidaxomicin is a narrow spectrum antibiotic being developed for the treatment of Clostridium difficile infection (CDI).  The FDA granted the Company’s request for six-month Priority Review of fidaxomicin, and has assigned a Prescription Drug User Fee Act (PDUFA) goal date of May 30, 2011. The Company also filed a MAA with the European Medicines Agency (EMA) for fidaxomicin. Pruvel™ is a prodrug in the fluoroquinolone class of antibiotics being developed as a treatment for 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 statements related to the potential of fidaxomicin to lower CDI recurrences, lower the costs of treating additional CDI episodes and reduce the spread of CDI, the potential to lower the cost burden to the healthcare system by reducing the spread of CDI, the development of fidaxomicin, the timing of NDA submissions, the incidence and effects of CDI, the efficacy of current CDI treatments and of fidaxomicin, potential regulatory approval of fidaxomicin, and the awareness of CDI among healthcare professionals. 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. 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 development of alternative treatments for or means of preventing CDI, whether regulatory authorities will review or approve Optimer's applications for marketing approval within Optimer's anticipated timelines or at all, the timing of any marketing approvals, Optimer's ability to complete its NDA submission in a timely manner, Optimer's ability to commercialize any products for which it receives marketing approval, whether healthcare professionals will prescribe fidaxomicin, if approved, whether fidaxomicin will receive reimbursement coverage from healthcare payors and government agencies and other risks detailed in Optimer's filings with the Securities and Exchange Commission.

SOURCE Optimer Pharmaceuticals, Inc.