SAN DIEGO, March 30, 2012 /PRNewswire/ -- Optimer Pharmaceuticals, Inc. (NASDAQ: [ OPTR ]) announced the presentation of results from a post-hoc subgroup analysis of the company's two large Phase 3 trials which demonstrated that cancer patients with Clostridium difficile-associated diarrhea (CDAD) had higher clinical cure rates, better sustained response and lower recurrence when treated with DIFICID® (fidaxomicin) tablets compared to oral vancomycin. The data will be presented at the 22nd European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in London.

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The analysis included 153 patients with active cancer who were treated in the two DIFICID Phase 3 studies and who received 8 days or more of treatment with DIFICID or oral vancomycin. In the overall combined population, patients with cancer had significantly lower cure and sustained response rates than patients without cancer. DIFICID was five times more likely than vancomycin to produce a clinical response and three times more likely to lead to a sustained response, while patients treated with vancomycin had a 2.6 fold greater risk of experiencing recurrence. Specifically, DIFICID provided superior response compared to vancomycin across all clinical endpoints studied: clinical response (97.3% vs. 87.5%, 95% CI 1.07-23.98; p=0.041), sustained response (83.6% vs. 61.3%, 95% CI 1.50-6.91; p=0.003) and disease recurrence (14.1% vs. 30.0%, 95% CI 0.16-0.89; p=0.025). Furthermore, cancer patients who were treated with DIFICID in the clinical studies had similar cure, recurrence and sustained response rates as non-cancer patients who received the drug, while cancer patients treated with vancomycin tended to have poorer outcomes than non-cancer patients. The overall safety profile was similar between the DIFICID and vancomycin treatment groups.

"CDAD is a common, but very serious complication for cancer patients and is a growing problem nationwide," said Roy F. Chemaly, M.D., M.P.H., F.A.C.P., F.I.D.S.A., associate professor and director of Infection Control in the Department of Infectious Diseases at The University of Texas MD Anderson Cancer Center in Houston, TX. "Because CDAD can have profound and disruptive effects in cancer patients, it is important that patients achieve both an initial cure and a sustained clinical response lasting beyond the initial treatment period."

Infections caused by C. difficile and the resulting CDAD pose a significant threat to cancer patients, primarily those with compromised immune systems due to chemotherapy or stem cell transplants. They also are at risk due to prolonged hospitalization and exposure to antibiotics. In fact, cancer patients with solid tumor or hematologic malignancies account for 16% of hospital CDAD cases.

"The results from this analysis reinforce the important role of DIFICID in the treatment of CDAD, especially its use as a front-line agent," said Sherwood L. Gorbach, M.D., Chief Scientific Officer and Senior Vice President of Optimer Pharmaceuticals, Inc. "We are encouraged by these results and look forward to conducting future clinical trials to explore the potential benefits of DIFICID in patients with cancer and others who are at high risk for CDAD."

About the Study
The results are based on two randomized, double-blind, non-inferiority Phase 3 trials conducted at sites in North America and Europe. Subjects with confirmed CDAD received either 200 mg DIFICID (fidaxomicin) dosed orally twice daily or 125 mg vancomycin dosed orally four times daily for 10 days. The primary objective of the trials was to compare the safety and efficacy of a 10-day course of DIFICID versus a 10-day course of vancomycin for the treatment of CDAD in adults. These studies served as the basis of approval for DIFICID by the U.S. Food and Drug Administration (FDA) in May 2011.

The subgroup analysis evaluated the treatment of 183 CDAD patients with active cancer – 153 of whom received 8 days or more of treatment – compared to 922 CDAD patients without cancer who were among the modified intent to treat population of the Phase 3 studies (N=1105). To be included in the analysis, patients must have had a current diagnosis of cancer at the time of CDAD diagnosis and were receiving various forms of treatment. Patients with active cancer (solid tumor or hematologic malignancy) were identified from medical history, concomitant medication indications, and adverse event entries in the case report forms. Clinical endpoints assessed in the 153 patients, included clinical cure at the end of treatment, recurrence of CDAD after clinical cure during the four week follow-up, and sustained clinical response (clinical cure with no recurrence in the four-week follow-up period).

About DIFICID® (fidaxomicin) Tablets
DIFICID is the first antibacterial drug indicated for Clostridium difficile-associated diarrhea (CDAD) to be approved in more than 25 years. It is indicated for the treatment of CDAD in adults 18 years of age or older. DIFICID is administered in 200 mg tablets given orally twice daily.

Important Safety Information for DIFICID
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%).

Please visit [ www.DIFICID.com ] or call 855-DIFICID (343-4243) for full prescribing information for DIFICID.

About CDAD
Clostridium difficile-associated diarrhea (CDAD) has become a significant medical problem in hospitals, long-term care facilities and in the community. CDAD 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 CDAD 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 CDAD, potentially because of a weakened immune system or the presence of underlying disease. Approximately two-thirds of CDAD patients are 65 years of age or older. Historically, approximately 20% to 30% of CDAD patients who initially respond to treatment experience a clinical recurrence.

About Optimer Pharmaceuticals
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 adult patients 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 statements related to any future clinical trials Optimer may conduct with respect to DIFICID, the potential benefits of DIFICID in treating certain patients and the risk, impact and burden of CDAD. 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 business including, without limitation, risks relating to: the possibility of alternative means of preventing or treating CDAD, whether Optimer will conduct additional clinical trials with respect to DIFICID or whether any such trials will be successful, and other risks detailed in Optimer's filings with the Securities and Exchange Commission. Forward-looking statements speak only as of the date of this release, and Optimer undertakes no obligation to update or revise these statements, except as may be required by law.

Contacts

Optimer Pharmaceuticals, Inc.
David Walsey, Vice President, Investor Relations and Corporate Communications
858-909-0736

Canale Communications, Inc.
Jason I. Spark, Senior Vice President
619-849-6005

SOURCE Optimer Pharmaceuticals, Inc.

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Optimer Pharmaceuticals, Inc. Announces Presentation at ECCMID of Post-Hoc Subgroup Analysis of DIFICID in Adult Cancer Patient

Optimer Pharmaceuticals, Inc. Announces Presentation at ECCMID of Post-Hoc Subgroup Analysis of DIFICID in Adult Cancer Patients Being Treated for Clostridium difficile-Associated Diarrhea (CDAD)

- Results Presented at the European Congress of Clinical Microbiology and Infectious Diseases Show Benefit in Adult Cancer Patients with CDAD -