Optimer Initiates Phase 3b Clinical Trial of DIFICID® for the Prevention of Clostridium difficile-Associated Diarrhea in Bone Marrow Transplant Patients

JERSEY CITY, N.J., Nov. 1, 2012 /PRNewswire/ -- Optimer Pharmaceuticals, Inc. (NASDAQ: OPTR) today announced that the first patient has been dosed in its DEFLECT-1, Phase 3b clinical trial of DIFICID® (fidaxomicin) tablets for the prevention of Clostridium difficile-associated diarrhea (CDAD) in patients undergoing hematopoietic stem cell transplant (HSCT), often referred to as bone marrow transplantation. CDAD can be a serious complication of HSCT.

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Patients undergoing HSCT present with multiple risk factors including immune suppression and the use of prophylactic antibiotics which make them susceptible to CDAD; it is estimated that up to 30% of patients undergoing the procedure will develop CDAD. HSCT patients with CDAD generally have longer hospital stays, increased average costs and are at increased risk of death.

"By nature of the procedure, patients undergoing HSCT have weakened immune systems and are often receiving antibiotics, both of which are significant risk factors for the development of CDAD," said Sherwood L. Gorbach M.D., Optimer's Chief Scientific Officer and Senior Vice President of R&D. "Consequently, the prevalence of CDAD in these patients is high and we believe that DIFICID has potential to prevent CDAD in this high-risk population. We hope that this trial will provide us data supporting this hypothesis."

This multi-center study will utilize a randomized, double-blind design to evaluate the safety and efficacy of DIFICID as prophylaxis in individuals undergoing HSCT. It will enroll an estimated 340 patients into two arms, one of which will receive 200 milligrams of DIFICID daily for thirty days and the other of which will receive a placebo, since the efficacy of CDAD prophylaxis has not been previously determined.  By using an innovative "adaptive design," a blinded interim analysis will be conducted after 170 evaluable subjects have completed treatment and the 30 day post-treatment follow up to re-estimate the sample size based on accumulated data. The primary endpoint is the incidence of CDAD from the first dose of study drug through the 30-day follow-up period after the last day of drug. The objective is to achieve a 60% improvement in the CDAD incidence rate in the DIFICID group over the placebo group. Initial data from the trial is expected in the first half of 2014.

"There are currently no demonstrated options to prevent CDAD in patients undergoing HSCT and the incidence rate in this population suggests that the need is very high. Pursuing a prophylaxis indication has the potential to help a new population at risk of CDAD and is an important step in the implementation of our life cycle management plan," said Pedro Lichtinger, President and CEO of Optimer.

About Clostridium difficile-associated Diarrhea (CDAD)
Clostridium difficile infection (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.  Clostridium difficile-associated diarrhea is the most common symptom of CDI.  In recent years, C. difficile has surpassed methicillin-resistant Staphylococcus aureus (MRSA) as the leading cause of healthcare-acquired infections in community hospitals.  Patients typically develop CDAD from the use of broad-spectrum antibiotics that disrupt normal gastrointestinal (gut) flora, possibly allowing C. difficile bacteria to flourish.

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

Important Safety Information for DIFICID
DIFICID is contraindicated in patients with hypersensitivity to fidaxomicin or to any of the excipients in the formulation. 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 Optimer Pharmaceuticals
Optimer Pharmaceuticals, Inc. is a global biopharmaceutical company focused on developing and commercializing innovative hospital specialty products that have a positive impact on society.  Optimer developed DIFICID® (fidaxomicin) tablets, an FDA-approved macrolide antibacterial drug for the treatment of Clostridium difficile-associated diarrhea (CDAD) in adults 18 years of age and older and is commercializing DIFICID in the U.S. and Canada.  Optimer also received marketing authorization for fidaxomicin tablets in the European Union where its partner, AstellasPharma Europe, is commercializing fidaxomicin under the trade name DIFICLIR™.  The Company 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 the potential of DIFICID to prevent CDAD, the safety and efficacy of DIFICID in individuals undergoing HSCT, the sample size of the Phase 3b clinical trial, the use of DIFICID to benefit additional populations at risk of CDAD and Optimer's life cycle management plans for DIFICID.  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 and Optimer undertakes no obligation to update or revise these statements, except as may be required by law. 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: Optimer's ability to continue driving adoption and use of DIFICID, DIFICID's ability to compete with cheaper generic competition, whether healthcare professionals will prescribe DIFICID, the extent to which DIFICID will be accepted on additional hospital formularies and the timing of hospital formulary decisions, whether Optimer's hospital contracting strategy will result in additional DIFICID prescriptions in the hospital or retail markets, whether Rx Assist is utilized and whether it will facilitate access to DIFICID and other risks detailed in Optimer's filings with the Securities and Exchange Commission.

Contacts
Optimer Pharmaceuticals, Inc.
David Walsey, Vice President, Investor Relations and Corporate Communications
858-964-3418

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

SOURCE Optimer Pharmaceuticals, Inc.