Optimer Pharmaceuticals Announces Positive Results from Second Phase 3 Study of Prulifloxacin for Infectious Diarrhea in Travelers

SAN DIEGO--(BUSINESS WIRE)--Optimer Pharmaceuticals, Inc. (Nasdaq:OPTR) today announced positive results from the second of two double-blind pivotal Phase 3 trials assessing the safety and efficacy of Prulifloxacin as a once-daily (600 mg), three-day oral therapy for the treatment of infectious diarrhea, including travelers’ diarrhea.

“Having met the primary endpoint in both of our Prulifloxacin Phase 3 clinical trials, we believe the results are adequate to support an NDA filing. If approved, we believe Prulifloxacin will provide patients unique benefits versus current antibiotics for infectious diarrhea, such as a convenient, once-daily three day treatment regimen.”

The top-line analysis of data from this study shows that Prulifloxacin met the study objective of superiority to placebo in the resolution of diarrhea, measured by Time to Last Unformed Stool (TLUS). Prulifloxacin showed a statistically significant benefit compared to placebo in TLUS in both the mITT (modified intent-to-treat; n=200) and microbiologically evaluable (per protocol; n=173) populations. The median TLUS for patients treated with Prulifloxacin was 32.8 hours; this was significantly different from the TLUS for placebo with a p-value of <0.0001. This trial also confirms the overall efficacy and safety profile observed in the previous Phase 3 trial, demonstrating that Prulifloxacin was generally well tolerated and had a similar safety profile compared to placebo.

“With the completion of two successful Phase 3 trials showing superiority over placebo, Prulifloxacin may represent a welcomed addition for the treatment of infectious diarrhea,” said Michael N. Chang, Ph.D., President and CEO of Optimer Pharmaceuticals. “Having met the primary endpoint in both of our Prulifloxacin Phase 3 clinical trials, we believe the results are adequate to support an NDA filing. If approved, we believe Prulifloxacin will provide patients unique benefits versus current antibiotics for infectious diarrhea, such as a convenient, once-daily three day treatment regimen.”

Prulifloxacin Clinical Study Design

This study, referenced as OPT-099-002, was conducted at sites in India, Guatemala, and Mexico and evaluated adult travelers from industrialized countries suffering from infectious diarrhea. The patients were randomized (1:1) to receive either 600mg of Prulifloxacin or placebo, once daily over three days. Stool specimens were collected before treatment and one to three days following the end of treatment to identify intestinal pathogens. The primary efficacy endpoint was Time to the Last Unformed Stool, which was defined as the time in hours from the first dose of study medication to the passage of the last unformed stool.

This is the second of two pivotal Phase 3 clinical studies performed in preparation for a NDA filing with the U.S. Food and Drug Administration. Data from the first Phase 3 study, referenced as OPT-099-001, was announced in July 2008, and also showed that Prulifloxacin met the primary endpoint of TLUS in both the mITT (n=187) and microbiologically evaluable (n=165) populations compared to placebo. The median TLUS for patients treated with Prulifloxacin in the first Phase 3 trial was approximately 24 hours, which was significantly different from the median TLUS for placebo with a p-value of <0.0001. The first Phase 3 study was conducted at sites in Mexico and Peru.

About Prulifloxacin

Prulifloxacin is a broad-spectrum fluoroquinolone antibiotic approved in Japan, Korea and several European countries for the treatment of various bacterial diseases including respiratory and urinary tract infections, skin infections, infectious enteritis, cystitis, and prostatitis. It is a prodrug and is metabolized in the body to the active compound ulifloxacin. Optimer acquired exclusive rights to discover, develop and commercialize Prulifloxacin in the U.S. from Nippon Shinyaku Co., Ltd., in June 2004.

About Infectious Diarrhea

Infectious diarrhea can be caused through infection by bacteria, viruses or parasites. Travelers’ diarrhea is infectious diarrhea contracted by the ingestion of contaminated food or water by travelers to a developing country. Symptoms include stomach cramps, vomiting, nausea, fever and headache. Approximately 85% of travelers’ diarrhea cases are caused by bacteria, such as E. coli, Shigella, Salmonella, or Campylobacter. The limitations of currently available antibiotics for infectious diarrhea include limited spectrum of activity, antimicrobial resistance, possible side effects, and poor compliance, which can reduce successful outcome.

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, 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 the efficacy and patient benefits of Prulifloxacin as a treatment of infectious diarrhea, the ability of Prulifloxacin Phase 3 trial results to support an NDA filing and any expected filing of an NDA with respect to Prulifloxacin. Words such as "believes," "anticipates," "plans," "expects," "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 development of treatments that may compete with Optimer’s drug candidates, the potential of negative factors that could arise following a full analysis of clinical trial data, the fact that past clinical results may not be indicative of future clinical results, the timing, progress and likelihood of success of Optimer’s product research and development programs, the fact that the FDA may not view Optimer’s clinical trial results as sufficient to allow marketing approval for its product candidates, the timing and status of Optimer’s preclinical and clinical development of potential drugs and related filings with the FDA, and other risks detailed in Optimer's filings with the Securities and Exchange Commission.