Second fidaxomicin Phase 3 clinical study data in patients with CDI to be presented at DDW 2010

May 5 2010

Optimer Pharmaceuticals, Inc. (Nasdaq: OPTR) announced the presentation of new data from its second fidaxomicin Phase 3 clinical study in patients with Clostridium difficile infection (CDI).  The data, presented by Stuart Johnson, M.D. during an oral session at the annual meeting of Digestive Disease Week (DDW) in New Orleans, indicated that treatment with fidaxomicin significantly improved the recurrence rate and global cure rate in CDI patients requiring concomitant antibiotics, compared to vancomycin.

Many patients have persistent infections or develop new infections during the course of CDI treatment.  In these situations, additional concomitant antibiotics often must be administered, which can have a negative effect by increasing recurrences and lowering global cures of CDI.  In the study presented by Dr. Johnson, 59% of subjects were receiving concomitant antibiotics during CDI treatment. New data from analyses of the study showed that, among subjects who were receiving concomitant antibiotics, treatment with fidaxomicin resulted in a significantly lower recurrence rate compared to treatment with vancomycin (17.6% vs. 29.5%,>

"The data presented today confirm the benefits of fidaxomicin in CDI treatment even when patients require concomitant antibiotics, a common scenario during CDI treatment," said Stuart Johnson, M.D., Infectious Disease Section, Loyola University Medical Center and Hines VA Hospital. "More importantly, fidaxomicin is the first CDI antibiotic treatment to show significantly lower recurrence rates over the only FDA approved therapy for CDI."

Dr. Johnson also presented the previously announced top-line results, baseline demographic, disease characteristics, and data related to subgroup analysis of the BI/NAP1/027 strain and the non-BI/NAP1/027 strains of Clostridium difficile.

Fidaxomicin Clinical Study Design

The second fidaxomicin Phase 3 clinical study was a multi-center, randomized, double-blind clinical trial, which enrolled 535 adult subjects.  Subjects with confirmed CDI received either fidaxomicin (200 mg q12h) or Vancocin (125 mg q6h). This study was conducted in approximately 100 clinical sites throughout North America and Europe.  The study was designed to evaluate safety and compare the response to treatment in subjects during and after a 10-day course of therapy. Non-inferiority in clinical cure (defined as patients requiring no further CDI therapy two days after completion of study medication, as determined by the investigator) 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, also a secondary endpoint, was defined as patients who were cured and did not have a recurrence during this subsequent four-week period.