Fidaxomicin, formerly known as OPT-80, PAR-101 or Difimicin, is a new class of antibiotics for the treatment of Clostridium difficile infection, or CDI, also known as Clostridium difficile-associated disease, or CDAD. We believe that Fidaxomicin offers advantages over current treatments due to its demonstrated activity against C. difficile, low rates of recurrence, evidence of low C. difficile resistance, minimal systemic exposure, limited disruption of normally occurring gastrointestinal bacteria and convenient dosing regimen. Our studies indicate that Fidaxomicin acts by inhibiting RNA polymerase, a bacterial enzyme, which results in the death of specific bacteria such as C. difficile.

We reported positive top-line results from our two Phase 3 trials comparing fidaxomicin to Vancocin in the treatment of CDI in February 2010 and November 2008. The two fidaxomicin trials combined represent the largest database of CDI clinical trial data in the world and largest comparative studies ever conducted against Vancocin. The top-line analysis of data from these trials showed that fidaxomicin achieved the primary endpoint of clinical cure (defined as patients requiring no further CDI therapy two days after completion of study medication, as determined by the investigator) and demonstrated a significantly lower recurrence rate and higher global cure rate (defined as cure with no recurrence within four weeks of completing therapy) compared to Vancocin, the only FDA-approved antibiotic for the treatment of CDI. Fidaxomicin was also well-tolerated in the trials. We currently hold worldwide rights to fidaxomicin and intend to seek one or more partners for the commercialization of fidaxomicin outside of United States. We plan to submit a NDA to the FDA in the second half of 2010 and are also preparing a MAA for submission to the EMA in Europe.

We are developing an oral suspension formulation which complements the existing tablet form of fidaxomicin. This formulation is intended for use with intensive care unit and elderly patients who cannot swallow tablets. We have submitted an IND to pursue development for this potential label indication expansion.