Optimer Reports Positive Phase III Data for Antibiotic against C. Difficile

Optimer Pharmaceuticals reported positive results from the second Phase III study evaluating its macrocycle antibiotic fidaxomicin for the treatment of Clostridium difficile infection (CDI). The company says that it will use the data to support an NDA submission for fidaxomicin, which it expects to file during the second half of this year.

The late-stage trial included 535 adults with confirmed CDI. Patients were treated using either fidaxomicin (200 mg q12h) or Vancocin (125 mg q6h) for 10 days. Vancocin is currently the only FDA-approved therapy for CDI, Optimer points out.

The results confirmed the noninferiority of fidaxomicin treatment compared to the approved drug. The clinical cure-rate for fidaxomicin was 91.7% and that for Vancocin was 90.6%. The company stresses that fidaxomicin was associated with significantly lower recurrence rates and higher global cure rates (cure with no recurrence within four weeks of completing therapy). Only 12.8% of fidaxomicin-treated patients experienced a recurrence, compared with 25.3% of patients given Vancocin. The global cure rate was 79.6% for the fidaxomicin cohort and 65.5% for the Vancocin cohort.

Positive data from the first Phase III fidaxomicin trial was reported in November 2008. “The robust results from our second Phase III trial of fidaxomicin confirm the results of our first Phase III trial showing fidaxomicin has the potential to be a first-in-class drug for the treatment of CDI,” claims Michael N. Chang, Ph.D., Optimer’s CEO. “A higher global cure demonstrates the potential for fidaxomicin to improve patient outcomes, reduce repeat visits to hospital, and reduce person-to-person transmission.”

Optimer is focused on the discovery and development of anti-infective products for diseases with unmet needs and where current therapeutic options have limitations. The company’s two late-stage products include fidaxomicin and prulifloxacin (Pruvel™). Prulifloxacin is a broad-spectrum antibiotic that has completed two Phase III trials as a treatment for travelers’ diarrhea. The antibiotic is already approved in Japan, Korea, and several European countries for the treatment of a range of bacterial diseases including respiratory and urinary tract infections, skin infections, infectious enteritis, cystitis, and prostatitis. Optimer acquired exclusive rights to develop and commercialize Pruvel in the U.S. from Nippon Shinyaku in June 2004.