Optimer Pharmaceuticals, Inc. announced that it has completed the submission of its New Drug Application (NDA) to the US Food and Drug Administration (FDA) for fidaxomicin to treat patients with Clostridium Difficile Infection (CDI) and to prevent recurrences of CDI. It is the most common cause of diarrhoea in the hospital, and according to the CDC contributes to 15,000-30,000 deaths each year, a number that surpasses Methicillin-Resistant Staphylococcus Aureus (MRSA).

“This NDA filing is one of the most significant achievements in the history of Optimer,” said Pedro Lichtinger, president and CEO of Optimer. “This submission is the culmination of many years of dedicated work by the Optimer team, as well as the efforts of our clinical trial investigators and advisors to bring this much needed therapy to CDI patients. We believe fidaxomicin represents a major advance in CDI treatment, and every step we move closer to the possibility of it reaching patients is meaningful to those who are impacted by the disease.”

Optimer has also requested priority review, which if granted could lead to an approval decision from the FDA in the second quarter of 2011. Fidaxomicin received Fast Track designation from the FDA in 2003 for the treatment of CDI, which allowed the Company to initiate a rolling NDA submission.

In August 2010, the Company’s Marketing Authorization Application (MAA) filing for fidaxomicin was accepted for review by the European Medicines Agency.

The two fidaxomicin Phase 3 clinical studies were multi-centre, randomized, double-blind trials, which enrolled a total of 1,164 adult subjects. Subjects with confirmed CDI received either fidaxomicin (200 mg q12h) or Vancocin (125 mg q6h), the only FDA approved product for the treatment of CDI. These studies were designed to evaluate safety and compare the response to treatment in subjects during and after a 10-day course of therapy.

The primary endpoint was non-inferiority compared to Vancocin in clinical cure (defined as patients requiring no further CDI therapy two days after completion of study medication). 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.

In both of these studies, fidaxomicin achieved its primary endpoint of non-inferiority compared to Vancocin. Fidaxomicin was also statistically superior to Vancocin in global cure rate and reduced CDI recurrences by 47%. Fidaxomicin was well tolerated in both studies.

Fidaxomicin is the first in a new class of antibiotics called macrocycles, which inhibit the bacterial enzyme RNA polymerase, resulting in the rapid killing of C. difficile. The narrow-spectrum profile of fidaxomicin eradicates C. difficile selectively with minimal disruption to the normal intestinal flora, while the alternative antibiotics used to treat CDI, metronidazole and vancomycin, have been shown to disrupt the gut flora.

Fidaxomicin facilitates the return of normal physiological conditions in the colon which may be responsible for reducing CDI recurrence. Optimer has filed applications in the US and the EU for marketing authorization for fidaxomicin for the treatment of CDI and for the prevention of recurrences.

Optimer Pharmaceuticals, Inc. is a biopharmaceutical company focused on discovering, developing and commercializing hospital specialty products to treat serious infections and address unmet medical needs. Optimer has two anti-infective product candidates in development, Fidaxomicin and Pruvel (prulifloxacin).