Optimer Pharmaceuticals, Inc, a global biopharmaceutical company focused on discovering, developing and commercializing innovative hospital specialty products and Astellas Pharma Europe Ltd., a European subsidiary of Tokyo-based Astellas Pharma Inc. informed that the European Commission has granted Marketing Authorization (MA) for Dificlir (fidaxomicin) tablets for the treatment of adults with Clostridium difficile infections (CDI) also known as Clostridium difficile-associated diarrhoea (CDAD).

CDI is a significant problem in hospitals and long-term care facilities all over the world. EMA approval was based on two large, multi-national, phase III clinical trials that demonstrated that Dificlir was as effective as oral vancomycin in treating CDI. Dificlir had a significantly lower rate of recurrence (including relapses) compared to vancomycin in the 30 days following treatment. It is the only drug approved by the EMA proven to significantly lower the rate of recurrence of CDI compared to oral vancomycin. The clinical trials included patients over the age of 65 and those taking concomitant antibiotics to treat multiple infections.

“The European approval is a key step in making fidaxomicin more widely available to patients across the globe to treat this very serious disease,” said Pedro Lichtinger, president and CEO of Optimer. “We believe we have obtained a very strong label recognizing the benefits of Dificlir versus vancomycin, including significant reductions in recurrence.”

The European approval affirms the recent positive opinion from the Committee of Medicinal Products for Human Use (CHMP) and is based on two phase III clinical trials that were conducted to ensure the safety and efficacy of 400mg/day Dificlir (fidaxomicin) tablets compared to 500mg/day oral vancomycin for 10 days in subjects with CDI. The first phase III study was carried out in 629 subjects in North America (US and Canada). The second phase III study was carried out in 535 subjects in North America and Europe. Of the subjects enrolled in these studies, 47.9 per cent were 65 years or older and 27.5 per cent were treated with concomitant antibiotics. Both studies met their primary endpoint of non-inferiority, demonstrating that the proportion of subjects in whom clinical cure was achieved at the end of 10 days was similar for both Dificlir and oral vancomycin. In both trials Dificlir proved to have a statistically significantly lower rate of recurrence of CDI as compared to oral vancomycin 30 days after the end of treatment. The most common treatment related adverse reactions were vomiting (1.2%), nausea (2.7%) and constipation (1.2%).

Dificlir is described in the EU label as a narrow spectrum antimicrobial drug with bactericidal activity against C. difficile and inhibitory activity against C. difficile sporulation in-vitro. Fidaxomicin, the active ingredient in Dificlir, is a member of a new class of antibacterials called macrocycles.

Astellas Pharma Europe Ltd. is Optimer's exclusive licensee to develop and commercialize Dificlir in Europe and additional countries in the Middle East, Africa and the Commonwealth of Independent States.

Optimer Pharmaceuticals, Inc. is a global biopharmaceutical company focused on discovering, developing and commercializing innovative hospital specialty products that have a positive impact on society.