CHMP Recommends Astellas Pharma Europe Ltd.'s (APEL) DIFICLIR™ for Approval in the EU

STAINES, England and SAN DIEGO, California, September 23, 2011 /PRNewswire/ --

Astellas Pharma Europe Ltd. (APEL) and Optimer Pharmaceuticals, Inc. (NASDAQ: OPTR) today announced that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) has adopted a positive opinion for DIFICLIR™ (fidaxomicin) tablets for the treatment of adults suffering with a Clostridium difficile infection (CDI), also known as C. difficile-associated diarrhoea (CDAD).^[1]

The CHMP positive opinion is based on Phase 3 clinical studies that were conducted to compare the safety and efficacy of 400mg/day fidaxomicin with 500mg/day oral vancomycin for 10 days in subjects with CDI.^[2] The first Phase 3 study was carried out in 629 subjects in North America (US and Canada).^[2] The second Phase 3 study was carried out in 535 subjects in North America and Europe.^[3] The results of the studies showed that the proportion of subjects in which clinical cure* was achieved at the end of 10 days of treatment, were similar for both treatments, thus fidaxomicin met its primary endpoint of non-inferiority to vancomycin.^[4] Furthermore in both trials, fidaxomicin had a significantly lower rate of recurrence of CDI compared to vancomycin.^[4]

"European patients with this potentially fatal disease can take encouragement from the positive CHMP opinion for DIFICLIR that a new medication for Clostridium difficile infection may soon be available," said Ken Jones, President and CEO of Astellas Pharma Europe Ltd.

DIFICLIR, which is known as DIFICID™ in the United States (US), was approved by the US FDA in May 2011 for the treatment of CDAD^[5] in adults 18 years of age and older.^[6]

The European Commission generally follows the recommendations of the CHMP and delivers its final decision within three months.

DIFICLIR is a novel macrocyclic antibiotic that specifically targets C. difficile.

About Clostridium Difficile Infection (CDI)

CDI is a serious illness resulting from infection of the internal lining of the colon by C. difficile bacteria. The bacteria produce toxins that cause inflammation of the colon, diarrhoea and, in some cases, death.^[7,8] Patients typically develop CDI after the use of broad-spectrum antibiotics that disrupt normal gastrointestinal flora, allowing C. difficile bacteria to flourish.^[9] Older patients are at greater risk of CDI recurrence specifically those aged 65 years of age or older.^[10]

About Astellas Pharma Europe Ltd.:

Astellas Pharma Europe Ltd., located in the UK, is a European subsidiary of Tokyo-based Astellas Pharma Inc. Astellas is a pharmaceutical company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceuticals. The organisation is committed to becoming a global company by combining outstanding R&D and marketing capabilities and continuing to grow in the world pharmaceutical market. Astellas Pharma Europe Ltd. is responsible for 21 affiliate offices located across Europe, the Middle East and Africa, an R&D site and three manufacturing plants. The company employs approximately 4,000 staff across these regions. For more information about Astellas Pharma Europe, please visit http://www.astellas.eu/.

About Optimer Pharmaceuticals, Inc.:

Optimer Pharmaceuticals, Inc. is a biopharmaceutical company focused on discovering, developing and commercialising hospital specialty products to treat serious infections and address unmet medical needs. Optimer has a further anti-infective product in development. Additional information can be found at http://www.optimerpharma.com/.

References

1. Awaiting confirmation of CHMP approval http://www.ema.europa.eu/docs/en_GB/document_library/Summary_of_opinion_-_Initial_authorisation/human/002087/WC500112845.pdf
2. Louie TJ, Miller MA, Mullane KM, et al. Fidaxomicin versus vancomycin for Clostridium difficile infection. N Engl J Med. 2011;364:422-31.

3. Data on file: Crook et al ECCMID 2010.

4. Mullane KM, Gorbach S. Fidaxomicin: first-in-class macrocyclic antibiotic. Expert Rev Anti Infect Ther. 2011;9:767-77.

5. Food and Drug Administration. FDA approves treatment for Clostridium difficile infection [Internet]. [updated May 27 2011; cited September 16 2011] Available from http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm257024.htm

6. DIFICID US Prescribing Information 2011.

7. Gerding DN, Johnson S, Peterson LR, et al. Clostridium difficile-associated diarrhea and colitis. Infect Control Hosp Epidemiol. 1995;16:459-77.

8. Sunenshine et al. Clostridium difficile-associated disease: New challenges from an established pathogen. Cleve Clin J Med 2006;73:187-97.

9. Kelly CP, LaMont JT. Clostridium difficile infection. Annu Rev Med. 1998;49:375-90.

10. Pepin, J et al. Increasing Risk of Relapse after Treatment of Clostridium difficile Colitis in Quebec, Canada. Clin Infec Diseases, Oxford Journals 2005.

*Please note: clinical cure was defined in these two clinical trials as patients requiring no further CDI therapy two days after completion of study medication, as determined by the investigator.