Sanofi Pasteur expands study of vaccine against Clostridium difficile into the U.S.

- Novel vaccine approach tested against one of the most common causes of hospital-acquired infection in Europe and North America -

Lyon, France and Swiftwater, PA, USA | December 15, 2009 | Sanofi Pasteur, the vaccines division of the sanofi-aventis Group, announced today that it is expanding its phase II clinical study of a vaccine against Clostridium difficile infection (CDI) into the United States. The trial started in the United Kingdom earlier this year.

The incidence of CDI has increased significantly in recent years in both North America and Europe. CDI-related treatments in these two regions of the world are estimated to be costing more than $7 billion a year. The recent emergence and spread of a hyper-virulent strain of C.difficile further highlights the importance of tackling CDI.

“While the target indication for the vaccine is prevention, this trial - in recently infected patients - aims to provide early proof-of-concept of a vaccine approach to preventing recurring infection,” said Michel DeWilde, Ph.D., Senior Vice President, Research and Development, Sanofi Pasteur. “Recurring infection occurs in at least 20 percent of patients experiencing a first CDI episode and even higher  requency in those who have had multiple episodes,” he explained.

CDI is among the most common causes of nosocomial (hospital-acquired) infection in North America and Europe. Current treatment of C.difficile infection involves the use of one of the two antibiotics recommended for CDI management. The trial is investigating the safety and efficacy of Sanofi Pasteur’s CDI candidate vaccine in the U.S. population.

“Non-antibiotic approaches for managing CDI are badly needed since antibiotics alter the gut microflora and permit the infection in the first place,” said Dr. DeWilde. “There is also considerable concern about the emergence of antibiotic-resistance in various bacterial species, including C.difficile. Vaccination has the potential to be a very effective strategy to combat the gastrointestinal symptoms caused by C.difficile in conjunction with better antibiotic stewardship and infection control practices,” he added.

Sanofi Pasteur’s candidate vaccine uses a toxoid-based approach, which has been used extensively  in licensed vaccines against tetanus, diphtheria and pertussis (whooping cough). This candidate vaccine has successfully completed phase I clinical trials in more than 200 participants to evaluate its safety and immunogenicity.

About the Clinical Trial

The phase IIb trial hopes to recruit approximately 600 participants with acute CDI across the United Kingdom and in the U.S. Participants will be randomized to four study groups, where three groups will receive vaccine, while the fourth group will be given a placebo vaccine. All subjects will receive standard of care antibiotics. For more information on the trial and the sites conducting the study, go to .

About C.difficile

C.difficile is an anaerobic spore-forming bacterium, present asymptomatically in approximately 60 percent of infants but only approximately three percent of healthy adults. It belongs to the Clostridium family of bacteria, which also includes C.tetani (tetanus) and C.botulinum (botulism). The C.difficile bacteria produce two potent toxins: A and B. When the natural microbial flora of the gut is disturbed, usually as a result of antibiotic treatment for other illnesses, and a patient ingests C.difficile spores, the bacteria can multiply and release the two toxins, which cause a broad range of gastrointestinal symptoms in humans known collectively as CDI.

Hospital-acquired infections caused by C.difficile are a considerable problem in many industrialized countries, including the U.S., Canada, and Europe. It is estimated that there are about 500,000 cases of CDI in the US alone1, with annual costs to the healthcare system of $3.2 billion2. In the EU, assuming a population of about 460 million people, the healthcare costs of CDI are estimated to be around $4.4 billion per year.3 Additional information is available at the US Centers for Disease Control and Prevention and UK Health Protection Agency C.difficile information  pages1,4.

About sanofi-aventis

Sanofi-aventis, a leading global pharmaceutical company, discovers, develops and distributes therapeutic solutions to improve the lives of everyone. Sanofi-aventis is listed in Paris (EURONEXT:  SAN) and in New York (NYSE: SNY). For more information, please visit: Sanofi Pasteur, the vaccines division of the sanofi-aventis Group, provided more than 1.6 billion doses of vaccine in 2008, making it possible to immunize more than 500 million people across the globe. A world leader in the vaccine industry, Sanofi Pasteur offers the broadest range of vaccines protecting against 20 infectious diseases. The company's heritage, to create vaccines that protect life, dates back more than a century. Sanofi Pasteur is the largest company entirely dedicated to vaccines. Every day, the company invests more than EUR 1 million in research and development. For more information, please visit: or


1. CDC:
2. O’Brien et al, The Emerging Infectious Challenge of Clostridium difficile-Associated Disease in Massachusetts Hospitals: Clinical and
Economic Consequences. Infection Control and Hospital Epidemiology, 2007; 28(11):1219-1227
3. European Centre for Disease Prevention and Control, Emergence of Clostridium difficile-associated disease in North America and
Europe, Clinical Microbiology and Infectious Diseases, 2006; 12 (Suppl. 6): 2–18
4. HPA:

SOURCE: Sanofi-aventis

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