Study of vaccine against Clostridium difficile expands into the U.S.

Lyon, France and Swiftwater, Pa. — Sanofi Pasteur announced Dec. 15 that it is expanding its phase II clinical study of a vaccine against Clostridium difficile infection into the United States.

The trial started in the United Kingdom earlier this year.

The incidence of C. difficile infections has increased significantly in recent years in both North America and Europe. Treatments in these two regions are estimated to cost more than $7 billion a year.

“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, senior vice president, research and development of Sanofi Pasteur.

“Recurring infection occurs in at least 20 percent of patients experiencing a first CDI episode and even higher frequency in those who have had multiple episodes,” he said.

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

“There is also considerable concern about the emergence of antibiotic-resistance in various bacterial species, including C. difficile,” DeWilde said. “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.”

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.

The phase IIb trial hopes to recruit approximately 600 people with acute C. difficile infections 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.