Following a planned interim analysis, the Independent Data Monitoring Committee (IDMC) for the phase III Cdiffense clinical trial program concluded that the probability that the study will meet its primary objective is low. Based on this, Sanofi has therefore decided to discontinue clinical development of its experimental Clostridium difficile vaccine, to focus on six key vaccine projects currently in development.

Cdiffense is a trial designed to test the efficacy and safety of a candidate toxoid vaccine in a subpopulation at risk of Clostridium difficile infection.

Sanofi Pasteur, the vaccines business of Sanofi responsible for the program, is informing all investigators, regulatory authorities and trial ethics committees. In addition, investigators are notifying study volunteers of the decision to stop the program.  Data from all vaccinated volunteers in this trial will continue to be analyzed for more information and shared with the scientific community.