Sanofi C. diff vaccine shows immune response in PhII trial

BOSTON--With new Phase II trial results for its Clostridium difficile vaccine, French drug giant Sanofi ($SNY) is leading the race ahead of Pfizer ($PFE) and Valneva for preventive therapies for the deadly bacterial infection.

The company's vaccine unit, Sanofi Pasteur, unveiled positive results for an investigational vaccine, reporting that the Phase II trial met its primary objectives and most trial participants had mild, short-lived reactions. The candidate vaccine, H-030-012, generated an immune response against two toxins that are responsible for most C. difficile infections, which can cause potentially life-threatening gut inflammation and diarrhea. The data were presented May 19 at the American Society for Microbiology General Meeting in Boston.

For the more than 336,000 Americans a year that acquire a C. difficile infection, a preventive measure could curb potentially life-threatening infections and avoid unnecessary healthcare costs.

"We know that this is a very challenging condition, and we think for all infectious diseases, prevention is something that is of value," Dr. Guy De Bruyn, director of clinical development at Sanofi Pasteur, told FierceVaccines in an interview.

C. difficile, which most often occurs after the use of antibiotic medications, is becoming increasingly prevalent in healthcare facilities and other settings in part because of rising antibiotic abuse. Pfizer and European biotech Valneva are also developing C. difficile vaccines, but both are still in early clinical trials. Meanwhile, Sanofi is recruiting 15,000 participants in 17 countries for its Phase III trial.

The trial was split in two stages--the first stage designed to select a dose and formulation among 455 volunteers, and the second among 206 additional participants to design a schedule for administering the vaccine. The study enrolled adults who were 40 to 75 years old and at risk of C. difficile infection, either because they were scheduled for hospitalization or were planning to enter a long-term healthcare facility.

The Phase II results suggest a vaccine schedule of three doses--an initial dose, and two additional ones, at 7 days and then 30 days after the initial one.

According to the Centers for Disease Control and Prevention, C. difficile is associated with 14,000 deaths annually, and a 2012 study found that C. difficile infections may have resulted in up to $4.8 billion in excess costs in U.S. acute care facilities in 2008.

"For C. difficile, if you do develop the disease you have a high risk of developing recurrence. About 20% to 30% of people have relapse after treatment," De Bruyn said. After a first recurrence, De Bruyn said the potential for another relapse is even higher, underscoring the need for a preventive measure.

- see the press release