A potential Clostridium difficile vaccine performed well in initial tests and now has moved into a large Phase III trial, researchers announced today. The news from developer Sanofi Pasteur raises hopes that the antibiotic-resistant infection can be prevented in long-term care facilities and other settings where it has become a deadly scourge.
The first two phases of vaccine testing involved about 650 volunteers between 40 and 75 years old, who were at risk of C. diff due to impending long-term care admission or hospitalization. High-dose and low-dose versions were tested in Phase I, and the high-dose formulation moved on to the second phase, according to a statement released in conjunction with an announcement at today’s General Meeting of the American Society for Microbiology.
“In this trial, we saw a significant increase in antibody production against C. diff toxins, across all dosing schedules and volunteer ages,” said ASM presenter Guy De Bruyn, MBBCh MPH, director of clinical development at Sanofi Pasteur.
Phase II participants responded best when vaccinated on day 0, 7 and 30 of the trial, with elderly recipients experiencing particularly strong immune responses, according to Sanofi. This administration schedule now is being tested in Phase III, which began in August and could involve 200 sites in 17 countries. The vaccine so far has proved safe, with the only reactions being mild and of short duration.
The investigational toxoid vaccine is meant to work in the same way as tetanus or whooping cough vaccines, by stimulating the immune system to fight C. diff when it appears, said Jamshid Saleh, M.D., principal investigator in the Phase III trial at Northern California Clinical Research Center in Redding, CA.
In the absence of a vaccine, long-term care professionals are seeking other ways of treating the intestinal condition, which is caused when C. diff bacteria infest a gut that is susceptible due to factors such as antibiotic exposure. Fecal transplant has emerged as one effective treatment.