Investigational vaccine against Clostridium difficile

Acambis has announced that earlier this month it started a Phase I clinical trial of its investigational vaccine against Clostridium difficile (C. difficile).

C. difficile infection, which is characterised by diarrhoea and colitis, represents one of the most common hospital-acquired infections around the world. A new virulent strain of C. difficile has also emerged, causing sharp increases in the number of infections and deaths associated with the infection in a number of countries including the UK, Canada, the Netherlands and the US.

The Phase I trial is designed to obtain information on the safety, tolerability and immunogenicity of Acambis' C. difficile vaccine when administered at different dose levels. The randomised, double-blind, placebo-controlled study in healthy adult subjects is being conducted at two study centres in the US. Acambis also plans to start a second Phase I trial of its C. difficile vaccine in elderly subjects.

Acambis has been developing a C. difficile vaccine for many years and has spent the last two years improving and optimising the formulation of the vaccine. During that time, it has also developed a robust and efficient manufacturing process to produce the vaccine at its own facility.

Today, no vaccine exists to protect individuals against C. difficile and Acambis is the only company known to be developing a vaccine against it. Its investigational toxoid vaccine was developed to provide immunity against toxins A and B, the toxins responsible for the development of C. difficile-associated diarrhoea.

C. difficile caused 43,000 infections in the UK in 2004, a 23% increase over the previous year. C. difficile infections also cause approximately 350,000 cases every year in the US and most of these involve elderly individuals who become infected in hospitals and long-term care facilities that have become reservoirs of this organism.