Results from a mid-stage clinical study of Emergent BioSolutions Inc's single dose, drinkable typhoid vaccine had reaffirmed pre-established clinical endpoints, the biopharmaceutical company said in a statement.
97 per cent of the children dosed developed an immune response, which was defined as an increase in Salmonella typhi LPS-specific IgG antibody levels and/or Salmonella typhi LPS-specific IgA antibody levels in the blood, suggestive of systemic and mucosal protective immunity, respectively. This represented a statistically significant difference from the placebo group. 93 per cent of the children developed responses as measured by increases in Salmonella typhi LPS-specific IgG antibody levels suggestive of systemic protective immunity and 94 per cent developed an immune response as measured by increase in Salmonella typhi LPS-specific IgA antibody levels suggestive of mucosal protective immunity.
The recently completed, randomised, placebo-controlled, blinded phase II clinical study reaffirmed that its single-dose, drinkable typhoid vaccine candidate was highly immunogenic and well-tolerated with an acceptable safety profile in the population studied. For the study, a total of 151 Vietnamese children between 5 and 14 years of age were enrolled. A total of 101 children received the vaccine candidate and 50 children received placebo. This clinical study is the first trial involving a paediatric population and was performed in collaboration with the Wellcome Trust, Oxford University and the Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam.
There were no safety concerns following administration of a single dose of the drinkable typhoid vaccine candidate. The proportion of subjects reporting adverse events was similar for the vaccinated group (26 per cent) and placebo group (22 per cent); this difference was not statistically significant.
There were no serious adverse events reported, no deaths and no subjects withdrew due to adverse events. There were small differences in specific adverse events with more gastrointestinal symptoms and headaches reported in the vaccinated group and more respiratory symptoms in the placebo group.
"We are pleased that the full analysis of the data from this Phase II study reaffirms that our typhoid vaccine candidate met the pre-established clinical endpoints. These data are encouraging and indicate great promise regarding both the safety and efficacy of what would be the first single-dose, drinkable typhoid vaccine," stated Fuad El-Hibri, chairman and chief executive officer, Emergent BioSolutions. "Typhoid is often endemic in developing countries and claims 200,000 lives annually. A Phase II trial in the United States and a phase IIb trial in an endemic population are both slated to begin by the end of 2008. Both of these trials will use clinical material produced using a scaled-up commercial manufacturing process."
The trial and development of the vaccine have been made possible by funding from the Wellcome Trust, the largest medical research charity in the United Kingdom.
Dr. Ted Bianco, director, technology transfer, Wellcome Trust, said, "We are delighted to have partnered with Emergent BioSolutions to support this trial in Vietnam. The trial will advance the development of a sorely needed vaccine for typhoid fever. The ease of administration of the product is one of its chief attractions from a public health perspective."
The company's typhoid vaccine candidate is a live attenuated strain of the Salmonella typhi bacterium designed to eliminate virulence by deletion of two specific genes. The vaccine is intended to be administered in a single, drinkable dose. If approved, this method of administration could provide a competitive advantage compared to currently approved typhoid vaccines.
Emergent BioSolutions Inc. is a biopharmaceutical company dedicated to one simple mission-to protect life. Emergent develops, manufactures and commercialises immunobiotics, consisting of vaccines and therapeutics that assist the body's immune system to prevent or treat disease.