The immunotherapeutic was discovered by Intercell and subsequently exclusively licensed to Merck & Co. in 2003. The latest data for V710, from a Phase I clinical trial of over 120 healthy volunteers, show the vaccine is safe and generally well tolerated.
Hospital acquired infections are a major cause of death and serious illness worldwide, costing heath systems in the developed world over $20bn (€14.8bn) annually. Generally, the number of these infections is rising due to the emergence of antibiotic-resistant strains of bacteria, including the well-known methicillin resistant Staphylococcus aureus (MRSA). As more strains develop resistance to existing drugs, treating the infections is becoming increasingly challenging.
In the clinical trial for V710, immune responses were observed within several weeks following vaccination and these immune responses persisted throughout the course of the study, according to Intercell.
Intercell used its in-house technology to identify suitable antigens to use in the vaccine, which could prevent and treat S. aureus infections. The Austrian-based company has extracted antibodies from patients who have successfully fought off infection and therefore produced molecules that will bind to antigens from the bacteria which, in turn, are both accessible and able to induce an immune response.
Once removed, the antibodies can be used to identify possible vaccine candidates. The candidates themselves are generated by randomly fragmenting DNA from the bacteria to produce "all possible peptide fragments encoded by the [bacteria's] genome", according to Intercell.
The fragments are then displayed on the surface of genetically engineered E. coli bacteria. Paramagnetic beads are used to capture the antibody-cell complex to identify those epitopes interacting with human antibodies. Intercell has used this technique to develop a number of vaccines against other targets such as S. epidermidis, and Streptococcal pneumoniae, pyogenes and agalactiae.
The company is also utilising the technology to discover therapeutic antibodies, although this research is still at the preclinical stage.
Nabi Biopharmaceuticals is also developing a vaccine against S. aureus infections. Called StaphVax, it is a polysaccharide conjugate vaccine that initially contained surface polysaccharides found in the outer coating of Types 5 and 8 S. aureus bacteria. Nabi is also developing a 'next-generation' vaccine that will contain S. aureus Type 336 antigen combined with S. aureus Types 5 and 8 antigens, as well as two other antigens against S. aureus-detoxified Panton-Valentine Leukocidin (PVL) and alpha toxin.
Nabi claim that this newer product "will have the ability to provide protection against virtually all clinically significant S. aureus and S. epidermidis infections known today". However, the programme is currently on hold pending partnership or external funding.
