When we talk about vaccines, most people think of an injection to prevent childhood infectious disease. However, in recent years the uses to which vaccines are being put has expanded dramatically. Hence, vaccines that are currently in development, target prevention or treatment of a wide range of non-infectious diseases, including allergy, diabetes, high blood pressure, heart disease, asthma, obesity, Alzheimer's disease and cancer.

At the novelty end of the spectrum, vaccines are being developed to treat conditions such as smoking and drug addiction. With these new vaccine applications, have come new challenges, such as how to break self-tolerance and how to induce immune responses against non-protein small molecules? Our Adelaide-based company, Vaxine, has been at the forefront of this revolution in non-traditional vaccine development, with current programs encompassing cancer, allergy, diabetes and Alzheimer's vaccines, in addition to a large array of more traditional infectious disease vaccines.

All vaccine function by the administration of a target substance called an antigen, which is typically a protein but can also be a sugar or a lipid. These antigen then trigger an immune response against itself resulting in the production of antibodies that bind the antigen and remove it from the body. Vaccine antigens can also activate T lymphocytes (T cells), which then are able to attack any cells that are expressing the antigen on their surface.

While the immune system has primarily evolved to attack and neutralize invading pathogens, this does not mean that it cannot respond against other molecules including those derived from our own tissues. This is the basis of cancer vaccines, which typically involve injection of antigens expressed by the tumour, together with an immune potentiator called an adjuvant, to try and trigger an immune response against the cancer.

To be successful a cancer vaccine must break self-tolerance, some thing that is hard to do as the body normally tries to avoid responding against itself in order to avoid autoimmune disease. To get around this problem cancer vaccines typically include a powerful inflammatory adjuvant that drives the immune system to respond to the antigen even although it may represent self. Another technique for administering cancer vaccines is to incubate the relevant antigen with dendritic cells in vitro, to allow uptake of the antigen and then injecting the antigen-labeled cells back into the patient. This is the basis of Provenge, currently the only approved human cancer vaccine that was developed by Dendreon, for treatment of patients with prostrate cancer.