Cancer immunotherapy – redefining vaccines
Box 1 | Guarding against viral cancer – Gardasil®
Cervical cancer is the second most common form of cancer in women in the world, with a greater incidence in women from developing countries. Being among the few cancers (less than 20 per cent) caused by viruses, cervical cancer can be prevented with conventional vaccine technology. By presenting parts of the virus to the immune system, these vaccines trick the body into producing antibodies, preventing future infection by the real thing.
An example that would be familiar to many Australians is the vaccine Gardasil®. In 2007 the Australian Government started a program to immunise all girls aged between 12 and 13 with Gardasil®. This vaccine was developed to prevent cervical cancer, which is almost always caused by human papillomaviruses (HPVs). It protects against two HPV strains that are responsible for 70 per cent of cervical cancers.
Gardasil® was developed using technology developed in Australia. In a breakthrough for the vaccine's development, Professor Ian Frazer (2006 Australian of the Year) and Dr Jian Zhou used gene technology to make virus-like particles which resemble HPV, but aren't infectious. When used in a vaccine, these virus-like particles are detected by our immune system which then produces antibodies against two HPV strains.
Trials with the vaccine have been pretty convincing. The drug company Merck showed Gardasil® is 100 per cent effective at protecting (previously unexposed) people against HPV strains 16 and 18. But it is not a cure-all. Vaccinated people can still be infected by one of the many other strains of HPV, so regular Pap screening for cervical cancer is still necessary.
Gardasil® is a prophylactic vaccine, that is, it prevents infection by HPV. Scientists are now working on developing therapeutic vaccines for women who have already been exposed to the virus.
Related sites
Controlling cancer through immunisation – a glass half full? (Sir Mark Oliphant Conferences, Australia)
Cancer vaccine (Behind the News, Australian Broadcasting Corporation, 5 September 2006)
Cervical cancer vaccine raises questions (ABC News in Science, Australian Broadcasting Corporation, 26 October 2005)
External sites are not endorsed by the Australian Academy of Science.
Posted September 2008.