“The great thing about this strategy is that the cancer cell does all the hard work,” says Nick Lemoine, director of the Cancer Research UK Clinical Centre at Bart’s Medical School, who led the team. “It makes more and more virus to infect its neighbouring cancer cells. But if a normal cell is infected, it commits suicide before it can make new virus and spread of the virus is contained.”
Removing the gene, called E1B-19kD, from the adenovirus not only removed its cloak that viruses normally use fo evade detection, but also provided another unexpected benefit. It enabled the viruses to replicate much faster than normal, which in turn helped burst the cancer cells–an effect that previous genetically modified viruses had not shown.
The team examined the effects of the GM virus on pancreatic, lung, ovarian, liver and colorectal cancers in the test tube, as well as on live tumour-bearing mice. They plan to begin clinical trials in people in 2005. “In tests so far it has proven both potent and selective, although only clinical trials will tell us whether the approach can be an effective treatment in people,” comments Robert Souhami, Cancer Research UK’s director of clinical and external affairs. Lemoine adds that the GM virus could also be armed with additional anti-cancer weapons, in the form of genes producing toxic compounds. “The fact that we have taken a gene out of the viral backbone means we could arm the virus with something that deliberately kills cancer.”