When chemotherapy and radiotherapy damage cells, the immune system is boosted to help in the repair process. Researchers have found that they can introduce a virus into the white immune cells and this kills off cancers cells and tumours in mice given prostate cancer. (Journal of Cancer Research).
The Trojan-horse therapy was studied by Professor Claire Lewis and her team at Sheffield. They used macrophages, a part of the immune system which normally attacks foreign invaders. These are mixed with a virus which, just like HIV, avoids being attacked and instead becomes a passenger in the white blood cell.
In the study, the mice were injected with the white blood cells two days after a course of chemotherapy ended. At this stage each white blood cell contained just a couple of viruses. However, once the macrophages enter the tumour the virus can replicate. After about 12 hours the white blood cells burst and eject up to 10,000 viruses each - which go on to infect, and kill, the cancerous cells. At the end of the 40-day study, all the mice who were given the Trojan treatment were still alive and had no signs of tumours.