University of Hong Kong researchers have turned the salmonella food poisoning bacteria into a “guided missile” that could deliver medicine into cancer cells and eliminate tumours. They have created a DNA-altered bacteria, called YB1, that can only reproduce in oxygen-free conditions. That means it can target malignant tumour growths without harming healthy tissue. An HKU spokeswoman said: “The researchers hope that [it] can be further developed into a tumour-targeting agent in the near future. The research team is currently exploring other potential use of this new bacterium. It is estimated that YB1 will be ready for clinical trials in a few years.” They have already applied for patents in different countries through HKU’s Technology Transfer Office, said the spokeswoman. A patent was recently granted in the United States. Salmonella is a bacteria commonly found in badly cooked meat and raw eggs, causing stomach pains and food poisoning. But the HKU scientists have engineered the bacteria into a new agent that can only survive in oxygen-deprived areas – such as the inside of a solid tumour. Lead researcher Professor Huang Jiandong , of HKU’s school of biomedical sciences, said the bacteria could act as a “guided missile” to carry drugs right into a tumour and destroy it. Its efficacy and safety had been tested in mice with liver and breast cancers with good results. With breast cancer, therapeutic drugs carried by YB1 successfully reduced tumour growth by 50 per cent, and cancer metastasis was completely inhibited when treated with YB1. For liver cancer, tumour growth was suppressed by 90 per cent in treated mice. Huang said using bacteria as therapeutic agents against solid tumours had become an emerging field in cancer therapy research in recent years. Scientists have known since the 1890s that anaerobic bacteria infections have in some cases caused partial or complete regression of malignant tumours. But it is difficult to target the benefits as some bacteria can cause severe infection and kill patients.