An experimental therapy that uses Listeria bacteria to infect pancreatic cancer cells and deliver tumour-killing drugs has shown promise in mice, say US scientists.
While it remains unknown whether the method might work in people, the researchers say they are encouraged by its ability to halt cancer’s spread.
“At this point, we can say that we have a therapy that is very effective for reducing metastasis in mice,” says co-author Dr Claudia Gravekamp, associate professor of microbiology and immunology at Albert Einstein College of Medicine of Yeshiva University in New York.
The experimental technique described in the Proceedings of the National Academies of Science works by using a weakened form of Listeria, a bacterium which in its wild form can cause foodborne illness.
Pancreatic cancer tends to spread quickly through the body and is particularly lethal, since it is often discovered only once it has progressed beyond the pancreas.
Untreated patients usually die within three to six months, and the five-year survival rate is just four per cent.
In previous research, Gravekamp’s team discovered that Listeria could be used to infect tumour cells with antigens. While the bacterium was cleared from normal cells by the body’s immune system within three to five days, it accumulated in the immunosuppressed tumours.
“Based on these results we hypothesized that Listeria could be used to deliver anticancer agents such as radionuclides,” they write.
In this experiment, the researchers attached a radioactive isotope to the bacteria and injected it into mice with pancreatic cancer. They found the radioactive bacteria infected cancer cells but not normal cells.
Ninety per cent of mice with pancreatic cancer treated with the technique showed no evidence of cancer spread after three weeks.
Researchers halted the experiment at 21 days because that is when the control mice, who had pancreatic cancer, but were not treated, began to die.
The treatment stopped the cancer’s spread in most cases, and appeared to have no ill effects on the mice, but more work needs to be done to see if it may extend survival time.
“With further improvements, our approach has the potential to start a new era in the treatment of metastatic pancreatic cancer,” says Gravekamp.
Abc.net.au [en línea] Sydney (AUS): abc.net.au, 29 de abril de 2013 [ref. 23 de abril de 2013] Disponible en Internet: http://www.abc.net.au/science/articles/2013/04/23/3743192.htm