Salmonella fights cancer

It may sound far-fetched, but salmonella may help in the fight against cancer.

The disease-causing bacteria which can trigger severe food poisoning is the foundation of a new cancer therapy being developed by researchers at the Helmholtz Centre for Infection Research (HZI) in Braunschweig, Germany.

The research team is using genetically modified, detoxified salmonella strains, which also have useful characteristics in the fight against diseases.

"We have known for 150 years that bacteria can destroy tumour cells," said Siegfried Weiss, who heads the HZI's Molecular Immunity project group.

Until now, however, researchers had been unable to control the danger of infection from bacteria used against cancer. But that is now possible, especially with the molecular and infection biology of salmonella, since bacteria can be genetically modified.

An eight-member HZI research team has been working on the project for six years and has come up with their first signs of success, putting them at the forefront worldwide in this area, according to Weiss. The researchers have been using the salmonella typhimurium bacteria and concentrating on colon cancer.

Salmonella live in tissues which are badly supplied with blood and thus have hardly any oxygen supply. Weiss said certain messengers are released in the immune system when they are injected into the body intravenously through the blood. It makes blood vessels in the cancerous tissue permeable.

Shortly thereafter, blood with the bacteria streams from the vessels into the cancerous tissue. The salmonella then conquer and destroy the tumour. Weiss reported that laboratory experiments with mice have already proved successful numerous times.

Weiss said the group is currently working on improving the force of the bacteria without the risk of blood poisoning. The researchers are also testing other options, such as toxins of other bacteria that, when planted in salmonella, are suited for cancer therapy.

Another is if messengers can mobilize and strengthen the immune system to fend off a cancer with the help of salmonella.

The project drew the interest of the Deutsche Krebshilfe (German Cancer Aid), which granted 245,000 euros (355,000 dollars) to Weiss's team.

"We've known a long time that tumours can be attacked by bacteria," said Gerd Nettekoven, the organization's managing director. "But actively using this phenomenon to improve the chances of recovery among cancer patients would be a big step in the treatment of cancer."

However, Weiss said it will still take time before the method is usable for human patients. The process could possibly be mastered within five years in animal experiments. Only then could clinical human testing even begin - which would also take years.

Weiss also assumes that this new therapy would only be used in accordance with, or instead of chemotherapy. The surgical removal of tumours will still be needed in the future, he said.

The salmonella method could also be used in diagnosis of cancers. A gene is inserted into the salmonella which encodes light-emitting proteins, helping to analyse the location and size of the tumour.