Salmonella for Skin Cancer?
Pawelek say he's not sure why the combined X-ray and Salmonella therapy seems to be so effective at slowing tumor growth in mice.
It's possible that the bacteria could interfere with the ability of tumor cells to repair themselves after they have been exposed to X-rays, or that X-rays themselves could "soften" up the cells, allowing Salmonella to come in for the "kill." A third possibility is that the presence of Salmonella might put the immune system on guard that the body has been invaded, and that X-rays might make tumor cells more vulnerable to immune attack, the authors speculate.
But a researcher who has collaborated with Pawelek on other projects cautions that the combined therapy may prove to be more useful for treating other forms of cancer.
"The work that John has done is very interesting, but you need to put it into context," says Mario Sznoll, MD, vice president for clinical affairs of Vion Pharmaceuticals, in an interview with WebMD. "Radiotherapy is not a standard treatment for melanoma, which is usually metastatic, so it's just representative of what one could do in other settings where radiotherapy is a useful modality."
Sznoll says his company has investigated the bacteria in combination with standard chemotherapy drugs in mice and found it to be just as effective as the radiation-Salmonella combination. Vion currently is working on a second generation of the bacteria modified to carry an enzyme that will convert a harmless drug into a cancer-killer when the drug is injected into the body.
The first generation of the modified bacteria currently is being investigated for safety in human clinical trials. If it proves to be safe, it can then be studied as a possible treatment for melanomas and perhaps other forms of cancer, Sznoll says.