A modified virus that only targets cancerous cells for death and leaves healthy cells alone is ready for trials in animals and possibly Phase I safety trials in people.

Researchers used a virus called Newcastle Virus, that infects chickens, but does not affect humans. But what it does in humans is home in on tumor cells as was seen in a few human trials. But such trials were ineffective because of lack of enough virus or failure to penetrate solid tumors.

The researchers got around this limitation by genetically engineering a protein that the virus uses to fuse to a cell to only interact with a prostate specific enzyme. This way the virus now seeks out and only infects prostate cancer cells. They now call the virus "Retargeted Newcastle Virus."

Retargeted Newcastle disease virus has major potential advantages over other cancer therapies, says Subbiah Elankumaran in a press release. First, its specificity for prostate cancer cells means it would not attack normal cells, thereby avoiding the various unpleasant side effects of conventional chemotherapies. In previous clinical trials, even with extremely large doses of naturally occurring strains, "only mild flu-like symptoms were seen in cancer patients," says Elankumaran. Second, it would provide a new treatment for hormone-refractory patients, without the side effects of testosterone suppression that result from hormonal treatments.

One in six men will be diagnosed with prostate cancer and one in 36 men will die of the disease.

The report in the journal Virology can be found here.