Virus gives cancer the cold treatment. (Biomedicine).

A genetically engineered version of a common cold virus appears to kill cancer cells without killing healthy tissue, according to a preliminary study in people with severe, untreatable gastrointestinal cancer that had spread to the liver. Their cancer couldn't be treated with surgery and no longer responded to currently available drugs.

The researchers injected the engineered virus into the artery leading to the liver. Most of the 35 patients reported only mild and transient side effects similar to cold symptoms, says lead researcher Daniel Y. Sze of Stanford University Medical Center.

Although the study was designed to test the safety of the therapy, not its effect, Sze says that tumor size decreased in about half the patients' livers. Further, the 28 patients who got the highest dose of the altered cold virus survived almost a year, compared with about 6 months for the seven patients who got the lowest doses. "It's encouraging data," says Sze, who hopes to try the treatment in a larger group of patients. He and his colleagues reported their results April 7 in Baltimore at a meeting of the Society of Cardiovascular and Interventional Radiology. --D.C.