Nicknamed "Visa," the molecularly engineered treatment includes a targeting agent, two components that boost gene expression in the targeted tissue, and a payload -- in the case of the current research, a gene known to kill cancer cells. The treatment is administered intravenously.

So far, it has been tested in mouse models by researchers at the University of Texas MD Anderson Cancer Center; they are planning to move to a Phase I clinical trial next. It could take as long as two years to meet the requirements of the US Food and Drug Administration before they can initiate the Phase I trial, however.

In the US, about 37,000 new cases of pancreatic cancer are diagnosed each year. Because early diagnosis is very difficult, it is often detected only after it has metastasized. Pancreatic cancer has one of the lowest survival rates of all types of cancer, with fewer than 4 percent of patients surviving more than five years following diagnosis.

In the tests conducted at MD Anderson, the therapy was used against two aggressive lines of pancreatic cancer in two different types of mice. Using the Visa system, researchers delivered BikDD, a mutant version of a gene that forces cancer cells to kill themselves.

Control mice that were given no treatment died within 40 days. Mice that were given the mutant gene using a different, less-targeted system all died with 90 days -- most significantly earlier. The mice treated with the Visa system lived longer, with no sign of metastases; at least half survived for 14 months with no cancer recurrence.

"This [Visa] vehicle, or vector, is so targeted and robust in its cancer-specific expression that it can be used for therapy and perhaps for imaging," noted senior author Mien-Chie Hung, PhD, professor and chair of MD Anderson's Department of Molecular and Cellular Oncology.

"This looks like a promising approach to gene therapy for pancreatic cancer and we are working to bring it to a clinical trial," said James Abbruzzese, MD, professor and chair of the MD Anderson Department of Gastrointestinal Oncology.

"All cancer drugs have some toxicity and so cause side effects, which affects the dose that can be administered," Hung said. The team looked for signs of acute systemic toxicity and of pancreatitis, a dangerous inflammation of the pancreas.

However, "VISA-BikDD produces virtually no systemically acute toxicity or acute pancreatitis," they reported.

Hung's team is continuing research on the gene expression vehicle. "Visa is versatile enough that if you change the promoter, you could target other cancers or even other diseases," Hung said.