By ED SUSMAN WEST PALM BEACH, Fla., July 9 (UPI) -- Pancreatic cancer tumors shrink or disappear in animals treated with a molecularly engineered therapy that attacks the malignancy without impacting healthy tissues, researchers said Monday.
"This is very promising and we are very excited about this treatment, but we had to be careful in letting patients know that we are at least a year to a year and a half before we will be able to treat people with this experimental therapy," James Abbruzzese, professor and chairman of the gastrointestinal medical oncology department at the University of Texas M.D. Anderson Cancer Center in Houston, told United Press International.
Researchers at M.D. Anderson, one of the leading cancer treatment centers in the United States, used genetic and molecular engineering to create a therapy that selectively attacks pancreatic cancer cells but doesn't destroy healthy tissue in the mouse model used in the pre-clinical tests.
The work, described in Monday's issue of the journal Cancer Cell by Mien-Chie Hung, professor and chair of molecular and cellular oncology at M.D. Anderson, involves packaging a targeting agent known as a promoter, two components that boost gene expression and a payload that consists of a gene known to kill cancer cells. It is all wrapped up in a liposome -- a fat molecule -- that can be injected intravenously into the patient.
Abbruzzese says the liposome circulates until it finds cancerous cells and then attaches to the cells and begins the cascade that kills the cancer. "This vehicle, or vector, is so targeted and robust in its cancer-specific expression that it can be used for therapy," said Hung.
"We are now gathering the information on toxicity and effectiveness in these animals so we can present it to the Food and Drug Administration in order to prepare for clinical trials," Abbruzzese said.
"There are few treatments that are successful in pancreatic cancer," he said. "The FDA is aware of the need for a treatment so we are all moving forward in trying to get this treatment to the clinic."
About 32,000 people in the United States die from pancreatic cancer each year. It is an equal opportunity killer, affecting similar numbers of men and women. About 37,000 cases of pancreatic cancer are diagnosed annually in the United States. Fewer than 4 percent of pancreatic cancer patients survive five years after diagnosis, one of the lowest cancer survival rates.
In studies with mice, control animals that were not given treatment for their pancreatic cancer all died within 40 days. A therapy without the targeted genetic approach but using some of the same tools lengthened survival to around 90 days.
Then Hung and colleagues loaded the liposome system with a version of a gene named Bik, which expresses a protein that naturally forces cancer cells to kill themselves. The mutant Bik created in the laboratory to be more lethal was named it BikDD.
When treated with the full package and BikDD, at least half of the mice survived for 14 months with no detectable sign of cancer recurrence.
The researchers experimented with two lines of pancreatic cells, including an aggressive form that rapidly spreads to other organs. No such spread was seen if the mice were treated with the experimental therapy.
"All cancer drugs have some toxicity and so cause side effects, which affects the dose that can be administered," Hung said. "We observed virtually no systemically acute toxicity or acute pancreatitis."
Abbruzzese said any clinical trial will advance under a National Cancer Institute Specialized Programs of Research Excellence grant in pancreatic cancer. SPORE awards are designed to translate scientific findings into the clinic.
