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Fat cells as Cancer fighting Smart Bombs!?!?!?!


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Fat cells pack a wallop as cancer 'smart bombs'

News & Observer, The (Raleigh, NC) (KRT) - Jan. 03, 2007

Jan. 3--Duke University Medical Center scientists have recruited humble fat particles as soldiers in the war against cancer.

Researchers have transformed microscopic fat cells into cancer "smart bombs" by packing them with chemotherapy drugs. Then, they turn the blobs loose on cancer tumors, which are heated to open blood vessels enough to absorb them. The particles melt on contact with the warmed tissue, delivering a concentrated payload of medicine.

In a recent study in rats, Duke scientists found the method delivered 30 times more medication to tumors than traditional chemotherapy, which pumps medicine throughout the body rather than targeting cancerous tissue directly. Researchers think the results -- published Tuesday in the Journal of the National Cancer Institute -- suggest the fat delivery system may prove a powerful advance that will eventually improve human cancer patients' lives.

Duke researchers are already testing the heat-sensitive fat particles in a small number of breast cancer patients with recurrent tumors. Scientists with the National Institutes of Health are testing the Duke-designed system in patients with liver tumors.

The hope is for a targeted treatment that could eliminate or shrink tumors better than traditional chemotherapy, with fewer side effects. A Maryland company, Celsion, licensed the exclusive rights to the Duke system in 1999 and hopes to develop it into a commercial therapy.

"We can actually measure how much drug is going to the tumor," said senior investigator Mark Dewhirst, a professor of radiation oncology at Duke and director of the university's hyperthermia program, which explores ways of using heat to improve cancer treatments. "When we give cancer drugs to patients today, we really don't know at all where the drug is going."

Special fat cells made

The Duke rat study, funded by the National Cancer Institute, compared animals who received heat therapy before, during and after intravenous infusions of fat particles packed with a common cancer drug. Rodents' tumors were warmed by passing hot water through a thin plastic tube placed through the lesion's center. In people, external heaters warm the body near the tumor.

The fat cells used in the treatment are special ones called liposomes that are created in a laboratory, not the common variety found in abundance on most Americans. Designed by Duke engineering professor David Needham, the liposomes are microscopic -- about 1/100th the size of a red blood cell -- but still too large to be readily absorbed by organs and body tissues.

Heating cancer tumors causes the vessels that supply the tumor with blood to expand and take in the fat particles, giving the "bombs" the opportunity to deliver the medicine, Dewhirst said.

Rats whose tumors were heated during the infusion fared best. Tumors were eliminated in two of seven rats treated in this manner. Treatment significantly slowed the growth of tumors in the other rats, helping them to survive 35 days longer than a control group of rats that received no treatment. For rodents, 35 days is the human equivalent of several years.

Researchers also tested different ways of targeting the liposomes to determine whether hitting the edges or center of the tumor with medicine was more effective, or whether delivering a uniform dose throughout the cancer tissue was best. Blanketing a tumor's edges, areas rich in blood vessels, caused rodent tumors to shrink the most, Dewhirst said.

Work on large tumors?

"Based on the animal studies, we are very encouraged," said Dr. Zeljko Vujaskovic, a radiation oncologist and co-clinical director of the Duke hyperthermia program. He is one of the investigators testing the heat-sensitive liposomes in breast cancer patients.

The Duke breast cancer study will help establish what doses of drug patients can safely tolerate. But Vujaskovic said the long term goal is to demonstrate that the liposome system may be an effective first-line treatment for patients with large tumors. The therapy might shrink a breast tumor enough that a patient could have a lumpectomy, rather than mastectomy to remove the entire breast, for example.

"That's still down the road, but it's very exciting," said Vujaskovic.

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