December 11, 2010

`Natural killers' unleashed to search and destroy cancer

Doctors at the University of Miami are treating liver cancer patients by giving immune-system cells more muscle in the lab to recognize and attack their cancer cells.


They're called ``natural killer cells'' but they're a part of the human immune system that helps save lives. Now doctors from Miami and Japan have developed new ways to pump up the cells to attack cancer even more aggressively.

Encarnacion Miranda, a 58-year-old car salesman from Key Largo, is counting on the cells -- which exist in healthy livers -- to save his life. He's the first patient in a clinical trial at the University of Miami of 25 liver patients seeking Food and Drug Administration approval of the new treatment.

``It's scary,'' Miranda said Thursday, during an announcement of the medical trial. ``But I feel really good.''

Miranda's liver had been dogging him since 1979, when he contracted hepatitis C from a blood transfusion. By October 2009, chronic exhaustion forced him to give up his favorite sport, fishing for yellowtail snapper in the Florida Keys. That's when he learned his hepatitis had become liver cancer.

Doctors gave Miranda a liver transplant. But, knowing that liver cancer recurs in up to 20 percent of cases due to tumor cells left hiding in the body, they went further. Before the transplant, they took blood from the donated liver, extracted the natural killer immune cells from it, then cultured and expanded them in laboratory flasks for four days to increase their power against any remaining cancer cells. They fed them intravenously back into Miranda's new liver.

Doctors say the killer cells, which recognize cancer cells as alien and try to destroy them, also will help fight any remaining hepatitis C. They aren't sure yet whether their findings on natural killer cell expansion might be broadened to work in other organs and combat other cancers.

The procedure was studied for four years at the University of Hiroshima. Dr. Masahiro Ohira performed the procedure on 24 patients; 22 survived cancer-free for more than three years. It cut in half the recurrence of cancer.

``The killer cells act like smart bombs in going after the cancer,'' Ohira said.

Miranda is grateful to the team at the University of Miami Medical School that worked with him at Jackson Memorial Medical Center.

``I was up and walking three days after my [Oct. 19] transplant,'' he said. ``Yesterday I walked six miles.''

Treating Miranda was actually far more complicated than his recovery would indicate. When his three liver tumors were found, they were too big to permit a transplant. So the team from UM used several courses of chemotherapy and radio-frequency ablation -- the use of radio-frequency waves to destroy tumor tissue -- to attack them, finally reducing them enough to make possible the transplant.

When a donor liver became available, the doctors flushed out some of its natural killer cells before transplanting it into Miranda. Ohira put the cells into a laboratory flask and applied an agent known to increase the cells' potency, even though it doesn't increase their number.

``It increases their activity against cancer and hepatitis C by four times,'' he said.

The team included Dr. Andreas Tzakis, director of the Liver Transplant Program, Ohira, now a research associate in the UM Department of Surgery and Drs. Seigo Nishida and David Levi, professors of clinical surgery at UM.

``They're my heroes,'' Miranda said. ``They never gave up.''

Miranda's prognosis?

``We think it's good,'' Tzakis said. ``Of course there are no guarantees.''

Miranda says he has far more energy now.

``Last year I was so exhausted I felt like I was passing away. Today I feel like a new person.''

Miranda's doctors say by next year he and his companion of 14 years, Linda Cozby, can return to catching yellowtail snapper.

Miranda grinned.

``Next year is only three weeks away.''


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