The cells were then returned to the patients' bodies to rebuild their immune systems.
The engineered cells showed signs of persisting in most of the patients' bodies two months after they were reintroduced.
Broad Applications
Previously, researchers had attempted to treat melanoma by removing naturally occurring tumor-fighting T cells from patients.
They used chemotherapy to clear out a patient's old T cells and then repopulated the patient's immune system with the harvested antitumor cells.
But researchers could only get cancer-fighting immune cells from half of the melanoma patients.
And similar cancer-fighting cells were not found in patients with other cancers, such as breast cancer and colon cancer.
"So the approach was only good for the half of the melanoma patients in whom you could find the cells and not suitable for any other cancer patients," Rosenberg said.
Melanoma makes up only 5 percent of known cancers.
But the newly engineered cells can be tailored to fight tumors other than melanoma, scientists say.
"We now have receptors that will recognize about half of all common cancers in humans, including breast and lung cancer," Rosenberg said.
Refinement Needed
Patrick Hwu, chair of the melanoma department at the University of Texas M.D. Anderson Cancer Center in Houston, calls the research a "landmark study."
"It potentially changes the whole area of using the immune system to attack cancer," he said. "It opens the door to generalizing this kind of treatment for other cancers."
The new findings are the first time that scientists have shown that genetically modified immune cells can be used to affect cancer regression in patients, he says.
But more research is needed before the technique can be widely applied.
Only 2 of the 17 people treated for melanoma showed improvement.
"The other patients did not respond, but we think we know why," Rosenberg said. "We had relatively poor [cancer-detecting] receptors available when we started this trial compared to the ones we have available now."
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