Tumors Shrunk by Engineered Immune Cells, Scientists Say
Stefan Lovgren
for National Geographic News
August 31, 2006
Normal immune cells that were genetically altered to recognize and destroy cancer cells have successfully shrunk large tumors, scientists say.
Two of 17 people with advanced melanoma-a deadly form of skin cancer-who underwent experimental treatment with the engineered immune cells saw their tumors shrivel.
A year and a half after therapy began, the two patients were declared free of the disease.
"This is the first example of an effective gene therapy that works in cancer patients," said Steven Rosenberg, chief of surgery at the National Cancer Institute in Bethesda, Maryland, and leader of the research team.
The therapy has so far been applied only to melanoma patients. But the researchers are optimistic that their treatment can be used for many other types of cancer.
The team has already engineered similar immune cells for more common tumors, such as breast, lung, and liver cancers.
The research appears in tomorrow's issue of the journal Science.
Engineered to Kill
Scientists have long been looking for ways to boost the body's immune system against cancer. (Related: "Dogs Smell Cancer in Patients' Breath, Study Shows" [January 2006].)
"There's been a lot of hype about gene therapy for many years, hoping that by genetically manipulating cells we can do good things," Rosenberg said.
His team focused on T (thymus) cells, a type of specialized immune cell that can learn to recognize and attack specific "foreign" objects, such as the cancer cells that make up tumors.
In the new study, researchers created tumor-fighting cells by harvesting normal T cells from melanoma patients and genetically engineering these cells to carry receptor proteins on their surfaces that recognize cancer markers.
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.
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."
for National Geographic News
August 31, 2006
Normal immune cells that were genetically altered to recognize and destroy cancer cells have successfully shrunk large tumors, scientists say.
Two of 17 people with advanced melanoma-a deadly form of skin cancer-who underwent experimental treatment with the engineered immune cells saw their tumors shrivel.
A year and a half after therapy began, the two patients were declared free of the disease.
"This is the first example of an effective gene therapy that works in cancer patients," said Steven Rosenberg, chief of surgery at the National Cancer Institute in Bethesda, Maryland, and leader of the research team.
The therapy has so far been applied only to melanoma patients. But the researchers are optimistic that their treatment can be used for many other types of cancer.
The team has already engineered similar immune cells for more common tumors, such as breast, lung, and liver cancers.
The research appears in tomorrow's issue of the journal Science.
Engineered to Kill
Scientists have long been looking for ways to boost the body's immune system against cancer. (Related: "Dogs Smell Cancer in Patients' Breath, Study Shows" [January 2006].)
"There's been a lot of hype about gene therapy for many years, hoping that by genetically manipulating cells we can do good things," Rosenberg said.
His team focused on T (thymus) cells, a type of specialized immune cell that can learn to recognize and attack specific "foreign" objects, such as the cancer cells that make up tumors.
In the new study, researchers created tumor-fighting cells by harvesting normal T cells from melanoma patients and genetically engineering these cells to carry receptor proteins on their surfaces that recognize cancer markers.
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.
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."