Scientists Genetically Engineer Human Cells to Fight Cancer

BySiri Nilsson

Aug. 31, 2006 — -- Seven years ago, Mark Origer was diagnosed with a malignant melanoma, a sometimes curable skin cancer that can be deadly if it spreads to other parts of the body.

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By 2004, his cancer had spread to his liver, lung and lymph nodes.

Origer, 53, was optimistic about a cure, but conventional treatments failed him.

"I was hopeful every time I tried a new treatment. I hoped it would be the end of my disease," Origer said.

But nothing worked.

"It felt defeating," he said.

Desperate for a cure, Origer enrolled in a clinical trial at the National Cancer Institute in Bethesda, Md. The trial tested a very experimental therapy that had never before been used in people.

What attracted Origer, of Waterville, Wis., to the cancer institute was a unique process where genetic engineering is applied to humans.

The process is usually associated with hybrid animals and super foods, but is being tested to fight diseases in people.

The cancer institute's researchers are using genetically engineered immune cells to shrink tumors in cancer patients like Origer.

"This is the first gene therapy for cancer. … That is why it is so important," said Dr. Steven A. Rosenberg, who headed the trial as chief of surgery at the National Cancer Institute.

Researchers took immune system cells from the blood of 17 advanced melanoma patients who, like Origer, had not been helped by conventional treatments. Origer had only three months to four months left to live when the experimental treatment began.

These ordinary blood cells, called T cells, were genetically engineered to become cancer-fighting cells that could recognize and attack the life-threatening melanoma.

The cancer-fighting cells were then injected back into each patient. Researchers hoped that the new T cells would multiply and fight off the cancers.

The experimental therapy could be a major medical and scientific advance.

The therapy is also important because, for Origer, it worked.

After he was injected with his own engineered cancer-fighting T cells, he was dismissed from the hospital.

Doctors told him they would know within a month whether the therapy had worked.

"There was a lot of anxiety and apprehension that month," Origer said. "I felt like a gladiator in the arena when I was waiting to see that doctor. I was waiting for 'thumbs up' or 'thumbs down.'"

He received the thumbs up.

"Oh, it was euphoric," Origer said. "It really was."

Doctors said that Origer's tumors had shrunk by 50 percent after one month, including those that had spread to his liver and other parts of his body.

He was one of two patients on the trial to be declared disease free, even 18 months after the experimental therapy had started.

Not all of the patients were helped by the therapy -- the other 15 died from their disease.

Researchers are not sure exactly why the therapy did not work for everyone. They speculate that the cancer cells may have mutated so the cancer-fighting T cells could not recognize them.

The therapy could also have potential side effects, though Origer said he had not had any unusual side effects.

Dr. Patrick Hwu, chairman of melanoma medical oncology at the University of Texas' M.D. Anderson Cancer Center, expressed concerns that these tumor-fighting T cells might turn around and attack the patients' own tissues.

"T cells are being genetically modified to recognize receptors on the specific cancer cells and to attack those receptors. One must remember that cancer arises from normal tissue," he said. "The side effect could potentially be that the T cells will attack normal tissue that has those same receptors."

Obviously, scientists still have a lot to learn about this approach.

Hwu said, "It is not ready to be used in common practice."

Researchers will keep working on it, though.

"In the future, we plan to perform further trials with patients who have breast, lung or ovarian cancer, but these trials have not begun," Rosenberg said.

This experimental treatment may not be ready for common practice, but it gives science a potential, new approach to cancer therapy.

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