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Researchers from the National Cancer Institute (NCI) say they have found a way to turn normal white blood cells into cancer fighters. What's more, their technique actually helped 2 patients overcome melanoma that had spread to distant parts of their bodies. If their method can be perfected, it holds promise for attacking other common types of cancer, they write in a paper published online today in Science Express.

Cancer researchers have been trying for decades to find a way to make the body's immune system recognize cancer cells and attack them, the same way it attacks viruses or transplanted organs. This approach is known as immunotherapy, and researchers sometimes speak of cancer "vaccines" when describing these types of treatments. White blood cells are part of the immune system.

The NCI researchers used gene therapy to make normal immune system cells deadly to metastatic melanoma, a particularly difficult form of cancer to treat.

In lab work, they also created altered immune cells that would attack other types of cancer cells, hinting at wider uses for this treatment.

"These results represent the first time gene therapy has been used successfully to treat cancer," said Elias Zerhouni, MD, director of the National Institutes of Health, of which NCI is a part. "Moreover, we hope it will be applicable not only to melanoma, but also for a broad range of common cancers, such as breast and lung cancer."

Though the results are exciting, they're not ready for widespread use yet, said Len Lichtenfeld, MD, deputy chief medical officer of the American Cancer Society.

"It is probably going to take several years of further investigation before we fully understand the impact of this approach, " he said.

Nevertheless, "We look forward to continued reports as this research enters its next phase in the treatment of patients with cancer," he added.

Some people with melanoma already have immune cells that naturally attack the tumor cells. Researchers have been able to isolate those cells, multiply them in the lab, and then put them back into the patient to fight the cancer with some success.

But not everyone with melanoma has those natural tumor fighters. Though they are often present in other types of cancer, they can be hard to identify.

Researchers led by Steven Rosenberg, MD, PhD, a noted expert in cancer immunology, wanted to find a way to make normal immune system cells behave like these hard-to-find natural tumor fighters.

First the researchers took T cells, a type of white blood cell, from 17 people with metastatic melanoma that had not responded to treatment. They used gene therapy to make those T cells recognize and attack the melanoma. Then they put the altered T cells back into the patients.

Two of the patients responded especially well to the treatment. The tumors that had spread into other parts of their body (lung or liver) either disappeared or shrank enough to be removed. Both were still alive 18 and 19 months after treatment, and appear to be cancer-free. The treatment produced no toxic side effects in any of the patients.

Lichtenfeld applauded the researchers for bringing together decades of prior work into a technique that "produces results."

"It melds several lines of investigation, including our improved understanding of the immune system, highly sophisticated technology for genetic engineering, and what we have learned about the targets in the cancer cell that offer us opportunities to develop new treatments," he explained. "Each of these areas on its own is exciting enough, but to put all of them into one effort that produces results is outstanding."

Cancer Regression In Patients Mediated by Transfer of Genetically Engineered Lymphocytes. Published online Aug. 31, 2006, by the journal Science in Science Express. First author: R.A. Morgan, National Cancer Institute.