A team of scientists from the National Cancer Institute (NCI) reported success this week in shrinking melanoma tumors by tailoring a patient's own cancer-fighting cells to handle the job.

Six of 13 patients with advanced melanoma had their tumors shrink by half or more in the study, researchers reported in the Sept. 19 online journal Sciencexpress (www.sciencexpress.org).

The researchers achieved these results by replacing cancer patients' immune system cells with those "trained" in the lab to recognize their tumors as targets.

"We've seen something here that is unlike anything else we or anyone else has ever seen," said the report's lead author, Steven A. Rosenberg, MD, PhD, of the NCI.

But perhaps even more important, it's an approach that may be useful against many types of cancer, according to the study authors.

Cancer-fighting immune system cells, called T-lymphocytes, or T-cells, have been "trained" and injected before, said Rosenberg.

But in earlier efforts, few of the injected cells lived 24 hours and none lasted two weeks, so they didn’t survive long enough to effectively fight the cancer, Rosenberg said.

What's new — and likely responsible for the tumor shrinkage — is that researchers have found a better way to make large numbers of trained T-cells in the lab, and a way to allow them to survive in the patients' bodies for a long time, said Rosenberg.

Rosenberg's team suspected that levels of cancer-fighting cells usually dropped quickly after being injected into patients because their immune systems were attacking the cells.

They first used chemotherapy to suppress the immune system in the 13 patients with widespread melanoma.

Then they gave each patient his or her own T-cells that had been withdrawn earlier and exposed in the lab to that patient's own tumor cells. That exposure "primed" the T-cells to recognize, track down, and attack similar tumor cells in the patient's body.

The researchers added a hormone-like substance, IL-2, that stimulates the T-cells to multiply.

With the patients' immune systems already suppressed by chemotherapy, the injected T-cells survived. Stimulated by IL-2, they multiplied at a rapid rate and began attacking the tumors.

In six of the 13 patients, tumors shrank by half or more. Four other patients had some tumor shrinkage. Tests months later showed cancer cells still under attack by T-cells.

Side effects were mild, the researchers noted, with some patients developing minor infections or skin discoloration and one patient developing eye irritation, all of which were easily controlled. These were due to the immune T–cells attacking normal cells in the patients.

These side effects stopped as the patients own immune system cells recovered. This took about four months.

"This is real progress," said Martin A. Weinstock, MD, PhD, professor of dermatology at Brown University and chair of the American Cancer Society (ACS) skin cancer advisory board.

It's the first time such a therapy, called adoptive immunotherapy, has shrunk tumors by half or more in a substantial portion of patients, said Weinstock.

In most melanoma patients whose cancer has spread, tumors don't shrink by half even with aggressive chemotherapy, said Weinstock.

Larger studies will likely follow this small one, and improvements will be sought, said Weinstock.

"It's not a breakthrough for immediate wide use by patients, but it points the way to an approach that could be promising," noted Weinstock.

Asked if it was known yet why some patients responded to the therapy and others didn't, Rosenberg said researchers are in the lab "working literally around the clock" to try to answer that question. Patients interested in clinical trials for melanoma can call the NCI at 1-888-624-1937, he said.