Technique Tracks Cancer-Killing Cells

WEDNESDAY Nov. 19, 2008 -- U.S. researchers say they've developed a new long-term method of monitoring the location and survival of cancer-killing cells within the body.

Modifying a patient's own immune cells to find and attack infected or diseased cells is a promising treatment approach for many disorders, a team from Stanford University School of Medicine reports. However, efforts to track these cells after they've been reintroduced into the body have relied on short-term monitoring techniques that don't provide complete information about the cells' status.

According to the Stanford group, this new method can provide information about the status of these cells for months and possibly years, enabling researchers, doctors and patients to assess the cells' disease-fighting performance over time.

"This has never before been done in a human. Until now, we've been shooting blind, never knowing why failed therapies didn't work. Did the cells die? Did they not get where we wanted them to go? Now we can repeatedly monitor them throughout their lifetime," study senior author Dr. Sanjiv Gambhir, director of Stanford's molecular imaging program, explained in a university news release.

The new method involves two steps. First, the therapeutic cells are modified to express a reporter gene shared by no other cells in the body. Second, patients are injected with an imaging agent that's trapped only in cells expressing the reporter gene. The cells can then be tracked using a PET-CT scanner.

The technique was tested in a middle-aged man with an aggressive glioblastoma brain tumor. The researchers removed immune system killer T-cells from the man, and inserted genes that gave the T-cells the ability to find and destroy cancer. The modified T-cells were returned to the site of the man's brain tumor over a period of five weeks. The new imaging method showed the T-cells had moved into the tumor and also had traveled to a second, previously unidentified tumor site.

The study wasn't designed to assess the modified T-cells' ability to kill tumor cells, but the imaging results showed they did reach their targets.

The study was published Nov. 18 in the journal Nature Clinical Practice Oncology.

More information

The U.S. National Cancer Institute has more about biological therapies.

Posted: November 2008


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