The researchers studied 13 patients in the advanced stages of melanoma that had resisted the usual treatments. The researchers removed parts of the patients' tumors, which contained relatively small amounts of anti-tumor T cells, and grew the T cells in culture, until they had multiplied by approximately 1,000 times.
Before transferring the cells to the patients, Rosenberg's team gave the patients a round of chemotherapy that suppressed their immune systems' tendency to reject new cells. A few days after the T cell transfer, the number of tumor-fighting T cells shot up in more than half of the patients. After the transfer, the cells proliferated and traveled to the tumor sites, the scientists found.
"We generated and grew cells in the body to numbers that have never been approached before," Rosenberg said.
Four of the 13 patients had mixed responses, in which certain tumors shrank while others did not. Six others had clear regression of tumors at a variety of sites in the body, lasting from two to 21 months, the authors report.
Of these six, "patient 9" showed a regression of more than 95 percent of his melanoma, results that were ongoing 8 months later. Ninety-nine percent of "patient 10's" tumors had disappeared 7 months after the treatment, according to the study.
The researchers are currently working to improve the therapy so that a greater proportion of patients respond the way patients 9 and 10 did, Rosenberg said.
T cells are usually made up of a number of subfamilies, each capable of recognizing a slightly different type of antigen. Antigens are the molecules that trigger an immune response, whether they are from foreign pathogens or the body's own cells. In several of the patients, a relatively large portion of T cells (around 90 percent in
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Contact: Lisa Onaga
lonaga@aaas.org
202-326-7088
American Association for the Advancement of Science
19-Sep-2002