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August 31, 2006

Gene Therapy Halts Two Cases Of Melanoma

Topics: Medical Science News

Migrating Human T lymphocytes.jpgScientists at the National Cancer Institute are finding success in treating cancer with gene therapy, hoping to find a more effective treatment than chemotherapy or radiation. Recently, they have found success in two melanoma patients by engineering the patient's own white blood cells to recognize and attack the cancer cells. It is hoped that this success will lead to treating a number of common cancers:

Autologous lymphocytes -- a person's own white blood cells -- have previously been used to treat metastatic melanoma. In a process called adoptive cell transfer, lymphocytes are first removed from patients with advanced melanoma.

Next, the most aggressive tumor-killing cells are isolated, multiplied in the lab, and then reintroduced to patients who have been depleted of all remaining lymphocytes. While reasonably successful, this method can only be used for melanoma patients and only for those who already have a population of specialized lymphocytes that recognize tumors as abnormal cells.

Thus, NCI researchers, led by Steven A. Rosenberg, M.D., Ph.D., sought an effective way to convert normal lymphocytes in the lab into cancer-fighting cells. To do this, they drew a small sample of blood that contained normal lymphocytes from individual patients and infected the cells with a retrovirus in the laboratory. The retrovirus acts like a carrier pigeon to deliver genes that encode specific proteins, called T cell receptors (TCRs), into cells.

When the genes are turned on, TCRs are made and these receptor proteins decorate the outer surface of the lymphocytes. The TCRs act as homing devices in that they recognize and bind to certain molecules found on the surface of tumor cells. The TCRs then activate the lymphocytes to destroy the cancer cells.

n this study, newly engineered lymphocytes were infused into 17 patients with advanced metastatic melanoma. There were three groups of patients in this study.

Two patients experienced cancer regression, had sustained high levels of genetically altered lymphocytes, and remained disease-free over one year.

Continue reading, "Researchers Find Success in Engineering White Blood Cells to Kill Cancer Cells."

For a Q&A on gene therapy techniques similar to those used in this study, go here.

Posted by Richard at August 31, 2006 11:14 PM

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