Gene therapy as a treatment for cancer has advanced from the theoretical to the possible: in a pilot study published in August in the journal Science, investigators reported that two of 17 patients with advanced melanoma responded to a treatment known as genetically engineered therapy.
Genetically engineered gene therapy uses autologous T-cells that are extracted and cultured and treated with cytokines. Therefore, when they are reimplanted, they can activate the immune system.
In a study led by Steven A. Rosenberg, MD, PhD, chief of surgery at the National Cancer Institute in Bethesda, Md., investigators harvested one patient’s T-cells and genetically isolated the T-cell receptor so that it would be specific to melanoma. They then removed T-cells from 17 melanoma patients and genetically spliced in the one patient’s tumor-specific receptors. Finally, they cultured those cells and transfused them into the patients. Among these patients, the investigators documented “dramatic and durable regression” of the tumors in two patients.
This study is one of several steps in a long process to develop immunotherapy approaches for the treatment of metastatic melanoma, said Dr. Rosenberg in a phone interview. “We have studied immunotherapy for the treatment of metastatic melanoma, and we have reported on cell transfer therapies that represent the most effective treatment for metastatic melanoma.”
Genetically engineered gene therapy may offer promise for refractory cases, he said. “If otolaryngologists have patients with metastatic melanoma, and it’s refractory to standard treatments, we may have something for them,” he said. “The ongoing clinical trials are continuing to show the promise reflected in the recently published trial. If a physician has patients with refractory metastatic melanoma, he or she should consider referring such patients for one of these newer cell transfer therapies.”
An Important First Step
Two gene therapy experts who were not involved in the study stressed that the findings are exciting despite the fact that only two patients had responded at the time of publication.
“The exciting thing about the current research is that the investigators took cells from the blood and made them cancer-specific,” said Andrew G. Sikora, MD, PhD, in a phone interview. Dr. Sikora, who was not involved in the current research, is a clinical fellow in Head and Neck Surgery at the M. D. Anderson Cancer Center in Houston. “It’s one of the first studies utilizing gene therapy in which patients have had a positive response to treatment.” Dr. Sikora, who is currently doing cancer immunology research with the department of Melanoma Medical Oncology, also pointed out that the investigators in the current study treated patients with the most advanced disease states. “If the approach is validated in patients with serious, advanced melanoma, it may be that patients who have less advanced disease have a better chance of responding to it,” he said.
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