BACKGROUND: Melanoma is a deadly skin cancer. While chemotherapy has improved the outcome of cancer patients with breast cancer, colorectal cancer, and prostate cancer, chemotherapy drugs do not seem to work for melanoma patients. Researchers are now focusing on gene therapy for melanoma patients. The challenge has been getting the gene into the tumor. The overall goal is for the gene to stimulate the immune system to fight the cancer. For the first time, researchers are using electroporation on humans to deliver gene therapy in melanoma patients.

ELECTROPORATION: Electroporation involves the use of a handheld device with a number of prongs on the end of it. The device is put into the tumor on the skin and delivers electricity. Researchers say this stimulation opens up pores in the tumor cell membrane, allowing small molecules called DNA plasmids to get inside the tumor before the tumor membrane pores close again. These plasmids contain the gene for interleukin-12. Adil Daud, M.D., an oncologist at Moffitt Cancer Center in Tampa says, “It will be like a flag that says danger or warning to the immune system and cause the immune system to destroy that tumor.”

LAB RESULTS: Six years of laboratory, studies were done before the initial human trials. In those studies, researchers say 80 percent of mice with melanoma were cured with electroporation. Even when the tumor cells were re-injected into the mice, the mice rejected the tumors. Researchers say it was a key finding because it suggests the immune system forms a memory response, which could prevent future growth. They hope to see the same results in human patients.

CLINICAL TRIALS: The first clinical trials began in 2005. So far, seven patients with stage four melanoma have been treated with electroporation. Dr. Daud says the purpose of this study is to see if it is safe for the patient. However, they are encouraged by the findings thus far. Dr. Daud says biopsies and blood samples reveal they are getting the expression of the interleukin-12 gene protein into the tumor. He has also seen tumor shrinkage in several of the patients treated. However, he cautions that they have only done this on a handful of patients.

SIDE EFFECTS: There are no major side effects associated with this treatment; however, one downside is discomfort for the patient. The treatment involves shocking the patient’s tumor for six seconds for each treatment. Each patient undergoes anywhere from three to twelve shocks. While this is a downside for some patients, Dr. Daud says the treatment pain does not last. He says electroporation could be a promising approach to gene therapy.

FOR MORE INFORMATION, PLEASE CONTACT:
Pat Urbas
Moffitt Cancer Center
MCC Core
12902 Magnolia Drive
Tampa, FL 33612
(813) 745-8352
urbaspa@moffitt.usf.edu
www.moffitt.usf.edu