Gene therapy is an experimental treatment that involves inserting genetic material into your cells to give them a new function or restore a missing function, as cancer may be caused by damaged or missing genes, also known as gene mutations. Although gene therapy may be one way to overcome these changes and treat or prevent cancer, it is currently only available through clinical trials.
Definition of treatment
Cancer is caused by changes in our genes. Genes are inherited from our parents, and determine our traits and characteristics. They are made of biological molecules called deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA and RNA are responsible for making proteins, which have many functions, such as helping a cell to maintain its shape or controlling its growth and division. Changes or mutations in genes can affect the proteins and may sometimes lead to diseases, such as cancer.
Gene therapy is designed to modify cancer cells at the molecular level and replace a missing or bad gene with a healthy one. The new gene is delivered to the target cell via a ‘vector,’ which is usually an inactive virus or liposome, a tiny fat bubble.
Types of treatment
Gene therapy can be done in two ways: outside (ex vivo) or inside (in vivo) your body. Ex-vivo techniques involve taking some of the cancer cells out of your body, injecting them with good genes, and then putting them back into your body. The in-vivo process requires that good genes be put directly into a tumor, which may be difficult depending on its location or if the cancer has spread. Scientists generally use two types of cells in gene therapy – the tumor cells themselves and immune system cells that attack the tumors.
UC San Diego Health System expertise
Researchers from Moores Cancer Center at UC San Diego Health System are studying several gene therapy techniques for breast cancer, melanoma, leukemia and pancreatic cancer.
For example, they have been integrally involved in the development of Herceptin, a targeted therapy that is proving to be effective in curing localized human epidermal growth factor receptor-2 (HER2) breast cancer. HER2 controls how cells grow, divide and repair themselves.
Researchers have also been injecting a modified herpes virus into melanoma tumors, with the intention of improving the body’s immune defenses against the disease.
Gene therapy called TNFerade Biologic involves a DNA carrier containing the gene for tumor necrosis factor-alpha, an immune system protein with potent and well-documented anti-cancer effects. TNFerade is being studied in combination with radiation therapy for first-time treatment of inoperable pancreatic cancer.
TNFerade and the herpes strategies use gene therapy to enhance the killing effect of the primary mechanism – radiation in TNFerade and viral induced cell lysis, or splitting, in the herpes virus.
When will gene therapy be available?
Gene therapy is only available as a cancer treatment through clinical trials.
Are there any risks associated with gene therapy clinical trials?
Yes. Viral vectors might infect healthy cells as well as cancer cells, a new gene might be inserted in the wrong location in the DNA, or the transferred genes could be “overexpressed” and produce too much of the missing protein, causing harm. All risks for any procedure should be discussed with your doctor.