Gene therapy has become a new innovative approach to target cancer cells at the source, by manipulating its gene structure. Genes are required for every cell life function: The genetic code helps cells to grow, function and divide. When genes are malfunctioning, they give rise to proteins that cannot do their job. They are not able to carry out maintaining a healthy cell life. A gene can be overactive or missing which interferes with normal bodily functions that keep us healthy. The ultimate goal for gene therapy is to target genes and fix them at the source.
The job of gene therapy is to replace abnormal or missing genes with healthy genes that will allow the cell to make use of its proteins. This can also help the way genes function so that over or underactive genes can once again work normally. Gene therapy will transform genes in cells that will ultimately change the cell’s function or survival.
Gene therapy is now under works to combat cancer. It is being explored as a cancer treatment in its early stages; and studies are being done in a lab setting or with clinical research trials. One approach that is similar to gene therapy is called CAR T-cell therapy, which is an approved cancer treatment by the FDA for certain groups of patients.
Gene therapy research is currently being conducted in various areas, such as genetically engineered viruses that will kill cancer cells and immunotherapy, such as CAR T-cell therapy, which builds up the immune system to fight off and kill tumor cells.
Genetically Engineered Viruses
This treatment will use modified viruses (oncolytic viruses) to kill cancer cells while leaving healthy cells unharmed. These viruses contain specific genes to infect cancer cells, causing the proteins in the cell to die.
Promising results were achieved from animal studies with genetically engineered viruses, who had cancers of the colon, bladder or osteosarcoma (bone cancer). Using this kind of treatment on humans is challenging since most humans develop antibodies to the viruses in animal studies. With humans, their immune system will many times kill the virus before it even has a chance to infect the cancer cells. As a result, researchers have been using different types of viruses in human trials.
A type of virus called the adenovirus is used in human trials. This type of viral therapy has shown positive results with different types of cancers such as squamous cancers in the neck and head, which will also be tested to use as a preventative type of treatment for oral tissue that is precancerous. Modified forms of the herpes simplex virus have been used in trials for patients with colorectal cancer that spread to the liver and malignant glioma (a type of brain cancer).
With gene transfer, a foreign gene will go into cancer cells or tissue surrounding the cells. With this technique, researchers will expect the gene to kill the cancer cells or stop the cancerous cells from giving blood to grow tumors, which are the nutrients that tumors need to survive. This is a substantial approach to treating cancer and offering promise, but there are obstacles researchers will face, like “gene silencing”, where the new genes in cells do not turn on. Gene transfer techniques in animals studies have promising results with treating pancreatic, prostate and lung tumors.
There have been many approaches in clinical trials involving gene transfer. They have treated cancers of the prostate, bladder liver, head, neck and other organs.
CAR T-cell therapy is a type of immunotherapy cancer treatment that tries to boost the patients natural cancer-fighting abilities of their T-cells. The patient will give a sample from their T-cells which is then mixed with viruses that have several specific genes. These viruses carry the genes to the nuclei in the patient’s T-cells and will go into the DNA of the cell. The T-cells will produce chimeric antigen receptor(CAR), a special protein, on their surface once the virus delivers the gene to the T-cell. The CAR will then give the T-cell a certain “address” to the tumor, which will program the CAR T cell to eliminate the cancer cell. Once the cells that changed into the CAR T cells are inside the patient, they search for tumor cells and will multiple, creating more cells that kill cancer.
When used in clinical trials, promising and often dramatic results with adults and children with Lymphoma and Leukemia were delivered with the CAR T-cell therapy. Unfortunately, the treatment can also have severe side effects with some people receiving the CAR T-cell therapy. One type of CAR T-cell therapy was approved last year from the FDA for all lymphoma types in children and one therapy was approved in adults with advanced stage lymphomas.
Cancer vaccines are another approach to immunotherapy which uses gene therapy. This will use tumor cells from a patient and genetically engineer them to be seen as a conspicuous gene by the immune system. Once the genes in the cells are changed, they are re-infused into the patient with an added immune-stimulating compound. The immune system will then initiate an aggressive attack on not just the newly infused cancer cells but cells that are similar in the body.