What is gene therapy?
Gene therapy is a type of cancer therapy, which alters the DNA and genetic function of cancer cells. It targets malignant changes through engineered therapeutic agents, such as CAR T cells. It aims to control the genetic mutations of a cancer cell to prevent the cancer’s growth.
Gene testing for cancer risk helps estimate how your genes can make you a potential candidate to develop cancer. It does this by looking for definite mutations in your genes and chromosomes. Your genes are present in every cell and control the functions and life of the cell.
When the gene undergoes a change and becomes cancerous, it commands the cell to also change. When the cancer gene will tell a cell to grow and divide at an uncontrolled rate, that cell becomes a cancer cell.
Gene therapy for cancer, still in its clinical trial stage, is used to treat a variety of diseases like cancer, AIDS, heart diseases, diabetes, hemophilia, and cystic fibrosis. To cure cancer, it is necessary to alter the gene that has “gone bad”. Gene therapy does just that.
Normally, the genes tell the cell to make proteins. A mutated gene causes the protein to become faulty. Gene therapy introduces a normal gene into the body to correct this faulty protein.
Purpose of gene therapy
The aim of gene therapy to treat cancer is to alter or replace this faulty and mutated gene, which causes cancer. Gene therapy replaces the faulty gene with a new one to try and cure the disease or enhance your body’s ability to fight it. It performs the following functions:
- To kill the tumor cells or to stop them from multiplying
- To make them more susceptible to the immune system
- To make them more vulnerable to chemotherapy or radiation or other cancer treatments
- Dendritic cells, which are immune cells are important to fight cancer cells. These cells are removed from the body, made more cancer-oriented in the laboratory, and introduced back into the body.
How are the therapeutic genes introduced into the body?
Genetic engineering is the science, which helps introduce genes into the body so that they can function. For an introduced gene to function, it requires a carrier to enter the cell. A modified virus, such as a retrovirus that has been rendered harmless, is used as a carrier to introduce the gene into the cell. Such a carrier virus is called a vector.
These viruses have the ability to recognize certain cells. Due to this ability, the carrier virus penetrates and infects the cell and introduces the new gene into the cell. Adenoviruses, Adeno-associated viruses, herpes viruses, lentiviruses, and poxviruses are also used as vectors. Liposomes (fat particles) are also used as vectors. The choice of vectors depends on the requirements suggested by the genetic study.
The vector is introduced by directly injecting the vector carrying the gene into the tissue, you want to target, or by an intravenous route. Alternately, tissue from the body is removed and the vector is injected into the tissue in vitro ( in the lab). The cells are then injected into the tumor in the body. The new gene will start making a normal and functioning protein.
Risks of gene therapy
As mentioned above, the treatment of cancer with gene therapy is still in the clinical trial stage. It is not without risks, some of which can be serious.
- Possible infection of healthy cells by the viruses, which are used as vectors. This may lead to damage to the healthy cells, causing diseases and even cancer itself.
- The genetic material may get wrongly introduced into the germ cells (sperm in men and eggs in women) of the reproductive system. The genetic changes caused will affect future generations if the patient has children after gene therapy treatment.
- The immune system of the body may see the introduced vectors as a foreign body and this could generate an autoimmune response. This could lead to inflammation or toxic reactions or may even cause organ failure.
- The modified viruses, used as vectors, may regain their original virulence and may cause diseases.
To minimize the risks, gene therapy for cancer is evaluated at multiple levels to ensure that safety is given top priority in carrying out clinical trials of gene therapy.