Gene therapy is an experimental new treatment for mesothelioma which has shown incredible promise. Genes consist of DNA and determine the characteristics of a cell. In humans, genes may be determined from the moment of conception, but they can also be altered throughout life by various factors. In the case of mesothelioma cells, the genes have malfunctioned due to asbestos exposure so that cells have begun dividing abnormally. The goal of gene therapy in mesothelioma treatment is to alter the malfunctioning genes so that they become healthy or are easier to destroy with cancer treatments.
The way that gene therapy works is by introducing a virus into the body. The virus has been programmed in a specific way and may only target cancerous cells. There are several ways which the viruses can be programmed in order to treat mesothelioma.
Though gene therapy for cancer is still in the clinical and pathology research stage, it offers a lot of hope to mesothelioma victims. The current prognosis for mesothelioma is not good despite advances in chemotherapy, surgical procedures and advanced radiation therapies. Since mesothelioma cells can be readily accessed through biopsy, researchers have easy access to tissue and fluid samples.
Suicide Gene Therapy
Suicide gene therapy is considered one of the most promising forms of gene therapy. With suicide gene therapy, a virus is programmed to affect only cancerous cells. The virus will cause the cancer cells to turn a normally non-toxic drug into a toxic drug. Then, the drug is given to the patient. As it is non toxic to the healthy cells, they will be unaffected. The cancerous cells will turn this non-toxic drug into a lethal substance, thus killing themselves.
In a recent study, a direct infusion of suicide gene-modified cells into a pleural effusion induced tumor was followed by another intravenous infusion of additional modified cells. The results of this study indicated that these anti-tumor mechanisms offer great potential by generating needed immunological responses.1 As research advances the development of these suicide cell lines offer enormous potential as a curative or therapeutic mesothelioma treatment.
This type of gene therapy works by introducing viruses into the body which carry genes which will block blood vessels from forming around tumors. Thus, the tumors are unable to receive blood and are either killed or have their growth slowed.
It has been known for many years that tumors grow by angiogenesis. Angiogenesis is a term that refers to the growth of new blood vessels by the tumor to obtain the sustenance the tumor needs to grow and thrive. The tumor cells actually attach to a protein that is found on the cells making up the lining of the blood vessels. It is this attachment that signals the blood vessel to grow new capillaries. The anti-angiogenesis therapy blocks the protein secretion that induces blood vessel growth that feeds the tumor.2
Replacement Gene Therapy
With replacement gene therapy, a virus is introduced which contains copies of a healthy gene. When the virus targets cancerous cells, it replaces or alters the damaged or missing gene with the healthy gene. In most cases, the gene is related to cell growth. This therapy remains in the experimental stage as a cancer treatment. In the past it was mostly used to treat hereditary diseases like sickle cell or cystic fibrosis.
Availability of Gene Therapy for Mesothelioma
Gene therapy is considered to be an excellent research avenue in the search for effective mesothelioma treatments. There are several reasons for this too. Mesothelioma tends to be localized for years and only spreads after many decades. Early detection couple with gene therapy could lead to excellent treatment results and an increase in survival rates. In addition, tumors are fairly easy to access in pleural mesothelioma through the chest wall. Finally, mesothelial cells composing the membrane create a large surface area for rapid and efficient diffusion of the genes transferred into the body.3
Currently, no form of gene therapy is approved for use for any type of cancer. Gene therapy is still in its experimental phases and much more research must be done in order to understand the full implications of this treatment. Patients with mesothelioma may be eligible to take part in clinical trials of gene therapy. These gene therapy clinical trials can provide researchers with valuable information and may lead to a cure for mesothelioma. Note, however, that the possible complications and adverse effects of gene therapy are not fully understood. For most patients though, the benefits of gene therapy will likely outweigh any possible risks.
1 Schwarzenberger P, Byrne P, Gaumer R, Norton J, Harrison L, Marrogi A, Kolls JK. (2011)Treatment of mesothelioma with gene-modified PA1STK cells and ganciclovir: a phase I study. Cancer Gene Therapy, doi: 10.1038/cgt.2011.60.
2 Study Sheds Light on How Tumors Grow (12 August 2008) Retrieved from American Society of Radiologic Technologists at: https://www.asrt.org/content/News/IndustryNewsBriefs/GenRes/StudySheds050812.aspx
3 Albelda, S. (1 June 2011) Gene Therapy for Mesothelioma. Current treatment options in oncology, 12:2, 173-180.