Gene Therapy

Gene therapy is an experimental procedure that treats or prevents various diseases through the manipulation of a patient’s genes. The first genetic disease to be successfully treated with this therapy was Severe Combined Immune Deficiency (SCID). Since this milestone was achieved by a French research group in 2000, international researchers have experimented with therapies for hemophilia, colorblindness, AIDS and several cancers, including mesothelioma.

With mesothelioma clinical trials, medical researchers hope to perfect gene therapy to improve upon the limited success rates of chemotherapy and other conventional cancer treatments. But targeting and repairing faulty genes is no simple task. Although it is a promising field of ongoing research, more studies must be done before it is adopted as a safe and widely available treatment option.

Even though gene therapy is safer for healthy cells than chemotherapy, there are several side effects and potential complications associated with the treatment. Patients may experience a variety of adverse reactions if their immune systems respond negatively to the procedure. Because of these and other concerns, the FDA has not yet approved the therapy.

How Does it Work?

The goal of gene therapy is to directly repair the problems caused by defective genes. Within nearly every cell in our bodies, a structure called the nucleus protects the genetic information stored in our DNA. Certain segments of DNA are responsible for passing on important genetic information when the cell multiplies. These segments are known as genes.

When carcinogens like asbestos enter our body, they sometimes cause genetic damage, or mutations, to occur in our DNA. This damage can drastically alter the production of proteins, which cells must create and use to function normally. If a gene mutation prevents certain proteins from doing their job, cells can divide rapidly and uncontrollably, which eventually causes cancerous tumors to form.

Gene therapy prevents this process by repairing the defective genes. Alternatively, the treatment can replace faulty genes with new ones that either cure a genetic disease or improve its outcome.

To access the defective genes, doctors typically inject their patients with a modified virus. Because viruses are essentially microscopic parasites, they serve as ideal vehicles for transporting genes into our cells. Their only means of reproduction requires them to invade host cells and inject their own genetic information.

Once the modified virus enters a target cell, it replaces the faulty gene with a functioning copy, or it repairs the gene so that it produces normal proteins instead of defective ones. Non-viral methods of gene therapy are also available, such as with the use of stem cells.

Uses with Mesothelioma

Genetic researchers are currently exploring ways to safely treat mesothelioma patients with this therapy. The location of pleural mesothelioma tumors is particularly advantageous for gene therapy, as doctors can easily access the pleural membrane surrounding the lungs to deliver genes, conduct biopsies and monitor treatment results. Regardless of the mesothelioma tumor’s location, this therapy can introduce genetic material that targets cancer cells and makes them more vulnerable to chemotherapeutic drugs.

Suicide gene therapy is one of the most promising forms of this therapy for the treatment of mesothelioma. With the help of a virus, doctors introduce a protein-producing gene that converts a non-toxic drug into one that can kill cancer cells. The genetically-altered virus is administered, and after a short waiting period, the patient is given a drug that is only toxic to cancerous cells. In one clinical trial conducted at the University of Pennsylvania Medical Center, suicide gene therapy caused tumors to decrease in size and severity for four of the 34 patients studied.

Another type of this therapy for mesothelioma patients uses modified viruses to deliver immune system molecules called cytokines. Cytokines are proteins that control and direct our immune response. Cytokines can help the immune system mount an attack against cancer cells.

Side Effects and Potential Complications

Because gene therapy is still in its infancy, the long-term side effects of the treatment remain unknown. Though it has not yet been observed, researchers are concerned that healthy cells may also become infected by the modified viruses, which could possibly cause new diseases or cancers to develop.

Some patients may experience common symptoms of infection after treatment, such as chills, fever, nausea, vomiting and headache. These symptoms are usually temporary, subsiding within 48 hours for most patients. Controlling the symptoms of infection is important because negative immune system responses may reduce the efficacy of gene therapy and make it difficult to repeat treatments.

These issues warrant further research in order to ensure safe and effective therapies for mesothelioma patients. At this stage of development, gene therapy does not offer a permanent cure for mesothelioma, but in some trials it has demonstrated noteworthy short-term benefits.