Research is continuously ongoing in an effort to find a cure for a variety of different cancers. A cure is always possible, and new studies are always producing more scientific breakthroughs. For mesothelioma and many other types of cancer, there is currently no cure. But emerging treatments could change all that.
Mesothelioma is a fast-acting cancer that aggressively attacks the lining of the lungs, abdominal cavity or heart. For now, the closest thing to a mesothelioma cure that we have is its prevention. The disease’s primary cause is exposure to asbestos fibers. While many governments have taken great strides toward eliminating asbestos production and use, the carcinogen still remains in a variety of industrial settings and in many older buildings.
Emerging treatments for mesothelioma are providing hope for patients who don’t have the luxury of preventing their asbestos exposure. New treatment methods are being developed and tested at a quickening pace, and hopefully, it is only a matter of time before one of them provides a major breakthrough in the successful treatment of mesothelioma.
How do these emerging treatments come about in the first place?
The primary way that new and emerging treatments are tested is with clinical trials. As the number of mesothelioma cases grows, more research is spurred to understand how the disease works and how it will react to new drugs and procedures. In large part, clinical trials are used to test how well already existing chemotherapy drugs work on mesothelioma.
But in many cases, emerging treatments for mesothelioma can also be tested. For many patients, clinical trials may be the best option for finding a successful treatment . The more traditional treatment options, such as surgery, chemotherapy, and radiation therapy, may have proven unsuccessful in fighting their disease. But a clinical trial that offers a newly emerging treatment could prove to be vital to a patient’s extended life expectancy.
In order to qualify for a clinical trial, patients will have to meet eligibility requirements. For mesothelioma trials, most researchers look for patients whose disease hasn’t progressed to the later stages. It is important for the patient to survive long enough for scientists to be able to monitor how their experimental treatment is working effectively. Unfortunately, most mesothelioma diagnoses occur when the disease is in stage 3 or 4 (the final stages), so patients don’t live long enough for the efficacy of the new treatment to be effectively measured.
Other criteria that clinical trials may look for in participants include:
- Overall health
- Whether the patient has undergone any other cancer treatments
- Type of mesothelioma (pleural, peritoneal, or pericardial)
- Whether the mesothelioma is an original occurrence or a recurrent one
Some clinical trials, however, do add patients who are in later stages of the disease. So no matter what your stage of mesothelioma might be, it’s always important to ask your doctor or local cancer center if any clinical trials are currently ongoing that you could join.
What emerging treatments might you find in a clinical trial?
Immunotherapy involves the use of medications to trigger an immune response that helps attack cancerous cells in the body. It has been used for a variety of other cancers, sometimes with great success.
Although immunotherapy isn’t widely used in cancer treatments yet, it could eventually play a pivotal role in treating numerous diseases. Mesothelioma immunotherapy treatments are currently only available in clinical trials.
There are four main types of immunotherapy treatments:
- Checkpoint inhibitors
- Therapeutic vaccines
- Adoptive cell therapy
- Monoclonal antibodies
Checkpoint inhibitors work by taking advantage of “checkpoints” that immune cells identify in other cells. Surface molecules (checkpoints) on both healthy and cancerous cells need to be triggered or disabled in order for an immune response to activate.
If an immune cell senses a particular protein on the surface of another cell, it may not attack that cell even if it is cancerous. Many cancerous cells contain proteins or molecules that prevent immune cells from attacking in this manner.
Checkpoint inhibitors effectively prevent those proteins or molecules from binding with cancerous cells, making it easier for immune cells to trigger an immune response against them. Some checkpoint inhibitors have been approved for use in other cancers.
Mesothelioma immunotherapy trials currently underway are utilizing certain checkpoint inhibitors including:
- Nivolumab (Opdivo)
- Pembrolizumab (Keytruda)
- Atezolizumab (Tecentriq)
Therapeutic vaccines are used to trigger an immune response against antigens that are exclusive to various tumors. Antigens like p53, MAGE-3, and survivin are commonly found in many types of lung cancers. A variety of vaccines have been developed for lung cancers, but none has yet been created specifically for mesothelioma.
Adoptive cell therapy uses a patient’s own master T cells (a specific type of immune cell) to try to activate an immune response. T cells are removed from a patient and enhanced chemically or genetically. They are then reinjected into the patient with the goal of triggering an immune response against cancer cells. Clinical trials for this method are currently ongoing.
Many mesothelioma immunotherapy treatments use monoclonal antibodies, which are key figures in killing off proteins responsible for tumor development and progression. Drugs like bevacizumab (Avastin) and ramucirumab (Cyramza) have been approved by the U.S. Food and Drug Administration (FDA). Clinical trials using monoclonal antibodies in the treatment of mesothelioma are ongoing.
Mesothelioma gene therapy works by switching out faulty genes for healthy ones. Many people develop diseases based on faulty genetic signals. If the malfunctioning genes are replaced, the body should be able to function properly. Organ systems and immune responses can be adversely affected by faulty genes.
There are generally four ways that gene therapy works:
- Suicide genes
- Limiting the energy supply to cancer cells
- Decreasing the speed of tumor growth
- p53 gene therapy
“Suicide genes” is a term applied to a set of genes that doctors use to replace cancer cell genes. While these genes are still cancerous in nature, they are much more vulnerable to the effects of other cancer treatments like chemotherapy and radiation therapy. In addition, cancer cell genes can be altered using the genes from a healthy cell. An altered cancer cell gene begins to release an enzyme that destroys neighboring cancer cells but leaves healthy ones alone.
Another method researchers have used in gene therapy is limiting the energy supply to cancer cells. Cancer cells replicate much more quickly and use more energy than healthy cells. They do this by consuming glucose in the body and producing a protein (PARP14) that allows them to live longer than normal cells. The goal of limiting energy supply is to reduce the amount of glucose that cancer cells receive so that they cannot function at such a high level.
Limiting the energy supply to cancer cells requires malfunctioning genes to be replaced, which can slow the production and growth of tumors. This can be done by inserting genetic material right into the tumor or using a virus to “infect” blood vessel linings that are contributing to the tumor’s growth.
A specific type of gene therapy, known as p53 gene therapy, focuses on the p53 protein found in many cells (including cancerous ones). The p53 protein often works as a tumor suppressant, but in many cancer patients the gene has mutated and is no longer functioning properly. To restore proper function to the p53 genes, doctors insert healthy p53 genes enclosed in a “deactivated” viral vector (viruses that have been genetically modified not to replicate.) If the p53 genes in the tumor cells return to normal working order, then tumor growth is usually stopped, and cancerous cells are killed.
These therapies are currently only available in clinical trials but have shown promise in treating mesothelioma and other cancers. (Need one more hopeful-sounding conclusory sentence here to make this paragraph complete.)
Cryotherapy and Hyperthermic Chemotherapy
Hyperthermic chemotherapy essentially uses hot temperatures to kill mesothelioma cells or help medicines work better. One study concluded in 2017, flooded the pleural (lung) cavities of mesothelioma and lung cancer patients with the chemotherapy drug cisplatin heated to 109 degrees Fahrenheit. The cisplatin was allowed to saturate the pleural space in each patient for about an hour, after which it was withdrawn. Researchers found that the cisplatin was more effective in doing its job than when delivered intravenously.
Cryotherapy essentially uses extremely cold temperatures to kill mesothelioma cells. Although using extremely cold temperatures to kill cancer has been around for generations, new methods for employing cold in the treatment of cancer have emerged. One new treatment researchers are testing is called “CryoSpray.” This involves spraying freezing cold liquid nitrogen onto tumors and diseased areas during open surgery. The novel therapy was able to improve prognoses and the quality of life of the patient, even though diseased cells remained in the body.
Another method researchers have used in cryoablation. This is much less invasive and generally involves applying freezing cold temperatures at incision sites after major surgery. The incidence of tumor formation was reduced as a result of the treatment.
The epigenome is essentially a record of chemical alterations made to DNA. The field of study known as epigenetics looks at how tumor suppressor genes can lose functionality even when DNA has not mutated. This happens when certain epigenetic “marks” in cell DNA tell proteins to process that strand of DNA in a different way. In some cases, these marks can cause an abnormal response leading to an environment more favorable to cancer growth.
The specifics of epigenetics are complicated. Essentially, epigenetic therapy seeks to alter the epigenetic marks that are essentially providing incorrect information on how proteins should process DNA. Cancers of all types (including mesothelioma) have epigenetic flaws that can eventually produce tumor growth.
One drug in development as a mesothelioma epigenetic therapy is belinostat. Phase II clinical trials have been completed which looked at the drug’s effect on mesothelioma. The therapy was shown to have fairly good efficacy with patients who had already undergone certain chemotherapy treatments. Still, more research will be required in order to discern the drug’s full potential.
There are several other FDA-approved medications for epigenetic therapy. Most of them have been approved for hematological tumors (affecting bone marrow, blood, lymphatic system, and lymph nodes).
These medications include:
Virotherapy is one of the most interesting emerging treatments for mesothelioma. It involves the injection of cancer-killing viruses into the body. Most viruses are injected at or near the tumor site. So, for pleural mesothelioma which affects the lining of the lungs, the injection would occur in the chest area.
There are no naturally-occurring viruses that seek out and kill cancer cells. However, some existing viruses have been modified by geneticists to induce them to seek out and kill cancer cells. Ideally, these viruses might someday independently track down and destroy cancer cells while leaving healthy cells alone. Scientists must also ensure that the virus would never cause further disease or infection.
The adenovirus is particularly adept as a cancer-killing agent. When it occurs naturally, the adenovirus can cause tonsillitis, conjunctivitis, and ear infections. But a modified adenovirus has been shown to be quite useful in attacking cancer cells. The resulting infection it may cause is considered minor compared to other viruses, yet extra care must be taken when exposing a patient with a weakened immune system to any virus, so much additional research must still be done. Like many other emerging treatments for mesothelioma, virotherapy is currently only available in clinical trials.
Photodynamic therapy (PDT) is an emerging cancer treatment that uses photosensitizing agents that are exposed to a particular wavelength of light. When exposed to this light, the photosensitizing agents break down and produce singlet oxygen, a more toxic variety of the triplet oxygen found in the air. Singlet oxygen then begins attacking cancer cells and tumors.
The procedure works by first injecting photosensitizing agents into the patient’s bloodstream. The agents travel through the body and eventually concentrate at tumor sites. The process usually takes two to three days.
Some common photosensitizing agents include:
After two or three days have passed, patients return to the doctor, and a specific wavelength of light is directed at the tumor site. The photosensitizing agent produces singlet oxygen and attacks cancer cells. The photosensitization procedure in the doctor’s office takes from five to 45 minutes.
There are few side effects to this treatment, but patients are advised to limit their exposure to the sun and other light sources for the following 30 days. PDT is a very new therapy with limited research available so far. Researchers are actively developing new photosensitizing agents and photodynamic medications that can further attack cancer cells.
Over time, it is hopeful that successful treatments for mesothelioma will be found. Eventually, one or more of these treatment options might become standard therapy for mesothelioma and other diseases. For now, however, it is important to maintain hope that a cure will come soon.