Mesothelioma is cancer that affects the lining of the lungs and is mainly associated with previous exposure to asbestos. It is becoming more common and affects around 3,000 people per year in the UK alone. Currently, treatment is aimed at controlling symptoms with chemotherapy, radiotherapy, and/or surgery. However, none of these approaches are very effective and there is a pressing need for research to develop better treatments for this cancer.
Immunotherapy is a method of treatment that kills cancer cells by activating the body’s natural defence network: the immune system.
The immune system protects the body from infectious diseases caused by infectious agents like viruses and bacteria. Recently, we have learned that the immune system also plays an important role protecting the body from cancer, and fighting cancer that has already developed.
While evidence shows that the immune system can slow cancer growth and help to prevent its spread to other parts of the body, cancer has its own natural defences as well. Cancers arise from our own cells, thereby appearing less “foreign” to the immune system, and thus averting detection. Furthermore, cancers can trick our immune system by providing signals to instruct our own immune cells not to attack them.
Immunotherapy is used to boost the immune system, overcome these obstacles, and encourage the attack and elimination of cancer cells. An important development in immunotherapy is the use of “gene therapy” to re-programme white blood cells of the immune system called “T-cells,” so that these T-cells can successfully recognize and attack cancer cells. The gene that is introduced into T-cells to program them for this purpose is known as a “CAR.” Recently, treatment with CAR T-cells has achieved spectacular results for patients with blood cancers, resulting in approval for the first-ever gene therapy for leukemia by the United States Food and Drug Administration (FDA).
A small number of scientists are researching immunotherapy treatments in mesothelioma, including CAR T-cell therapies. These therapies involve the use of harmless viruses to deliver CAR genes into T-cells from the blood of patients. These genes are designed to (i) equip the immune cells with the ability to attack mesothelioma cells, and (ii) facilitate the growth of these immune cells in the laboratory to achieve a sufficient dose for treating an adult patient. CAR T-cell therapies target the proteins mesothelin and FAP (fibroblast-activation protein) on mesothelioma tumors, and show promising results in the laboratory. These CAR T-cell therapies are currently undergoing clinical trials to test their efficacy in patients.
Other CAR therapies for mesothelioma are also in development. State-of-the-art CAR T-cell treatments like these are still under investigation and are not yet readily available to patients. However, these options have certainly opened a new path for the treatment of seemingly incurable cancers like mesothelioma.
Research article: Chimeric Antigen Receptor (CAR) T Cell Therapy for Malignant Pleural Mesothelioma (MPM),Cancers (Basel), 2017