The job of the immune system is to kill foreign cells in the body which could be harmful. The way that the immune system recognizes foreign cells is by their antigens – the molecules located on all types of cells. When the immune system senses foreign antigens, it triggers a response which attempts to destroy the foreign substance. Even though cancer cells are harmful, the immune system will not destroy them because they are not foreign. The goal of immunotherapy treatment for mesothelioma is to trick the immune system into believing that mesothelioma cells are foreign. Then the immune system will kill the cancerous cells.
It is a fact that studies have correlated immune responses that attack tumors with improved survival rates.1 Though it is not known whether this therapy type can eventually lead to a cure, it certainly holds the possibility of improving the quality of life for a longer period of time after diagnosis.
In order to trick the immune system into believing that mesothelioma cells are foreign, the antibodies on the cancerous cells must be altered. The main problem in doing this is that only the antibodies of the cancerous cells should be changed. If the antibodies of healthy cells are altered to appear foreign, then the immune system would attack them as well. Immunotherapy is still an experimental form of mesothelioma treatment but it is very promising. Even if immunotherapy will not cure mesothelioma, it could prevent its metastasis. Currently, there are three main types of immunotherapy which are used in cancer treatment.
Vaccine Immunotherapy
Vaccine immunotherapy is a type of active immunotherapy, meaning that it works by stimulating the immune system. The procedure works in a very similar way to virus vaccines but with one core difference: cancer vaccines must fight against a disease which has already invaded the body.
To create a mesothelioma vaccine, a patient will have a sample of the infected tissues taken. The mesothelioma cells will be used to make a vaccine specifically for the patient; the vaccine will not be able to be used in other patients. In a laboratory, the mesothelioma cells or antigens will be altered so the patient’s immune system will view them as foreign and fight against them.
There is some concern among researchers that phase II studies on therapeutic cancer vaccines have not progressed further; however, the current perspective is that immunotherapy including vaccines should include careful patient selection and the combining with other treatments like chemotherapy and radiotherapy.2 The main problem with vaccine immunotherapy is that cancer cells generally mutate or their antigens change as they grow and metastasize. Thus, the vaccine will have a limited effectiveness. Further, it is time consuming and costly to make a new vaccine for each individual patient.
Monoclonal Antibody Immunotherapy
Monoclonal antibody immunotherapy is a type of passive immunotherapy, meaning that it works by utilizing elements external to the body. It does not cause the immune system to directly attack the cancer cells. Rather, massive amounts of antibodies are made in a laboratory. These antibodies are designed to target cancer cells. The monoclonal antibodies produced may have drugs or radioactive materials fixed to them. When the monoclonal antibodies are injected into the patient, they will join tumor cells. The immune system will then recognize the tumor cells as foreign and destroy them.
Cytokine Immunotherapy
Cytokine immunotherapy is a type of non-specific immunotherapy, meaning that it does not use cancerous cells. Rather, it uses cytokines – proteins which are made by white blood cells as a response to infections. Cytokines primarily act as messengers to regulate the immune system’s response to an infection. Some cytokines have shown anti-cancer properties, such as interferon. These cytokines can be injected into a patient’s body and will cause the immune system to react to mesothelioma cells.
Availability of Immunotherapy for Mesothelioma
Some forms of immunotherapy have become common for treating cancer and other diseases. However, immunotherapy is still considered an experimental treatment for mesothelioma. Because mesothelioma is such a complex type of cancer, it may be difficult or impossible to distinguish its antibodies and make an effective immunotherapy treatment. If a faulty immunotherapy treatment is given, it could have dire results for the patient as healthy cells may be targeted by the patient’s own immune system.
One of the most recent discoveries in the area of immunotherapy is the “triple therapy” which shows promise as a combined immunotherapy for mesothelioma. It is called triple therapy because the immune system is manipulated in 3 ways and shows signs of perhaps being a curative therapy. Currently the immunotherapy treatments are therapeutic. The new treatment approach will begin being tested in clinical trials soon and they will last approximately 5 years.3
Patients diagnosed with mesothelioma may be eligible for immunotherapy clinical trials. While there is no promise of a cure with clinical trials, and they come with risks, the benefits of participating in an immunotherapy trial could outweigh the potential risks. Some patients choose to participate in clinical trials because they get access to state-of-the-art treatments. Since mesothelioma has a poor prognosis, these clinical trials offer some hope.
References
1 Bograd AJ, Suzuki K, Vertes E, Colovos C, Morales EA, Sadelain M, Adusumilli PS. (13 Sep 2011) Immune responses and immunotherapeutic interventions in malignant pleural mesothelioma. Cancer Immunology – Immunotherapy, v60:11, 1509-1527.
2 Dalgleish, Angus G. Therapeutic cancer vaccines: Why so few randomized phase III studies reflect the initial optimism of phase II studies.
3 New Immunotherapy Treatment Provides Hope for Mesothelioma Patients. (3 November 2011) Retrieved from Cancer New, Treatment and Research at http://cancernewsdigest.com/lung-mesothelioma-asbestos/new-immunotherapy-treatment-provides-hope-for-mesothelioma-patients/
