Complementary Therapy: Immunotherapy
A new and more viable option for mesothelioma treatment is immunotherapy. It is an alternative to the traditional methods of treatment. Immunotherapy treatments consist of drugs that are given to the patient to stimulate the immune system to kill mesothelioma cells. It is a treatment that is still in the process of being developed, but has shown success for other types of cancer. Specialists are optimistic that immunotherapy therapy could yield the same results for mesothelioma patients. Promising clinical trials have made this type of therapy one of the most advanced developments in cancer treatment in years.
Immunotherapy is a targeted approach which is different from standard treatments. Chemotherapy and radiation damage healthy cells while immunotherapy is designed to attack only the mesothelioma cells. This results in less side effects in the patient. It also provides an opportunity for treatment for patients with late-stage mesothelioma since there are very few side effects. It is feasible that immunotherapy can slow down or even prevent metastasis in some patients allowing them to remain healthier.
Currently, immunotherapy treatments can only be obtained through clinical trials, but may have a drastic impact on treatment for mesothelioma in the future. Some of the reasons why patients are considering immunotherapy as a treatment option include:
Because the immune system can remember previous invaders, it can be trained to target and kill mesothelioma cells. This would allow the treatment to continue to have benefits long after treatment was finished.
Targeted therapy is therapy that is targeted to only affect cancerous cells. This leaves healthy cells unaffected and the patient has fewer side effects and thus a better quality of life.
Active VS Passive Immunotherapy
Immunotherapy is considered active when a drug is introduced into the body which causes the immune system to actively go on a seek and destroy mission to kill cancer cells by itself. An antigen is introduced into the body which then produces a natural immune response.
Passive immunotherapy treatment is different in that a synthetic immune system protein is introduced into the body which mimics the immune system response and then destroys the cancerous cells. This man-made protein is manufactured and then given to the patient in order to make up for what the existing immune system is lacking.
Currently, mesothelioma immunotherapy is passive. It targets one specific type of cell or antigen instead of stimulating the whole immune system.
Modified T Cells (right) attacking mesothelioma cancer cells (left).
Types of Immunotherapy
Immunotherapy also uses cancer vaccines which will either prevent the disease or destroy a cancer that already exists by introducing a pathogen into the body. This stimulates the immune system and allows it to learn to fight that pathogen. At this time there are two preventative vaccines that have been approved by the FDA but no treatment vaccines.
Immune Checkpoint Inhibitors
There are specific proteins on the surface of cells which aid in signaling certain functions in other cells. Generally, this function is to continue reproducing either by generating new blood vessels or by feeding tumor growth. By using immune checkpoint inhibitors, those signals can be interfered with and prevent the metastasis of mesothelioma.
Monoclonal antibodies are different from cancer vaccines in that they directly attack mesothelioma cells instead of initiating a response in the immune system. These antibodies attach to the cells and are now able to recognize the mesothelioma cells as a threat and begin to consume them.
Clinical Trials for Immunotherapy
There are several clinical trials that are testing how effective these immunotherapy drugs are. There are different requirements for each trial and some trials may be administered with other mesothelioma treatments. The following immunotherapy drugs are currently in the testing phase:
PD-1 and PD-L1 (programmed death and programmed death ligand) are two proteins that are expressed on the surface of specific cells and may be used to draw attention of antibodies. The proteins send signals to each other and this interaction causes the T cells to stop killing healthy cells. A recent drug has shown some success in this drugs ability to enable the immune system to attack mesothelioma cells.
This is a relatively new drug that has been introduced for mesothelioma. It is a cancer vaccine and has shown some success in the early phases of the clinical trials. It is an engineered bacteria called Listeria and is designed to be less harmful to the overall health of a patient, while at the same time drawing the attention of T cells so that it can attack mesothelioma cells.
Tremelimumab is a monoclonal antibody. It has great potential to treat chemo-resistant patients. It binds to a protein in the body called CTLA-4 which can be found on the surface of the T cells. By blocking CTLA-4 T cells are allowed to do a better job and may kill the mesothelioma cells much more effectively.
Doctors are optimistic about immunotherapy treatments. Several drugs currently being tested for use in mesothelioma have already been approved for the treatment of other cancers. Patients who will benefit the most from this treatment are those who haven’t responded well to chemotherapy or radiation, have an advanced stage mesothelioma, and have already tried standard treatment. Doctors view immunotherapy as a type of management for mesothelioma. The disease is treated like a chronic illness which keeps the disease at bay rather than eradicate it completely.
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