The main advantage of this type of treatment is that it only targets mesothelioma cells and, in doing so, minimizes damage to healthy cells. Less damage to healthy cells means that a patient will experience less side effects. This allows patients who are not in the best overall health receive treatment that can improve their survival time.
How Immunotherapy Works
Normally the body’s immune system would recognize that mesothelioma cells are “foreign” and would quickly attempt to kill them. Mesothelioma tumors, however, grow quickly and metastasize (spread) at a high rate.
The fast metastasis of a mesothelioma tumor overwhelms the immune system and makes it difficult to attack. Immunotherapy provides a solution to this problem: it boosts the immune system, makes it stronger. and helps it target mesothelioma cells more effectively.
Immunotherapy is known as a “targeted treatment”, because it specifically targets mesothelioma cells. Targeted treatments are beneficial because they only attack cancer cells and cause no unintended damage to healthy cells.
Patients with advanced mesothelioma or whose health may not allow them to withstand the side effects of other mesothelioma treatments, like chemotherapy, can benefit from the targeted nature of immunotherapy because it’s safer and results in less overall side effects.
There are two approaches researchers take when they develop an immunotherapy treatment. The treatment can either be active or passive. Whether an immunotherapy treatment is considered active or passive depends on how it is developed and administered to the patient.
Active immunotherapy actively stimulates the immune system to attack mesothelioma cells. It uses special triggers (antigens) that are injected into the body to set off the immune system’s attack on foreign cancer cells.
Passive immunotherapy uses compounds created in the lab to attack mesothelioma directly. This type of immunotherapy is called passive because, unlike active immunotherapy, it doesn’t directly stimulate the immune system to kill cancer cells. Instead, special compounds created by researcher attack mesothelioma cells directly and have a passive effect on the immune system’s strength.
Types of Immunotherapy
There are several types of immunotherapy treatments currently being tested in clinical trials. Researchers use each type to help a patient’s own immune system fight mesothelioma in a different ways. There are four types of immunotherapy treatments showing promise in clinical trials:
Monoclonal antibodies are molecules that are made to target antigens on mesothelioma tumor cells. They can help stop the growth of mesothelioma in a few different ways:
- They can block the ability of mesothelioma cells to metastasize (spread) to other parts of the body.
- They can find and kill cancer cells directly.
- They can help deliver cancer-killing medicine to cancer cells.
Bevacizumab is an example of a monoclonal antibody currently testing in clinical trials. It prevents a special protein called the vascular endothelial growth factor (VEGF) from connecting to a receptor on mesothelioma cells. VEGF is a protein that allows tumors to grow blood vessels, which then provide the cancer cell nutrients it needs to grow and spread.
According to a recent study, researchers combined bevacizumab with chemotherapy drugs Alimta and cisplatin. The study reported that patients experienced a median survival rate of about 15 months, 3 months more than the average mesothelioma survival rate.
Immune Checkpoint Inhibitors
Immune checkpoint inhibitors work by blocking signaling molecules on cancer cells. These molecules send signals to help to regulate (turn off and on) immune system responses. Mesothelioma usually blocks these signals and makes it very difficult for the immune system to attack rapidly multiplying cancer cells.
Tremelimubab is one of the most prominent examples of an immune checkpoint inhibitor. It works by blocking an antigen that’s most commonly found on T cells, whose job is to destroy tumor cells. Blocking this antigen allows T the cells to attack mesothelioma cells and perform their job more effectively. A recent study reported that tremelimubab controlled the growth of mesothelioma in 31 percent of patients who received the treatment.
Tremelimubab is also one of the main immunotherapy treatments for mesothelioma that is currently being tested in clinical trials. Researchers consider it a promising treatment for patients whose mesothelioma does not respond to chemotherapy and are developing it into a better treatment for mesothelioma.
Therapeutic Cancer Vaccines
Researchers use therapeutic cancer vaccines to carry modified mesothelioma antigens into a patient’s body using a virus or bacteria. The immune system recognizes the antigen in the cancer vaccine as a signal for mesothelioma and is stimulated to attack any mesothelioma cells carrying that specific antigen.
Researchers are currently testing a number of promising cancer vaccines. One recent study combines chemotherapy with a vaccine called TroVax.
Another study is testing a vaccine carrying Wilms Tumor-1 (WT1). WT1 is a protein expressed in mesothelioma cells that helps it grow. The goal of the vaccine is to help the patient’s own immune system to delay the growth of mesothelioma or even prevent it from growing back after surgery.
Adoptive T Cell Transfer
Specialists remove T cells (cells that help kill viruses and cancer cells) from the patient own body and modify them to boost their strength. The T cells are then given back to the patient to strengthen the immune system’s anti-cancer response.
Researchers are currently developing a T cell transfer treatment using blood cells modified and grown in the lab. These blood cells can be modified to target a protein (called mesothelin) that’s heavily expressed in many cancers, including mesothelioma.
Blocking mesothelin can help shrink tumors, stop metastasis and extend life expectancy. The treatment is designed to help treat patients who would not normally have many available treatment options because of their advanced cancer stage.
Advances in Immunotherapy
Many immunotherapeutic treatments are currently being tested in clinical trials. Researchers are studying the effectiveness of immunotherapy on its own and combined with other mesothelioma treatments, like chemotherapy. There is an ongoing, large-scale trial evaluating the combination of the successful chemotherapeutic drugs Alimta/cisplation and bevacizumab. The results of this study are set to be released in early 2015.
If you have been diagnosed with mesothelioma and would like to learn more about emerging treatments like immunotherapy, get in touch with our Patient Help Team. A member of our team can provide more information about immunotherapy and can help connect you to clinical trials.