What Is Immunotherapy?
Immunotherapy, or immune therapy, is a form of treatment for cancers like asbestos-caused mesothelioma that recently emerged in 2010. The purpose of immunotherapy is to enhance the body’s immune system to fight off the growth and spread of cancer.
The immune system is the body’s defense against infection and disease. The body uses white blood cells, or leukocytes, to spot unrecognized cells, such as mesothelioma cells. The immune system also produces antibodies, or specialized proteins, which help white blood cells connect with and destroy unrecognized substances (antigens) that enter the body.
The immune system doesn’t always recognize the formation of cancer cells. For example, an individual’s body may not recognize the growth of tumors in a lung, mistaking them for normally-growing cells. When healthy cells mutate and become malignant (cancerous), it can be hard for the immune system to fight off. Immunotherapy is a treatment that helps increase the body’s ability to recognize cancer cells and attempt to eliminate them.
Patients typically receive immunotherapy through clinical trials or in palliative care. It is often combined with standard mesothelioma treatment options such as chemotherapy, radiation, or surgery. However, unlike procedures like chemotherapy, immunotherapy targets malignant cells, reducing the harm to healthy cells.
Immunotherapy Treatment for Mesothelioma
Mesothelioma is a form of cancer that develops years after initial asbestos exposure in at least one lung. The disease primarily starts in the pleura, a thin lining between the lung and the nearby chest wall. However, other types of mesothelioma develop in the abdominal and cardiac areas of the body.
Different factors determine the course of treatment, such as the type of mesothelioma the patient has been diagnosed with – pleural in the lining of the lung, peritoneal in the abdominal cavity, or pericardial in the heart cavity. It. also includes the cell type present in the tumors, the stage of cancer, and demographics (age or sex). Length and location of exposure can also have an effect. The goal of treatment is to extend life expectancy and relieve pain or discomfort.
Immunotherapy is becoming increasingly common in standard mesothelioma treatment. Doctors typically use immunotherapy on patients whose cancer continues to spread after going through chemotherapy.
Despite its growing popularity and legal status, immunotherapy is still commonly referred to as an emerging treatment. However, clinical trials have shown promising results in the extension of life expectancy in patients, as well as improved lung health.
While the FDA has not yet approved immunotherapy for mesothelioma patients following asbestos exposure, the treatment is approved for other types of cancer, like melanoma. The treatment is proven to have fewer harsh side effects than chemotherapy.
Several drugs are currently being studied for mesothelioma:
- Atezolizumab (Tecentriq)
- Ipilimumab (Yervoy)
- Nivolumab (Opdivo)
- Pembrolizumab (Keytruda)
Immunotherapy drugs like durvalumab, nivolumab, and pembrolizumab are called checkpoint inhibitors. When white blood cells are blocked from attacking tumor cells, the checkpoint inhibitor (medication) reveals the tumor cells to the attacking immune cells.
Popular drugs that have gone through clinical trials are CRS-207, tremelimumab, and pembrolizumab. The clinical trials test for effectiveness in different medications. Some of the medicines are also administered with other types of treatment, such as chemotherapy.
CRS-207 is a newer vaccination treatment for mesothelioma. The medication is a genetically-engineered version of a bacteria called Listeria and is modified to be less harmful to patients’ overall health. CRS-207 attracts the attention of the white blood cells (T cells), which inhibits them from attacking mesothelioma cells. The vaccination has shown success in the early phases of clinical trials.
This immunotherapy medication is a monoclonal antibody, which is a clone of white blood cells. The drug binds itself to a protein called CTLA-4 (cytotoxic T-lymphocyte antigen 4). CTLA-4 is found on the surface of white blood cells and prevents them from killing malignant cells. When tremelimumab attaches to CTLA-4, the white blood cells can successfully kill mesothelioma cells. Tremelimumab has shown promising results on patients who are resistant to chemotherapy.
PD-1 and PD-L1 are proteins that block the immune system’s ability to kill mesothelioma cells. These proteins are referred to as checkpoints and are found on the surface of certain cells. Checkpoints distract white blood cells by sending signals to each other, preventing white blood cells from killing mesothelioma cells.
Keytruda (pembrolizumab) is an Anti-DP-1/PD-L1 immunotherapy drug that inhibits communication between the proteins. By doing this, the immune system can attack malignant mesothelioma cells. The drug has shown success in clinical trials and was able to shrink tumors in 14 out of 25 patients.
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