Mesothelioma, a cancer of the lining of the lung and abdomen, suppresses the normal immune system response designed to ward off disease. Scientists have been trying to understand the mechanics of the immune suppression process to develop more effective therapies for mesothelioma, an aggressive form of cancer.
One promising treatment is immunotherapy that enlists the body’s natural defense system to shrink cancerous tumors. A number of immunotherapies are currently being tested in clinical trials. Mesothelioma is among the cancers that appear to be responsive to immunotherapy, researchers say. But the failure of immunotherapies to stop the growth of malignant mesothelioma tumors suggests that the immune suppression process is complex and involves multiple targets.
In an article published in the journal Immunology and Cell Biology, researchers at Harvard University investigate the roles of three factors affecting the immune response: regulatory T cells, intratumoural transforming growth factor (TGF)-â and the protein cytotoxic T lymphocyte-associated antigen-4, which plays a regulatory role in the immune system.
The researchers say that immunotherapy treatments targeting multiple regulators simultaneously appear to be more effective than focusing on one regulator protein that is suppressing immune response. They report that a triple treatment involving all three immune system factors led to long-term shrinkage of tumors and residual resistance to cancer cells if tumors reappeared.
“These data suggest that clinical application of immunotherapies against tumors may be improved by simultaneously targeting multiple mechanisms of immune suppression,” said lead investigator Haydn T. Kissick in a summary of the research.
Mesothelioma is caused by exposure to asbestos fibers. When a person breathes asbestos dust, the microscopic asbestos fibers can penetrate deep in the lungs and cause inflammation and eventually disease.
Approximately 2,500 to 3,000 people a year in the United States receive a diagnosis of malignant mesothelioma. Many victims of mesothelioma are older workers, retired workers and veterans who were exposed to asbestos decades ago in a workplace. The symptoms of mesothelioma typically take 20 years to 40 years to appear, but the disease is aggressive once it appears.