MESOTHELIOMA

New approaches to treat malignant mesothelioma are currently being tested. They often combine traditional treatments or include something entirely new. They include:* Angiogenesis and Anti-angiogenesis DrugsAlthough progress has been made in the early detection of cancer, and in improved treatment options once cancer is diagnosed, there are still many cancers, including mesothelioma, which can not be cured and remain difficult to treat effectively. In recent years, researchers have learned a great deal about how cancer cells differ from normal cells and, in an effort to find drugs without the potentially severe side effects of chemotherapy, have now discovered drugs which target the tumor itself while sparing the body’s normal cells. One such group are the anti-angiogenesis drugs.Learn more about anti-angiogenesis agents in the treatment of mesothelioma.* Immunotherapy, sometimes called biological therapy, uses the body's own immune system to protect itself against disease. Researchers have found that the immune system may be able to recognize the difference between healthy cells and cancer cells, and eliminate those that become cancerous. Immunotherapy is designed to repair, stimulate, or enhance the immune system's natural anticancer function.Substances used in immunotherapy, called biological response modifiers (BRMs) alter the interaction between the body's immune defenses and cancer, thereby improving the body's ability to fight disease. Some BRMs, such as cytokines and antibodies, occur naturally in the body, however, it is now possible to make BRMs in the laboratory that can imitate or influence natural immune response agents. These BRMs may:o Enhance the immune system to fight cancer cell growth.o Eliminate, regulate, or suppress body responses that permit cancer growth.o Make cancer cells more susceptible to destruction by the immune system.o Alter cancer cell's growth patterns to behave like normal cells.o Block or reverse the process that changes a normal cell into a cancer cell.o Prevent a cancer cell from spreading to other sites.Many BRMs are currently being used in cancer treatment, including interferons, interleukins, tumor necrosis factor, colony-stimulating factors, monoclonal antibodies, and cancer vaccines.More on immunotherapy for mesothelioma.* Photodynamic therapy (PDT) is a type of cancer treatment based on the premise that single-celled organisms, if first treated with certain photosensitive drugs, will die when exposed to light at a particular frequency. PDT destroys cancerous cells by using this fixed frequency light to activate photosensitizing drugs which have accumulated in body tissues.In PDT, a photosensitizing drug is administered intravenously. Within a specific time frame (usually a matter of days), the drug selectively concentrates in diseased cells, while rapidly being eliminated from normal cells. The treated cancer cells are then exposed to a laser light chosen for its ability to activate the photosensitizing agent. This laser light is delivered to the cancer site, (in the case of mesothelioma, the pleura), through a fiberoptic device that allows the laser light to be manipulated by the physician. As the agent in the treated cells absorbs the light, an active form of oxygen destroys the surrounding cancer cells. The light exposure must be carefully timed, so that it occurs when most of the photosensitizing drug has left the healthy cells, but is still present in cancerous ones.The major side effect of PDT is skin sensitivity. Patients undergoing this type of therapy are usually advised to avoid direct and even indirect sunlight for at least six weeks. Other side effects may include nausea, vomiting, a metallic taste in the mouth, and eye sensitivity to light. These symptoms may sometimes come as a result of the injection of the photosensitizing agent.* Gene therapy is an approach to treating potentially fatal or disabling diseases by modifying the expression of an individual's genes toward a therapeutic goal. The premise of gene therapy is based on correcting disease at the DNA level and compensating for the abnormal genes.

Mesothelioma development in rats has been demonstrated following intra-pleural inoculation of phosphorylated chrysotile fibres. It has been suggested that in humans, transport of fibres to the pleura is critical to the pathogenesis of mesothelioma. This is supported by the observed recruitment of significant numbers of macrophages and other cells of the immune system to localised lesions of accumulated asbestos fibres in the pleural and peritoneal cavities of rats. These lesions continued to attract and accumulate macrophages as the disease progressed, and cellular changes within the lesion culminated in a morphologically malignant tumour.

Experimental evidence suggests that asbestos acts as a complete carcinogen with the development of mesothelioma occurring in sequential stages of initiation and promotion. The molecular mechanisms underlying the malignant transformation of normal mesothelial cells by asbestos fibres remain unclear despite the demonstration of its oncogenic capabilities. However, complete in vitro transformation of normal human mesothelial cells to malignant phenotype following exposure to asbestos fibres has not yet been achieved. In general, asbestos fibres are thought to act through direct physical interactions with the cells of the mesothelium in conjunction with indirect effects following interaction with inflammatory cells such as macrophages.