New approaches to treat malignant mesothelioma are currently being tested. They often combine traditional treatments or include something entirely new. They include:
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:
Enhance the immune system to fight cancer cell growth.
Eliminate, regulate, or suppress body responses that permit cancer growth.
Make cancer cells more susceptible to destruction by the immune system.
Alter cancer cell's growth patterns to behave like normal cells.
Block or reverse the process that changes a normal cell into a cancer cell.
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.
Angiogenesis and Anti-angiogenesis Drugs
Although 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.
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.
Replacement gene therapy replaces a mutated or missing gene, most often a tumor suppressor gene, with a normal copy of that gene which serves to keep cell growth and division under control. The p53 gene, the most common gene mutated in cancer has become a prime target for gene replacement, and has met with some success in inhibiting cell growth, inhibiting angiogenesis (the development of a tumor's blood supply), and inducing apoptosis (cell death).
Knockout gene therapy targets the products of oncogenes (a gene that can induce tumor formation) in an effort to render them inactive and reduce cell growth.
With constantly expanding knowledge of the genes associated with cancer, their functions, and the delivery systems used in administering these genes, gene therapy has a promising future.
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.
Because mesothelioma is very hard to control, the National Cancer Institute (NCI) is sponsoring clinical trials (research studies with people) that are designed to find new treatments and better ways to use current treatments. Before any new treatment can be recommended for general use, doctors conduct clinical trials to find out whether the treatment is safe for patients and effective against the disease. Participation in clinical trials is an important treatment option for many patients with mesothelioma.
People considering clinical trials may be interested in the NCI booklet Taking Part in Cancer Treatment Research Studies. This booklet describes how research studies are carried out and explains their possible benefits and risks. People interested in taking part in a clinical trial should talk with their doctor. Information about clinical trials is available from the Cancer Information Service (CIS) (see below) at 1–800–4–CANCER. Information specialists at the CIS use PDQ®, NCI's cancer information database, to identify and provide detailed information about specific ongoing clinical trials. Patients also have the option of searching for clinical trials on their own.