Immunotherapy is a term for a variety of medical approaches that are employed with the goal of turning the body's immune system into a cancer fighting tool. A number of drugs have been developed that are designed to catalyze the immune system when there are cancer cells present in the body. These drugs are designed to initiate what is termed "active immunology," meaning that they catalyze the body's own immune system into starving or killing cancer cells. These agents are referred to generally as "biological response modifiers" or BRMs.
The drugs used for active immunology are referred to as 'vaccines' because they are designed to replicate the role traditional vaccines play. Vaccines for mumps, measles and chickenpox all expose us to weakened versions of the viruses or bacteria that cause the disease. The body in turn develops antibodies that are targeted specifically at the disease source that has been introduced. The result is immunity when exposed to the real thing, transmitted by a contagious person.
Types of Immunotherapy Cells
Interferons are an active immunology agent. They are a group of hormones that can slow cell growth and cause the immune system to react against cancerous viruses. Interleukins are a group of hormonal proteins that provide similar results via a different cell interaction process. Some show better success with blood cancers than with solid tumors; others work well in the early stages of cancer but are less effective in advanced stages. Medications of this type are generally used on a non-specific basis to strengthen the immune system against cancer cells.
Passive immunotherapy does not rely on the body to attack the disease; instead, it uses immune system components (such as antibodies) made in the lab. These cells can be designed to combat specific types of cancer; the antibody is designed in the test tube to attack an identifiable component of a cancer cell, called an antigen. The antigens in cancer cells are unique to that particular type of cancer.
The use of immunotherapy for mesothelioma is still in the experimental stages. There have been limited studies that have shown some degree of positive response when an immunotherapy drug approved for some other purpose is used in conjunction with chemotherapy for mesothelioma patients. The best results, however, seem to occur in cases that have had a relatively early diagnosis. Unfortunately most mesothelioma cases aren't diagnosed until the disease has developed significantly and spread.
Research goes on, however. Morphotek is a drug research company that is developing a series of cancer-specific antibodies. One of their projects is the development of an antibody to attack mesothelin, a protein that is prevalent in tumors of patients with pancreatic carcinoma and other cancers including non-small lung carcinoma, ovarian carcinoma and mesothelioma. The drug is currently in a stage III clinical trial for pancreatic cancer and in mid 2010 was recruiting patients for a phase II study for mesothelioma.
A Dutch research team recently published results of a small clinical trial that showed effective results using dendritic cell-based immunotherapy, which utilizes a type of cell capable of targeting specific malignancies. The technique had proven to be effective in mice and showed results with a limited number of mesothelioma patients.
- Immunotherapy/Biological Therapy, Robert Wood Johnson University Hospital, http://www.rwjuh.edu/health_information/adult_gyneonc_immuno.html
- Biological Response Modifiers, OncoLink, University of Pennsylvania, Goldwein et al, 2001, http://www.oncolink.org/treatment/article.cfm?c=2&s=9&id=54
- Efficacy Study…Malignant Pleural Mesothelioma, ClinicalTrials.gov, National Institutes of Health, http://www.clinicaltrials.gov/ct2/show/NCT00738582?term=MORAb-009&rank=4
- Consolidative Dendritic Cell-based Immunotherapy…against Malignant Mesothelioma, American Journal of Respiratory and Critical Care Medicine, Hegmans et al, April 2010, http://ajrccm.atsjournals.org/cgi/content/abstract/181/12/1383?maxtoshow=&hits=10&RESULTFORMAT=&author1=aerts,+j&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT