Can our own immune system help in the war on cancer?
Recently, genetic engineering has produced several methods which may be successful in defeating cancer. New vaccines and the B7 gene are two of the exciting new methods. These methods simply help the immune system identify cancer so that it may respond to the cancer.
Many vaccines have been produced that have displayed promising results. One vaccine used against kidney cancer is mixed with granulocyte-macrophage colony stimulating factor (GM-CSF). This gene assists in activating the immune system. Tumors disappeared in some patients who received the genetically engineered vaccine. In those patients who did not experience tumor remission, did show to have a stronger immune response than patients who did not receive the vaccine.(6) SuperVax is a new adjuvant used with vaccines that has displayed hopeful results. While trials have just begun, experiments with mice show a "marked enhancement of cell mediated immunity."(7) Another approach is to find genes "that encode antigens which are recognized by tumor-infiltrating lymphocytes (TILs)." By cloning the TILs which recognize the antigens and placing them in tumors, an immune response against the tumor can be increased. The difficult part of this procedure is finding antigen that is common to tumors in the majority of people. Unfortunately, not everyone possesses the same antigen, therefore different people need different TILs. Up to now only six genes that produce a TIL response have been identified.(9) With persistant experimentation, more genes can be identified and this method will become very useful in the fight against cancer.
The B7 gene is also another promising strategy being studied. The B7 surface molecule on the antigen presenting cell interacts with the CD28 receptor on the T cell. This interaction causes the immune response. By placing this gene onto tumor cells an immune response can be induced.(8) Once a B7 plasmid is placed in the tumor, the tumor begins to express the B7 antigen. The immune system is then able to respond to the tumor cells. This therapy has only shown to be successful against cancers that are susceptible to immune responses, such as melanoma.(9 and 10) This is very exciting because it is a way in which researchers can mark tumors. By marking tumors, the immune system will seek them out and destroy them. Before this, the immune system was inneffective at controlling the growth of tumor cells.
All of these experiments seem to be very promising. Genetic engineering has produced a variety of new treatments and we have many more to look forward to. We possess many of materials needed to defeat cancer. These treatments allow the materials to be used effectively and efficeintly.
- Schmidt, W., Buschle, M., Zauner, W., Kirlappos, H., Mechtler, K., Trska, B., and Birnstiel, M.L. (1997) Proc. Natl. Acad. Sci. USA.94:3262-3267.
- Buschle, M., Schmidt, W., Zauner, W., Mechtler, K., Trska, B., Kirlappos, H., and Birnstiel, M.L. (1997) Proc. Natl. Sci. Acad. USA. 94:3256 -3261.
- Folkman, J. September 1996 Scientific American, 150-154.
- Harris, A.L. (1997) The Lancet. 349(supp.):13-15.
- Peng, L., Shu, S., and Krauss, J.C.(1997) Cancer Research 57:1-13.
- La Voie, Angela (1997) Medical Tribune News Service, Vaccine helps stop cancer spread.
- http://www.jennerbio.com Oct. 13, 1997, Jenner Biotherapies Initiates Clinical Trials of New Adjuvant for Cancer Therapy
- http://www.brown.edu/courses/bio_160/
- Rosenberg, Steven April 1997 Immunology Today
Comments
Post a Comment