Immunotherapy is one of the experimental methods for tumor treatment. This approach is based on the understanding that a key to the origins, development and outcome of malignant neoplasms is the immune system. In this line of thought, if the functional status of the latter is fortified in the right way, it is likely that it is activated to such an extent that it would control the tumor process.
There are 4 types of antitumor immunotherapy. The first type is called active non-specific immunotherapy. It refers to substances of natural or synthetic origins. They are introduced into the bloodstream and cause the global activation of all immune system components, including those responsible for antitumor protection.
For example, it was shown that the components of the BCG vaccine can activate anti-tumor white blood cells. This effect is used in the experimental treatment of carcinoma of the bladder and of malignant melanoma. The vaccine is injected into tumor masses and directed the activated the immune cells to the neoplastic process. In some patients, however, the effect is contrary to the desired one. This explains why the considered type of immunotherapy has not been a uniform way for treating these tumors.
Another interesting example of non-specific active immunotherapy is the use of viruses for the experimental treatment of certain tumors. The Duke University, USA, has conducted a clinical study in which the cells of malignant brain tumor – glioblastoma, were infected with a modified embodiment of the polio virus. In statistically significant percentage of cases, this lead to both the direct death of the infected tumor cells and the activation of the immune system which fiercely attacked them.
The second type of anti-tumor immunotherapy is active specific immunotherapy. It is implemented through a variety of vaccines containing molecules found in tumor cells. This means that immunotherapy is directed towards this tumor and does not activate the entire immune system, but only the part of it that is responsible for anti-tumor protection. This is the most intensive form of developing immunotherapy and high hopes have been laid on it.
Interesting forms of this type of immunotherapy are DNA vaccines. Through them the tumor cells are inserted in the so called plasmids that make the cells more visible to the immune system. Vaccines with the so called dendritic cells which are pre-activated tumor killers are also being developed.
The third type of anti-tumor immunotherapy is passive humoral immunotherapy. It consists in introducing specific anti-tumor antibodies in the organism. The latter are fastened to the surface of tumor cells and thus direct the immune system thereto. A serious problem here is the significant antigenic variability of malignant tumors. Therefore, in some cases, the antibodies appear to be “outdated” and are not taken where needed.
The last type is gene immunotherapy. This is the most original and highest form of experimental treatment. The idea of this therapy is to achieve the genetic apparatus of the specific tumor and, figuratively speaking, to suppress the “bad” genes, and stimulate the “good” ones. Gene therapy carries risks for normal cells. Therefore it is subject to strict control.
In conclusion, we can say that science is continuously evolving and perhaps every day it takes a step forward towards improvement. The numerous experimental studies in the field of immunotherapy are an embodiment of this statement. Some forms of immunotherapy give encouraging results. Being still an experimental treatment, however, immunotherapy is the last line of treatment in oncology.