Tumour Immunotherapy - Essay Example

One such treatment option is known as immunotherapy (also known as biologic therapy or biotherapy) in which the body's immune mechanism is utilized to fight against cancer. Immunotherapy includes active immunotherapy (cancer vaccines) and passive immunotherapy (monoclonal antibodies). Active immunotherapy stimulates the body's own immune system to fight the disease; on the other hand passive immunotherapy utilizes immune system components (such as monoclonal antibodies) which have been created outside the body (Waldmann, 269).

Active immunotherapy against cancer has been much less active against cancer in comparison to other infectious diseases. Even though vaccines (targeted against cancer antigens) for providing protection against various cancers, (especially cancer cervix) have been developed, their efficacy has yet not been significantly proven (Waldmann, 270). Besides the limited success with active immunization, there may be many challenges which may reduce the efficacy of active immunization. The review of literature by Waldman (269-272) discusses some of these challenges and the ways to deal with them.

One of the main challenges is identification of antigens on tumour tissue (tumour rejection antigens) which can produce rejection in the host by producing an elaborate T-cell response. Some of the tumour rejection antigens include tumour specific antigens, the results of mutations, viral antigens in cancers associated with viruses and tumour specific differentiation antigens (Waldmann, 269). One method of defining cancer associated antigens is to define antigens recognized by the tumour bearing host by identifying the circulating antibodies developed against tumour antigens in the host.

Technique of serological identification by recombinant expression cloning called SEREX is used to identify circulating IgG that are specific to the tumour antigens. Screening cDNA libraries from tissues using tumour reactive T-cell lines and clones, followed by mass spectrophotometeric analysis is another approach that can be used (Waldmann, 269, 270). Other ways of improving the efficacy of active immunization include: enhancement of the function of antigen presenting cells by inducing the maturation of dendridic cells using agents like GM-CSF, IL-4, TNF-, etc.

Efforts have been made to enhance the function of T-cells. Certain cytokines have been introduced into the vaccine preparations in order to improve their efficacy. Assays of measuring vaccine efficacy by measuring their cytotoxicity, cytokine secretion etc have also been developed (Waldmann, 272). Challenges associated with passive immunotherapyInactivation of transferred anti-tumour T cells for immunotherapy by the "hostile" immunosuppressive microenvironment created by the tumour tissue has currently limited the scope of passive immunotherapy.

However in future there is a possibility to develop better and more effective immunotherapies by adopting inactivating mechanisms, which would protect anti-tumor T cells in the tumour microenvironment, thereby resulting in the destruction of the cancerous tissue. One such immunosupressive mechanism involves cAMP-elevating Gs-protein coupled A2 receptors. These receptors