Cancer immunotherapy uses the patient's immune system to combat cancer. This is achieved in two different ways: active and passive treatments. Active therapy seeks to stimulate the patient's immune to system to attack the cancer, usually accomplished through vaccines. Passive cancer immunotherapy does not rely upon the body to respond to the cancer, but offers man made tools to the body to fight the disease. These tools are usually antibodies.
People with weakened immune systems are more susceptible to cancer. This is not to say that someone with a healthy immune system cannot succumb to cancer, but the incidence is much higher if one's health is seriously compromised. Cancer immunotherapy attempts to give the patient's immune system the tools or training, as is the case with vaccines, to battle cancer.
Many tumors produce antigens. Antigens are proteins that the body perceives as dangerous. Sometimes the antigens are not different enough from the cells around the tumor, however.
The body also often does not categorize tumors as foreign to it. Aggressive immunological attacks, therefore, against the tumor rarely occur. The situation is further complicated because the micro-environment surrounding the tumor is immunosuppressive, which makes it difficult for the immune system to attack the cancer.
Vaccines can stimulate the immune system to recognize the cancer as foreign. Antigen vaccines attempt to get the body to produce antibodies that will try to neutralize the tumor cells. Vaccines can also decrease immunosuppression, alter tumor cells so that they are more likely to be attacked by the immune system, or improve the body's response to chemotherapy. Vaccines may also be used as a preventative measure.
The human papillomavirus (HPV) vaccine is an example of preventative cancer immunotherapy. The HPV vaccine seeks to prevent cervical cancer by protecting the body against the HPV virus. HPV is thought to be the cause of some cervical cancers.
Cancer vaccines can also be made from cancer cells and can be classified as either autologous or allogeneic. Autologous vaccines are created from cells from the patient, custom-made for just for one patient. Allogeneic vaccines are developed from cancer cells from someone else, in a process analogous to how viral vaccines are created.
While active therapy helps the body's immune system to properly respond, passive cancer immunotherapy gives the body man-made antibodies. Monoclonal antibodies (MoAbs or MAbs) are used most often. Antibodies can be given to the patient in two different ways. The first is "naked," which is just the antibodies. The second is "conjugated," in which the antibodies are given to the patient in conjunction with other treatments, such as chemotherapy.