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What is cancer immunotherapy?
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The use of immunotherapy in cancer, often called immuno-oncology, involves the stimulation of a person’s immune system to target and attack cancer cells.
There are several types of immunotherapy used for patients with cancer. These include cancer vaccines, monoclonal antibodies and non-specific immunotherapies.
Cancer vaccines
Although most vaccines are administered to healthy people to prevent infections, cancer vaccines are injected into a person’s body to prevent or treat the cancer.
One example of a vaccine to prevent cancer is the HPV vaccine. This helps prevent specific cancer types, including anal, cervical and throat cancers.
Cancer vaccines that treat certain cancer types stimulate the immune system to attack cancer cells within the body.
The only FDA-approved vaccine for cancer treatment is sipuleucel-T (Provenge, Dendreon). This vaccine is used for the treatment of prostate cancer that has advanced despite the use of hormone therapy.
There are ongoing clinical trials of cancer vaccines administered concurrently with other types of cancer treatments, including chemotherapy, radiation therapy and surgery.
Data have indicated that cancer vaccines appear most effective when administered in combination with other cancer therapies. Moreover, cancer vaccines have appeared to increase the effectiveness of other treatment regimens.
Monoclonal antibodies
Monoclonal antibodies, composed of synthetic immune-system proteins, attack a specific portion of a cancer cell. Examples include naked, conjugated and bispecific monoclonal antibodies.
All are administered through IV injection and sometimes lead to adverse effects, including fever, chills, weakness, headache and nausea.
One example of a monoclonal antibody is cetuximab (Erbitux; Bristol-Myers Squibb, Lilly). Cetuximab, approved to treat colon cancer and head and neck cancers, attaches to receptors on cancer cells that accept epidermal growth factor. The blocking of this signaling prevents the uncontrolled growth of cancers with epidermal growth factor receptor mutations.
Another example is ipilimumab (Yervoy, Bristol-Myers Squibb), which targets CTLA-4, a protein receptor that downregulates the immune system.
In patients with cancer, cytotoxic T lymphocytes are inhibited from recognizing and destroying cancer cells. Ipilimumab — approved for the treatment of melanoma — counteracts that inhibitory mechanism and essentially takes the “brakes” off the immune system, allowing cytotoxic T lymphocytes to function properly.
Ongoing clinical trials are evaluating use of ipilimumab in patients with bladder cancer, lung cancer and prostate cancer.
In addition, physicians are able to deliver radiation directly to cancer cells by combining a radioactive particle with a monoclonal antibody. This approach prevents the destruction of surrounding healthy cells.
These antibodies deliver low levels of radiation during an extended period of time, a technique considered to be as effective as high-dose external beam radiation.
Non-specific immunotherapy
Non-specific immunotherapy treatment aids in attacking cancer cells by boosting a person’s immune system.
Examples of non-specific immunotherapy treatment include cytokines, interleukins and interferons. These are administered on their own or in combination with a main treatment to help boost the immune system.
Cytokines — chemicals that are constructed of immune system cells — are critical in the growth and activity of other immune system cells and blood cells in the body.
Investigations into the use of novel immunotherapies is a rapidly expanding and evolving aspect of cancer research. Researchers currently are testing complex treatments that boost particular components of the immune system, including chimeric antigen receptor T-cell therapy, as well as tumor-infiltrating lymphocytes and interleukin-2.
For more information:
http://www.cancer.org/treatment/treatmentsandsideeffects/treatmenttypes/immunotherapy/index
http://www.mayoclinic.org/diseases-conditions/cancer/in-depth/monoclonal-antibody/ART-20047808