Radioimmunotherapy is a combination of both radiation therapy and immunotherapy. Immunotherapy refers to treatments that use the body’s own immune system to combat cancer.
Several specific types of immunotherapy engage monoclonal antibodies. These antibodies then target select antigens that exist on the surface of cancer cells. They will then attach to cancer cells and act as a “disease-fighters” in the immune system.
Monoclonal antibodies, without radionuclides attached, are commonly used to treat cancer. These monoclonal antibodies are called “naked antibodies.” When conjugated or attached, monoclonal antibodies are paired with a radioactive substance and injected into the bloodstream. When used in radioimmunotherapy, they often travel and bind to cancer cells and deliver high doses of radiation directly to tumor cells. These conjugated monoclonal antibodies will then target the antigen directly. This specific approach is notably less damaging to the existing normal cells in other parts of the body as opposed to naked antibodies.
Radiolabeled antibodies such as ibritumomab tiuxetan attach to the CD20 antigen found on lymphocytes when treating non-Hodgkin lymphoma. Lymphoma starts in the a type of white blood cells known as lymphocytes and will then travel throughout the body and settle into several places, simultaneously.
Notably, researchers have begun studying antibody pairings with different radioactive agents and their potential uses in treating many other blood cancers or solid tumors. These cancers include prostate cancer, melanoma, ovarian cancer, leukemia, high-grade brain glioma, and colorectal cancer.