Radioimmunotherapy (RIT) uses an antibody labeled with a radionuclide to deliver cytotoxic radiation to a target cell. In cancer therapy, an antibody with specificity for a tumor-associated antigen is used to deliver a lethal dose of radiation to the tumor cells. The ability for the antibody to specifically bind to a tumor-associated antigen increases the dose delivered to the tumor cells while decreasing the dose to normal tissues. By its nature, RIT requires a tumor cell to express an antigen that is unique to the neoplasm or is not accessible in normal cells.
These medications were the first agents of radioimmunotherapy, and they were approved for the treatment of refractory non-Hodgkins lymphoma. This means they are used in patients whose lymphoma is refractory to conventional chemotherapy and the monoclonal antibody rituximab. A set of radioimmunotherapy drugs that rely upon an alpha particle-emitting isotope (e.g., Bi-213 or, preferably, Ac-225), rather than a beta emitter, as the killing source of radiation is being developed. The most developed drug is directed to treating acute myeloid leukemia and is in patient clinical trials (as of the fourth quarter of 2010).
Other applications (non-approved indications)
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