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.

A set of radioimmunotherapy drugs that rely upon an alpha-emitting isotope (e.g., bismuth-213 or, preferably, actinium-225), rather than a beta emitter, as the killing source of radiation is being developed.

Several phase II clinical trials for the treatment of acute myeloid leukemia have been carried out using alpha-emitting RITs.

[20] Components of the extracellular matrix and the tumor microenvironment can also be targeted by radioimmunotherapy, such as Netrin-1 [21] (an axon guidance protein) and FAP (a marker for cancer associated fibroblasts).