Targeted radiotherapy with alpha particle emitting radionuclides

One of the most important considerations in the development of radiopharmaceuticals for the targeted radiotherapy of cancers is the selection of the type of radiation emitted during the decay of the radionuclide. Alpha particle emitters have emerged as a promising approach for certain clinical applications such as compartmentally spread disease and neoplasms present in the blood. An attractive feature of radionuclides decaying by the emission of α particles is that they offer the prospect of matching the cell specific reactivity of targeting vehicles, such as receptor avid peptides and monoclonal antibodies, with radiation with a range of only a few cell diameters. In addition, α particles have important radiobiological advantages when compared with conventional external beam radiotherapy and α particles including a more potent cytotoxic effectiveness, with sterilizing potential nearly independent of oxygen concentration, dose rate and cell cycle position. This review summarizes the current status of targeted radiotherapy with α particle emitting radionuclides. Because they have reached the stage of clinical investigation, monoclonal antibodies labelled with the promising α particle emitting radionuclides 213Bi, 225Ac and 211At will be highlighted. (author)