Radionuclide selection and model absorbed dose calculations for radiolabeled tumor associated antibodies.

An absorbed dose calculation comparison has been computed for radiolabeled tumor associated antibodies distributed over a standard geometry and tumor location. Half-life data, maximum specific activities, and relative organ doses of nine radionuclides, Cu-67, Br-77, Br-82, Y-90, Tc-99m, In-111, I-131, Re-186, and At-211, have been compiled in which the radionuclides were assumed to be coupled with antibody. These nuclides were chosen on the basis of physical characteristics that warranted their inclusion as either imaging or therapy radiolabels. Radionuclide biodistribution data based on current available estimates for antibody uptake and clearance in humans has been adopted. Re-186 and Y-90 have been determined to be among the best therapy radiolabels since they possess sufficiently long half lives necessary for tumor localization, little or no gamma radiation, intermediate beta energy, stable daughter products, and have a reasonable chance to form a stable chelate with an antibody system.