We review the current status of imaging as applied to targeted
therapy with particular focus on antibody-based
therapeutics.
Antibodies have high
tumor specificity and can be engineered to optimize delivery to, and retention within, the
tumor. Whole
antibodies can activate natural immune effector mechanisms and can be conjugated to beta- and alpha-emitting
radionuclides, toxins,
enzymes, and nanoparticles for enhanced
therapeutic effect. Imaging is central to the development of these agents and is used for patient selection, performing dosimetry and assessment of response. gamma- and positron-emitting
radionuclides may be used to image the distribution of antibody-targeted
therapeutics While some
radionuclides such as
iodine-131 emit both beta and gamma radiation and are therefore suitable for both imaging and
therapy, others are more suited to imaging or
therapy alone. Hence for
radionuclide therapy of
neuroendocrine tumors, patients can be selected for
therapy on the basis of gamma-emitting
indium-111-octreotide imaging and treated with beta-emitting yttrium-90-octreotate. Positron-emitting
radionuclides can give greater sensitivity that gamma-emitters but only a single
radionuclide can be imaged at one time and the range of
radionuclides is more limited. The multiple options for antibody-based therapeutic molecules, imaging technologies and therapeutic scenarios mean that very large amounts of diverse data are being acquired. This can be most effectively shared and progress accelerated by use of common data standards for imaging,
biological, and clinical data.