Radionuclide imaging of drug delivery for patient selection in targeted therapy

Abstract

Molecular imaging of drug delivery clearly has potential for patient selection for targeted therapy. The main advantage of this technique is that not only can antigen expression be measured noninvasively but also target accessibility is taken into account. However, up to now, most of these studies have been performed in preclinical models. Therefore, future research should focus on bringing promising tracers to the clinic, preferable in an early stage of drug development in order to test their potential role as a biomarker.

Site‐Specific Radioiodination of HER2‐Targeting Affibody Molecules using 4‐Iodophenethylmaleimide Decreases Renal Uptake of Radioactivity

“…A possible approach to the development of imaging agents is the radiolabeling of therapeutic Mabs using nuclides emitting gamma quanta that can be detected outside the patients body . The use of Mabs as imaging agents has, however, certain downsides.…”

“…The use of Mabs as imaging agents has, however, certain downsides. Antibodies are relatively bulky proteins (150 kDa); this limits their rates of extravasation, tumor penetration, and blood clearance of unbound tracers . Therefore, imaging is possible only several days after injection.…”

“…Therefore, imaging is possible only several days after injection. In addition, antibodies have a tendency to accumulate in tumors nonspecifically due to an “enhanced permeability and retention” (EPR) effect, which might cause false positive diagnoses . Small engineered scaffold affinity proteins, for example, Affibody molecules, are strong alternatives to antibodies in the development of imaging agents .…”

“…[6] Ap ossible approacht ot he development of imaging agents is the radiolabeling of therapeutic Mabs using nuclides emitting gamma quanta that can be detected outside the patient's body. [7] The use of Mabs as imaging agentsh as, however,c ertain downsides. Antibodies are relativelyb ulky proteins (150 kDa);t his limits their rates of extravasation, tumor penetration,a nd blood clearance of unboundt racers.…”

“…Antibodies are relativelyb ulky proteins (150 kDa);t his limits their rates of extravasation, tumor penetration,a nd blood clearance of unboundt racers. [7,8] Therefore, imaging is possible only several days after injection. In addition, antibodies have at endency to accumulate in tumors nonspecifically due to an "enhanced permeability and retention" (EPR) effect, which might cause false positive diagnoses.…”