Tumor Targeting Using Radiolabeled Antibodies for Image-Guided Drug Delivery.

Due to their high target affinity and specificity, antibodies are very suitable tumor-targeting vehicles for imaging and therapeutic application. This enables a theranostic approach of imaging targeted drug delivery in oncology and opens the way for personalized medicine, predicting drug delivery, response, and treatment outcome in the individual patient. Of the currently available molecular imaging techniques, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are the best suited imaging techniques to visualize and determine drug delivery to the target tissue quantitatively. Using the same antibody for imaging and targeted therapy may eliminate some limitations of antibody-based molecular imaging and therapy, like heterogeneous antigen expression and poor accessibility. However, challenges of this approach remain, for example in the pharmacokinetic behavior of radiolabeled antibodies and antibody-drug-conjugates. Despite these challenges, also exciting opportunities are at the horizon, by using antibodies as multimodal vehicles carrying both a diagnostic agent and a therapeutic agent. In this review, both the challenges and the opportunities of using radiolabeled antibodies for image-guided drug delivery are discussed.