Development of RGD-based radiotracers for tumor imaging and therapy: translating from bench to bedside.

The cell adhesion molecule integrin αvβ3 is an important player in the process of angiogenesis. In the last decades, a series of radiolabeled Arg-Gly-Asp (RGD) peptides targeting integrin αvβ3 has been prepared and optimized for positron emission tomography (PET) and single-photon-emission computed tomography (SPECT) imaging of integrin αvβ3 expression. Several promising radiotracers have been tested in clinical trials. In this review, we will introduce strategies that have been used to optimize and accelerate RGD radiotracers towards clinical translation; illustrate RGD-based radiotracers that have been investigated in clinical trials; and discuss the other applications of RGD radiotracers aside from tumor detection.