125I-Radiolabeled Morpholine-Containing Arginine–Glycine–Aspartate (RGD) Ligand of αvβ3 Integrin As a Molecular Imaging Probe for Angiogenesis

In this paper, using a hybrid small-animal Micro SPECT/CT imaging system, we report that a new 125I-Cilengitide-like RGD-cyclopentapeptide, containing d-morpholine-3-carboxylic acid, interacts in vivo with αvβ3 integrin expressed by melanoma cells. Images clearly show that the 125I-compound has the capacity to monitor the growth of a melanoma xenograft. Indeed, retention of the labeled ligand in the tumor mass has a good tumor/background ratio, and a significant reduction of its uptake was observed after injection of unlabeled ligand. These results suggest that the use of 125I-labeled morpholine-based RGD-cyclopentapeptides targeting αvβ3 positive tumors may play a role in future therapeutic strategies.