An overview of Bioactive Peptides for in vivo Imaging and Therapy in Human Diseases

Radiolabeled peptides, designed to bind with high affinity receptors selectively expressed on cell membranes of different human tissues, represent valuable tools for in vivo imaging of several human diseases. Solid-phase peptide synthesis as well as availability of bifunctional chelating agents and prosthetic groups allows the production and radiolabeling of several peptide-based molecules which are useful to target specific receptors on different cancer types. Among them, octreotide and other analogues of somatostatin, vasoactive intestinal peptide, CCK analogues, bombesin, α-MSH analogues, neurotensin, exendin, RGD substance P, conjugated to appropriate chelators, such as DTPA, NOTA, DOTA or TETA, and radiolabeled with specific radionuclides, have already been translated into the clinical practice with remarkable sensitivity and diagnostic accurateness. This review recapitulates the current applications in clinical practice of radiolabeled peptides with a particular attention to those employed for diagnosis and therapy in oncologic as well as non-oncologic human diseases.