TY - JOUR T1 - Triple-Peptide Receptor Targeting In Vitro Allows Detection of All Tested Gut and Bronchial NETs JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 613 LP - 615 DO - 10.2967/jnumed.114.153189 VL - 56 IS - 4 AU - Jean Claude Reubi AU - Beatrice Waser Y1 - 2015/04/01 UR - http://jnm.snmjournals.org/content/56/4/613.abstract N2 - A high proportion of gut and bronchial neuroendocrine tumors (NETs) overexpresses somatostatin receptors, especially the sst2 subtype. It has also recently been observed that incretin receptors, namely glucagonlike peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) receptors, can be overexpressed in gut and bronchial NETs. However, because not all tumors can express these receptors in sufficient amounts, in vivo imaging with a single radioligand may not always be successful. We therefore evaluated with in vitro methods whether a cocktail of radioligands targeting these 3 receptors would improve tumor labeling. Methods: In vitro receptor autoradiography was performed on 55 NETs, comparing in each successive section of tumor the binding with a single radioligand, either 125I-Tyr3-octreotide, 125I-GLP-1(7–36)amide, or 125I-GIP(1–30), with the binding using a cocktail of all 3 radioligands, given concomitantly under identical experimental conditions. Results: Using the cocktail of radioligands, all tumors without exception showed moderate to very high binding, with a receptor density corresponding to 1,000–10,000 dpm/mg of tissue; conversely, single-ligand binding, although identifying most tumors as receptor-positive, failed to detect receptors or measured only a low density of receptors below 1,000 dpm/mg in a significant number of tumors. In addition, the cocktail of radioligands always provided a homogeneous labeling of the whole tumor, whereas single radioligands occasionally showed heterogeneous labeling. Conclusion: The study suggests that the use of a cocktail of 3 radioligands binding to somatostatin receptors, GLP-1 receptors, and GIP receptors would allow detecting virtually all NETs and labeling them homogeneously in vivo, representing a significant improvement for imaging and therapy in NETs. ER -