Synthesis and Evaluation of 68Ga- and 177Lu-Labeled [Pro14]bombesin(8–14) Derivatives for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer

The gastrin-releasing peptide receptor (GRPR) is overexpressed in a variety of cancers and represents a promising target for diagnosis and therapy. However, the extremely high accumulation in the pancreas observed for most of the clinically evaluated GRPR-targeted radiopharmaceuticals could limit their applications. In this study, we synthesized one GRPR antagonist (ProBOMB5) and two GRPR agonists (LW02056 and LW02057) by replacing the 4-thiazolidinecarboxylic acid (Thz