GB-6, a short linear peptide that selectively binds to the gastrin releasing peptide receptor (GRPR), shows potential as a high-contrast imaging probe due to its tumor selectivity and specific accumulation. Overexpression of GRPR in pancreatic cancer enables GB-6, when labeled with near-infrared (NIR) fluorescent dyes or the radionuclide technetium-99m (99mTc), to serve as an effective agent for tumor visualization. Demonstrating excellent in vivo stability, GB-6 yields tumor to pancreatic and intestinal fluorescence signal ratios of 5.2 and 6.3, respectively, in SW1990 subcutaneous xenograft models. Its rapid tumor targeting capability and precise tumor boundary delineation signify GB-6's extensive potential for clinical applications [1].