High-Contrast Detection of Somatostatin Receptor Subtype-2 for Fluorescence-Guided Surgery

Abstract

Dye design can influence the ability of fluorescently labeled imaging agents to generate tumor contrast and has become an area of significant interest in the field of fluorescence-guided surgery (FGS). Here, we show that the charge-balanced nearinfrared fluorescent (NIRF) dye FNIR-Tag enhances the imaging properties of a fluorescently labeled somatostatin analogue. In vitro studies showed that the optimized fluorescent conjugate MMC-(FNIR-Tag)-TOC bound primarily via somatostatin receptor subtype-2 (SSTR2), whereas its negatively charged counterpart with IRDye 800CW had higher off-target binding. NIRF imaging in cell line-and patient-derived xenograft models revealed markedly higher tumor contrast with MMC(FNIR-Tag)-TOC, which was attributed to increased tumor specificity. Ex vivo staining of surgical biospecimens from primary and metastatic tumors, as well as involved lymph nodes, demonstrated binding to human tumors. Finally, in an orthotopic tumor model, a simulated clinical workflow highlighted our unique ability to use standard preoperative nuclear imaging for selecting patients likely to benefit from SSTR2-targeted FGS. Our findings demonstrate the translational potential of MMC(FNIR-Tag)-TOC for intraoperative imaging and suggest broad utility for using FNIR-Tag in fluorescent probe development.

Somatostatin Receptor Subtype-2 Targeting System for Specific Delivery of Temozolomide

“…For radioactive studies, the selection of 68 Ga ( t 1/2 = 68 min) or 67 Ga ( t 1/2 = 3.3 days) was performed based on the objective of each experiment. Accordingly, 9 was reacted with 68 GaCl 3 or 67 GaCl 3 using published methods (Scheme ) − and produced the radiolabeled PDC with high radiochemical yield (>60% non-decay-corrected) and purity (>95%) (Figure S1B).…”

Method To Diversify Cyanine Chromophore Functionality Enables Improved Biomolecule Tracking and Intracellular Imaging

“…Therefore, we sought to introduce additional structural modifications. Our studies and others have found that careful balance and placement of charged functional groups significantly improve the properties of various targeted imaging agents. ,− In particular, our recent studies identified a first-generation FNIR-Tag, which contains an O -alkyl quaternary amine at the C4′ position and improves the tumor targeting of mAb and peptide conjugates. , Here, we explore placing additional charged functional groups adjacent to the polymethine chromophore. With this goal in mind, we designed FNIR-Tag-766 (Figure A), which contains both trimethyl-propyl ammonium indolenine substituents and a N -trimethyl-propyl-ammonium- N -butyl-sulfonate tertiary amide, which we used previously, at the 2-position of the C4′ aryl ring …”

Combined multiphoton microscopy and somatostatin receptor type 2 imaging of pancreatic neuroendocrine tumors

“…All 12 samples were stained with a novel fluorescent near-infrared SSTR2-targeted peptide, MMC(FNIR-Tag)-TOC, developed by the Azhdarinia laboratory following their established protocol, 9 and subsequently wet mounted using Fluoromount-G®. Samples were then imaged with an inverted Olympus IX71 microscope with a 20x objective (1-U2B825-U, Olympus), illuminated with a xenon light source (U-LH75XEAPO, Olympus), and and ORCA-Flash 4.0 digital CMOS camera (C11440-22CU, Hamamatsu Photonics K.K.).…”