FAP-Targeted\nFluorescent Imaging Agents to Study Cancer-Associated\nFibroblasts In Vivo

Cancer-associated fibroblasts (CAFs) expressing fibroblast\nactivation\nprotein alpha (FAP) are abundant in tumor microenvironments and represent\nan emerging target for PET cancer imaging. While different quinolone-based\nsmall molecule agents have been developed for whole-body imaging,\nthere is a scarcity of well-validated fluorescent small molecule imaging\nagents to better study these cells in vivo. Here, we report the synthesis\nand characterization of a series of fluorescent FAP imaging agents\nbased on the common quinolone azide inhibitor. Our data show excellent\nperformance of some synthesized FAP Targeting Fluorescent probes (FTFs)\nfor both topical application and intravenous delivery to label CAF\npopulations in solid tumors. These results suggest that FTF can be\nused to study CAF biology and therapeutic targeting in vivo.