Development of 18F-Labeled Acridone Analogue for Tumor Imaging via Stimulator of Interferon Genes Targeting

Thestimulator of interferon genes (STING) is a pivotal proteinin the production of STING-dependent type I interferon, which hasthe potential to enhance tumor rejection. The visualization of STINGin the tumor microenvironment is valuable for STING-related treatments,but few STING imaging probes have been reported to date. In this study,we developed a novel F-18-labeled agent ([F-18]F-CRI1)with an acridone core structure for the positron emission tomography(PET) imaging of STING in CT26 tumors. The probe was successfullyprepared with a nanomolar STING binding affinity of K (d) = 40.62 nM. [F-18]F-CRI1 accumulated quicklyin the tumor sites and its uptake reached a maximum of 3.02 +/- 0.42% ID/g after 1 h i.v. injection. The specificity of [F-18]F-CRI1 was confirmed both in in vitro cell uptake and in vivo PETimaging by blocking studies. Our findings suggest that [F-18]F-CRI1 may be a potential agent for visualizing STING in the tumormicroenvironment.