Development and evaluation of 18 F-JR-1002:a PET tracer for targeting cannabinoid type 2 receptor

JIN Can; XU Yangyang; CHEN Junwei; MAO Dilong; JIN Chentao; DU Kang; SONG Shuang; ZHU Yuankai; CAO Shuxia; ZHU Xiaohua; HE Qinggang

doi:10.12122/j.issn.1674-4500.2025.07.01

Abstract：Objective To develop a novel PET tracer,18F-JR-1002,targeting the cannabinoid type 2 receptor(CB2R),to enhance molecular imaging capabilities for CB2R-related diseases.Methods The synthesis of a PET tracer targeting cannabinoid type 2 receptor(N-(4-(diethylamino)benzyl)-4-(2-(fluoro-18F)ethoxy)-N-(p-tolyl)benzenesulfonamide)was designed and prepared stably and efficiently on the automatic synthesizer,denoted as 18F-JR-1002.Cell affinity and specificity experiments,in vitro stability experiments,whole-body dynamic and static scanning of mice,and spleen autoradiography were carried out.Results The decay-corrected radiochemical yield was 34.7%±8.1%(n=12),corresponding to a molar activity Am of 264.5±41.2 GBq/μmol.Stability tests showed that 18F-JR-1002 had excellent in vitro stability.The cellular uptake assays and spleen tissue autoradiography showed that 18F-JR-1002 exhibits high binding affinity and specific imaging capability for CB2R.In mice,most of the 18F-JR-1002 probes were concentrated in the small intestine,followed by obvious uptake in the liver,kidneys,and bladder.The spleen and lungs had relatively low uptake,and the bones basically did not take up the tracer.According to dynamic scanning data,the PET tracer accumulated in the liver and kidneys in the early stage.Over time,the uptake of the tracer in the small intestine and bladder increased significantly and then stabilized.Conclusion This study developed a high-affinity,specific and metabolically stable CB2R probe 18F-JR-1002,which improved the accuracy and reliability of CB2R imaging and provided more accurate imaging support for clinical practice.