Wei_2022_Eur.J.Nucl.Med.Mol.Imaging_49_2761

PURPOSE: In this pilot study, we developed a new tracer, [(18)F]AlF-labeled FAPI-04 chelated with NOTA, denoted as [(18)F]AlF-NOTA-FAPI-04, and tested the specificity, biodistribution, and clinical application for PET/computed tomography (CT) imaging of various types of cancers in patients. METHODS: In vitro binding specificity of FAPI-04 to FAP was verified in U87 cells confocal of a fluorescence-labeled variant. In vivo imaging, competition, and dynamic scanning analyses were conducted to evaluate [(18)F]AlF-NOTA-FAPI-04 imaging in xenograft mouse model using small-animal PET/CT. The application of [(18)F]AlF-NOTA-FAPI-04 was analyzed by imaging different types of cancers in patients. RESULTS: Both in vitro and in vivo results showed high binding specificity of FAPI-04 to FAP. High intratumoral uptake and fast body clearance of the tracer were observed in the xenograft mouse model and cancer patients. High-contrast images and negligible radiation exposure to normal tissue were observed on [(18)F]AlF-NOTA-FAPI-04 PET/CT in 28 patients with 8 different types of cancers. Five of 28 patients underwent PET/CT scanning at 1 h, 2 h, and 4 h after intravenous injection of [(18)F]AlF-NOTA-FAPI-04. Seven patients with advanced lung cancer underwent dual-tracer imaging, and 44 and 37 metastatic lesions were detected by [(18)F]AlF-NOTA-FAPI-04 PET/CT and [(18)F]F-FDG PET/CT, respectively. Overall, 80.0% of metastatic lesions was identified by both [(18)F]AlF-NOTA-FAPI-04 and (18)F-FDG, 17.8% by [(18)F]AlF-NOTA-FAPI-04 PET/CT only, and 2.2% by [(18)F]FDG PET/CT only. CONCLUSION: [(18)F]AlF-NOTA-FAPI-04 offers high specificity as a tracer for FAP imaging and allows fast imaging with high contrast in tumors. [(18)F]AlF-NOTA-FAPI-04 is better at identifying metastatic lesions in patients with advanced lung cancer than [(18)F]FDG, and its use may facilitate tumor staging.