Optimization and automation of the radiosynthesis of [¹⁸F]Lu-LuFL as a clinically useful PET ligand targeting FAP for tumor imaging

Recently, a novel radiohybrid tracer [¹⁸F]Lu-LuFL targeting the fibroblast activation protein (FAP) has been developed for PET imaging of solid tumors. This tracer has shown promising results, prompting us to conduct a first-in-human study to evaluate its efficacy for PET imaging of FAP in human body. In order to facilitate the routine production and clinical application of [¹⁸F]Lu-LuFL, a straightforward and efficient automated synthesis is described. The optimum labeling parameters were determined at laboratory scale, and subsequently incorporated into an automated production process. Further studies have demonstrated that clinical doses of [¹⁸F]Lu-LuFL can be prepared within 19 min, with excellent radio chemical purity (>99%) and activity yield (23.58% ± 2.20%, non-decay corrected), coupled with solid phase extraction (SPE) purification method. All the quality control results satisfy the required criteria for release. In conclusion, we have successfully synthesized [¹⁸F]Lu-LuFL with sufficient radioactivity and superior quality, thereby establishing its potential for further clinical application.