GMP-Compliant Automated Radiolabeling and Quality Controls of [⁶⁸Ga]Ga-FAPI-46 for Fibroblast Activation Protein-Targeted PET Imaging in Clinical Settings

Abstract

In nuclear medicine, molecular imaging of the tumor microenvironment using radiopharmaceuticals (RPs) targeting cancer-associated fibroblasts is gaining significant interest. Among these RPs, [⁶⁸Ga]Ga-FAPI-46 for positron emission tomography (PET) imaging is frequently used in clinical research protocols. To ensure that the production of this RP complies with good manufacturing practices, process automation is widely adopted. In this context, an automated method for preparing [⁶⁸Ga]Ga-FAPI-46 was designed using a GAIA^® synthesizer. Additionally, a HPLC method was developed and validated to determine the radiochemical purity (RCP) of [⁶⁸Ga]Ga-FAPI-46 and ensure product quality. The validated HPLC method showed excellent repeatability, with coefficients of variation (%CV) for RCP and retention time (t_R) below 0.03 and 0.16%, respectively, across 10 measurements. The radiochemical identification of [⁶⁸Ga]Ga-FAPI-46 showed comparable tr values to [^natGa]Ga-FAPI-46 (6.65 and 6.59 min, respectively). The limits of detection (LOD) and quantification (LOQ) were 79 and 42 kBq/mL, respectively, with a linear detector response between 62.9 and 0.08 MBq/mL (R² = 0.9999). The method proved robust, tolerating minor variations in mobile phase flow rate and composition. This validated radio-HPLC method can be used routinely for the quality control of [⁶⁸Ga]Ga-FAPI-46. Finally, three RP validation batches were produced using the automated method described and subjected to multiple quality controls. All three synthesis products met the expected specifications, notably regarding appearance, chemical and isotope identification, pH, sterility, stability, and radionuclidic and radiochemical purity.