Development of a 68Ga-Fluorinated Porphyrin Complex as a Possible PET Imaging Agent

Aim Due to the interesting pharmacologic properties of porphyrins, the idea of developing a possible tumor imaging agent using PET by incorporating 68 Ga into a suitable porphyrin ligand was investigated. Methods 68 Ga-labeled 5,10,15,20-tetrakis(pentafluoro-13 phenyl) porphyrin ( 68 Ga-TFPP) was prepared using freshly eluted [ 68 Ga]GaCl 3 obtained from a 68Ge/68Ga generator developed in-house and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (H2TFPP) for 60 min at 100°C. Results The complex was prepared with high radiochemical purity (>99% ITLC, >99% HPLC, specific activity: 13–14 GBq/mmol). Stability of the complex was checked in the final formulation and in human serum for 5 h. The partition coefficient was calculated for the compound (log P = 0.62). The biodistribution of the labeled compound in vital organs of Swiss mice bearing fibrosarcoma tumors was studied using scarification studies and SPECT imaging up to 1 h. The complex was mostly washed out from the circulation through kidneys and liver. The tumor-to-muscle ratio 1 h post injection was 5.13. Conclusion The radiolabeled porphyrin complex demonstrated potential for further imaging studies in other tumor models.