Synthesis and preliminary biological studies of the novel conjugate 188Re-labeled meso-tetrakis(4-sulfophenyl)porphyrin in mice

ObjectiveThe objective of this study was to evaluate the biological behaviors of a novel 188Re-labeled meso-tetrakis(4-sulfophenyl)porphyrin (TPPS4) in normal mice and tumor-bearing mice.MethodsTPPS4 was synthesized and labeled by 188ReO4−. Normal KM mice and BALB/c nude mice bearing melanoma or hepatoma were prepared for distribution studies.ResultsThe [188Re]TPPS4 yield was >98% with a specific activity of 11.2 GBq/mol, and vitamin C could increase its stability in vitro. In normal KM mice, [188Re]TPPS4 had a fast blood clearance (∼90%, 24 h postinjection), low retention in vital organs and hepatotropic characteristics. In nude mice, uptakes of >4.1% and 6.5% ID/g tumor at 8 h postinjection were observed in melanoma and hepatoma, respectively; this remained at high levels of 4.7% and 5.7%, respectively, after 24 h. At 8 h, the tumor/blood and tumor/muscle ratios in melanoma-bearing and hepatoma-bearing mice were 6.2–15.2 and 6.1–24.2, respectively. Twenty-four hours later, these high ratios still continued at 8.6–22.1 and 12–26.1, respectively.ConclusionThe results obtained in this study indicate that [188Re]TPPS4 has a high tumor affinity and retainable accumulation characteristics in carcinoma, which can potentially be used for tumor-targeted therapy.