Radiolabeling, quality control and cell binding studies of a new 99mTc-labeled bisphosphonates: 99mTc-ibandronate sodium

INTRODUCTION: Early detection of bone cancer is critical for treating symptoms, minimizing pain, and increasing overall quality of life. It is critical to develop novel radiopharmaceuticals with high labeling efficiency and stability for the diagnosis of bone cancer. The goal of this research is to design a novel radiopharmaceutical that may be utilized to diagnose bone cancer.
METHODS: In this study, ibandronate sodium (IBD), a bisphosphonate analogue, was radiolabeled with technetium-99m (99mTc) and quality control tests of the newly developed radiopharmaceutical ([99mTc]Tc-IBD) were done using radioactive thin layer chromatography (RTLC). After that, the incorporation of [99mTc]Tc-IBD into hydroxyapatite crystals and a human bone osteosarcoma cell line (U2OS) was tested.
RESULTS: According to the results obtained, optimal radiolabeling procedure was obtained for [99mTc]Tc-IBD with 200 µg.mL-1 IBD, 20 µg stannous chloride and 99mTc with 37 MBq radioactivity. The reaction mixture was adjusted to pH 5.5 and incubated at room temperature for 15 min. The radiochemical purity of [99mTc]Tc-IBD was found to be greater than 95% at room temperature for up to 6 h. In addition, chromatography analysis showed >95% [99mTc]Tc-IBD complex formation with promising stability for up to 24 h in saline and up to 2 h in cell medium. The percent binding of IBD to hydroxyapatite was 83.70±3.67 and the logP of [99mTc]Tc-IBD was -1.1014. The radiolabeled complex showed a higher rate of cell incorporation to U2OS cells compared to Reduced/Hydrolyzed 99mTcO4-.
DISCUSSION AND CONCLUSION: The newly produced radiopharmaceutical is very promising, according to the results of in vitro cell culture, hydroxyapatite binding, and quality studies, and will be a step forward for further studies in nuclear medicine for bone cancer diagnostics.