Radioiodination of Pimonidazole as a Novel Theranostic Hypoxia Probe

Background: Tumors are defined as abnormal tissue masses, and one of the most important factors leading to the growth of these abnormal tissue masses is Vascular Endothelial Growth Factor, which stimulates angiogenesis by releasing cells under hypoxic conditions. Hypoxia has a vital role in cancer therapy, thus it is important to monitor hypoxia. The hypoxia marker Pimonidazole (PIM) is a candidate biomarker of cancer aggressiveness. Objective: The study aimed to perform radioiodination of PIM with Iodine-131 (¹³¹I) to join a theranostic approach. For this purpose, PIM was derived as PIM-TOS to be able to be radioiodinated. Methods: PIM was derived via a tosylation reaction. Derivatization product (PIM-TOS) was radioiodinated by using iodogen method and was analyzed by High-Performance Liquid Chromatography and Liquid chromatography-mass spectrometry. Thin layer radiochromatography was utilized for its quality control studies. Results: PIM was derived successfully after the tosylation reaction. The radioiodination yield of PIM-TOS was over 85%. Conclusion: In the current study, radioiodination potential of PIM with ¹³¹I, as a potential theranostic hypoxia agent was investigated. Further experimental studies should be performed for developing a novel hypoxia probe including theranostics approaches.