Synthesis of a radioiodinated thymidine phosphorylase inhibitor and its preliminary evaluation as a potential SPECT tracer for angiogenic enzyme expression

• Published in: Journal of labelled compounds & radiopharmaceuticals 2008-10, Vol.51 (11), p.384-387
• Main Authors: Takahashi, Masayuki, Seki, Koh-ichi, Nishijima, Ken-ichi, Zhao, Songji, Kuge, Yuji, Tamaki, Nagara, Ohkura, Kazue
• Format: Article
• Language: English
• Subjects: angiogenesis; Biological and medical sciences; Contrast media. Radiopharmaceuticals; inhibitor; Medical sciences; Pharmacology. Drug treatments; radioiodination; SPECT; thymidine phosphorylase (TP)
• ISSN: 0362-4803; 1099-1344
• DOI: 10.1002/jlcr.1544

The expression of thymidine phosphorylase (TP) is strongly associated with angiogenesis in tumors and activation of antitumor agents. We designed a novel 5‐125I‐labeled 6‐(2‐iminoimidazolidinyl)methyluracil hydrochloride ([125I]5I6IMU‐HCl) to develop an effective radiotracer for in vivo assessment of TP expression in tumors and prognosis of cancer chemotherapy. Radiotracer synthesis was achieved by radioiodination of the precursor, 6‐(2‐iminoimidazolidinyl)methyluracil at the C‐5 position with NCS/radioiodide. After purification by HPLC, [125I]5I6IMU‐HCl was obtained in high radiochemical yield with satisfactory specific activity. The radiotracer showed high inhibitory potency for the target enzyme and good stability in vivo. Copyright © 2008 John Wiley & Sons, Ltd. The aim of this work was to synthesize a novel radioiodinated uracil derivative as an effective tracer for in vivo assessment of thymidine phosphorylase expression in tumors and prognosis of cancer chemotherapy. [125I]5I6IMU‐HCl was prepared in high radiochemical yield by simple labeling procedure. The radiotracer showed high inhibitory potency for the target enzyme and good stability in vivo. Copyright © 2008 John Wiley & Sons, Ltd.