Evaluation of 99mTc-HYNIC-(ser)3-LTVPWY peptide for glioblastoma imaging.

Purpose: Early and accurate imaging of glioblastoma is of great value in staging, metastatic detection, treatment management and prognosis. The human epidermal growth factor receptor 2 (HER2) plays an essential role in the tumorigenesis and tumor progression in cancer. The aim of this study was to develop HER2-targeted peptide for glioma tumor imaging.Material and methods: HYNIC-(Ser)3-LTVPWY peptide was labeled with technetium-99m in presence of EDDA/tricine mixture as co-ligands. 99mTc-HYNIC-(Ser)3-LTVPWY peptide was assessed for cellular specific binding and receptor-binding affinity. The biodistribution study and tumor imaging were conducted in nude mice bearing U-87 MG glioma xenografts.Results: The in vitro blocking study demonstrated specific binding of 99mTc-HYNIC-(Ser)3-LTVPWY in cultured U-87 MG cells with a KD of 9.7 ± 2.0 nM. Biodistribution study revealed tumor to blood and tumor to muscle ratios were about 5.55 and 6.65 respectively after 1 h injection of radiolabeled peptide. Blocking study with non-labeled counterpart indicated a significant reduction (68%) in tumor uptake of 99mTc-HYNIC-(Ser)3-LTVPWY that is indicated the tumor specificity of the radiolabeled peptide on glioblastoma. Gamma planar imaging revealed that the U-87 MG tumor was clearly visualized at 1 h.Conclusion: The results of this study showed that the 99mTc-HYNIC-(Ser)3-LTVPWY peptide specifically accumulates in glioma and is, therefore, a promising probe for the diagnosis of glioma.