• Journal of Radiopharmaceuticals and Molecular Probes
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• v.10 no.1
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• pp.83-96
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• 2024

Peptide-based radiopharmaceuticals have brought significant advancements in the diagnosis and treatment of various cancers, serving as a powerful tool in nuclear medicine. These radiopharmaceuticals utilize the high specificity of peptides for certain cell receptors, such as the prostate-specific membrane antigen in prostate cancer and somatostatin receptors in neuroendocrine tumors. This review paper aims to describe the clinical benefits of peptide-based radiopharmaceuticals, emphasizing their high target affinity, improved imaging quality, and therapeutic efficacy. By integrating ongoing research and clinical trial data, the innovative impact of peptide-based radiopharmaceuticals in nuclear medicine is highlighted.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.129-137
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• 2022

Bombesin has a high binding affinity to gastrin-releasing peptide receptor (GRPR) and can be used as a targeting ligand in GRPR-related cancers. Because GRPR is overexpressed in prostate cancer, bombesin analogues have been investigated extensively for diagnosis and treatment of prostate cancer. In nuclear medicine, bombesin derivatives labeled with radiometals such as ^55/57Co, ⁶⁴Cu, ⁶⁸Ga, ^99mTc, and ¹⁷⁷Lu or radiohalogen such as ¹³¹I and ²¹¹At were developed as markers for early detection of tumors and theragnostic tool for cancer treatment. This review focuses on the introduction of bombesin-based radiopharmaceuticals that are studied in pre-clinical or clinical research.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.2 no.2
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• pp.96-102
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• 2016

Apoptosis, a genetically determined process of programmed cell death, is considered a vital component of various processes including normal cell turnover, animal development, and tissue homeostasis. It has a crucial role in many medical disorders and hence the development of non-invasive imaging tool is highly demanded. Recently, we have developed a peptide-based radioactive probe (ApoPep-1) for apoptosis detection. In that work the potential of probe for apoptosis detection was verified, however in vivo stability of radiolabeled peptide was not enough to monitor apoptosis for extended period. In current study, we prepared cyclic ApoPep-1 peptides to improve the stability of origianl linear ApoPep-1 and carried out direct comparison studies in vitro and in vivo. A targeting efficacy of newly synthesized cyclic ApoPep-1 peptide for apoptosis was confirmed in acute myocardial infarct model.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.2
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• pp.153-159
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• 2021

This article provides an efficient ¹⁸F-labeling protocol based on a rapid condensation reaction between 2-cyanobenzothiazole (CBT) and N-terminal cysteine-containing biomolecules. The ¹⁸F-labeled CBT (¹⁸F-1) was prepared by radiofluorination of the tosylated precursor 4 with 18-crown-6/K+/[¹⁸F]F- complex. Using the purified ¹⁸F-1, ¹⁸F-labeled peptide (¹⁸F-7) and protein (¹⁸F-8) could be synthesized efficiently under mild conditions. This strategy would provide a convenient approach for rapid and site-specific ¹⁸F-labeling of various peptides and proteins for in vivo imaging and biomedical applications.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.2 no.2
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• pp.63-68
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• 2016

Peptides have been developed for in vivo imaging probes against to the specific biomarker in the biological process of living systems. Peptide based imaging probes have been applied to identify and detect their active sites using imaging modalities, such as PET, SPECT and MRI. Especially, tumor receptor imaging with the peptides has been widely used to specific tumor detection. This review discusses the targeting peptides that have been successfully characterized for tumor diagnosis by receptor imaging.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.6 no.2
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• pp.92-101
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• 2020

The cyclic Arg-Gly-Asp (cRGD) peptide is well-known as a binding molecule to the integrin α_vβ₃ receptor which is highly expressed on activated endothelial cells and new blood vessels in tumors. Although numerous results have been reported by the usage of cRGD peptide-based ligands for cancer diagnosis and therapy, the distinct mechanisms, and functions of cRGD-integrin binding to cancer cells are still being investigated. In this study, we evaluated the internalization efficacy of different types of cRGD peptides (monomer, dimer and tetramer form) in integrin α_vβ₃ overexpressing cancer cells. Western blot and flow cytometric analysis showed U87MG expresses highly integrin α_vβ₃, whereas CT-26 does not show integrin α_vβ₃ expression. Cytotoxicity assay indicated that all cRGD peptides (0-200 µM) had at least 70-80% of viability in U87MG cells. Fluorescence images showed cRGD dimer peptides have the highest cellular internalization compare to cRGD monomer and cRGD tetramer peptides. Additionally, transmission electron microscope results clearly visualized the endocytic internalization of integrin α_vβ₃ receptors and correlated with confocal microscopic results. These results support the rationale for the use of cRGD dimer peptides for imaging, diagnosis, or therapy of integrin α_vβ₃-rich glioblastoma.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.44-51
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• 2017

Herein we report an efficient radiolabeling method based on a rapid condensation reaction between N-terminal cysteine and 2-cyanobenzothiazole (CBT). Radioiodination of 2-cyano-6-hydroxybenzothiazole 2 was carried out using chloramine-T to give $^{125}I$-labeled CBT ([$^{125}I$]1) with a high radiochemical yield ($90{\pm}6%$ isolated yield, n=3) and radiochemical purity (>99%). To evaluate the radiolabeling efficiency of $^{125}I$-labeled CBT, model compounds, L-cysteine and N-terminal cysteine conjugated cRGD peptide were reacted with [$^{125}I$]1 under mild conditions. The radiolabeling reactions rapidly provided the $^{125}I$-labeled products [$^{125}I$]5 and [$^{125}I$]6 with excellent radiochemical yields and radiochemical purity. Therefore, we demonstrate that [$^{125}I$]1 will be a useful prosthetic group for radioactive iodine labeling of N-terminal cysteine bearing biomolecules.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.2
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• pp.58-65
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• 2006

Since the development of sophisticated molecular carriers such as octereotides for peptide receptor targeting and monoclonal antibodies against various antigens associated with specific tumor types, radionuclide therapy (RNT) employing open sources of therapeutic agents is promising modality for treatment of tumors. furthermore, the emerging of new therapeutic regimes and new approaches for tumor treatment using radionuclide are anticipated in near future. In targeted radiotherapy using peptides and other receptor based tarrier molecules, the use of radionuclide with high specific activity in formulating the radiopharmaceutical is essential in order to deliver sufficient number of radionuclides to the target site without saturating the target. In order to develop effective radiopharmaceuticals for therapeutic applications, it is crucial to carefully consider the choice of appropriate radionuclides as well as the tarrier moiety with suitable pharmacokinetic properties that could result in good in vivo localization and desired excretion. Up to date, only a limited number of radionuclides have been applied in radiopharmaceutical development due to the constraints in compliance with their physical half-life, decay characteristics, cost and availability in therapeutic applications. In this review article, we intend to provide with the improved understanding of the factors of importance of appropriate radionuclide for therapy with respect to their physical properties and therapeutic applications.