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Kanellopoulos P, Nock BA, Rouchota M, Loudos G, Krenning EP, Maina T. Side-Chain Modified [ 99mTc]Tc-DT1 Mimics: A Comparative Study in NTS 1R-Positive Models. Int J Mol Sci 2023; 24:15541. [PMID: 37958525 PMCID: PMC10647616 DOI: 10.3390/ijms242115541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Radiolabeled neurotensin analogs have been developed as candidates for theranostic use against neurotensin subtype 1 receptor (NTS1R)-expressing cancer. However, their fast degradation by two major peptidases, neprilysin (NEP) and angiotensin-converting enzyme (ACE), has hitherto limited clinical success. We have recently shown that palmitoylation at the ε-amine of Lys7 in [99mTc]Tc-[Lys7]DT1 (DT1, N4-Gly-Arg-Arg-Pro-Tyr-Ile-Leu-OH, N4 = 6-(carboxy)-1,4,8,11-tetraazaundecane) led to the fully stabilized [99mTc]Tc-DT9 analog, displaying high uptake in human pancreatic cancer AsPC-1 xenografts but unfavorable pharmacokinetics in mice. Aiming to improve the in vivo stability of [99mTc]Tc-DT1 without compromising pharmacokinetics, we now introduce three new [99mTc]Tc-DT1 mimics, carrying different pendant groups at the ε-amine of Lys7: MPBA (4-(4-methylphenyl)butyric acid)-[99mTc]Tc-DT10; MPBA via a PEG4-linker-[99mTc]Tc-DT11; or a hydrophilic PEG6 chain-[99mTc]Tc-DT12. The impact of these modifications on receptor affinity and internalization was studied in NTS1R-positive cells. The effects on stability and AsPC-1 tumor uptake were assessed in mice without or during NEP/ACE inhibition. Unlike [99mTc]Tc-DT10, the longer-chain modified [99mTc]Tc-DT11 and [99mTc]Tc-DT12 were significantly stabilized in vivo, resulting in markedly improved tumor uptake compared to [99mTc]Tc-DT1. [99mTc]Tc-DT11 was found to achieve the highest AsPC-1 tumor values and good pharmacokinetics, either without or during NEP inhibition, qualifying for further validation in patients with NTS1R-positive tumors using SPECT/CT.
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Affiliation(s)
| | - Berthold A. Nock
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (B.A.N.)
| | - Maritina Rouchota
- BIOEMTECH, Lefkippos Attica Technology Park NCSR “Demokritos”, 15310 Athens, Greece; (M.R.); (G.L.)
| | - George Loudos
- BIOEMTECH, Lefkippos Attica Technology Park NCSR “Demokritos”, 15310 Athens, Greece; (M.R.); (G.L.)
| | - Eric P. Krenning
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
| | - Theodosia Maina
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (B.A.N.)
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Kanellopoulos P, Nock BA, Krenning EP, Maina T. Toward Stability Enhancement of NTS 1R-Targeted Radioligands: Structural Interventions on [ 99mTc]Tc-DT1. Pharmaceutics 2023; 15:2092. [PMID: 37631306 PMCID: PMC10459693 DOI: 10.3390/pharmaceutics15082092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/04/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
The neurotensin subtype 1 receptor (NTS1R) is overexpressed in a number of human tumors, thereby representing a valid target for cancer theranostics with radiolabeled neurotensin (NT) analogs like [99mTc]Tc-DT1 (DT1, N4-Gly7-NT(8-13)). Thus far, the fast degradation of intravenously injected NT-radioligands by neprilysin (NEP) and angiotensin-converting enzyme (ACE) has compromised their clinical applicability. Aiming at metabolic stability enhancements, we herein introduce (i) DT7 ([DAsn14]DT1) and (ii) DT8 ([β-Homoleucine13]DT1), modified at the C-terminus, along with (iii) DT9 ([(palmitoyl)Lys7]DT1), carrying an albumin-binding domain (ABD) at Lys7. The biological profiles of the new [99mTc]Tc-radioligands were compared with [99mTc]Tc-DT1, using NTS1R-expressing AsPC-1 cells and mice models without or during NEP/ACE inhibition. The radioligands showed enhanced in vivo stability vs. [99mTc]Tc-DT1, with [99mTc]Tc-DT9 displaying full resistance to both peptidases. Furthermore, [99mTc]Tc-DT9 achieved the highest cell internalization and tumor uptake even without NEP/ACE-inhibition but with unfavorably high background radioactivity levels. Hence, unlike C-terminal modification, the introduction of a pendant ABD group in the linker turned out to be the most promising strategy toward metabolic stability, cell uptake, and tumor accumulation of [99mTc]Tc-DT1 mimics. To improve the observed suboptimal pharmacokinetics of [99mTc]Tc-DT9, the replacement of palmitoyl on Lys7 by other ABD groups is currently being pursued.
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Affiliation(s)
| | - Berthold A. Nock
- Molecular Radiopharmacy, INRaSTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (B.A.N.)
| | - Eric P. Krenning
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
| | - Theodosia Maina
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
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Maina T, Nock BA. Peptide radiopharmaceuticals for targeted diagnosis & therapy of human tumors. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00078-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Abstract
Introduction: Neurotensin is a gut-brain peptide hormone, a 13 amino acid neuropeptide found in the central nervous system and in the GI tract. The neurotensinergic system is implicated in various physiological and pathological processes related to neuropsychiatric and metabolic machineries, cancer growth, food, and drug intake. NT mediates its functions through its two G protein-coupled receptors: neurotensin receptor 1 (NTS1/NTSR1) and neurotensin receptor 2 (NTS2/NTSR2). Over the past decade, the role of NTS3/NTSR3/sortilin has also gained importance in human pathologies. Several approaches have appeared dealing with the discovery of compounds able to modulate the functions of this neuropeptide through its receptors for therapeutic gain.Areas covered: The article provides an overview of over four decades of research and details the drug discovery approaches and patented strategies targeting NTSR in the past decade.Expert opinion: Neurotensin is an important neurotransmitter that enables crosstalk with various neurotransmitter and neuroendocrine systems. While significant efforts have been made that have led to selective agonists and antagonists with promising in vitro and in vivo activities, the therapeutic potential of compounds targeting the neurotensinergic system is still to be fully harnessed for successful clinical translation of compounds for the treatment of several pathologies.
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Affiliation(s)
- Malliga R Iyer
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA
| | - George Kunos
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA
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5
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Kanellopoulos P, Nock BA, Krenning EP, Maina T. Optimizing the Profile of [ 99mTc]Tc-NT(7-13) Tracers in Pancreatic Cancer Models by Means of Protease Inhibitors. Int J Mol Sci 2020; 21:ijms21217926. [PMID: 33114537 PMCID: PMC7663772 DOI: 10.3390/ijms21217926] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 12/17/2022] Open
Abstract
Background: The overexpression of neurotensin subtype 1 receptors (NTS1Rs) in human tumors may be elegantly exploited for directing neurotensin (NT)-based radionuclide carriers specifically to cancer sites for theranostic purposes. We have recently shown that [99mTc]Tc–DT1 ([99mTc]Tc–[N4–Gly7]NT(7–13)) and [99mTc]Tc–DT5 ([99mTc]Tc–[N4–βAla7,Dab9]NT(7–13)) show notably improved uptake in human colon adenocarcinoma WiDr xenografts in mice treated with neprilysin (NEP) inhibitors and/or angiotensin-converting enzyme (ACE) inhibitors compared with untreated controls. Aiming toward translation of this promising approach in NTS1R-positive pancreatic ductal adenocarcinoma (PDAC) patients, we now report on the impact of registered NEP/ACE inhibitors on the performance of [99mTc]Tc–DT1 and [99mTc]Tc–DT5 in pancreatic cancer models. Methods: The cellular uptake of [99mTc]Tc–DT1 and [99mTc]Tc–DT5 was tested in a panel of pancreatic cell lines, and their stability was assessed in mice treated or not treated with Entresto, lisinopril, or their combinations. Biodistribution was conducted in severe combined immunodeficiency (SCID) mice bearing pancreatic AsPC-1 xenografts. Results: The Entresto + lisinopril combination maximized the metabolic stability of the fast-internalizing [99mTc]Tc–DT1 in mice, resulting in notably enhanced tumor uptake (7.05 ± 0.80% injected activity (IA)/g vs. 1.25 ± 0.80% IA/g in non-treated controls at 4 h post-injection; p < 0.0001). Conclusions: This study has shown the feasibility of optimizing the uptake of [99mTc]Tc–DT1 in pancreatic cancer models with the aid of clinically established NEP/ACE inhibitors, in favor of clinical translation prospects.
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Affiliation(s)
- Panagiotis Kanellopoulos
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece;
- Molecular Pharmacology, School of Medicine, University of Crete, Heraklion, 70013 Crete, Greece
- Correspondence: (P.K.); (T.M.); Tel.: +30-210-650-3891 (P.K.); +30-210-650-3908 (T.M.)
| | - Berthold A. Nock
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece;
| | - Eric P. Krenning
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece;
- Correspondence: (P.K.); (T.M.); Tel.: +30-210-650-3891 (P.K.); +30-210-650-3908 (T.M.)
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Kanellopoulos P, Kaloudi A, de Jong M, Krenning EP, Nock BA, Maina T. Key-Protease Inhibition Regimens Promote Tumor Targeting of Neurotensin Radioligands. Pharmaceutics 2020; 12:pharmaceutics12060528. [PMID: 32526874 PMCID: PMC7356968 DOI: 10.3390/pharmaceutics12060528] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/05/2020] [Accepted: 06/06/2020] [Indexed: 02/06/2023] Open
Abstract
Neurotensin subtype 1 receptors (NTS1R) represent attractive molecular targets for directing radiolabeled neurotensin (NT) analogs to tumor lesions for diagnostic and therapeutic purposes. This approach has been largely undermined by the rapid in vivo degradation of linear NT-based radioligands. Herein, we aim to increase the tumor targeting of three 99mTc-labeled NT analogs by the in-situ inhibition of two key proteases involved in their catabolism. DT1 ([N4-Gly7]NT(7-13)), DT5 ([N4-βAla7,Dab9]NT(7-13)), and DT6 ([N4-βAla7,Dab9,Tle12]]NT(7-13)) were labeled with 99mTc. Their profiles were investigated in NTS1R-positive colon adenocarcinoma WiDr cells and mice treated or not with the neprilysin (NEP)-inhibitor phosphoramidon (PA) and/or the angiotensin converting enzyme (ACE)-inhibitor lisinopril (Lis). Structural modifications led to the partial stabilization of 99mTc-DT6 in peripheral mice blood (55.1 ± 3.9% intact), whereas 99mTc-DT1 and 99mTc-DT5 were totally degraded within 5 min. Coinjection of PA and/or Lis significantly stabilized all three analogs, leading to a remarkable enhancement of tumor uptake for 99mTc-DT1 and 99mTc-DT5, but was less effective in the case of poorly internalizing 99mTc-DT6. In conclusion, NEP and/or ACE inhibition represents a powerful tool to improve tumor targeting and the overall pharmacokinetics of NT-based radioligands, and warrants further validation in the field of NTS1R-targeted tumor imaging and therapy.
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Affiliation(s)
- Panagiotis Kanellopoulos
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (A.K.); (B.A.N.)
- Molecular Pharmacology, School of Medicine, University of Crete, 70013 Heraklion, Greece
| | - Aikaterini Kaloudi
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (A.K.); (B.A.N.)
| | - Marion de Jong
- Department of Radiology & Nuclear Medicine Erasmus MC, 3015 CN Rotterdam, The Netherlands;
| | - Eric P. Krenning
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
| | - Berthold A. Nock
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (A.K.); (B.A.N.)
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece; (P.K.); (A.K.); (B.A.N.)
- Correspondence: ; Tel.: +30-210-650-3908
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7
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Structural modifications of amino acid sequences of radiolabeled peptides for targeted tumor imaging. Bioorg Chem 2020; 99:103802. [DOI: 10.1016/j.bioorg.2020.103802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/19/2020] [Accepted: 03/25/2020] [Indexed: 12/18/2022]
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Abstract
Single photon emission computed tomography (SPECT) is the state-of-the-art imaging modality in nuclear medicine despite the fact that only a few new SPECT tracers have become available in the past 20 years. Critical for the future success of SPECT is the design of new and specific tracers for the detection, localization, and staging of a disease and for monitoring therapy. The utility of SPECT imaging to address oncologic questions is dependent on radiotracers that ideally exhibit excellent tissue penetration, high affinity to the tumor-associated target structure, specific uptake and retention in the malignant lesions, and rapid clearance from non-targeted tissues and organs. In general, a target-specific SPECT radiopharmaceutical can be divided into two main parts: a targeting biomolecule (e.g., peptide, antibody fragment) and a γ-radiation-emitting radionuclide (e.g., 99mTc, 123I). If radiometals are used as the radiation source, a bifunctional chelator is needed to link the radioisotope to the targeting entity. In a rational SPECT tracer design, these single components have to be critically evaluated in order to achieve a balance among the demands for adequate target binding, and a rapid clearance of the radiotracer. The focus of this chapter is to depict recent developments of tumor-targeted SPECT radiotracers for imaging of cancer diseases. Possibilities for optimization of tracer design and potential causes for design failure are discussed and highlighted with selected examples.
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9
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Schindler L, Bernhardt G, Keller M. Modifications at Arg and Ile Give Neurotensin(8-13) Derivatives with High Stability and Retained NTS 1 Receptor Affinity. ACS Med Chem Lett 2019; 10:960-965. [PMID: 31223455 DOI: 10.1021/acsmedchemlett.9b00122] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 05/10/2019] [Indexed: 12/16/2022] Open
Abstract
Due to its expression in various malignant tumors, the neurotensin receptor 1 (NTS1R) has been suggested and explored as a target for tumor diagnosis and therapy. Animal model-based investigations of various radiolabeled NTS1R ligands derived from the hexapeptide neurotensin(8-13) (NT(8-13)), e.g. 68Ga- and 18F-labeled compounds for PET diagnostics, give rise to optimize such radiotracers for clinical use. As NT(8-13) is rapidly degraded in vivo; structural modifications are required in terms of increased metabolic stability. In this study, the stabilization of the peptide backbone of NT(8-13) against enzymatic degradation was systematically explored by performing an N-methyl scan, replacing Ile12 by tert-butylglycine12 (Tle12) and N-terminal acylation. N-Methylation of either arginine, Arg8, or Arg9, combined with the Ile12/Tle12 exchange, proved to be most favorable with respect to NTS1R affinity (K i < 2 nM) and stability in human plasma (t 1/2 > 48 h), a valuable result regarding the development of radiopharmaceuticals derived from NT(8-13).
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Affiliation(s)
- Lisa Schindler
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Günther Bernhardt
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | - Max Keller
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
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10
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Rezazadeh F, Sadeghzadeh N. Tumor targeting with 99m Tc radiolabeled peptides: Clinical application and recent development. Chem Biol Drug Des 2018; 93:205-221. [PMID: 30299570 DOI: 10.1111/cbdd.13413] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/19/2018] [Accepted: 09/23/2018] [Indexed: 01/16/2023]
Abstract
Targeting overexpressed receptors on the cancer cells with radiolabeled peptides has become very important in nuclear oncology in the recent years. Peptides are small and have easy preparation and easy radiolabeling protocol with no side-effect and toxicity. These properties made them a valuable tool for tumor targeting. Based on the successful imaging of neuroendocrine tumors with 111 In-octreotide, other receptor-targeting peptides such as bombesin (BBN), cholecystokinin/gastrin analogues, neurotensin analogues, glucagon-like peptide-1, and RGD peptides are currently under development or undergoing clinical trials. The most frequently used radionuclides for tumor imaging are 99m Tc and 111 In for single-photon emission computed tomography and 68 Ga and 18 F for positron emission tomography imaging. This review presents some of the 99m Tc-labeled peptides, with regard to their potential for radionuclide imaging of tumors in clinical and preclinical application.
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Affiliation(s)
- Farzaneh Rezazadeh
- Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.,Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran
| | - Nourollah Sadeghzadeh
- Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
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11
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Maschauer S, Prante O. Radiopharmaceuticals for imaging and endoradiotherapy of neurotensin receptor-positive tumors. J Labelled Comp Radiopharm 2018; 61:309-325. [DOI: 10.1002/jlcr.3581] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 10/13/2017] [Accepted: 10/24/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Simone Maschauer
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine; Friedrich Alexander University Erlangen-Nürnberg (FAU); Erlangen Germany
| | - Olaf Prante
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine; Friedrich Alexander University Erlangen-Nürnberg (FAU); Erlangen Germany
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12
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Emrarian I, Sadeghzadeh N, Abedi SM, Abediankenari S. New neurotensin analogue radiolabeled by 99m-technetium as a potential agent for tumor identification. Chem Biol Drug Des 2017; 91:304-313. [DOI: 10.1111/cbdd.13082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/24/2017] [Accepted: 07/27/2017] [Indexed: 01/20/2023]
Affiliation(s)
- Iman Emrarian
- Department of Radiopharmacy; Faculty of Pharmacy; Mazandaran University of Medical Sciences; Sari Iran
| | - Nourollah Sadeghzadeh
- Department of Radiopharmacy; Faculty of Pharmacy; Mazandaran University of Medical Sciences; Sari Iran
| | - Seyed Mohammad Abedi
- Department of Radiology; Faculty of Medicine; Mazandaran University of Medical Sciences; Sari Iran
| | - Saeid Abediankenari
- Immunogenetics Research Center; Mazandaran University of Medical Sciences; Sari Iran
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13
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Charron CL, Hickey JL, Nsiama TK, Cruickshank DR, Turnbull WL, Luyt LG. Molecular imaging probes derived from natural peptides. Nat Prod Rep 2017; 33:761-800. [PMID: 26911790 DOI: 10.1039/c5np00083a] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Covering: up to the end of 2015.Peptides are naturally occurring compounds that play an important role in all living systems and are responsible for a range of essential functions. Peptide receptors have been implicated in disease states such as oncology, metabolic disorders and cardiovascular disease. Therefore, natural peptides have been exploited as diagnostic and therapeutic agents due to the unique target specificity for their endogenous receptors. This review discusses a variety of natural peptides highlighting their discovery, endogenous receptors, as well as their derivatization to create molecular imaging agents, with an emphasis on the design of radiolabelled peptides. This review also highlights methods for discovering new and novel peptides when knowledge of specific targets and endogenous ligands are not available.
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Affiliation(s)
- C L Charron
- Department of Chemistry, The University of Western Ontario, London, Canada.
| | - J L Hickey
- Department of Chemistry, The University of Western Ontario, London, Canada.
| | - T K Nsiama
- London Regional Cancer Program, Lawson Health Research Institute, London, Canada
| | - D R Cruickshank
- Department of Chemistry, The University of Western Ontario, London, Canada.
| | - W L Turnbull
- Department of Chemistry, The University of Western Ontario, London, Canada.
| | - L G Luyt
- Department of Chemistry, The University of Western Ontario, London, Canada. and Departments of Oncology and Medical Imaging, The University of Western Ontario, London, Canada and London Regional Cancer Program, Lawson Health Research Institute, London, Canada
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14
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Jia Y, Zhang W, Fan W, Brusnahan S, Garrison J. Investigation of the Biological Impact of Charge Distribution on a NTR1-Targeted Peptide. Bioconjug Chem 2016; 27:2658-2668. [PMID: 27661393 DOI: 10.1021/acs.bioconjchem.6b00418] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The neurotensin receptor 1 (NTR1) has been shown to be a promising target, due to its increased level of expression relative to normal tissue, for pancreatic and colon cancers. This has prompted the development of a variety of NTR1-targeted radiopharmaceuticals, based on the neurotensin (NT) peptide, for diagnostic and radiotherapeutic applications. A major obstacle for the clinical translation of NTR1-targeted radiotherapeutics would likely be nephrotoxicity due to the high levels of kidney retention. It is well-known that for many peptide-based agents, renal uptake is influenced by the overall molecular charge. Herein, we investigated the effect of charge distribution on receptor binding and kidney retention. Using the [(N-α-Me)Arg8,Dmt11,Tle12]NT(6-13) targeting vector, three peptides (177Lu-K2, 177Lu-K4, and 177Lu-K6), with the Lys moved closer (K6) or further away (K2) from the pharmacophore, were synthesized. In vitro competitive binding, internalization and efflux, and confocal microscopy studies were conducted using the NTR1-positive HT-29, human colon cancer cell line. The 177/natLu-K6 demonstrated the highest binding affinity (21.8 ± 1.2 nM) and the highest level of internalization (4.06% ± 0.20% of the total added amount). In vivo biodistribution, autoradiography, and metabolic studies of 177Lu-radiolabeled K2, K4, and K6 were examined using CF-1 mice. 177Lu-K4 and 177Lu-K6 gave the highest levels of in vivo uptake in NTR1-positive tissues, whereas 177Lu-K2 yielded nearly 2-fold higher renal uptake relative to the other radioconjugates. In conclusion, the position of the Lys (positively charged amino acid) influences the receptor binding, internalization, in vivo NTR1-targeting efficacy, and kidney retention profile of the radioconjugates. In addition, we have found that hydrophobicity likely play a role in the unique biodistribution profiles of these agents.
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Affiliation(s)
- Yinnong Jia
- Department of Pharmaceutical Sciences, College of Pharmacy, ‡Center for Drug Delivery and Nanomedicine, §Department of Biochemistry and Molecular Biology, College of Medicine, and ∥Eppley Cancer Center, University of Nebraska Medical Center , Omaha, Nebraska 985830, United States
| | - Wenting Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, ‡Center for Drug Delivery and Nanomedicine, §Department of Biochemistry and Molecular Biology, College of Medicine, and ∥Eppley Cancer Center, University of Nebraska Medical Center , Omaha, Nebraska 985830, United States
| | - Wei Fan
- Department of Pharmaceutical Sciences, College of Pharmacy, ‡Center for Drug Delivery and Nanomedicine, §Department of Biochemistry and Molecular Biology, College of Medicine, and ∥Eppley Cancer Center, University of Nebraska Medical Center , Omaha, Nebraska 985830, United States
| | - Susan Brusnahan
- Department of Pharmaceutical Sciences, College of Pharmacy, ‡Center for Drug Delivery and Nanomedicine, §Department of Biochemistry and Molecular Biology, College of Medicine, and ∥Eppley Cancer Center, University of Nebraska Medical Center , Omaha, Nebraska 985830, United States
| | - Jered Garrison
- Department of Pharmaceutical Sciences, College of Pharmacy, ‡Center for Drug Delivery and Nanomedicine, §Department of Biochemistry and Molecular Biology, College of Medicine, and ∥Eppley Cancer Center, University of Nebraska Medical Center , Omaha, Nebraska 985830, United States
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Maschauer S, Einsiedel J, Hübner H, Gmeiner P, Prante O. 18F- and 68Ga-Labeled Neurotensin Peptides for PET Imaging of Neurotensin Receptor 1. J Med Chem 2016; 59:6480-92. [DOI: 10.1021/acs.jmedchem.6b00675] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Simone Maschauer
- Department
of Nuclear Medicine, Molecular Imaging and Radiochemistry, Friedrich-Alexander University (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
| | - Jürgen Einsiedel
- Department
of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich-Alexander University (FAU), Schuhstraße 19, 91052 Erlangen, Germany
| | - Harald Hübner
- Department
of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich-Alexander University (FAU), Schuhstraße 19, 91052 Erlangen, Germany
| | - Peter Gmeiner
- Department
of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich-Alexander University (FAU), Schuhstraße 19, 91052 Erlangen, Germany
| | - Olaf Prante
- Department
of Nuclear Medicine, Molecular Imaging and Radiochemistry, Friedrich-Alexander University (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
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Jia Y, Shi W, Zhou Z, Wagh NK, Fan W, Brusnahan SK, Garrison JC. Evaluation of DOTA-chelated neurotensin analogs with spacer-enhanced biological performance for neurotensin-receptor-1-positive tumor targeting. Nucl Med Biol 2015; 42:816-23. [PMID: 26302836 DOI: 10.1016/j.nucmedbio.2015.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/25/2015] [Accepted: 07/21/2015] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Neurotensin receptor 1 (NTR1) is overexpressed in many cancer types. Neurotensin (NT), a 13 amino acid peptide, is the native ligand for NTR1 and exhibits high (nM) affinity to the receptor. Many laboratories have been investigating the development of diagnostic and therapeutic radiopharmaceuticals for NTR1-positive cancers based on the NT peptide. To improve the biological performance for targeting NTR1, we proposed NT analogs with a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelation system and different lengths of spacers. METHODS We synthesized four NTR1-targeted conjugates with spacer lengths from 0 to 9 atoms (null (N0), β-Ala-OH (N1), 5-Ava-OH (N2), and 8-Aoc-OH (N3)) between the DOTA and the pharmacophore. In vitro competitive binding, internalization and efflux studies were performed on all four NT analogs. Based on these findings, metabolism studies were carried out on our best performing conjugate, (177)Lu-N1. Lastly, in vivo biodistribution and SPECT/CT imaging studies were performed using (177)Lu-N1 in an HT-29 xenograft mouse model. RESULTS As shown in the competitive binding assays, the NT analogs with different spacers (N1, N2 and N3) exhibited lower IC50 values than the NT analog without a spacer (N0). Furthermore, N1 revealed higher retention in HT-29 cells with more rapid internalization and slower efflux than the other NT analogs. In vivo biodistribution and SPECT/CT imaging studies of (177)Lu-N1 demonstrated excellent accumulation (3.1 ± 0.4%ID/g) in the NTR1-positive tumors at 4h post-administration. CONCLUSIONS The DOTA chelation system demonstrated some modest steric inhibition of the pharmacophore. However, the insertion of a 4-atom hydrocarbon spacer group restored optimal binding affinity of the analog. The in vivo assays indicated that (177)Lu-N1 could be used for imaging and radiotherapy of NTR1-positive tumors.
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Affiliation(s)
- Yinnong Jia
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830
| | - Wen Shi
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830
| | - Zhengyuan Zhou
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830
| | - Nilesh K Wagh
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830
| | - Wei Fan
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830
| | - Susan K Brusnahan
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830
| | - Jered C Garrison
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 985830 Nebraska Medical Center, Omaha, NE, USA, 68198-5830.
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Development of a (99m)Tc-labeled lactam bridge-cyclized alpha-MSH derivative peptide as a possible single photon imaging agent for melanoma tumors. Ann Nucl Med 2015; 29:709-20. [PMID: 26152564 DOI: 10.1007/s12149-015-0998-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 06/17/2015] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Melanocortin-1 (MC1) receptor is an attractive melanoma-specific target which has been used for melanoma imaging and therapy. In this work, a new lactam bridge α-MSH analog was labeled with (99m)Tc via HYNIC and EDDA/tricine as coligands including gamma aminobutyric acid (GABA) as a three carbon chain spacer between HYNIC and the N-terminus of the cyclic peptide. Also, stability in human serum, receptor bound internalization, in vivo tumor uptake, and tissue biodistribution were thoroughly investigated. METHODS HYNIC-GABA-Nle-CycMSHhept was synthesized using a standard Fmoc strategy. Labeling was performed at 95 °C and analysis involved instant thin layer chromatography and high performance liquid chromatography methods. The receptor bound internalization rate was studied in MC1 receptor expressing B16/F10 cells. Biodistribution of radiopeptide was studied in nude mice bearing B16/F10 tumor. RESULTS Labeling yield of >98 % (n = 3) was obtained corresponding to a specific activity of 81 MBq/nmol. Peptide conjugate showed efficient stability in the presence of human serum. The radioligand showed specific internalization into B16/F10 cells (12.45 ± 1.1 % at 4 h). In biodistribution studies, a receptor-specific uptake was observed in MC1 receptor-positive organs so that after 2 h the uptake in mouse tumor was 5.10 ± 0.08 % ID/g, while low accumulation in the kidney uptake was observed (4.58 ± 0.68 % ID/g at 2 h after injection). CONCLUSIONS The obtained results show that the presented new designed labeled peptide conjugate may be a suitable candidate for diagnosis of malignant tumors.
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Oliveira EA, Faintuch BL. Radiolabeling and biological evaluation of the GX1 and RGD-GX1 peptide sequence for angiogenesis targeting. Nucl Med Biol 2014; 42:123-30. [PMID: 25311749 DOI: 10.1016/j.nucmedbio.2014.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/03/2014] [Accepted: 09/15/2014] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Aiming to develop a novel (99m)Tc-labeled imaging agent, for angiogenesis and tumor receptors, two peptides obtained from phage display library, namely GX1 and the heterodimer RGD-GX1, were synthesized in a cyclic conformation. They were radiolabeled with (99m)Tc, employing the HYNIC chelator, for radiochemical evaluation and biological properties. METHODS Radiolabeling, radiochemical control, plasma protein binding, and partition coefficient were assessed for both radioconjugates. Biodistribution in healthy Balb/c mice was carried out, in order to evaluate the biological behaviour of the radiocomplexes. RESULTS The conjugates displayed a rather similar pharmacokinetic profile. They were prepared with high radiochemical purity (>96%), and both were hydrophilic (log P of -2.25 and -2.51 respectively). Preferential renal excretion was observed. Kidney uptake (42.31±5.35 %ID/g) for (99m)Tc-HYNIC-E-[c(RGDfk)-c(GX1)], 1h post-injection was about three times higher than the uptake of (99m)Tc-HYNIC-PEG4-c(GX1) (11.92±4.77%ID/g). Total blood, bone and muscle values revealed a slightly slower clearance for the RGD-GX1 radiocomplex. CONCLUSION The high radiochemical purity achieved, and the similar in vivo profile observed for both radioconjugates, make them potential candidates for radiopharmaceuticals for tumor imaging. Further investigations of binding affinity, and uptake of GX1 and RGD-GX1 peptides in tumor models, are warranted.
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Affiliation(s)
- E A Oliveira
- Radiopharmacy, Institute of Energy and Nuclear Research, Sao Paulo, SP, Brazil, Av. Prof. Lineu Prestes, 2242 05508-000 São Paulo, SP, Brazil.
| | - B L Faintuch
- Radiopharmacy, Institute of Energy and Nuclear Research, Sao Paulo, SP, Brazil, Av. Prof. Lineu Prestes, 2242 05508-000 São Paulo, SP, Brazil
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Maschauer S, Ruckdeschel T, Tripal P, Haubner R, Einsiedel J, Hübner H, Gmeiner P, Kuwert T, Prante O. In vivo monitoring of the antiangiogenic effect of neurotensin receptor-mediated radiotherapy by small-animal positron emission tomography: a pilot study. Pharmaceuticals (Basel) 2014; 7:464-81. [PMID: 24743103 PMCID: PMC4014703 DOI: 10.3390/ph7040464] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/04/2014] [Accepted: 04/10/2014] [Indexed: 12/22/2022] Open
Abstract
The neurotensin receptor (NTS1) has emerged as an interesting target for molecular imaging and radiotherapy of NTS-positive tumors due to the overexpression in a range of tumors. The aim of this study was to develop a 177Lu-labeled NTS1 radioligand, its application for radiotherapy in a preclinical model and the imaging of therapy success by small-animal positron emission tomography (µPET) using [68Ga]DOTA-RGD as a specific tracer for imaging angiogenesis. The 177Lu-labeled peptide was subjected to studies on HT29-tumor-bearing nude mice in vivo, defining four groups of animals (single dose, two fractionated doses, four fractionated doses and sham-treated animals). Body weight and tumor diameters were determined three times per week. Up to day 28 after treatment, µPET studies were performed with [68Ga]DOTA-RGD. At days 7–10 after treatment with four fractionated doses of 11–14 MBq (each at days 0, 3, 6 and 10), the tumor growth was slightly decreased in comparison with untreated animals. Using a single high dose of 51 MBq, a significantly decreased tumor diameter of about 50% was observed with the beginning of treatment. Our preliminary PET imaging data suggested decreased tumor uptake values of [68Ga]DOTA-RGD in treated animals compared to controls at day 7 after treatment. This pilot study suggests that early PET imaging with [68Ga]DOTA-RGD in radiotherapy studies to monitor integrin expression could be a promising tool to predict therapy success in vivo. Further successive PET experiments are needed to confirm the significance and predictive value of RGD-PET for NTS-mediated radiotherapy.
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Affiliation(s)
- Simone Maschauer
- Department of Nuclear Medicine, Laboratory of Molecular Imaging and Radiochemistry, Friedrich Alexander University, Schwabachanlage 6, 91054 Erlangen, Germany.
| | - Tina Ruckdeschel
- Department of Nuclear Medicine, Laboratory of Molecular Imaging and Radiochemistry, Friedrich Alexander University, Schwabachanlage 6, 91054 Erlangen, Germany.
| | - Philipp Tripal
- Department of Nuclear Medicine, Laboratory of Molecular Imaging and Radiochemistry, Friedrich Alexander University, Schwabachanlage 6, 91054 Erlangen, Germany.
| | - Roland Haubner
- Department of Nuclear Medicine, Innsbruck Medical University, Anichstr. 35, 6020 Innsbruck, Austria.
| | - Jürgen Einsiedel
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany.
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany.
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany.
| | - Torsten Kuwert
- Department of Nuclear Medicine, Laboratory of Molecular Imaging and Radiochemistry, Friedrich Alexander University, Schwabachanlage 6, 91054 Erlangen, Germany.
| | - Olaf Prante
- Department of Nuclear Medicine, Laboratory of Molecular Imaging and Radiochemistry, Friedrich Alexander University, Schwabachanlage 6, 91054 Erlangen, Germany.
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Erfani M, Zarrabi Ahrabi N, Shafiei M, Shirmardi SP. A (99m) Tc-tricine-HYNIC-labeled peptide targeting the neurotensin receptor for single-photon imaging in malignant tumors. J Labelled Comp Radiopharm 2014; 57:125-31. [PMID: 24395489 DOI: 10.1002/jlcr.3176] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/19/2013] [Accepted: 11/27/2013] [Indexed: 11/06/2022]
Abstract
In this study, a new neurotensin (NT) analog was labeled with (99m) Tc via HYNIC chelator and tricine as coligand and investigated further. An NT (7-13) analog was prepared, and labeling with (99m) Tc was performed. The internalization rate and biodistribution of radiopeptide were studied in HT-29 cells and nude mice bearing tumor, respectively. Radiolabeling with (99m) Tc was performed at high specific activities (54 MBq/nmol) with an acceptable labeling yield (>95%). In vitro cell line studies showed a specific internalization uptake up to 13.23 ± 0.45% during 4 h which was blocked in the presence of excess cold peptide to 0.83 ± 0.15%. In biodistribution studies, uptake was observed in NT receptor-positive organs so that after 1 h the uptakes in mouse intestine and tumor were 1.23 ± 0.16% ID/g and 1.12 ± 0.11% ID/g, respectively. In animals co-injected with excess cold peptide, reduction uptake in tumor and intestines were 73% (1.10% vs. 0.29% ID/g at 4 h) and 61% (1.22% vs. 0.47% ID/g at 4 h) respectively. Predominant renal excretion pathway with a highest accumulation of activity in bladder was observed for this radiopeptide. This radiolabeled peptide could be a candidate for detection of NT positive tumors.
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Affiliation(s)
- Mostafa Erfani
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Atomic Energy Organization of Iran (AEOI), PO Box: 11365-3486, end of Karegar Ave., Tehran, Iran
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Ahrabi NZ, Erfani M, Parivar K, Beiki D, Jalilian AR. Preparation and evaluation of a new neurotensin analog labeled with 99mTc for targeted imaging of neurotensin receptor positive tumors. J Radioanal Nucl Chem 2013. [DOI: 10.1007/s10967-013-2795-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Single photon emission computed tomography (SPECT) is the state-of-the-art imaging modality in nuclear medicine despite the fact that only a few new SPECT tracers have become available in the past 20 years. Critical for the future success of SPECT is the design of new and specific tracers for the detection, localization, and staging of a disease and for monitoring therapy. The utility of SPECT imaging to address oncologic questions is dependent on radiotracers that ideally exhibit excellent tissue penetration, high affinity to the tumor-associated target structure, specific uptake and retention in the malignant lesions, and rapid clearance from non-targeted tissues and organs. In general, a target-specific SPECT radiopharmaceutical can be divided into two main parts: a targeting biomolecule (e.g. peptide, antibody fragment) and a γ-radiation emitting radionuclide (e.g. (99m)Tc, (123)I). If radiometals are used as the radiation source, a bifunctional chelator is needed to link the radioisotope to the targeting entity. In a rational SPECT tracer design these single components have to be critically evaluated in order to achieve a balance among the demands for adequate target binding, and a rapid clearance of the radiotracer. The focus of this chapter is to depict recent developments of tumor-targeted SPECT radiotracers for imaging of cancer diseases. Possibilities for optimization of tracer design and potential causes for design failure are discussed and highlighted with selected examples.
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Affiliation(s)
- Cristina Müller
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, Villigen-PSI, Switzerland.
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Fani M, Maecke HR, Okarvi SM. Radiolabeled peptides: valuable tools for the detection and treatment of cancer. Am J Cancer Res 2012; 2:481-501. [PMID: 22737187 PMCID: PMC3364555 DOI: 10.7150/thno.4024] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/31/2012] [Indexed: 12/17/2022] Open
Abstract
Human cancer cells overexpress many peptide receptors as molecular targets. Radiolabeled peptides that bind with high affinity and specificity to the receptors on tumor cells hold great potential for both diagnostic imaging and targeted radionuclide therapy. The advantage of solid-phase peptide synthesis, the availability of different chelating agents and prosthetic groups and bioconjugation techniques permit the facile preparation of a wide variety of peptide-based targeting molecules with diverse biological and tumor targeting properties. Some of these peptides, including somatostatin, bombesin, vasoactive intestinal peptide, gastrin, neurotensin, exendin and RGD are currently under investigation. It is anticipated that in the near future many of these peptides may find applications in nuclear oncology. This article presents recent developments in the field of small peptides, and their applications in the diagnosis and treatment of cancer.
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Gabriel M, Decristoforo C, Wöll E, Eisterer W, Nock B, Maina T, Moncayo R, Virgolini I. [99mTc]demotensin VI: biodistribution and initial clinical results in tumor patients of a pilot/phase I study. Cancer Biother Radiopharm 2011; 26:557-63. [PMID: 21883013 DOI: 10.1089/cbr.2010.0952] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Neurotensin subtype 1 receptor overexpression is found in a variety of human tumors. The aim of this pilot/phase I study was to assess the safety profile, pharmacokinetics, and imaging characteristics of (99m)Tc-Demotensin VI in tumor patients. METHODS Scintigraphy with (99m)Tc-Demotensin VI was performed in 14 patients (2 female and 12 male) with advanced tumor stages. The diagnoses were pancreatic adenocarcinoma (n=4), small cell lung cancer (SCLC) (n=4), non-small cell lung cancer (NSCLC) (n=4), and colon carcinoma (n=2). Patients were injected with 500-550 MBq (99m)Tc-Demotensin VI. Blood samples were taken at various time points and urine was also collected up to 24 hours post-injection (p.i.) Planar images were acquired at 15-30 minutes, 1-2 hours, 4 hours, and 24 hours p.i. with additional SPECT imaging at 4 hours. RESULTS Radiochemical purity always exceeded 95% up to 4 hours. Urinary and blood excretion was rapid with 5.05% ID (mean: n=5) in plasma after 4 hours. No side effects were observed after injection of (99m)Tc-Demotensin VI. Focal tracer accumulation was observed in 3 patients with brain metastases due to NSCLC, although specificity of this uptake could not be proven. Further, no tumor-related findings were observed. Although stability tests in human plasma revealed that (99m)Tc-Demotensin VI remained intact up to 2 hours incubation, ex vivo urine analysis indicated rapid metabolism. CONCLUSION (99m)Tc-Demotensin VI was well tolerated by patients and showed favorable pharmacokinetics; however, tumor targeting was limited to brain metastases. Further studies on stability issues and receptor characterization in tumors are warranted to introduce neurotensin receptors (NTSR) imaging into the clinic.
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Affiliation(s)
- Michael Gabriel
- Department of Nuclear Medicine and Endocrinology, General Hospital of Linz, Linz, Austria
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Röhrich A, Bergmann R, Kretzschmann A, Noll S, Steinbach J, Pietzsch J, Stephan H. A novel tetrabranched neurotensin(8-13) cyclam derivative: synthesis, 64Cu-labeling and biological evaluation. J Inorg Biochem 2011; 105:821-32. [PMID: 21497581 DOI: 10.1016/j.jinorgbio.2011.02.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/21/2011] [Accepted: 02/21/2011] [Indexed: 12/11/2022]
Abstract
New macrocyclic 1,4,8,11-tetraazacyclotetradecane (cyclam) derivatives with 1, 2 and 4 neurotensin(8-13) units 4, 5 and 7 have been synthesized. Compounds 4 and 5 were prepared by the reaction of non-stabilized neurotensin(8-13) and cyclamtetrapropionic acid 2 using 1-ethyl-3-(3-dimethylaminocarbonyl)carbodiimide-hydrochloride and N-hydroxysulfosuccinimide. The tetrameric compound 7 was synthesized by Michael addition of neurotensin(8-13) acrylamide 6 and cyclam 1. The copper(II) complexation behavior of 4, 5 and 7 was investigated by UV/visible spectrophotometry and shows that the metal center resides inside the N4 chromophore with additional apical interactions established with pendant arms. The novel tetrabranched NT(8-13) cyclam 7 with nanomolar neurotensin receptor 1 binding affinity was efficiently radiolabeled with (64)Cu under mild conditions. (64)Cu⊂7 showed slow transchelation in the presence of a large amount of cyclam as competing ligand, while it completely remains intact in the presence of EDTA. The in vivo behavior of (64)Cu⊂7 was studied in rats and mice. The metabolic stability in rodent models was high with a half-life of intact (64)Cu⊂7 in plasma of 34 min in rats and 60 min in the mice, respectively. The binding affinity was high enough to demonstrate in vivo binding of (64)Cu⊂7 to NTR1 overexpressing HT-29 tumor xenotransplants in nude mice. Regarding elimination, (64)Cu⊂7 showed a substantial renal and reticuloendothelial accumulation. On the other hand, metabolization of the compound in vivo with a resulting metabolite-postulated to be the (64)Cu-cyclam-tetraarginine complex-also showed long retention in the circulating blood, preventing a better contrast of tumor imaging.
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Affiliation(s)
- Anika Röhrich
- Institute of Radiopharmacy, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
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Correia JDG, Paulo A, Raposinho PD, Santos I. Radiometallated peptides for molecular imaging and targeted therapy. Dalton Trans 2011; 40:6144-67. [DOI: 10.1039/c0dt01599g] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Maschauer S, Einsiedel J, Hocke C, Hübner H, Kuwert T, Gmeiner P, Prante O. Synthesis of a (68)ga-labeled peptoid-Peptide hybrid for imaging of neurotensin receptor expression in vivo. ACS Med Chem Lett 2010; 1:224-8. [PMID: 24900199 DOI: 10.1021/ml1000728] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 05/14/2010] [Indexed: 12/11/2022] Open
Abstract
The neurotensin receptor subtype 1 (NTS1) represents an attractive molecular target for imaging various tumors. Positron emission tomography (PET) gained widespread importance due to its sensitivity. We combined the design of a metabolically stable neurotensin analogue with a (68)Ga-radiolabeling approach. The (68)Ga-labeled peptoid-peptide hybrid [(68)Ga]3 revealed high stability, specific tumor uptake (0.7%ID/g, 65 min p.i.), and advantageous biokinetics in vivo using HT29 tumor-bearing nude mice. Because of the ability to internalize into NTS1-expressing tumor cells, [(68)Ga]3 proved to be highly suitable for a reliable and practical visualization of NTS1-expressing tumors in vivo by small animal PET.
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Affiliation(s)
- Simone Maschauer
- Laboratory of Molecular Imaging, Clinic of Nuclear Medicine, Friedrich-Alexander University, Schwabachanlage 6, D-91054 Erlangen, Germany
| | | | - Carsten Hocke
- Laboratory of Molecular Imaging, Clinic of Nuclear Medicine, Friedrich-Alexander University, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Harald Hübner
- Department of Chemisty and Pharmacy, Emil Fischer Center
| | - Torsten Kuwert
- Laboratory of Molecular Imaging, Clinic of Nuclear Medicine, Friedrich-Alexander University, Schwabachanlage 6, D-91054 Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemisty and Pharmacy, Emil Fischer Center
| | - Olaf Prante
- Laboratory of Molecular Imaging, Clinic of Nuclear Medicine, Friedrich-Alexander University, Schwabachanlage 6, D-91054 Erlangen, Germany
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Alshoukr F, Rosant C, Maes V, Abdelhak J, Raguin O, Burg S, Sarda L, Barbet J, Tourwé D, Pelaprat D, Gruaz-Guyon A. Novel neurotensin analogues for radioisotope targeting to neurotensin receptor-positive tumors. Bioconjug Chem 2009; 20:1602-10. [PMID: 19610615 DOI: 10.1021/bc900151z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The increased expression of the neurotensin (NT) receptor NTS1 by different cancer cells, such as pancreatic adenocarcinoma and ductal breast cancer cells, as compared to normal epithelium, offers the opportunity to target these tumors with radiolabeled neurotensin analogues for diagnostic or therapeutic purposes. The aim of the present study was to design and synthesize new neurotensin radioligands and to select a lead molecule with high in vivo tumor selectivity for further development. Two series of neurotensin analogues bearing DTPA were tested: a series of NT(8-13) analogues, with DTPA coupled to the α-NH(2), sharing the same peptide sequence with analogues previously developed for radiolabeling with technetium or rhenium, as well as an NT(6-13) series in which DTPA was coupled to the ε-NH(2) of Lys(6). Changes were introduced to stabilize the bonds between Arg(8)-Arg(9), Pro(10)-Tyr(11), and Tyr(11)-Ile(12) to provide metabolic stability. Structure-activity studies of NT analogues have shown that the attachment of DTPA induces an important loss of affinity unless the distance between the chelator and the NT(8-13) sequence, which binds to the NTS1 receptor, is increased. The doubly stabilized DTPA-NT-20.3 exhibits a high affinity and an elevated stability to enzymatic degradation. It shows specific tumor uptake and high tumor to blood, to liver, and to intestine activity uptake ratios and affords high-contrast planar and SPECT images in an animal model. The DTPA-NT-20.3 peptide is a promising candidate for imaging neurotensin receptor-positive tumors, such as pancreatic adenocarcinoma and invasive ductal breast cancer. Analogues carrying DOTA are being developed for yttrium-90 or lutetium-177 labeling.
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Schottelius M, Wester HJ. Molecular imaging targeting peptide receptors. Methods 2009; 48:161-77. [DOI: 10.1016/j.ymeth.2009.03.012] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 03/11/2009] [Indexed: 02/08/2023] Open
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