1
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Brandt F, Ullrich M, Wodtke J, Kopka K, Bachmann M, Löser R, Pietzsch J, Pietzsch HJ, Wodtke R. Enzymological Characterization of 64Cu-Labeled Neprilysin Substrates and Their Application for Modulating the Renal Clearance of Targeted Radiopharmaceuticals. J Med Chem 2023; 66:516-537. [PMID: 36595224 DOI: 10.1021/acs.jmedchem.2c01472] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The applicability of radioligands for targeted endoradionuclide therapy is limited due to radiation-induced toxicity to healthy tissues, in particular to the kidneys as primary organs of elimination. The targeting of enzymes of the renal brush border membrane by cleavable linkers that permit the formation of fast eliminating radionuclide-carrying cleavage fragments gains increasing interest. Herein, we synthesized a small library of 64Cu-labeled cleavable linkers and quantified their substrate potentials toward neprilysin (NEP), a highly abundant peptidase at the renal brush border membrane. This allowed for the derivation of structure-activity relationships, and selected cleavable linkers were attached to the somatostatin receptor subtype 2 ligand [Tyr3]octreotate. Radiopharmacological characterization revealed that a substrate-based targeting of NEP in the kidneys with small peptides entails their premature cleavage in the blood circulation by soluble and endothelium-derived NEP. However, for a kidney-specific targeting of NEP, the additional targeting of albumin in the blood is highlighted.
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Affiliation(s)
- Florian Brandt
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069Dresden, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany
| | - Johanna Wodtke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069Dresden, Germany.,National Center for Tumor Diseases (NCT) Dresden, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307Dresden, Germany.,German Cancer Consortium (DKTK), Partner Site Dresden, Fetscherstraße 74, 01307Dresden, Germany
| | - Michael Bachmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany.,National Center for Tumor Diseases (NCT) Dresden, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307Dresden, Germany
| | - Reik Löser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069Dresden, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069Dresden, Germany
| | - Hans-Jürgen Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069Dresden, Germany
| | - Robert Wodtke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328Dresden, Germany
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2
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Hörmann AA, Plhak E, Klingler M, Rangger C, Pfister J, Schwach G, Kvaternik H, von Guggenberg E. Automated Synthesis of 68Ga-Labeled DOTA-MGS8 and Preclinical Characterization of Cholecystokinin-2 Receptor Targeting. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27062034. [PMID: 35335396 PMCID: PMC8949806 DOI: 10.3390/molecules27062034] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/16/2022] [Accepted: 03/20/2022] [Indexed: 11/16/2022]
Abstract
The new minigastrin analog DOTA-MGS8 targeting the cholecystokinin-2 receptor (CCK2R) used in this study displays the combination of two site-specific modifications within the C-terminal receptor binding sequence together with an additional N-terminal amino acid substitution preventing fast metabolic degradation. Within this study, the preparation of 68Ga-labeled DOTA-MGS8 was validated using an automated synthesis module, describing the specifications and analytical methods for quality control for possible clinical use. In addition, preclinical studies were carried out to characterize the targeting potential. [68Ga]Ga-DOTA-MGS8 showed a high receptor-specific cell internalization into AR42J rat pancreatic cells (~40%) with physiological expression of rat CCK2R as well as A431-CCK2R cells transfected to stably express human CCK2R (~47%). A favorable biodistribution profile was observed in BALB/c nude mice xenografted with A431-CCK2R cells and mock-transfected A431 cells as control. The high tumor uptake of ~27% IA/g together with low background activity and limited uptake in non-target tissue confirms the potential for high-sensitivity positron emission tomography of stabilized MG analogs in patients with MTC and other CCK2R-related malignancies.
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Affiliation(s)
- Anton Amadeus Hörmann
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (C.R.); (J.P.)
| | - Elisabeth Plhak
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria;
- Department of Radiology, Division of Nuclear Medicine, Medical University of Graz, 8036 Graz, Austria;
| | - Maximilian Klingler
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (C.R.); (J.P.)
| | - Christine Rangger
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (C.R.); (J.P.)
| | - Joachim Pfister
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (C.R.); (J.P.)
| | - Gert Schwach
- Division of Immunology and Pathophysiology, Otto Loewi Research Center, Medical University of Graz, 8010 Graz, Austria;
| | - Herbert Kvaternik
- Department of Radiology, Division of Nuclear Medicine, Medical University of Graz, 8036 Graz, Austria;
| | - Elisabeth von Guggenberg
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (C.R.); (J.P.)
- Correspondence: ; Tel.: +43-512-504-80960
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Nock BA, Kanellopoulos P, Chepurny OG, Rouchota M, Loudos G, Holz GG, Krenning EP, Maina T. Nonpeptidic Z360-Analogs Tagged with Trivalent Radiometals as Anti-CCK2R Cancer Theranostic Agents: A Preclinical Study. Pharmaceutics 2022; 14:pharmaceutics14030666. [PMID: 35336041 PMCID: PMC8954547 DOI: 10.3390/pharmaceutics14030666] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/11/2022] [Accepted: 03/15/2022] [Indexed: 02/05/2023] Open
Abstract
(1) Background: Theranostic approaches in the management of cholecystokinin subtype 2 receptor (CCK2R)-positive tumors include radiolabeled gastrin and CCK motifs. Moving toward antagonist-based CCK2R-radioligands instead, we herein present three analogs of the nonpeptidic CCK2R-antagonist Z360, GAS1/2/3. Each was conjugated to a different chelator (DOTA, NODAGA or DOTAGA) for labeling with medically relevant trivalent radiometals (e.g., Ga-68, In-111, Lu-177) for potential use as anti-CCK2R cancer agents; (2) Methods: The in vitro properties of the thee analogs were compared in stably transfected HEK293-CCK2R cells. Biodistribution profiles were compared in SCID mice bearing twin HEK293-CCK2R and wtHEK293 tumors; (3) Results: The GAS1/2/3 analogs displayed high CCK2R-affinity (lower nM-range). The radioligands were fairly stable in vivo and selectively targeted the HEK293-CCK2R, but not the CCK2R-negative wtHEK293 tumors in mice. Their overall pharmacokinetic profile was found strongly dependent on the radiometal-chelate. Results could be visualized by SPECT/CT for the [111In]In-analogs; (4) Conclusions: The present study highlighted the high impact of the radiometal-chelate on the end-pharmacokinetics of a new series of Z360-based radioligands, revealing candidates with promising properties for clinical translation. It also provided the impetus for the development of a new class of nonpeptidic radioligands for CCK2R-targeted theranostics of human cancer.
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Affiliation(s)
- Berthold A. Nock
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece; (B.A.N.); (P.K.)
| | | | - Oleg G. Chepurny
- Departments of Medicine and Pharmacology, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA and Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA; (O.G.C.); (G.G.H.)
| | - 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.)
| | - George G. Holz
- Departments of Medicine and Pharmacology, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA and Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA; (O.G.C.); (G.G.H.)
| | - Eric P. Krenning
- Cyclotron Rotterdam BV, Erasmus MC, 3015 CE Rotterdam, The Netherlands;
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, 15341 Athens, Greece; (B.A.N.); (P.K.)
- Correspondence: ; Tel.: +30-210-650-3908 or +30-210-650-3891
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4
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Maina T, Nock BA. Gamma camera imaging by radiolabeled gastrin/cholecystokinin analogs. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00183-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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5
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Update on Preclinical Development and Clinical Translation of Cholecystokinin-2 Receptor Targeting Radiopharmaceuticals. Cancers (Basel) 2021; 13:cancers13225776. [PMID: 34830930 PMCID: PMC8616406 DOI: 10.3390/cancers13225776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Peptide analogs, derived from the natural peptide hormone gastrin, are promising candidates for improving the visualization and treatment of tumors. Gastrin specifically binds to the cholecystokinin-2 receptor, a G-protein-coupled receptor expressed on the cell surface of different tumors. This enables specific targeting of tumor cells using gastrin analogs, labeled with radioisotopes. The receptor is expressed at high incidence in medullary thyroid carcinoma, a rare form of thyroid cancer lacking effective treatments at an advanced stage. Different radiolabeled gastrin analogs as well as nonpeptidic compounds targeting CCK2R have been developed. Specific modifications have been introduced in order to safely deliver the radiation to the tumor site. In this review, recent strategies applied to improve the targeting properties are described. These developments enabled the introduction of new radiolabeled peptide analogs for imaging and therapy in cancer patients. In addition to highlighting the current clinical trials, the perspectives for future applications are given. Abstract The cholecystokinin-2 receptor (CCK2R) has been a target of interest for molecular imaging and targeted radionuclide therapy for two decades. However, so far CCK2R targeted imaging and therapy has not been introduced in clinical practice. Within this review the recent radiopharmaceutical development of CCK2R targeting compounds and the ongoing clinical trials are presented. Currently, new gastrin derivatives as well as nonpeptidic substances are being developed to improve the properties for clinical use. A team of specialists from the field of radiopharmacy and nuclear medicine reviewed the available literature and summarized their own experiences in the development and clinical testing of CCK2R targeting radiopharmaceuticals. The recent clinical trials with novel radiolabeled minigastrin analogs demonstrate the potential for both applications, imaging as well as targeted radiotherapy, and reinforce the clinical applicability within a theranostic concept. The intense efforts in optimizing CCK2R targeting radiopharmaceuticals has led to new substances for clinical use, as shown in first imaging studies in patients with advanced medullary thyroid cancer. The first clinical results suggest that the wider clinical implication of CCK2R-targeted radiopharmaceuticals is reasonable.
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Improved Tumor-Targeting with Peptidomimetic Analogs of Minigastrin 177Lu-PP-F11N. Cancers (Basel) 2021; 13:cancers13112629. [PMID: 34071914 PMCID: PMC8199036 DOI: 10.3390/cancers13112629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/21/2021] [Accepted: 05/24/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Several radiolabeled peptides targeting CCK2R-positive types of cancer (such as medullary thyroid cancer and small cell lung cancer) have been reported in the last 25 years, some of which have entered clinical trials. In an effort to improve its tumor-targeting properties, we applied chemical modifications to the backbone of the peptide 177Lu-PP-F11N, an analog of minigastrin in clinical trials. The generated radiolabeled peptidomimetics showed significantly improved characteristics in mice bearing CCK2R-positive tumor xenografts, such as higher tumor uptake, slower tumor washout, and increased tumor-to-kidney ratios. These properties make the novel compounds promising candidates for the imaging and therapy of CCK2R-positive tumors and metastases. Abstract The cholecystokinin-2 receptor (CCK2R) is an attractive target in nuclear medicine due to its overexpression by different tumors. Several radiolabeled peptidic ligands targeting the CCK2R have been investigated in the past; however, their low stability against proteases can limit their uptake in tumors and metastases. Substitution of single or multiple amide bonds with metabolically stable 1,4-disubstituted 1,2,3-triazoles as amide bond bioisosteres proved a promising strategy for improving the tumor-targeting properties of a truncated analog of minigastrin. In this study, we applied the previously studied structural modifications to improve the pharmacokinetic and pharmacodynamic properties of PP-F11N, a minigastrin analog currently in clinical trials. Novel minigastrins (NMGs) as analogs of PP-F11N with one or two amide bonds substituted by 1,2,3-triazoles were synthesized, radiolabeled with 177Lu3+, and subjected to full evaluation in vitro (cell internalization, receptor affinity, stability in blood plasma) and in vivo (stability, biodistribution, SPECT/CT imaging). NMGs with triazoles inserted between the amino acids DGlu10-Ala11 and/or Tyr12-Gly13 showed a significantly increased cellular uptake and affinity toward the CCK2R in vitro. Resistance against the metabolic degradation of the NMGs was comparable to those of the clinical candidate PP-F11N. Imaging by SPECT/CT and biodistribution studies demonstrated a higher uptake in CCK2R-positive tumors but also in the CCK2R-positive stomach. The peptidomimetic compounds showed a slow tumor washout and high tumor-to-kidney ratios. The structural modifications led to the identification of analogs with promising properties for progression to clinical applications in the diagnosis and therapy of CCK2R-positive neoplasms.
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7
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Klingler M, Hörmann AA, Guggenberg EV. Cholecystokinin-2 Receptor Targeting with Radiolabeled Peptides: Current Status and Future Directions. Curr Med Chem 2021; 27:7112-7132. [PMID: 32586246 DOI: 10.2174/0929867327666200625143035] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 05/01/2020] [Accepted: 05/13/2020] [Indexed: 02/08/2023]
Abstract
A wide variety of radiolabeled peptide analogs for specific targeting of cholecystokinin- 2 receptors (CCK2R) has been developed in the last decades. Peptide probes based on the natural ligands Minigastrin (MG) and Cholecystokinin (CCK) have a high potential for molecular imaging and targeted radiotherapy of different human tumors, such as Medullary Thyroid Carcinoma (MTC) and Small Cell Lung Cancer (SCLC). MG analogs with high persistent uptake in CCK2R expressing tumors have been preferably used for the development of radiolabeled peptide analogs. The clinical translation of CCK2R targeting has been prevented due to high kidney uptake or low metabolic stability of the different radiopeptides developed. Great efforts in radiopharmaceutical development have been undertaken to overcome these limitations. Various modifications in the linear peptide sequence of MG have been introduced mainly with the aim to reduce kidney retention. Furthermore, improved tumor uptake could be obtained by in situ stabilization of the radiopeptide against enzymatic degradation through coinjection of peptidase inhibitors. Recent developments focusing on the stabilization of the Cterminal receptor binding sequence (Trp-Met-Asp-Phe-NH2) have led to new radiolabeled MG analogs with highly improved tumor uptake and tumor-to-kidney ratio. In this review, all the different aspects in the radiopharmaceutical development of CCK2R targeting peptide probes are covered, giving also an overview on the clinical investigations performed so far. The recent development of radiolabeled MG analogs, which are highly stabilized against enzymatic degradation in vivo, promises to have a high impact on the clinical management of patients with CCK2R expressing tumors in the near future.
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Affiliation(s)
- Maximilian Klingler
- Department of Nuclear Medicine, Medical University of Innsbruck, A-6020 Innsbruck, Austria
| | - Anton Amadeus Hörmann
- Department of Nuclear Medicine, Medical University of Innsbruck, A-6020 Innsbruck, Austria
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Hörmann AA, Klingler M, Rezaeianpour M, Hörmann N, Gust R, Shahhosseini S, von Guggenberg E. Initial In Vitro and In Vivo Evaluation of a Novel CCK2R Targeting Peptide Analog Labeled with Lutetium-177. Molecules 2020; 25:molecules25194585. [PMID: 33049999 PMCID: PMC7583830 DOI: 10.3390/molecules25194585] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/25/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023] Open
Abstract
Targeting of cholecystokinin-2 receptor (CCK2R) expressing tumors using radiolabeled minigastrin (MG) analogs is hampered by rapid digestion of the linear peptide in vivo. In this study, a new MG analog stabilized against enzymatic degradation was investigated in preclinical studies to characterize the metabolites formed in vivo. The new MG analog DOTA-DGlu-Pro-Tyr-Gly-Trp-(N-Me)Nle-Asp-1Nal-NH2 comprising site-specific amino acid substitutions in position 2, 6 and 8 and different possible metabolites thereof were synthesized. The receptor interaction of the peptide and selected metabolites was evaluated in a CCK2R-expressing cell line. The enzymatic stability of the 177Lu-labeled peptide analog was evaluated in vitro in different media as well as in BALB/c mice up to 1 h after injection and the metabolites were identified based on radio-HPLC analysis. The new radiopeptide showed a highly increased stability in vivo with >56% intact radiopeptide in the blood of BALB/c mice 1 h after injection. High CCK2R affinity and cell uptake was confirmed only for the intact peptide, whereas enzymatic cleavage within the receptor specific C-terminal amino acid sequence resulted in complete loss of affinity and cell uptake. A favorable biodistribution profile was observed in BALB/c mice with low background activity, preferential renal excretion and prolonged uptake in CCK2R-expressing tissues. The novel stabilized MG analog shows high potential for diagnostic and therapeutic use. The radiometabolites characterized give new insights into the enzymatic degradation in vivo.
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Affiliation(s)
- Anton Amadeus Hörmann
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (M.R.)
| | - Maximilian Klingler
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (M.R.)
| | - Maliheh Rezaeianpour
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (M.R.)
- Pharmaceutical Chemistry and Radiopharmacy Department, School of Pharmacy, Shahid Beheshti University of Medical Sciences, 1991953381 Tehran, Iran;
| | - Nikolas Hörmann
- Department of Pharmaceutical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria; (N.H.); (R.G.)
| | - Ronald Gust
- Department of Pharmaceutical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria; (N.H.); (R.G.)
| | - Soraya Shahhosseini
- Pharmaceutical Chemistry and Radiopharmacy Department, School of Pharmacy, Shahid Beheshti University of Medical Sciences, 1991953381 Tehran, Iran;
| | - Elisabeth von Guggenberg
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria; (A.A.H.); (M.K.); (M.R.)
- Correspondence: ; Tel.: +43-512-504-80960
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9
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Kaloudi A, Kanellopoulos P, Radolf T, Chepurny OG, Rouchota M, Loudos G, Andreae F, Holz GG, Nock BA, Maina T. [ 99mTc]Tc-DGA1, a Promising CCK 2R-Antagonist-Based Tracer for Tumor Diagnosis with Single-Photon Emission Computed Tomography. Mol Pharm 2020; 17:3116-3128. [PMID: 32568549 DOI: 10.1021/acs.molpharmaceut.0c00605] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Radiolabeled gastrin analogues have been proposed for theranostics of cholecystokinin subtype 2 receptor (CCK2R)-positive cancer. Peptide radioligands based on other receptor antagonists have displayed superior pharmacokinetics and higher biosafety than agonists. Here, we present DGA1, a derivative of the nonpeptidic CCK2R antagonist Z-360 carrying an acyclic tetraamine, for [99mTc]Tc labeling. Preclinical comparison of [99mTc]Tc-DGA1 with [99mTc]Tc-DG2 (CCK2R-agonist reference) was conducted in HEK293-CCK2R/CCK2i4svR cells and mice models, qualifying [99mTc]Tc-DGA1 for further study in patients with CCK2R-positive tumors and single-photon emission computed tomography/CT.
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Affiliation(s)
- Aikaterini Kaloudi
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", 15310 Athens, Greece
| | | | - Thorsten Radolf
- piCHEM Forschungs-und Entwicklungs GmbH, Parkring 3, 8074 Grambach, Austria
| | - Oleg G Chepurny
- SUNY Upstate Medical University, IHP 4310 at 505 Irving Avenue, Syracuse, New York 13210, United States
| | - Maritina Rouchota
- BIOEMTECH, Lefkippos Attica Technology Park NCSR "Demokritos", 15310 Athens, Greece
| | - George Loudos
- BIOEMTECH, Lefkippos Attica Technology Park NCSR "Demokritos", 15310 Athens, Greece
| | - Fritz Andreae
- piCHEM Forschungs-und Entwicklungs GmbH, Parkring 3, 8074 Grambach, Austria
| | - George G Holz
- SUNY Upstate Medical University, IHP 4310 at 505 Irving Avenue, Syracuse, New York 13210, United States
| | | | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", 15310 Athens, Greece
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Evans BJ, King AT, Katsifis A, Matesic L, Jamie JF. Methods to Enhance the Metabolic Stability of Peptide-Based PET Radiopharmaceuticals. Molecules 2020; 25:molecules25102314. [PMID: 32423178 PMCID: PMC7287708 DOI: 10.3390/molecules25102314] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/28/2022] Open
Abstract
The high affinity and specificity of peptides towards biological targets, in addition to their favorable pharmacological properties, has encouraged the development of many peptide-based pharmaceuticals, including peptide-based positron emission tomography (PET) radiopharmaceuticals. However, the poor in vivo stability of unmodified peptides against proteolysis is a major challenge that must be overcome, as it can result in an impractically short in vivo biological half-life and a subsequently poor bioavailability when used in imaging and therapeutic applications. Consequently, many biologically and pharmacologically interesting peptide-based drugs may never see application. A potential way to overcome this is using peptide analogues designed to mimic the pharmacophore of a native peptide while also containing unnatural modifications that act to maintain or improve the pharmacological properties. This review explores strategies that have been developed to increase the metabolic stability of peptide-based pharmaceuticals. It includes modifications of the C- and/or N-termini, introduction of d- or other unnatural amino acids, backbone modification, PEGylation and alkyl chain incorporation, cyclization and peptide bond substitution, and where those strategies have been, or could be, applied to PET peptide-based radiopharmaceuticals.
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Affiliation(s)
- Brendan J. Evans
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.J.E.); (A.T.K.)
| | - Andrew T. King
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.J.E.); (A.T.K.)
| | - Andrew Katsifis
- Department of Molecular Imaging, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia;
| | - Lidia Matesic
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia;
| | - Joanne F. Jamie
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.J.E.); (A.T.K.)
- Correspondence: ; Tel.: +61-2-9850-8283
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11
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Mitran B, Rinne SS, Konijnenberg MW, Maina T, Nock BA, Altai M, Vorobyeva A, Larhed M, Tolmachev V, de Jong M, Rosenström U, Orlova A. Trastuzumab cotreatment improves survival of mice with PC-3 prostate cancer xenografts treated with the GRPR antagonist 177 Lu-DOTAGA-PEG 2 -RM26. Int J Cancer 2019; 145:3347-3358. [PMID: 31077356 PMCID: PMC6852655 DOI: 10.1002/ijc.32401] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 04/19/2019] [Accepted: 05/02/2019] [Indexed: 12/24/2022]
Abstract
Gastrin‐releasing peptide receptors (GRPRs) are overexpressed in prostate cancer and are suitable for targeted radionuclide therapy (TRT). We optimized the bombesin‐derived GRPR‐antagonist PEG2‐RM26 for labeling with 177Lu and further determined the effect of treatment with 177Lu‐labeled peptide alone or in combination with the anti‐HER2 antibody trastuzumab in a murine model. The PEG2‐RM26 analog was coupled to NOTA, NODAGA, DOTA and DOTAGA chelators. The peptide‐chelator conjugates were labeled with 177Lu and characterized in vitro and in vivo. A preclinical therapeutic study was performed in PC‐3 xenografted mice. Mice were treated with intravenous injections (6 cycles) of (A) PBS, (B) DOTAGA‐PEG2‐RM26, (C) 177Lu‐DOTAGA‐PEG2‐RM26, (D) trastuzumab or (E) 177Lu‐DOTAGA‐PEG2‐RM26 in combination with trastuzumab. 177Lu‐DOTAGA‐PEG2‐RM26 demonstrated quantitative labeling yield at high molar activity (450 GBq/μmol), high in vivo stability (5 min pi >98% of radioligand remained when coinjected with phosphoramidon), high affinity to GRPR (KD = 0.4 ± 0.2 nM), and favorable biodistribution (1 hr pi tumor uptake was higher than in healthy tissues, including the kidneys). Therapy with 177Lu‐DOTAGA‐PEG2‐RM26 induced a significant inhibition of tumor growth. The median survival for control groups was significantly shorter than for treated groups (Group C 66 days, Group E 74 days). Trastuzumab together with radionuclide therapy significantly improved survival. No treatment‐related toxicity was observed. In conclusion, based on in vitro and in vivo characterization of the four 177Lu‐labeled PEG2‐RM26 analogs, we concluded that 177Lu‐DOTAGA‐PEG2‐RM26 was the most promising analog for TRT. Radiotherapy using 177Lu‐DOTAGA‐PEG2‐RM26 effectively inhibited tumor growth in vivo in a murine prostate cancer model. Anti‐HER2 therapy additionally improved survival. What's new? Targeted radionuclide therapy (TRT) using radiolabeled peptides seeking gastrin‐releasing peptide receptors (GRPRs) in tumors is a promising approach to treat disseminated prostate cancer. The possibility to improve the therapeutic index via combination therapies also warrants further investigation. Here, the authors developed and characterized a promising GRPR‐targeting radioligand and demonstrated its therapeutic efficacy in prostate cancer xenografts. Moreover, this study using the anti‐HER2 antibody trastuzumab presents the first in vivo proof‐of‐principle that the effects of anti‐GRPR radiotherapy can be amplified by co‐administration of anti‐HER2 treatment leading to prolonged survival.
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Affiliation(s)
- Bogdan Mitran
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Sara S Rinne
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Mark W Konijnenberg
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece
| | - Berthold A Nock
- Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece
| | - Mohamed Altai
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Anzhelika Vorobyeva
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Mats Larhed
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden.,Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Marion de Jong
- Department of Radiology & Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Ulrika Rosenström
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden.,Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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12
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Cholecystokinin-2 Receptor Targeting with Novel C-terminally Stabilized HYNIC-Minigastrin Analogs Radiolabeled with Technetium-99m. Pharmaceuticals (Basel) 2019; 12:ph12010013. [PMID: 30650563 PMCID: PMC6469167 DOI: 10.3390/ph12010013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/08/2019] [Accepted: 01/10/2019] [Indexed: 12/19/2022] Open
Abstract
The high overexpression of cholecystokinin-2 receptors (CCK2R) in tumors, such as medullary thyroid carcinoma, allows for highly specific diagnostic and therapeutic targeting with radiolabeled peptide probes derived from natural ligands for the receptor. Based on the ideal imaging characteristics, high availability and low cost of technetium-99m (99mTc)-labeled radiopharmaceuticals we have developed two hydrazinonicotinic acid (HYNIC) conjugated minigastrin analogs allowing labeling at high specific activity. The CCK2R targeting peptide conjugates show specific amino acid substitutions in the C-terminal receptor-specific sequence with the aim to increase stability and tumor targeting. The CCK2R affinity and the cell uptake of the new radioligands were analyzed using A431 human epidermoid carcinoma cells stably transfected with human CCK2R and mock transfected cells. Metabolic studies in BALB/c mice revealed a high resistance against enzymatic degradation for both radioligands. Biodistribution studies in tumor-xenografted athymic BALB/c nude mice at 1 h and 4 h p.i. showed that the two 99mTc-labeled compounds showed varying uptake in receptor expressing organs, stomach and pancreas (1.3–10.4% IA/g), as well as kidneys, the main route of excretion (7.8–19.9% IA/g). The tumor uptake in A431-CCK2R xenografts was 24.75 ± 4.38% IA/g for [99mTc]Tc-HYNIC-MGS5 and 42.48 ± 6.99% IA/g for [99mTc]Tc-HYNIC-MGS11 at 4 h p.i., whereas the tumor-to-kidney ratio was comparable (2.6–3.3). On demand availability and potential application for radioguided surgery of a 99mTc-labeled minigastrin analog support the further evaluation of these highly promising new compounds.
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13
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Franco Machado J, Silva RD, Melo R, G Correia JD. Less Exploited GPCRs in Precision Medicine: Targets for Molecular Imaging and Theranostics. Molecules 2018; 24:E49. [PMID: 30583594 PMCID: PMC6337414 DOI: 10.3390/molecules24010049] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 12/07/2018] [Accepted: 12/09/2018] [Indexed: 12/18/2022] Open
Abstract
Precision medicine relies on individually tailored therapeutic intervention taking into account individual variability. It is strongly dependent on the availability of target-specific drugs and/or imaging agents that recognize molecular targets and patient-specific disease mechanisms. The most sensitive molecular imaging modalities, Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET), rely on the interaction between an imaging radioprobe and a target. Moreover, the use of target-specific molecular tools for both diagnostics and therapy, theranostic agents, represent an established methodology in nuclear medicine that is assuming an increasingly important role in precision medicine. The design of innovative imaging and/or theranostic agents is key for further accomplishments in the field. G-protein-coupled receptors (GPCRs), apart from being highly relevant drug targets, have also been largely exploited as molecular targets for non-invasive imaging and/or systemic radiotherapy of various diseases. Herein, we will discuss recent efforts towards the development of innovative imaging and/or theranostic agents targeting selected emergent GPCRs, namely the Frizzled receptor (FZD), Ghrelin receptor (GHSR-1a), G protein-coupled estrogen receptor (GPER), and Sphingosine-1-phosphate receptor (S1PR). The pharmacological and clinical relevance will be highlighted, giving particular attention to the studies on the synthesis and characterization of targeted molecular imaging agents, biological evaluation, and potential clinical applications in oncology and non-oncology diseases. Whenever relevant, supporting computational studies will be also discussed.
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Affiliation(s)
- João Franco Machado
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal.
| | - Rúben D Silva
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
| | - Rita Melo
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
- Center for Neuroscience and Cell Biology; Rua Larga, Faculdade de Medicina, Polo I, 1ºandar, Universidade de Coimbra, 3004-504 Coimbra, Portugal.
| | - João D G Correia
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
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14
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Multimerization results in formation of re-bindable metabolites: A proof of concept study with FSC-based minigastrin imaging probes targeting CCK2R expression. PLoS One 2018; 13:e0201224. [PMID: 30059514 PMCID: PMC6066219 DOI: 10.1371/journal.pone.0201224] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 07/11/2018] [Indexed: 12/21/2022] Open
Abstract
Positron emission tomography (PET) with radiolabelled peptide-based tracers has attracted great interest in oncology over the past decades. The success of imaging is closely related to sufficient uptake of the radiotracer in malignant tissue and for this sufficient biological half-life, particularly in the bloodstream, is mandatory. Fast enzymatic degradation during circulation leading to insufficient imaging abilities of peptide-based radioligands remains a major issue. The design of multimeric constructs, bearing multiple targeting moieties, has been widely applied to improve target interaction. This concept may also be applied to prolong the biological half-life of peptide-based radiopharmaceuticals as enzymatic degradation can result in formation of metabolites still capable to interact with the target binding site. In this study we aimed to identify such metabolites and therefore we utilized the siderophore-based bifunctional chelator fusarinine C (FSC) for the design of novel mono- and multimeric constructs, bearing minigastrin (MG) analogues as targeting moieties to address cholecystokinin-2 receptors (CCK2R) which are overexpressed in a variety of cancerous diseases and are well known for fast enzymatic degradation, particularly for truncated des-(Glu)5-MG members, such as MG11. FSC-based imaging probes were radiolabelled with gallium-68 and characterized in vitro (logD, protein binding, affinity and cell-uptake studies, stability and metabolite studies, as well as generation of corresponding metabolites by artificial enzymatic degradation) and in vivo (biodistribution in A431-CCK2R/A431-mock tumour xenografted BALB/c nude mice and stability in blood of living BALB/c mice and analysis of corresponding organ homogenates and urine to identify degradation products). In summary, multimerization was accompanied by partial improvement towards targeting abilities. Identified metabolites formed by artificial enzymatic cleavage of trimeric FSC-MG conjugates in vitro contained intact binding sequences for the receptor. Furthermore, the 68Ga-labelled trimers exhibiting increasing uptake of radioligand in tumour tissue over time and improved in vivo stability in blood samples of living animals of the trimers compared to corresponding mono- and dimers, strongly supporting our hypothesis.
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15
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Sauter AW, Mansi R, Hassiepen U, Muller L, Panigada T, Wiehr S, Wild AM, Geistlich S, Béhé M, Rottenburger C, Wild D, Fani M. Targeting of the Cholecystokinin-2 Receptor with the Minigastrin Analog 177Lu-DOTA-PP-F11N: Does the Use of Protease Inhibitors Further Improve In Vivo Distribution? J Nucl Med 2018; 60:393-399. [PMID: 30002107 DOI: 10.2967/jnumed.118.207845] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 06/29/2018] [Indexed: 12/19/2022] Open
Abstract
Patients with metastatic medullary thyroid cancer (MTC) have limited systemic treatment options. The use of radiolabeled gastrin analogs targeting the cholecystokinin-2 receptor (CCK2R) is an attractive approach. However, their therapeutic efficacy is presumably decreased by their enzymatic degradation in vivo. We aimed to investigate whether the chemically stabilized analog 177Lu-DOTA-PP-F11N (177Lu-DOTA-(dGlu)6-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2) performs better than reference analogs with varying in vivo stability, namely 177Lu-DOTA-MG11 (177Lu-DOTA-dGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2) and 177Lu-DOTA-PP-F11 (177Lu-DOTA-(dGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2), and whether the use of protease inhibitors further improves CCKR2 targeting. First human data on 177Lu-DOTA-PP-F11N are also reported. Methods: In vitro stability of all analogs was assessed against a panel of extra- and intracellular endoproteases, whereas their in vitro evaluation was performed using the human MTC MZ-CRC-1 and the transfected A431-CCK2R(+) cell lines. Biodistribution without and with the protease inhibitors phosphoramidon and thiorphan was assessed 4 h after injection in MZ-CRC-1 and A431-CCK2R(+) dual xenografts. Autoradiography of 177Lu-DOTA-PP-F11N (without and with phosphoramidon) and NanoSPECT/CT were performed. SPECT/CT images of 177Lu-DOTA-PP-F11N in a metastatic MTC patient were also acquired. Results: natLu-DOTA-PP-F11N is less of a substrate for neprilysins than the other analogs, whereas intracellular cysteine proteases, such as cathepsin-L, might be involved in the degradation of gastrin analogs. The uptake of all radiotracers was higher in MZ-CRC-1 tumors than in A431-CCK2R(+), apparently because of the higher number of binding sites on MZ-CRC-1 cells. 177Lu-DOTA-PP-F11N had the same biodistribution as 177Lu-DOTA-PP-F11; however, uptake in the MZ-CRC-1 tumors was almost double (20.7 ± 1.71 vs. 11.2 ± 2.94 %IA [percentage injected activity]/g, P = 0.0002). Coadministration of phosphoramidon or thiorphan increases 177Lu-DOTA-MG11 uptake significantly in the CCK2R(+) tumors and stomach. Less profound was the effect on 177Lu-DOTA-PP-F11, whereas no influence or even reduction was observed for 177Lu-DOTA-PP-F11N (20.7 ± 1.71 vs. 15.6 ± 3.80 [with phosphoramidon] %IA/g, P < 0.05 in MZ-CRC-1 tumors). The first clinical data show high 177Lu-DOTA-PP-F11N accumulation in tumors, stomach, kidneys, and colon. Conclusion: The performance of 177Lu-DOTA-PP-F11N without protease inhibitors is as good as the performance of 177Lu-DOTA-MG11 in the presence of inhibitors. The human application of single compounds without unessential additives is preferable. Preliminary clinical data spotlight the stomach as a potential dose-limiting organ besides the kidneys.
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Affiliation(s)
- Alexander W Sauter
- Division of Nuclear Medicine, University Hospital Basel, Basel, Switzerland.,Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Tuebingen, Germany
| | - Rosalba Mansi
- Division of Radiopharmaceutical Chemistry, University Hospital Basel, Basel, Switzerland
| | - Ulrich Hassiepen
- Novartis Pharma AG, Institutes for Biomedical Research, Novartis Campus, Basel, Switzerland; and
| | - Lionel Muller
- Novartis Pharma AG, Institutes for Biomedical Research, Novartis Campus, Basel, Switzerland; and
| | - Tania Panigada
- Novartis Pharma AG, Institutes for Biomedical Research, Novartis Campus, Basel, Switzerland; and
| | - Stefan Wiehr
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Tuebingen, Germany
| | - Anna-Maria Wild
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Tuebingen, Germany
| | - Susanne Geistlich
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland
| | - Martin Béhé
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland
| | | | - Damian Wild
- Division of Nuclear Medicine, University Hospital Basel, Basel, Switzerland
| | - Melpomeni Fani
- Division of Radiopharmaceutical Chemistry, University Hospital Basel, Basel, Switzerland
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16
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Matters GL, Harms JF. Utilizing Peptide Ligand GPCRs to Image and Treat Pancreatic Cancer. Biomedicines 2018; 6:biomedicines6020065. [PMID: 29865257 PMCID: PMC6027158 DOI: 10.3390/biomedicines6020065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 05/28/2018] [Indexed: 12/18/2022] Open
Abstract
It is estimated that early detection of pancreatic ductal adenocarcinoma (PDAC) could increase long-term patient survival by as much as 30% to 40% (Seufferlein, T. et al., Nat. Rev. Gastroenterol. Hepatol.2016, 13, 74–75). There is an unmet need for reagents that can reliably identify early cancerous or precancerous lesions through various imaging modalities or could be employed to deliver anticancer treatments specifically to tumor cells. However, to date, many PDAC tumor-targeting strategies lack selectivity and are unable to discriminate between tumor and nontumor cells, causing off-target effects or unclear diagnoses. Although a variety of approaches have been taken to identify tumor-targeting reagents that can effectively direct therapeutics or imaging agents to cancer cells (Liu, D. et al., J. Controlled Release2015, 219, 632–643), translating these reagents into clinical practice has been limited, and it remains an area open to new methodologies and reagents (O’Connor, J.P. et al., Nat. Rev. Clin. Oncol. 2017, 14, 169–186). G protein–coupled receptors (GPCRs), which are key target proteins for drug discovery and comprise a large proportion of currently marketed therapeutics, hold significant promise for tumor imaging and targeted treatment, particularly for pancreatic cancer.
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Affiliation(s)
- Gail L Matters
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
| | - John F Harms
- Department of Biological Sciences, Messiah College, Mechanicsburg, PA 17055, USA.
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17
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Klingler M, Decristoforo C, Rangger C, Summer D, Foster J, Sosabowski JK, von Guggenberg E. Site-specific stabilization of minigastrin analogs against enzymatic degradation for enhanced cholecystokinin-2 receptor targeting. Am J Cancer Res 2018; 8:2896-2908. [PMID: 29896292 PMCID: PMC5996369 DOI: 10.7150/thno.24378] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/01/2018] [Indexed: 12/12/2022] Open
Abstract
Minigastrin (MG) analogs show high affinity to the cholecystokinin-2 receptor (CCK2R) and have therefore been intensively studied to find a suitable analog for imaging and treatment of CCK2R-expressing tumors. The clinical translation of the radioligands developed thus far has been hampered by high kidney uptake or low enzymatic stability. In this study, we aimed to develop new MG analogs with improved targeting properties stabilized against degradation through site-specific amino acid modifications. Method: Based on the lead structure of a truncated MG analog, four new MG derivatives with substitutions in the C-terminal part of the peptide (Trp-Met-Asp-Phe-NH2) were synthesized and derivatized with DOTA at the N-terminus for radiolabeling with trivalent radiometals. The in vitro properties of the new analogs were characterized by analyzing the lipophilicity, the protein binding, and the stability of the Indium-111 (111In)-labeled analogs in different media. Two different cell lines, AR42J cells physiologically expressing the rat CCK2R and A431 cells transfected with human CCK2R (A431-CCK2R), were used to study the receptor affinity and cell uptake. For the two most promising MG analogs, metabolic studies in normal BALB/c mice were carried out as well as biodistribution and imaging studies in tumor xenografted athymic BALB/c nude mice. Results: Two out of four synthesized peptide analogs (DOTA-MGS1 and DOTA-MGS4) showed retained receptor affinity and cell uptake when radiolabeled with 111In. These two peptide analogs, however, showed a different stability against enzymatic degradation in vitro and in vivo. When injected to normal BALB/c mice, for 111In-DOTA-MGS1 at 10 min post injection (p.i.) no intact radiopeptide was found in the blood, whereas for 111In-DOTA-MGS4 more than 75% was still intact. 111In-DOTA-MGS4 showed a clear increase in injected activity per gram tissue (IA/g) for A431-CCK2R xenografts (10.40±2.21% IA/g 4 h p.i.) when compared to 111In-DOTA-MGS1 (1.23±0.15% IA/g 4 h p.i.). The tumor uptake of 111In-DOTA-MGS4 was also combined with a low uptake in stomach and kidney leading to high-contrast NanoSPECT/CT images. Conclusion: Of the four new MG analogs developed, the best results in terms of enzymatic stability and increased tumor targeting were obtained with 111In-DOTA-MGS4 showing two substitutions with N-methylated amino acids. 111In-DOTA-MGS4 was also superior to other MG analogs reported thus far and seems therefore an extremely promising targeting molecule for theranostic use with alternative radiometals.
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18
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Lipiński PFJ, Garnuszek P, Maurin M, Stoll R, Metzler-Nolte N, Wodyński A, Dobrowolski JC, Dudek MK, Orzełowska M, Mikołajczak R. Structural studies on radiopharmaceutical DOTA-minigastrin analogue (CP04) complexes and their interaction with CCK2 receptor. EJNMMI Res 2018; 8:33. [PMID: 29663167 PMCID: PMC5902437 DOI: 10.1186/s13550-018-0387-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 04/06/2018] [Indexed: 12/16/2022] Open
Abstract
Background The cholecystokinin receptor subtype 2 (CCK-2R) is an important target for diagnostic imaging and targeted radionuclide therapy (TRNT) due to its overexpression in certain cancers (e.g., medullary thyroid carcinoma (MTC)), thus matching with a theranostic principle. Several peptide conjugates suitable for the TRNT of MTC have been synthesized, including a very promising minigastrin analogue DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 (CP04). In this contribution, we wanted to see whether CP04 binding affinity for CCK-2R is sensitive to the type of the complexed radiometal, as well as to get insights into the structure of CP04-CCK2R complex by molecular modeling. Results In vitro studies demonstrated that there is no significant difference in CCK-2R binding affinity and specific cellular uptake between the CP04 conjugates complexed with [68Ga]Ga3+ or [177Lu]Lu3+. In order to investigate the background of this observation, we proposed a binding model of CP04 with CCK-2R based on homology modeling and molecular docking. In this model, the C-terminal part of the molecule enters the cavity formed between the receptor helices, while the N-terminus (including DOTA and the metal) is located at the binding site outlet, exposed in large extent to the solvent. The radiometals do not influence the conformation of the molecule except for the direct neighborhood of the chelating moiety. Conclusions The model seems to be in agreement with much of structure-activity relationship (SAR) studies reported for cholecystokinin and for CCK-2R-targeting radiopharmaceuticals. It also explains relative insensitivity of CCK-2R affinity for the change of the metal. The proposed model partially fits the reported site-directed mutagenesis data.
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Affiliation(s)
- Piotr F J Lipiński
- Neuropeptides Department, Mossakowski Medical Research Centre Polish Academy of Sciences, Pawińskiego 5 Str., 02-106, Warszawa, Poland.
| | - Piotr Garnuszek
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
| | - Michał Maurin
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
| | - Raphael Stoll
- Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Nils Metzler-Nolte
- Faculty of Chemistry and Biochemistry, Ruhr University of Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Artur Wodyński
- Świerk Computing Centre, National Centre for Nuclear Research, A. Sołtana 7 Str., 05-400, Otwock, Poland.,Institut für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Jan Cz Dobrowolski
- Institute of Nuclear Chemistry and Technology, Dorodna 16 Street, 03-195, Warszawa, Poland.,National Medicines Institute, Chełmska 30/34 Str., 00-725, Warszawa, Poland
| | - Marta K Dudek
- Centre of Molecular and Macromolecular Studies Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
| | - Monika Orzełowska
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
| | - Renata Mikołajczak
- Radioisotope Centre POLATOM, National Centre for Nuclear Research, A. Sołtana 7 Str, 05-400, Otwock, Poland
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19
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Exploiting the Concept of Multivalency with 68Ga- and 89Zr-Labelled Fusarinine C-Minigastrin Bioconjugates for Targeting CCK2R Expression. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:3171794. [PMID: 29849512 PMCID: PMC5914118 DOI: 10.1155/2018/3171794] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/20/2018] [Indexed: 11/17/2022]
Abstract
Cholecystokinin-2 receptors (CCK2R) are overexpressed in a variety of malignant diseases and therefore have gained certain attention for peptide receptor radionuclide imaging. Among extensive approaches to improve pharmacokinetics and metabolic stability of minigastrin (MG) based radioligands, the concept of multivalency for enhanced tumour targeting has not been investigated extensively. We therefore utilized fusarinine C (FSC) as chelating scaffold for novel mono-, di-, and trimeric bioconjugates for targeting CCK2R expression. FSC-based imaging probes were radiolabelled with positron emitting radionuclides (gallium-68 and zirconium-89) and characterized in vitro (logD, IC50, and cell uptake) and in vivo (metabolic stability in BALB/c mice, biodistribution profile, and microPET/CT imaging in A431-CCK2R/A431-mock tumour xenografted BALB/c nude mice). Improved targeting did not fully correlate with the grade of multimerization. The divalent probe showed higher receptor affinity and increased CCK2R mediated cell uptake while the trimer remained comparable to the monomer. In vivo biodistribution studies 1 h after administration of the 68Ga-labelled radioligands confirmed this trend, but imaging at late time point (24 h) with 89Zr-labelled counterparts showed a clearly enhanced imaging contrast of the trimeric probe compared to the mono- and dimer. Furthermore, in vivo stability studies showed a higher metabolic stability for multimeric probes compared to the monomeric bioconjugate. In summary, we could show that FSC can be utilized as suitable scaffold for novel mono- and multivalent imaging probes for CCK2R-related malignancies with partly improved targeting properties for multivalent conjugates. The increased tumour accumulation of the trimer 24 h postinjection (p.i.) can be explained by slower clearance and increased metabolic stability of multimeric conjugates.
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New Insights in the Design of Bioactive Peptides and Chelating Agents for Imaging and Therapy in Oncology. Molecules 2017; 22:molecules22081282. [PMID: 28767081 PMCID: PMC6152110 DOI: 10.3390/molecules22081282] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/25/2017] [Indexed: 11/16/2022] Open
Abstract
Many synthetic peptides have been developed for diagnosis and therapy of human cancers based on their ability to target specific receptors on cancer cell surface or to penetrate the cell membrane. Chemical modifications of amino acid chains have significantly improved the biological activity, the stability and efficacy of peptide analogues currently employed as anticancer drugs or as molecular imaging tracers. The stability of somatostatin, integrins and bombesin analogues in the human body have been significantly increased by cyclization and/or insertion of non-natural amino acids in the peptide sequences. Moreover, the overall pharmacokinetic properties of such analogues and others (including cholecystokinin, vasoactive intestinal peptide and neurotensin analogues) have been improved by PEGylation and glycosylation. Furthermore, conjugation of those peptide analogues to new linkers and bifunctional chelators (such as AAZTA, TETA, TRAP, NOPO etc.), produced radiolabeled moieties with increased half life and higher binding affinity to the cognate receptors. This review describes the most important and recent chemical modifications introduced in the amino acid sequences as well as linkers and new bifunctional chelators which have significantly improved the specificity and sensitivity of peptides used in oncologic diagnosis and therapy.
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Grob NM, Behe M, von Guggenberg E, Schibli R, Mindt TL. Methoxinine - an alternative stable amino acid substitute for oxidation-sensitive methionine in radiolabelled peptide conjugates. J Pept Sci 2017; 23:38-44. [PMID: 28054429 DOI: 10.1002/psc.2948] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 11/18/2016] [Accepted: 11/21/2016] [Indexed: 01/29/2023]
Abstract
Radiolabelled peptides with high specificity and affinity towards receptors that are overexpressed by tumour cells are used in nuclear medicine for the diagnosis (imaging) and therapy of cancer. In some cases, the sequences of peptides under investigations contain methionine (Met), an amino acid prone to oxidation during radiolabelling procedures. The formation of oxidative side products can affect the purity of the final radiopharmaceutical product and/or impair its specificity and affinity towards the corresponding receptor. The replacement of Met with oxidation resistant amino acid analogues, for example, norleucine (Nle), can provide a solution. While this approach has been applied successfully to different radiolabelled peptides, a Met → Nle switch only preserves the length of the amino acid side chain important for hydrophobic interactions but not its hydrogen-bonding properties. We report here the use of methoxinine (Mox), a non-canonical amino acid that resembles more closely the electronic properties of Met in comparison to Nle. Specifically, we replaced Met15 by Mox15 and Nle15 in the binding sequence of a radiometal-labelled human gastrin derivative [d-Glu10 ]HG(10-17), named MG11 (d-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 ). A comparison of the physicochemical properties of 177 Lu-DOTA[X15 ]MG11 (X = Met, Nle, Mox) in vitro (cell internalization/externalization properties, receptor affinity (IC50 ), blood plasma stability and logD) showed that Mox indeed represents a suitable, oxidation-stable amino acid substitute of Met in radiolabelled peptide conjugates. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
- Nathalie M Grob
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH, Vladimir-Prelog Weg 4, CH-8093, Zurich, Switzerland
| | - Martin Behe
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | | | - Roger Schibli
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH, Vladimir-Prelog Weg 4, CH-8093, Zurich, Switzerland.,Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, CH-5232, Villigen, Switzerland
| | - Thomas L Mindt
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH, Vladimir-Prelog Weg 4, CH-8093, Zurich, Switzerland.,Ludwig Boltzmann Institute Applied Diagnostics, General Hospital of Vienna, Währinger Gürtel 18-20, A-1090, Vienna, Austria
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(99m)Tc-labeled gastrins of varying peptide chain length: Distinct impact of NEP/ACE-inhibition on stability and tumor uptake in mice. Nucl Med Biol 2016; 43:347-54. [PMID: 27260775 DOI: 10.1016/j.nucmedbio.2016.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 03/14/2016] [Indexed: 01/24/2023]
Abstract
INTRODUCTION In situ inhibition of neutral endopeptidase (NEP) has been recently shown to impressively increase the bioavailability and tumor uptake of biodegradable gastrin radioligands. Furthermore, angiotensin converting enzyme (ACE) has been previously shown to cleave gastrin analogs in vitro. In the present study, we have assessed the effects induced by single or dual NEP/ACE-inhibition on the pharmacokinetic profile of three (99m)Tc-labeled gastrins of varying peptide chain length: [(99m)Tc]SG6 ([(99m)Tc-N4-Gln(1)]gastrin(1-17)), [(99m)Tc]DG2 ([(99m)Tc-N4-Gly(4),DGlu(5)]gastrin(4-17)) and [(99m)Tc]DG4 ([(99m)Tc-N4-DGlu(10)]gastrin(10-17)). METHODS Mouse blood samples were collected 5min after injection of each of [(99m)Tc]SG6/DG2/DG4 together with: a) vehicle, b) the NEP-inhibitor phosphoramidon (PA), c) the ACE-inhibitor lisinopril (Lis), or d) PA plus Lis and were analyzed by RP-HPLC for radiometabolite detection. Biodistribution was studied in SCID mice bearing A431-CCK2R(+/-) xenografts at 4h postinjection (pi). [(99m)Tc]SG6 or [(99m)Tc]DG4 was coinjected with either vehicle or the above described NEP/ACE-inhibitor regimens; for [(99m)Tc]DG2 control and PA animal groups were only included. RESULTS Treatment of mice with PA induced significant stabilization of (99m)Tc-radiotracers in peripheral blood, while treatment with Lis or Lis+PA affected the stability of des(Glu)5 [(99m)Tc]DG4 only. In line with these findings, PA coinjection led to notable amplification of tumor uptake of radiopeptides compared to controls (P<0.01). Only [(99m)Tc]DG4 profited by single Lis (2.06±0.39%ID/g vs 0.99±0.13%ID/g in controls) or combined Lis+PA coinjection (8.91±1.61%ID/g vs 4.89±1.33%ID/g in PA-group). Furthermore, kidney uptake remained favourably low and unaffected by PA and/or Lis coinjection only in the case of [(99m)Tc]DG4 (<1.9%ID/g) resulting in the most optimal tumor-to-kidney ratios. CONCLUSIONS In situ NEP/ACE-inhibition diversely affected the in vivo profile of (99m)Tc-radioligands based on different-length gastrins. Truncated [(99m)Tc]DG4 exhibited overall the most attractive profile during combined NEP/ACE-inhibition in mouse models, providing new opportunities for CCK2R-expressing tumor imaging in man with SPECT.
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