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Zierke MA, Rangger C, Samadikhah K, Panzer M, Dichtl S, Hörmann N, Wilflingseder D, Schmid AM, Haubner R. [ 68Ga]Ga-NODAGA-TriGalactan, a low molecular weight tracer for the non-invasive imaging of the functional liver reserve. EJNMMI Radiopharm Chem 2024; 9:41. [PMID: 38750246 PMCID: PMC11096148 DOI: 10.1186/s41181-024-00271-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 04/29/2024] [Indexed: 05/18/2024] Open
Abstract
BACKGROUND Determination of the functional liver mass is important in a variety of clinical settings including liver surgery and transplantation. [99mTc]Tc-diethylenetriamine-pentaacetic acid galactosyl human serum albumin (99mTc-GSA) is a radiotracer targeting the asialoglycoprotein receptor (ASGR) and is routinely used in Japan for this purpose. Here we describe the development and evaluation of [68Ga]Ga-NODAGA-TriGalactan a low molecular weight PET-tracer targeting this structure. RESULTS For synthesis TRIS as branching unit and NODAGA as chelator for labelling with [68Ga]Ga are included. Three galactose moieties are conjugated via a click chemistry approach resulting in the desired labelling precursor.68Ga-labelling could be accomplished in high radiochemical yield and purity. [68Ga]Ga-NODAGA-TriGalactan is very hydrophilic and revealed high plasma stability and low plasma protein binding. Fluorescence imaging showed binding on ASGR-positive organoids and the IC50-value was in the nanomolar range. Most importantly, both biodistribution as well as animal imaging studies using normal mice demonstrated high liver uptake with rapid elimination from all other organs leading to even higher liver-to-background ratios as found for 99mTc-GSA. CONCLUSION [68Ga]Ga-NODAGA-TriGalactan shows high in vitro stability and selectively binds to the ASGR allowing imaging of the functional liver mass with high contrast. Thus, our first generation compound resulted already in an alternative to 99mTc-GSA for imaging the functional liver reserve and might allow the broader use of this imaging technique.
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Affiliation(s)
- Maximilian A Zierke
- Department of Nuclear Medicine, Medical University Innsbruck, Anichstr. 35, Innsbruck, 6020, Austria
| | - Christine Rangger
- Department of Nuclear Medicine, Medical University Innsbruck, Anichstr. 35, Innsbruck, 6020, Austria
| | - Kimia Samadikhah
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, 73076, Tübingen, Germany
| | - Marlene Panzer
- Department of Internal Medicine I, Medical University Innsbruck, Anichstr. 35, Innsbruck, 6020, Austria
| | - Stefanie Dichtl
- Institute of Hygiene and Medical Microbiology, Medical University Innsbruck, Schöpfstr. 41, Innsbruck, 6020, Austria
| | - Nikolas Hörmann
- Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Innsbruck, Innrain, 80-82, Innsbruck, 6020, Austria
| | - Doris Wilflingseder
- Institute of Hygiene and Medical Microbiology, Medical University Innsbruck, Schöpfstr. 41, Innsbruck, 6020, Austria
| | - Andreas M Schmid
- Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University Tübingen, Röntgenweg 13, 73076, Tübingen, Germany
| | - Roland Haubner
- Department of Nuclear Medicine, Medical University Innsbruck, Anichstr. 35, Innsbruck, 6020, Austria.
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Corlett A, Pinson JA, Rahimi MN, Zuylekom JV, Cullinane C, Blyth B, Thompson PE, Hutton CA, Roselt PD, Haskali MB. Development of Highly Potent Clinical Candidates for Theranostic Applications against Cholecystokinin-2 Receptor Positive Cancers. J Med Chem 2023; 66:10289-10303. [PMID: 37493526 DOI: 10.1021/acs.jmedchem.3c00377] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Peptide receptor radionuclide therapy (PRRT) is a promising form of systemic radiation therapy designed to eradicate cancer. Cholecystokinin-2 receptor (CCK2R) is an important molecular target that is highly expressed in a range of cancers. This study describes the synthesis and in vivo characterization of a novel series of 177Lu-labeled peptides ([177Lu]Lu-2b-4b) in comparison with the reference CCK2R-targeting peptide CP04 ([177Lu]Lu-1b). [177Lu]Lu-1b-4b showed high chemical purity (HPLC ≥ 94%), low Log D7.4 (-4.09 to -4.55) with strong binding affinity to CCK2R (KD 0.097-1.61 nM), and relatively high protein binding (55.6-80.2%) and internalization (40-67%). Biodistribution studies of the novel 177Lu-labeled peptides in tumors (AR42J and A431-CCK2R) showed uptake one- to eight-fold greater than the reference compound CP04 at 1, 24, and 48 h. Rapid clearance and high tumor uptake and retention were established for [177Lu]Lu-2b-4b, making these compounds excellent candidates for theranostic applications against CCK2R-expressing tumors.
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Affiliation(s)
- Alicia Corlett
- Department of Nuclear Medicine, The Royal Melbourne Hospital, Parkville, Victoria, 3000, Australia
| | - Jo-Anne Pinson
- The Radiopharmaceutical Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Marwa N Rahimi
- The Radiopharmaceutical Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Jessica Van Zuylekom
- Models of Cancer Translational Research Centre, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Carleen Cullinane
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria 3010, Australia
- The Centre for Molecular Imaging and Translational Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Benjamin Blyth
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria 3010, Australia
- Models of Cancer Translational Research Centre, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria 3052, Australia
| | - Craig A Hutton
- School of Chemistry, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Peter D Roselt
- Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- The Radiopharmaceutical Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Mohammad B Haskali
- Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- The Radiopharmaceutical Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria 3010, Australia
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Holzleitner N, Günther T, Daoud-Gadieh A, Lapa C, Wester HJ. Investigation of the structure-activity relationship at the N-terminal part of minigastrin analogs. EJNMMI Res 2023; 13:65. [PMID: 37421545 DOI: 10.1186/s13550-023-01016-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/29/2023] [Indexed: 07/10/2023] Open
Abstract
BACKGROUND Over the last years, several strategies have been reported to improve the metabolic stability of minigastrin analogs. However, currently applied compounds still reveal limited in vitro and in vivo stability. We thus performed a glycine scan at the N-terminus of DOTA-MGS5 (DOTA-D-Glu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1-Nal) to systematically analyze the peptide structure. We substituted N-terminal amino acids by simple PEG spacers and investigated in vitro stability in human serum. Furthermore, we evaluated different modifications on its tetrapeptide binding sequence (H-Trp-(N-Me)Nle-Asp-1-Nal-NH2). RESULTS Affinity data of all glycine scan peptides were found to be in a low nanomolar range (4.2-8.5 nM). However, a truncated compound lacking the D-γ-Glu-Ala-Tyr sequence revealed a significant loss in CCK-2R affinity. Substitution of the D-γ-Glu-Ala-Tyr-Gly sequence of DOTA-γ-MGS5 (DOTA- D-γ-Glu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1-Nal-NH2) by polyethylene glycol (PEG) spacers of different length exhibited only a minor influence on CCK-2R affinity and lipophilicity. However, in vitro stability of the PEG-containing compounds was significantly decreased. In addition, we confirmed that the tetrapeptide sequence H-Trp-Asp-(N-Me)Nle-1-Nal-NH2 is indeed sufficient for high CCK-2R affinity. CONCLUSION We could demonstrate that a substitution of D-γ-Glu-Ala-Tyr-Gly by PEG spacers simplified the peptide structure of DOTA-MGS5 while high CCK-2R affinity and favorable lipophilicity were maintained. Nevertheless, further optimization with regard to metabolic stability must be carried out for these minigastrin analogs.
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Affiliation(s)
- Nadine Holzleitner
- Department of Chemistry, Technical University of Munich, 85748, Garching, Germany
| | - Thomas Günther
- Department of Chemistry, Technical University of Munich, 85748, Garching, Germany.
| | - Amira Daoud-Gadieh
- Department of Chemistry, Technical University of Munich, 85748, Garching, Germany
| | - Constantin Lapa
- Nuclear Medicine, University Hospital Augsburg, 86156, Augsburg, Germany
| | - Hans-Jürgen Wester
- Department of Chemistry, Technical University of Munich, 85748, Garching, Germany
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Khalily MP, Soydan M. Peptide-based diagnostic and therapeutic agents: Where we are and where we are heading? Chem Biol Drug Des 2023; 101:772-793. [PMID: 36366980 DOI: 10.1111/cbdd.14180] [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: 07/26/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
Peptides are increasingly present in all branches of medicine as innovative drugs, imaging agents, theragnostic, and constituent moieties of other sophisticated drugs such as peptide-drug conjugates. Due to new developments in chemical synthesis strategies, computational biology, recombinant technology, and chemical biology, peptide drug development has made a great progress in the last decade. Numerous natural peptides and peptide mimics have been obtained and studied, covering multiple therapeutic areas. Even though peptides have been investigated across the wide therapeutic spectrum, oncology, metabolism, and endocrinology are the most frequent medical indications of them. This review summarizes the current use of and the emerging new opportunities of peptides for diagnosis and treatment of various diseases.
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Affiliation(s)
- Melek P Khalily
- Department of Basic Science and Health, Cannabis Research Institute, Yozgat Bozok University, Yozgat, Turkey
| | - Medine Soydan
- Department of Chemistry, Faculty of Arts and Science, Middle East Technical University, Ankara, Turkey
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Hörmann AA, Klingler M, Rangger C, Mair C, Joosten L, Franssen GM, Laverman P, von Guggenberg E. Effect of N-Terminal Peptide Modifications on In Vitro and In Vivo Properties of 177Lu-Labeled Peptide Analogs Targeting CCK2R. Pharmaceutics 2023; 15:pharmaceutics15030796. [PMID: 36986657 PMCID: PMC10058949 DOI: 10.3390/pharmaceutics15030796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023] Open
Abstract
The therapeutic potential of minigastrin (MG) analogs for the treatment of cholecystokinin-2 receptor (CCK2R)-expressing cancers is limited by poor in vivo stability or unfavorable accumulation in non-target tissues. Increased stability against metabolic degradation was achieved by modifying the C-terminal receptor-specific region. This modification led to significantly improved tumor targeting properties. In this study, further N-terminal peptide modifications were investigated. Two novel MG analogs were designed starting from the amino acid sequence of DOTA-MGS5 (DOTA-DGlu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1Nal-NH2). Introduction of a penta-DGlu moiety and replacement of the four N-terminal amino acids by a non-charged hydrophilic linker was investigated. Retained receptor binding was confirmed using two CCK2R-expressing cell lines. The effect on metabolic degradation of the new 177Lu-labeled peptides was studied in human serum in vitro, as well as in BALB/c mice in vivo. The tumor targeting properties of the radiolabeled peptides were assessed using BALB/c nude mice bearing receptor-positive and receptor-negative tumor xenografts. Both novel MG analogs were found to have strong receptor binding, enhanced stability, and high tumor uptake. Replacement of the four N-terminal amino acids by a non-charged hydrophilic linker lowered the absorption in the dose-limiting organs, whereas introduction of the penta-DGlu moiety increased uptake in renal tissue.
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Affiliation(s)
- Anton Amadeus Hörmann
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Maximilian Klingler
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Christine Rangger
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Christian Mair
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Lieke Joosten
- Department of Medical Imaging, Nuclear Medicine, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Gerben M. Franssen
- Department of Medical Imaging, Nuclear Medicine, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Peter Laverman
- Department of Medical Imaging, Nuclear Medicine, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| | - Elisabeth von Guggenberg
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
- Correspondence: ; Tel.: +43-512-504-80960
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6
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Zavvar TS, Hörmann AA, Klingler M, Summer D, Rangger C, Desrues L, Castel H, Gandolfo P, von Guggenberg E. Effects of Side Chain and Peptide Bond Modifications on the Targeting Properties of Stabilized Minigastrin Analogs. Pharmaceuticals (Basel) 2023; 16:278. [PMID: 37052226 PMCID: PMC9959130 DOI: 10.3390/ph16020278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/02/2023] [Accepted: 02/06/2023] [Indexed: 02/16/2023] Open
Abstract
Different attempts have been made in the past two decades to develop radiolabeled peptide conjugates with enhanced pharmacokinetic properties in order to improve the application for tumor imaging and peptide receptor radionuclide therapy (PRRT), which targets the cholecystokinin-2 receptor (CCK2R). In this paper, the influence of different side chain and peptide bond modifications has been explored for the minigastrin analog DOTA-DGlu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1Nal-NH2 (DOTA-MGS5). Based on this lead structure, five new derivatives were synthesized for radiolabeling with trivalent radiometals. Different chemical and biological properties of the new derivatives were analyzed. Receptor interaction of the peptide derivatives and cell internalization of the radiolabeled peptides were studied in A431-CCK2R cells. The stability of the radiolabeled peptides in vivo was investigated using BALB/c mice. Tumor targeting of all 111In-labeled peptide conjugates, and of a selected compound radiolabeled with gallium-68 and lutetium-177, was evaluated in BALB/c nude mice xenografted with A431-CCK2R and A431-mock cells. All 111In-labeled conjugates, except [111In]In-DOTA-[Phe8]MGS5, showed a high resistance against enzymatic degradation. A high receptor affinity with IC50 values in the low nanomolar range was confirmed for most of the peptide derivatives. The specific cell internalization over time was 35.3-47.3% for all radiopeptides 4 h after incubation. Only [111In]In-DOTA-MGS5[NHCH3] exhibited a lower cell internalization of 6.6 ± 2.8%. An overall improved resistance against enzymatic degradation was confirmed in vivo. Of the radiopeptides studied, [111In]In-DOTA-[(N-Me)1Nal8]MGS5 showed the most promising targeting properties, with significantly increased accumulation of radioactivity in A431-CCK2R xenografts (48.1 ± 9.2% IA/g) and reduced accumulation of radioactivity in stomach (4.2 ± 0.5% IA/g). However, in comparison with DOTA-MGS5, a higher influence on the targeting properties was observed for the change of radiometal, resulting in a tumor uptake of 15.67 ± 2.21% IA/g for [68Ga]Ga-DOTA-[(N-Me)1Nal8]MGS5 and 35.13 ± 6.32% IA/g for [177Lu]Lu-DOTA-[(N-Me)1Nal8]MGS5.
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Affiliation(s)
- Taraneh Sadat Zavvar
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anton Amadeus Hörmann
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Maximilian Klingler
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Dominik Summer
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Christine Rangger
- Department of Nuclear Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Laurence Desrues
- Inserm U1245, University Rouen Normandie, 76000 Rouen, France
- Institute of Research and Biomedical Innovation (IRIB), 76000 Rouen, France
| | - Hélène Castel
- Inserm U1245, University Rouen Normandie, 76000 Rouen, France
- Institute of Research and Biomedical Innovation (IRIB), 76000 Rouen, France
| | - Pierrick Gandolfo
- Inserm U1245, University Rouen Normandie, 76000 Rouen, France
- Institute of Research and Biomedical Innovation (IRIB), 76000 Rouen, France
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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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Khan NUH, Corlett A, Hutton CA, Haskali MB. Investigation of Fluorine-18 Labelled Peptides for Binding to Cholecystokinin-2 Receptors with High Affinity. Int J Pept Res Ther 2021. [DOI: 10.1007/s10989-021-10310-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AbstractMany cancers of neuroendocrine origin overexpress cholecystokinin-2 receptors (CCK-2R) including medullary thyroid cancer, small cell lung cancer and other lung carcinoids. Fluorine-18 labelled peptides targeting CCK-2R enable direct visualization and quantification of this receptor in vivo using positron emission tomography imaging. CP04 1 and MG11 2 are two previously described truncated peptides derived from the native CCK-2R hormone ligand, gastrin. The N-terminus of the MG11 2 octopeptide was chemically modified with various fluorine containing aromatic (4-fluorobenzoate), heterocyclic (6-fluoronicotinate) and aliphatic (2-fluoropropionate) moieties. To assess the impact these modifications had on CCK-2R binding, ligand-binding assays were conducted using A431 cells overexpressing human CCK-2R. MG11 2 modified by 4-fluorobenzoate (FB-MG11 3) demonstrated the highest binding affinity (0.20 nM) followed by MG11 2 modified by 6-fluoronicotinate (FNic-MG11 4; 0.74 nM) and 2-fluoropropionate (FP-MG11 5; 1.80 nM), respectively. Whilst indirect labelling of MG11 2 using fluorine-18 labelled activated esters of fluorobenzoate and 6-fluoronicotinate was unsuccessful, direct fluorine-18 labelling at the N-terminus modified with 6-nitronicotinate afforded a 47.6% radiochemical yield of [18F]FNic-MG11. Unfortunately, [18F]FNic-MG11 4 was chemically unstable, decomposing slowly through defluorination, thereby impeding any further work with this radiotracer.
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9
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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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Radiopharmaceutical Formulation and Preclinical Testing of 68Ga-Labeled DOTA-MGS5 for the Regulatory Approval of a First Exploratory Clinical Trial. Pharmaceuticals (Basel) 2021; 14:ph14060575. [PMID: 34208516 PMCID: PMC8235783 DOI: 10.3390/ph14060575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 12/15/2022] Open
Abstract
The new minigastrin analog DOTA-MGS5 is a promising new candidate for targeting cholecystokinin-2 receptor (CCK2R)-expressing tumors. To enable the clinical translation of PET/CT imaging using 68Ga-labeled DOTA-MGS5, different quality and safety aspects need to be considered to comply with the regulatory framework for clinical trial application. The preparation of the radiopharmaceutical was established using a cassette-based automated synthesis unit. Product specifications, including analytical procedures and acceptance criteria, were adopted from Ph. Eur. monographs for other 68Ga-labeled radiopharmaceuticals. Non-clinical studies included receptor affinity and cell uptake studies using two different CCK2R-expressing cell lines, as well as pharmacokinetic biodistribution studies in BALB/c mice for dosimetry calculations and toxicological studies in Wistar rats. The produced masterbatches fulfilled the defined acceptance criteria. DOTA-MGS5, with confirmed affinity to the CCK2R, showed a high specific cell uptake and no interaction with other receptors in vitro when radiolabeled with gallium-68. Favorable in vivo properties were observed in biodistribution and dosimetry studies. An effective dose of ~0.01 mSv/MBq was estimated for humans utilizing OLINDA/EXM software. A maximum peptide dose of 50 µg was established for the initial clinical dose based on the toxicity study in rats. The standardized production of [68Ga]Ga-DOTA-MGS5 using an automated synthesis module and the performed non-clinical safety studies support a first exploratory clinical trial with this new PET imaging agent.
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Corlett A, Sani MA, Van Zuylekom J, Ang CS, von Guggenberg E, Cullinane C, Blyth B, Hicks RJ, Roselt PD, Thompson PE, Hutton CA, Haskali MB. A New Turn in Peptide-Based Imaging Agents: Foldamers Afford Improved Theranostics Targeting Cholecystokinin-2 Receptor-Positive Cancer. J Med Chem 2021; 64:4841-4856. [PMID: 33826325 DOI: 10.1021/acs.jmedchem.0c02213] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Proteins adopt unique folded secondary and tertiary structures that are responsible for their remarkable biological properties. This structural complexity is key in designing efficacious peptides that can mimic the three-dimensional structure needed for biological function. In this study, we employ different chemical strategies to induce and stabilize a β-hairpin fold of peptides targeting cholecystokinin-2 receptors for theranostic application (combination of a targeted therapeutic and a diagnostic companion). The newly developed peptides exhibited enhanced folding capacity as demonstrated by circular dichroism (CD) spectroscopy, ion-mobility spectrometry-mass spectrometry, and two-dimensional (2D) NMR experiments. Enhanced folding characteristics of the peptides led to increased biological potency, affording four optimal Ga-68 labeled radiotracers ([68Ga]Ga-4b, [68Ga]Ga-11b-13b) targeting CCK-2R. In particular, [68Ga]Ga-12b and [68Ga]Ga-13b presented improved metabolic stability, enhanced cell internalization, and up to 6 fold increase in tumor uptake. These peptides hold great promise as next-generation theranostic radiopharmaceuticals.
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Affiliation(s)
- Alicia Corlett
- Department of Nuclear Medicine, The Royal Melbourne Hospital, Melbourne, VIC 3000, Australia
| | | | - Jessica Van Zuylekom
- The Centre for Molecular Imaging and Translational Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia
| | - Ching-Seng Ang
- The Mass Spectrometry and Proteomics Facility, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville 3010, Australia
| | | | - Carleen Cullinane
- The Centre for Molecular Imaging and Translational Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Benjamin Blyth
- The Centre for Molecular Imaging and Translational Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Rodney J Hicks
- The Centre for Molecular Imaging and Translational Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Peter D Roselt
- The Radiopharmaceutical Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University (Parkville Campus), Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville VIC 3052, Australia
| | | | - Mohammad B Haskali
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC 3010, Australia.,The Radiopharmaceutical Research Laboratory, The Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia
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