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Shinada M, Suzuki H, Hanyu M, Igarashi C, Matsumoto H, Takahashi M, Hihara F, Tachibana T, Sogawa C, Zhang MR, Higashi T, Sato H, Kurihara H, Yoshii Y, Doi Y. Trace Metal Impurities Effects on the Formation of [ 64Cu]Cu-diacetyl-bis( N4-methylthiosemicarbazone) ([ 64Cu]Cu-ATSM). Pharmaceuticals (Basel) 2023; 17:10. [PMID: 38275997 PMCID: PMC10821298 DOI: 10.3390/ph17010010] [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: 11/15/2023] [Revised: 12/15/2023] [Accepted: 12/19/2023] [Indexed: 01/27/2024] Open
Abstract
[64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM) is a radioactive hypoxia-targeting therapeutic agent being investigated in clinical trials for malignant brain tumors. For the quality management of [64Cu]Cu-ATSM, understanding trace metal impurities' effects on the chelate formation of 64Cu and ATSM is important. In this study, we conducted coordination chemistry studies on metal-ATSM complexes. First, the effects of nonradioactive metal ions (Cu2+, Ni2+, Zn2+, and Fe2+) on the formation of [64Cu]Cu-ATSM were evaluated. When the amount of Cu2+ or Ni2+ added was 1.2 mol or 288 mol, equivalent to ATSM, the labeling yield of [64Cu]Cu-ATSM fell below 90%. Little effect was observed even when excess amounts of Zn2+ or Fe2+ were added to the ATSM. Second, these metals were reacted with ATSM, and chelate formation was measured using ultraviolet-visible (UV-Vis) absorption spectra. UV-Vis spectra showed a rapid formation of Cu2+ and the ATSM complex upon mixing. The rate of chelate formation by Ni2+ and ATSM was lower than that by Cu-ATSM. Zn2+ and Fe2+ showed much slower reactions with the ATSM than Ni2+. Trace amounts of Ni2+, Zn2+, and Fe2+ showed little effect on [64Cu]Cu-ATSM' quality, while the concentration of impurity Cu2+ must be controlled. These results can provide process management tools for radiopharmaceuticals.
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Affiliation(s)
- Mitsuhiro Shinada
- Faculty of Science, Toho University, Funabashi 274-8510, Japan; (M.T.); (T.T.); (Y.D.)
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
- Kanagawa Cancer Center, Kanagawa 241-8515, Japan; (H.S.); (H.K.)
| | - Hisashi Suzuki
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Masayuki Hanyu
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Chika Igarashi
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
- Kanagawa Cancer Center, Kanagawa 241-8515, Japan; (H.S.); (H.K.)
| | - Hiroki Matsumoto
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
- Kanagawa Cancer Center, Kanagawa 241-8515, Japan; (H.S.); (H.K.)
| | - Masashi Takahashi
- Faculty of Science, Toho University, Funabashi 274-8510, Japan; (M.T.); (T.T.); (Y.D.)
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Fukiko Hihara
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Tomoko Tachibana
- Faculty of Science, Toho University, Funabashi 274-8510, Japan; (M.T.); (T.T.); (Y.D.)
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Chizuru Sogawa
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Ming-Rong Zhang
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Tatsuya Higashi
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
| | - Hidemitsu Sato
- Kanagawa Cancer Center, Kanagawa 241-8515, Japan; (H.S.); (H.K.)
| | - Hiroaki Kurihara
- Kanagawa Cancer Center, Kanagawa 241-8515, Japan; (H.S.); (H.K.)
| | - Yukie Yoshii
- Institute for Quantum Medical Science, National Institutes for Quantum Science and Technology, Chiba 263-8555, Japan; (H.S.); (M.H.); (C.I.); (H.M.); (F.H.); (C.S.); (M.-R.Z.); (T.H.)
- Kanagawa Cancer Center, Kanagawa 241-8515, Japan; (H.S.); (H.K.)
| | - Yoshihiro Doi
- Faculty of Science, Toho University, Funabashi 274-8510, Japan; (M.T.); (T.T.); (Y.D.)
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Brown AM, Butman JL, Lengacher R, Vargo NP, Martin KE, Koller A, Śmiłowicz D, Boros E, Robinson JR. N, N-Alkylation Clarifies the Role of N- and O-Protonated Intermediates in Cyclen-Based 64Cu Radiopharmaceuticals. Inorg Chem 2023; 62:1362-1376. [PMID: 36490364 DOI: 10.1021/acs.inorgchem.2c02907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Radioisotopes of Cu, such as 64Cu and 67Cu, are alluring targets for imaging (e.g., positron emission tomography, PET) and radiotherapeutic applications. Cyclen-based macrocyclic polyaminocarboxylates are one of the most frequently examined bifunctional chelators in vitro and in vivo, including the FDA-approved 64Cu radiopharmaceutical, Cu(DOTATATE) (Detectnet); however, connections between the structure of plausible reactive intermediates and their stability under physiologically relevant conditions remain to be established. In this study, we share the synthesis of a cyclen-based, N,N-alkylated spirocyclic chelate, H2DO3AC4H8, which serves as a model for N-protonation. Our combined experimental (in vitro and in vivo) and computational studies unravel complex pH-dependent speciation and enable side-by-side comparison of N- and O-protonated species of relevant 64Cu radiopharmaceuticals. Our studies suggest that N-protonated species are not inherently unstable species under physiological conditions and demonstrate the potential of N,N-alkylation as a tool for the rational design of future radiopharmaceuticals.
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Affiliation(s)
- Alexander M Brown
- Department of Chemistry, Brown University, Providence, Rhode Island02912, United States
| | - Jana L Butman
- Department of Chemistry, Brown University, Providence, Rhode Island02912, United States
| | - Raphael Lengacher
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York11794, United States
| | - Natasha P Vargo
- Department of Chemistry, Brown University, Providence, Rhode Island02912, United States
| | - Kirsten E Martin
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York11794, United States
| | - Angus Koller
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York11794, United States
| | - Dariusz Śmiłowicz
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York11794, United States
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York11794, United States
| | - Jerome R Robinson
- Department of Chemistry, Brown University, Providence, Rhode Island02912, United States
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Herrero Álvarez N, Bauer D, Hernández-Gil J, Lewis JS. Recent Advances in Radiometals for Combined Imaging and Therapy in Cancer. ChemMedChem 2021; 16:2909-2941. [PMID: 33792195 DOI: 10.1002/cmdc.202100135] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Indexed: 12/14/2022]
Abstract
Nuclear medicine is defined as the use of radionuclides for diagnostic and therapeutic applications. The imaging modalities positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are based on γ-emissions of specific energies. The therapeutic technologies are based on β- -particle-, α-particle-, and Auger electron emitters. In oncology, PET and SPECT are used to detect cancer lesions, to determine dosimetry, and to monitor therapy effectiveness. In contrast, radiotherapy is designed to irreparably damage tumor cells in order to eradicate or control the disease's progression. Radiometals are being explored for the development of diagnostic and therapeutic radiopharmaceuticals. Strategies that combine both modalities (diagnostic and therapeutic), referred to as theranostics, are promising candidates for clinical applications. This review provides an overview of the basic concepts behind therapeutic and diagnostic radiopharmaceuticals and their significance in contemporary oncology. Select radiometals that significantly impact current and upcoming cancer treatment strategies are grouped as clinically suitable theranostics pairs. The most important physical and chemical properties are discussed. Standard production methods and current radionuclide availability are provided to indicate whether a cost-efficient use in a clinical routine is feasible. Recent preclinical and clinical developments and outline perspectives for the radiometals are highlighted in each section.
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Affiliation(s)
- Natalia Herrero Álvarez
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - David Bauer
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Javier Hernández-Gil
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.,Biomedical MRI/MoSAIC, Department of Imaging and Pathology, Katholieke Universiteit, Herestraat 49, 3000, Leuven, Belgium
| | - Jason S Lewis
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA.,Department of Radiology, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA.,Department of Pharmacology, Weill-Cornell Medical College, New York, NY, 10065, USA
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4
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Knighton RC, Troadec T, Mazan V, Le Saëc P, Marionneau-Lambot S, Le Bihan T, Saffon-Merceron N, Le Bris N, Chérel M, Faivre-Chauvet A, Elhabiri M, Charbonnière LJ, Tripier R. Cyclam-Based Chelators Bearing Phosphonated Pyridine Pendants for 64Cu-PET Imaging: Synthesis, Physicochemical Studies, Radiolabeling, and Bioimaging. Inorg Chem 2021; 60:2634-2648. [PMID: 33496592 DOI: 10.1021/acs.inorgchem.0c03492] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein we present the preparation of two novel cyclam-based macrocycles (te1pyp and cb-te1pyp), bearing phosphonate-appended pyridine side arms for the coordination of copper(II) ions in the context of 64Cu PET imaging. The two ligands have been prepared through conventional protection-alkylation sequences on cyclam, and their coordination properties have been thoroughly investigated. The corresponding copper complexes have been fully characterized in the solid state (X-ray diffraction analysis) and in solution (EPR and UV-vis spectroscopies). Potentiometric studies combined with spectrometry have also allowed us to determine their thermodynamic stability constants, confirming their high affinity for copper(II) cations. The kinetic inertness of the complexes has been verified by acid-assisted dissociation experiments, enabling their use in 64Cu-PET imaging in mice for the first time. Indeed, the two ligands could be quantitatively radiolabeled under mild conditions, and the resulting 64Cu complexes have demonstrated excellent stability in serum. PET imaging demonstrated a set of features emerging from the combination of picolinates and phosphonate units: high stability in vivo, fast clearance from the body via renal elimination, and most interestingly, very low fixation in the liver. This is in contrast with what was observed for monopicolinate cyclam (te1pa), which had a non-negligible accumulation in the liver, owing probably to its different charge and lipophilicity. These results thus pave the way for the use of such phosphonated pyridine chelators for in vivo 64Cu-PET imaging.
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Affiliation(s)
- Richard C Knighton
- Univ. Brest, UMR CNRS 6521, 6 Avenue Victor Le Gorgeu, 29200 Brest, France
| | - Thibault Troadec
- Univ. Brest, UMR CNRS 6521, 6 Avenue Victor Le Gorgeu, 29200 Brest, France
| | - Valérie Mazan
- Université de Strasbourg, CNRS, UMR 7042-LIMA, Equipe de Chimie Bioorganique et Médicinale, ECPM, 25 rue Becquerel, Strasbourg 67087, France
| | - Patricia Le Saëc
- Université de Nantes, CHRU de Nantes, Centre de Recherche en Cancérologie et Immunologie Nantes Angers (CRCINA), Unité INSERM 1232-CNRS 6299, 8 quai Moncousu, BP 70721, 44007 Nantes Cedex, France
| | - Séverine Marionneau-Lambot
- Université de Nantes, CHRU de Nantes, Centre de Recherche en Cancérologie et Immunologie Nantes Angers (CRCINA), Unité INSERM 1232-CNRS 6299, 8 quai Moncousu, BP 70721, 44007 Nantes Cedex, France
| | - Thomas Le Bihan
- Univ. Brest, UMR CNRS 6521, 6 Avenue Victor Le Gorgeu, 29200 Brest, France
| | | | - Nathalie Le Bris
- Univ. Brest, UMR CNRS 6521, 6 Avenue Victor Le Gorgeu, 29200 Brest, France
| | - Michel Chérel
- Université de Nantes, CHRU de Nantes, Centre de Recherche en Cancérologie et Immunologie Nantes Angers (CRCINA), Unité INSERM 1232-CNRS 6299, 8 quai Moncousu, BP 70721, 44007 Nantes Cedex, France
| | - Alain Faivre-Chauvet
- Université de Nantes, CHRU de Nantes, Centre de Recherche en Cancérologie et Immunologie Nantes Angers (CRCINA), Unité INSERM 1232-CNRS 6299, 8 quai Moncousu, BP 70721, 44007 Nantes Cedex, France
| | - Mourad Elhabiri
- Université de Strasbourg, CNRS, UMR 7042-LIMA, Equipe de Chimie Bioorganique et Médicinale, ECPM, 25 rue Becquerel, Strasbourg 67087, France
| | - Loïc J Charbonnière
- UMR 7178, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, ECPM, , 25 rue Becquerel, 67087 Strasbourg Cedex 2, France
| | - Raphaël Tripier
- Univ. Brest, UMR CNRS 6521, 6 Avenue Victor Le Gorgeu, 29200 Brest, France
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Sana A, Rasheed R, Rafique A, Khaliq T, Jabeen N, Murtaza G. Gynaecological Cancer Diagnostics: 99mTc-Cisplatin Complex as a Future Approach for Early, Prompt and Efficient Diagnosis of Gynaecological Cancer. Curr Med Imaging 2020; 15:611-621. [PMID: 32008509 DOI: 10.2174/1573405614666180809123233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 07/06/2018] [Accepted: 07/16/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Gynaecological cancers (GCCa) are common and have a significant mortality rate all over the world. Early diagnosis of cancer can play a key role in the treatment and survival of a patient. Identification, staging, treatment, and monitoring of gynaecological malignancies is being done successfully by nuclear medicines. DISCUSSION Currently, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) centered imaging techniques are being developed for use in patients with GCCa as a diagnostic tool. The present work elucidates several clinical studies on the use of radiopharmaceuticals, based on their effectiveness, in the early detection and management of GCCa. It also highlights the importance of reconsidering the biology for nuclear imaging as a future modality for early, rapid and efficient diagnosis of gynecological cancers. This comprehensive review is a part of our study designed to detect gynaecological cancers at an early stage using radionuclide complex, 99m Tc-Cisplatin. CONCLUSION This article summarizes the significance of radioscintigraphy such as single-photon emission computed tomography (SPECT) and PET for identification of GCCa in the experimental humans and animals.
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Affiliation(s)
- Ayesha Sana
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad, Pakistan
| | - Rashid Rasheed
- Institute of Nuclear, Medicines, Oncology and Radiations (INOR), Ayub Medical Hospital, Abbottabad, Pakistan
| | - Asma Rafique
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad, Pakistan
| | - Tooba Khaliq
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad, Pakistan
| | - Nazish Jabeen
- Department of Pharmacy, COMSATS University Islamabad, Abbottabad, Pakistan
| | - Ghulam Murtaza
- Department of Pharmacy, COMSATS University Islamabad, Lahore, Pakistan
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6
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Le Bihan T, Le Bris N, Bernard H, Platas-Iglesias C, Tripier R. Synthesis of Orthogonal N
-Protected C
-Functional Side-Bridged Cyclams to Give Access to Unsymmetrical Constrained BCAs. European J Org Chem 2019. [DOI: 10.1002/ejoc.201901013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Thomas Le Bihan
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
| | - Nathalie Le Bris
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
| | - Hélène Bernard
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
| | - Carlos Platas-Iglesias
- Departamento de Química; Facultade de Ciencias & Centro de Investigaciones Científicas Avanzadas; Universidade da Coruña; 15071 A Coruña Spain
| | - Raphaël Tripier
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
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7
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Pandya DN, Bhatt N, Yuan H, Day CS, Ehrmann BM, Wright M, Bierbach U, Wadas TJ. Zirconium tetraazamacrocycle complexes display extraordinary stability and provide a new strategy for zirconium-89-based radiopharmaceutical development. Chem Sci 2017; 8:2309-2314. [PMID: 28451334 PMCID: PMC5363373 DOI: 10.1039/c6sc04128k] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/12/2016] [Indexed: 11/21/2022] Open
Abstract
We report our initial investigations into the use of tetraazamacrocycles as zirconium-89 chelators. We describe the synthesis and complete characterization of several Zr tetraazamacrocycle complexes, and definitively describe the first crystal structure of zirconium 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (Zr-DOTA) using single crystal X-ray diffraction analysis. After evaluating several radioactive analogs, we found that 89Zr-DOTA is superior to 89Zr-DFO, the only 89Zr-complex to be used clinically in 89Zr-radiopharmaceutical applications. Finally, we provide a rationale for the unanticipated and extraordinary stability of these complexes in vitro and in vivo. These results may inform the development of safer and more robust immuno-PET agents for precision medicine applications.
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Affiliation(s)
- Darpan N Pandya
- Department of Cancer Biology , Wake Forest School of Medicine , Winston-Salem , NC 27157 , USA . ;
| | - Nikunj Bhatt
- Department of Cancer Biology , Wake Forest School of Medicine , Winston-Salem , NC 27157 , USA . ;
| | - Hong Yuan
- Department of Radiology , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Cynthia S Day
- Department of Chemistry , Wake Forest University , Winston-Salem , NC 27109 , USA
| | - Brandie M Ehrmann
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599 , USA
| | - Marcus Wright
- Department of Chemistry , Wake Forest University , Winston-Salem , NC 27109 , USA
| | - Ulrich Bierbach
- Department of Chemistry , Wake Forest University , Winston-Salem , NC 27109 , USA
| | - Thaddeus J Wadas
- Department of Cancer Biology , Wake Forest School of Medicine , Winston-Salem , NC 27157 , USA . ;
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8
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Jurek P, Reibenspies JH, Kiefer GE. CB-TE2A(+)·Cl(-)·3H2O: a short intermolecular hydrogen bond between zwitterionic bicyclo[6.6.2]tetraamine macrocycles. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2016; 72:139-42. [PMID: 26846499 DOI: 10.1107/s2053229616000358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 01/07/2016] [Indexed: 11/10/2022]
Abstract
1,4,8,11-Tetraazabicyclo[6.6.2]hexadecane-4,11-diacetic acid (CB-TE2A) is of much interest in nuclear medicine for its ability to form copper complexes that are kinetically inert, which is beneficial in vivo to minimize the loss of radioactive copper. The structural chemistry of the hydrated HCl salt of CB-TE2A, namely 11-carboxymethyl-1,8-tetraaza-4,11-diazoniabicyclo[6.6.2]hexadecane-4-acetate chloride trihydrate, C16H31N4O4(+)·Cl(-)·3H2O, is described. The compound crystallized as a positively charged zwitterion with a chloride counter-ion. Two of the amine groups in the macrocyclic ring are protonated. Formally, a single negative charge is shared between two of the carboxylic acid groups, while one chloride ion balances the charge. Two intramolecular hydrogen bonds are observed between adjacent pairs of N atoms of the macrocycle. Two intramolecular hydrogen bonds are also observed between the protonated amine groups and the pendant carboxylate groups. A short intermolecular hydrogen bond is observed between two partially negatively charged O atoms on adjacent macrocycles. The result is a one-dimensional polymeric zigzag chain that propagates parallel to the crystallographic a direction. A second intermolecular interaction is a hydrogen-bonding network in the crystallographic b direction. The carbonyl group of one macrocycle is connected through the three water molecules of hydration to the carbonyl group of another macrocycle.
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Affiliation(s)
- Paul Jurek
- Macrocyclics, Inc., 1309 Record Crossing, Dallas TX 75235, USA
| | | | - Garry E Kiefer
- Macrocyclics, Inc., 1309 Record Crossing, Dallas TX 75235, USA
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9
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Matz DL, Jones DG, Roewe KD, Gorbet MJ, Zhang Z, Chen Z, Prior TJ, Archibald SJ, Yin G, Hubin TJ. Synthesis, structural studies, kinetic stability, and oxidation catalysis of the late first row transition metal complexes of 4,10-dimethyl-1,4,7,10-tetraazabicyclo[6.5.2]pentadecane. Dalton Trans 2015; 44:12210-24. [PMID: 25876140 DOI: 10.1039/c5dt00742a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synthetic details for 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.5.2]pentadecane, the dimethyl ethylene cross-bridged homocyclen ligand are presented for the first time. Its novel Mn(2+), Fe(2+), Mn(3+), and Fe(3+) complexes have been synthesized and characterized. X-ray crystal structures were obtained for both manganese complexes, along with five additional Co(3+), Cu(2+), and Zn(2+) structures, the first structural characterization of complexes of this ligand. Each complex has the cis-V configuration of the cross-bridged macrocycle ring, leaving cis labile binding sites for interaction of the complex with oxidants and/or substrates. The copper(II) complex kinetic stability in 5 M HCl and at elevated temperatures was determined and compared to related complexes in the literature. The electronic properties of the manganese and iron complexes were evaluated using solid state magnetic moment determination and acetonitrile solution electronic spectroscopy, revealing high spin metal complexes in all cases. Cyclic voltammetry in acetonitrile of the divalent iron and manganese complexes revealed reversible redox processes, suggesting catalytic reactivity involving electron transfer processes are possible for both complexes. Screening of the Mn(2+) and Fe(2+) complexes for oxidation catalysis using hydrogen peroxide as the terminal oxidant showed both complexes are worthy of continued development.
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Affiliation(s)
- Dallas L Matz
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA.
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10
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Yang YK, Pack EC, Lee SH, Yoo HS, Choi DW, Ly SY. Real-time Detection of Trace Copper in Brain and Kidney of Fish for Medical Diagnosis. Toxicol Res 2015; 30:311-6. [PMID: 25584152 PMCID: PMC4289933 DOI: 10.5487/tr.2014.30.4.311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 12/24/2014] [Accepted: 12/26/2014] [Indexed: 11/24/2022] Open
Abstract
For the detection of trace copper to be used in medical diagnosis, a sensitive handmade carbon nanotube paste electrode (PE) was developed using voltammetry. Analytical optimized conditions were found at 0.05 V anodic peak current. In the same conditions, various common electrodes were compared using stripping voltammetry, and the PE was found to be more sharply sensitive than other common electrodes. At optimum conditions, the working ranges of 3~19 μgL−1 were obtained. The relative standard deviation of 70.0 μgL−1 was determined to be 0.117% (n = 15), and the detection limit (S/N) was found to be 0.6 μgL−1 (9.4 × 10−9 M). The results were applied in detecting copper traces in the kidney and the brain cells of fish.
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Affiliation(s)
- Young Kyun Yang
- Department of Basic Education, Seoul National University of Technology, Seoul, Korea
| | - Eun Chul Pack
- Department of Public Health Science, Graduate School, Korea University, Seoul, Korea
| | - Seung Ha Lee
- Department of Public Health Science, Graduate School, Korea University, Seoul, Korea
| | - Hai-Soo Yoo
- Korea Ocean R&D Institute, P. O. Box 29, Ansan, Kore
| | - Dal Woong Choi
- Department of Public Health Science, Graduate School, Korea University, Seoul, Korea
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Sugiura G, Kühn H, Sauter M, Haberkorn U, Mier W. Radiolabeling strategies for tumor-targeting proteinaceous drugs. Molecules 2014; 19:2135-65. [PMID: 24552984 PMCID: PMC6271853 DOI: 10.3390/molecules19022135] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 01/16/2014] [Accepted: 02/01/2014] [Indexed: 12/15/2022] Open
Abstract
Owing to their large size proteinaceous drugs offer higher operative information content compared to the small molecules that correspond to the traditional understanding of druglikeness. As a consequence these drugs allow developing patient-specific therapies that provide the means to go beyond the possibilities of current drug therapy. However, the efficacy of these strategies, in particular "personalized medicine", depends on precise information about individual target expression rates. Molecular imaging combines non-invasive imaging methods with tools of molecular and cellular biology and thus bridges current knowledge to the clinical use. Moreover, nuclear medicine techniques provide therapeutic applications with tracers that behave like the diagnostic tracer. The advantages of radioiodination, still the most versatile radiolabeling strategy, and other labeled compounds comprising covalently attached radioisotopes are compared to the use of chelator-protein conjugates that are complexed with metallic radioisotopes. With the techniques using radioactive isotopes as a reporting unit or even the therapeutic principle, care has to be taken to avoid cleavage of the radionuclide from the protein it is linked to. The tracers used in molecular imaging require labeling techniques that provide site specific conjugation and metabolic stability. Appropriate choice of the radionuclide allows tailoring the properties of the labeled protein to the application required. Until the event of positron emission tomography the spectrum of nuclides used to visualize cellular and biochemical processes was largely restricted to iodine isotopes and 99m-technetium. Today, several nuclides such as 18-fluorine, 68-gallium and 86-yttrium have fundamentally extended the possibilities of tracer design and in turn caused the need for the development of chemical methods for their conjugation.
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Affiliation(s)
- Grant Sugiura
- Department of Nuclear Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg D-69120, Germany
| | - Helen Kühn
- Department of Nuclear Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg D-69120, Germany
| | - Max Sauter
- Department of Nuclear Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg D-69120, Germany
| | - Uwe Haberkorn
- Department of Nuclear Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg D-69120, Germany
| | - Walter Mier
- Department of Nuclear Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 400, Heidelberg D-69120, Germany.
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12
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Lozza C, Navarro-Teulon I, Pèlegrin A, Pouget JP, Vivès E. Peptides in receptor-mediated radiotherapy: from design to the clinical application in cancers. Front Oncol 2013; 3:247. [PMID: 24093086 PMCID: PMC3782707 DOI: 10.3389/fonc.2013.00247] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/06/2013] [Indexed: 12/29/2022] Open
Abstract
Short peptides can show high affinity for specific receptors overexpressed on tumor cells. Some of these are already used in cancerology as diagnostic tools and others are in clinical trials for therapeutic applications. Therefore, peptides exhibit great potential as a diagnostic tool but also as an alternative or an additional antitumoral approach upon the covalent attachment of a therapeutic moiety such as a radionuclide or a cytotoxic drug. The chemistry offers flexibility to graft onto the targeting-peptide either fluorine or iodine directly, or metallic radionuclides through appropriate chelating agent. Since short peptides are straightforward to synthesize, there is an opportunity to further improve existing peptides or to design new ones for clinical applications. However, several considerations have to be taken into account to optimize the recognition properties of the targeting-peptide to its receptor, to improve its stability in the biological fluids and its residence in the body, or to increase its overall therapeutic effect. In this review, we highlight the different aspects which need to be considered for the development of an efficient peptide receptor-mediated radionuclide therapy in different neoplasms.
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Affiliation(s)
- Catherine Lozza
- Institut de Recherche en Cancérologie de Montpellier , Montpellier , France ; INSERM, U896 , Montpellier , France ; Université Montpellier 1 , Montpellier , France ; Institut Régional du Cancer Montpellier , Montpellier , France
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13
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Yan X, Zhou Y, Liu S. Optical imaging of tumors with copper-labeled rhodamine derivatives by targeting mitochondria. Theranostics 2012; 2:988-98. [PMID: 23139726 PMCID: PMC3493204 DOI: 10.7150/thno.4818] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 08/21/2012] [Indexed: 11/22/2022] Open
Abstract
In this study, we evaluated Cu(L1) in two xenografted tumor-bearing (U87MG and MDA-MB-435) animal models to prove the concept that Cu(II)-labeled rhodamine derivatives, Cu(L) (L = L1 - L4) are useful as selective fluorescent probes for tumor imaging. We found that both multidrug resistance (MDR) negative U87MG gliomas and MDR-positive MDA-MB-435 breast tumors could be visualized. Because of tissue attenuation, accurate quantification of tumor uptake was difficult by optical methods. Therefore, 64Cu(L) (L = L1 - L4) were evaluated to compare their biodistribution properties. It was found that all four 64Cu radiotracers had a high glioma uptake (64Cu(L1): 5.71± 1.43 %ID/g; 64Cu(L2): 5.98 ± 2.75 %ID/g; 64Cu(L3): 4.28 ± 1.45 %ID/g; and 64Cu(L4): 6.25 ± 3.42 %ID/g) with 64Cu(L1) showing the highest tumor/background ratios. In athymic nude mice bearing MDA-MB-435 breast cancer xenografts, 64Cu(L4) showed almost identical normal organ uptake to that in the glioma-bearing animals, but its breast tumor uptake (1.26 ± 0.10% ID/g) was significantly lower (p < 0.001) than that in the glioma (6.25 ± 3.42% ID/g) because of MDR Pgps (P-glycoproteins) and MRPs (multidrug resistance-associated proteins) overexpressed in the xenografted MDA-MB-435 breast tumors. Results from cellular staining assays showed that both Cu(L2) and Cu(L4) were able to localize in mitochondria of U87MG cells, and their tumor selectivity was caused by the elevated negative mitochondrial potential in U87MG glioma cells as compared to that in human fibroblast cells. On the basis of these results, it was concluded that Cu(L) (L = L1 - L4) are useful as selective fluorescent probes for cellular staining assays and optical tumor imaging while 64Cu(L) (L = L1 - L4) have the potential as PET radiotracers for tumor imaging. This study represents a good example of dual modality imaging (PET and optical) using two agents, 64Cu(L) and Cu(L), with identical chemical composition. Future research will focus on developing new fluorescent probes with longer wavelength and reduced liver uptake.
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14
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Guo Y, Ferdani R, Anderson CJ. Preparation and biological evaluation of (64)Cu labeled Tyr(3)-octreotate using a phosphonic acid-based cross-bridged macrocyclic chelator. Bioconjug Chem 2012; 23:1470-7. [PMID: 22663248 DOI: 10.1021/bc300092n] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Somatostatin receptors (SSTr) are overexpressed in a wide range of neuroendocrine tumors, making them excellent targets for nuclear imaging and therapy, and radiolabeled somatostatin analogues have been investigated for positron emission tomography imaging and radionuclide therapy of SSTr-positive tumors, especially of the subtype-2 (SSTr2). The aim of this study was to develop a somatostatin analogue, Tyr(3)-octreotate (Y3-TATE), conjugated to a novel cross-bridged macrocyclic chelator, 11-carboxymethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4-methanephosphonic acid (CB-TE1A1P). Unlike traditional cross-bridged macrocycles, such as 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (CB-TE2A), CB-TE1A1P-Y3-TATE was radiolabeled with (64)Cu in high purity and high specific activity using mild conditions. Saturation binding assays revealed that (64)Cu-CB-TE1A1P-Y3-TATE had comparable binding affinity but bound to more binding sites in AR42J rat pancreatic tumor cell membranes than (64)Cu-CB-TE2A-Y3-TATE. Both radiopharmaceuticals showed comparable uptake in SSTr2 positive tissues in AR42J tumor-bearing rats. (64)Cu-CB-TE1A1P-Y3-TATE demonstrated improved blood clearance compared to (64)Cu-CB-TE2A-Y3-TATE, as the tumor/blood ratios of (64)Cu-CB-TE1A1P-Y3-TATE were shown to be significantly higher than those of (64)Cu-CB-TE2A-Y3-TATE at 4 and 24 h postinjection. (64)Cu-CB-TE1A1P-Y3-TATE, in spite of a relatively high kidney uptake, accumulated less in nontarget organs such as liver, lung, and bone. Small animal PET/CT imaging of (64)Cu-CB-TE1A1P-Y3-TATE in AR42J tumor bearing rats validated significant uptake and good contrast in the tumor. This study suggests that CB-TE1A1P is a promising bifunctional chelator for (64)Cu-labeled for Y3-TATE, owing to high binding affinity and target tissue uptake, the ability to radiolabel the agent at lower temperatures, and improved tumor/nontarget organ ratios over (64)Cu-CB-TE2A-Y3-TATE.
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Affiliation(s)
- Yunjun Guo
- Mallinckrodt Institute of Radiology, Washington University, St. Louis, MO, USA
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15
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Ferdani R, Stigers DJ, Fiamengo AL, Wei L, Li BTY, Golen JA, Rheingold AL, Weisman GR, Wong EH, Anderson CJ. Synthesis, Cu(II) complexation, 64Cu-labeling and biological evaluation of cross-bridged cyclam chelators with phosphonate pendant arms. Dalton Trans 2012; 41:1938-50. [PMID: 22170043 PMCID: PMC3462348 DOI: 10.1039/c1dt11743b] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new class of cross-bridged cyclam-based macrocycles featuring phosphonate pendant groups has been developed. 1,4,8,11-tetraazacyclotetradecane-1,8-di(methanephosphonic acid) (CB-TE2P, 1) and 1,4,8,11-tetraazacyclotetradecane-1-(methanephosphonic acid)-8-(methanecarboxylic acid) (CB-TE1A1P, 2) have been synthesized and have been shown to readily form neutral copper(II) complexes at room temperature as the corresponding dianions. Both complexes showed high kinetic inertness to demetallation and crystal structures confirmed complete encapsulation of copper(II) ion within each macrocycle's cleft-like structure. Unprecedented for cross-bridged cyclam derivatives, both CB-TE2P (1) and CB-TE1A1P (2) can be radiolabeled with (64)Cu at room temperature in less than 1 h with specific activities >1 mCi μg(-1). The in vivo behavior of both (64)Cu-CB-TE2P and (64)Cu-CB-TE1A1P were investigated through biodistribution studies using healthy male Lewis rats. Both new compounds showed rapid clearance with similar or lower accumulation in non-target organs/tissues when compared to other copper chelators including CB-TE2A, NOTA and Diamsar.
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Affiliation(s)
- Riccardo Ferdani
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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16
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Abstract
Alteration in mitochondrial transmembrane potential (ΔΨ(m)) is an important characteristic of cancer. The observation that the enhanced negative mitochondrial potential is prevalent in tumor cell phenotype provides a conceptual basis for development of mitochondrion-targeting therapeutic drugs and molecular imaging probes. Since plasma and mitochondrial potentials are negative, many delocalized organic cations, such as rhodamine-123 and (3)H-tetraphenylphosphonium, are electrophoretically driven through these membranes, and able to localize in the energized mitochondria of tumor cells. Cationic radiotracers, such as (99m)Tc-Sestamibi and (99m)Tc-Tetrofosmin, have been clinically used for diagnosis of cancer by single photon emission computed tomography (SPECT) and noninvasive monitoring of the multidrug resistance (MDR) transport function in tumors of different origin. However, their diagnostic and prognostic values are often limited due to their insufficient tumor localization (low radiotracer tumor uptake) and high radioactivity accumulation in the chest and abdominal regions (low tumor selectivity). In contrast, the (64)Cu-labeled phosphonium cations represent a new class of PET (positron emission tomography) radiotracers with good tumor uptake and high tumor selectivity. This review article will focus on our recent experiences in evaluation of (64)Cu-labeled phosphonium cations as potential PET radiotracers. The main objective is to illustrate the impact of radiometal chelate on physical, chemical, and biological properties of (64)Cu radiotracers. It will also discuss some important issues related to their tumor selectivity and possible tumor localization mechanism.
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Affiliation(s)
- Yang Zhou
- School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, Phone: 765-494-0236
| | - Shuang Liu
- School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907, Phone: 765-494-0236
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17
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Zhou Y, Kim YS, Yan X, Jacobson O, Chen X, Liu S. 64Cu-labeled lissamine rhodamine B: a promising PET radiotracer targeting tumor mitochondria. Mol Pharm 2011; 8:1198-208. [PMID: 21545131 DOI: 10.1021/mp200025m] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Enhanced mitochondrial potential in carcinoma cells is an important characteristic of cancer. It is of great current interest to develop a radiotracer that is sensitive to mitochondrial potential changes at the early stage of tumor growth. In this report, we present the synthesis and evaluation of (64)Cu-labeled Lissamine rhodamine B (LRB), (64)Cu(DOTA-LRB) (DOTA-LRB = 2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)-5-(N-(2-(2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclo-dodecan-1-yl)acetamido)ethyl)sulfamoyl)benzenesulfonate) as a new radiotracer for imaging tumors in athymic nude mice bearing U87MG human glioma xenografts by positron emission tomography (PET). We also explored its localization mechanism using Cu(DOTA-LRB) as the fluorescent probe in both the U87MG human glioma cell line and the cultured primary U87MG glioma cells. It was found that (64)Cu(DOTA-LRB) had the highest tumor uptake (6.54 ± 1.50, 6.91 ± 1.26, 5.68 ± 1.13, 7.58 ± 1.96, and 5.14 ± 1.50%ID/g at 0.5, 1, 2, 4, and 24 h postinjection, respectively) among many (64)Cu-labeled organic cations evaluated in the same animal model. The cellular staining study indicated that Cu(DOTA-LRB) was able to localize in mitochondria of U87MG glioma cells due to the enhanced negative mitochondrial potential. This statement is completely supported by the results from decoupling experiment with carbonylcyanide-m-chlorophenylhydrazone (CCCP). MicroPET data showed that the U87MG glioma tumors were clearly visualized as early as 30 min postinjection with (64)Cu(DOTA-LRB). (64)Cu(DOTA-LRB) remained stable during renal excretion, but underwent extensive degradation during hepatobiliary excretion. On the basis of the results from this study, it was concluded that (64)Cu(DOTA-LRB) represents a new class of promising PET radiotracers for noninvasive imaging of the MDR-negative tumors.
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Affiliation(s)
- Yang Zhou
- School of Health Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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18
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Rockey WM, Huang L, Kloepping KC, Baumhover NJ, Giangrande PH, Schultz MK. Synthesis and radiolabeling of chelator-RNA aptamer bioconjugates with copper-64 for targeted molecular imaging. Bioorg Med Chem 2011; 19:4080-90. [PMID: 21658962 DOI: 10.1016/j.bmc.2011.05.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/04/2011] [Accepted: 05/09/2011] [Indexed: 12/14/2022]
Abstract
Ribonucleic acid (RNA) aptamers with high affinity and specificity for cancer-specific cell-surface antigens are promising reagents for targeted molecular imaging of cancer using positron emission tomography (PET). For this application, aptamers must be conjugated to chelators capable of coordinating PET-radionuclides (e.g., copper-64, (64)Cu) to enable radiolabeling for in vivo imaging of tumors. This study investigates the choice of chelator and radiolabeling parameters such as pH and temperature for the development of (64)Cu-labeled RNA-based targeted agents for PET imaging. The characterization and optimization of labeling conditions are described for four chelator-aptamer complexes. Three commercially available bifunctional macrocyclic chelators (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid mono N-hydroxysuccinimide [DOTA-NHS]; S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid [p-SCN-Bn-NOTA]; and p-SCN-Bn-3,6,9,15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid [p-SCN-Bn-PCTA]), as well as the polyamino-macrocyclic diAmSar (3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane-1,8-diamine) were conjugated to A10-3.2, a RNA aptamer which has been shown to bind specifically to a prostate cancer-specific cell-surface antigen (PSMA). Although a commercial bifunctional version of diAmSar was not available, RNA conjugation with this chelator was achieved in a two-step reaction by the addition of a disuccinimidyl suberate linker. Radiolabeling parameters (e.g., pH, temperature, and time) for each chelator-RNA conjugate were assessed in order to optimize specific activity and RNA stability. Furthermore, the radiolabeled chelator-coupled RNA aptamers were evaluated for binding specificity to their target antigen. In summary, key parameters were established for optimal radiolabeling of RNA aptamers for eventual PET imaging with (64)Cu.
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Affiliation(s)
- William M Rockey
- Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, United States
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19
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Ma Y, Kiesewetter DO, Lang L, Gu D, Chen X. Applications of LC-MS in PET radioligand development and metabolic elucidation. Curr Drug Metab 2011; 11:483-93. [PMID: 20540692 DOI: 10.2174/138920010791636167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 05/11/2010] [Indexed: 11/22/2022]
Abstract
Positron emission tomography (PET) is a very sensitive molecular imaging technique that when employed with an appropriate radioligand has the ability to quantititate physiological processes in a non-invasive manner. Since the imaging technique detects all radioactive emissions in the field of view, the presence and biological activity of radiolabeled metabolites must be determined for each radioligand in order to validate the utility of the radiotracer for measuring the desired physiological process. Thus, the identification of metabolic profiles of radiolabeled compounds is an important aspect of design, development, and validation of new radiopharmaceuticals and their applications in drug development and molecular imaging. Metabolite identification for different chemical classes of radiopharmaceuticals allows rational design to minimize the formation and accumulation of metabolites in the target tissue, either through enhanced excretion or minimized metabolism. This review will discuss methods for identifying and quantitating metabolites during the pre-clinical development of radiopharmaceuticals with special emphasis on the application of LC/MS.
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Affiliation(s)
- Ying Ma
- Laboratory of Molecular Imaging and Nanomedicine (LOMIN), National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of health (NIH), Bethesda, MD 20892, USA
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20
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Zhou Y, Kim YS, Shi J, Jacobson O, Chen X, Liu S. Evaluation of 64Cu-labeled acridinium cation: a PET radiotracer targeting tumor mitochondria. Bioconjug Chem 2011; 22:700-8. [PMID: 21413736 DOI: 10.1021/bc100458p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This report presents the synthesis and evaluation of (64)Cu(DO3A-xy-ACR) (DO3A-xy-ACR = 2,6-bis(dimethylamino)-10-(4-((4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)methyl)benzyl)acridin-10-ium) as a radiotracer for imaging tumors in athymic nude mice bearing U87MG glioma xenografts by PET (positron emission tomography). The biodistribution data suggested that (64)Cu(DO3A-xy-ACR) was excreted mainly through the renal system with >65% of injected radioactivity being recovered from urine samples at 1 h postinjection (p.i.). The tumor uptake of (64)Cu(DO3A-xy-ACR) was 1.07 ± 0.23, 1.58 ± 0.55, 2.71 ± 0.66, 3.47 ± 1.19, and 3.52 ± 1.72%ID/g at 0.5, 1, 2, 4, and 24 h p.i., respectively. (64)Cu(DO3A-xy-ACR) had very high liver uptake (31.90 ± 3.98, 24.95 ± 5.64, 15.20 ± 4.29, 14.09 ± 6.82, and 8.18 ± 1.27%ID/g at 0.5, 1, 2, 4, and 24 h p.i., respectively) with low tumor/liver ratios. MicroPET studies showed that the tumors were clearly visualized as early as 30 min p.i. in the glioma-bearing mouse administered with (64)Cu(DO3A-xy-ACR). The high liver radioactivity accumulation was also seen. (64)Cu(DO3A-xy-ACR) had a relatively high metabolic stability during excretion via both renal and hepatobiliary routes, but it was completely decomposed in the liver homogenate. We explored the localization mechanism of Cu(DO3A-xy-ACR) using both U87MG human glioma and the cultured primary U87MG glioma cells. The results from the cellular staining assays showed that (64)Cu(DO3A-xy-ACR) is able to localize in the mitochondria of living U87MG glioma cells due to the enhanced negative mitochondrial potential as compared to normal cells. Although (64)Cu(DO3A-xy-ACR) is not an ideal PET radiotracer for tumor imaging due to its high liver uptake, the results from this study strongly suggest that (64)Cu-labeled acridinium cations are indeed able to localize in the energized mitochondria of tumor cells.
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Affiliation(s)
- Yang Zhou
- School of Health Sciences, Purdue University , West Lafayette, Indiana, United States
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Wadas TJ, Wong EH, Weisman GR, Anderson CJ. Coordinating radiometals of copper, gallium, indium, yttrium, and zirconium for PET and SPECT imaging of disease. Chem Rev 2010; 110:2858-902. [PMID: 20415480 PMCID: PMC2874951 DOI: 10.1021/cr900325h] [Citation(s) in RCA: 668] [Impact Index Per Article: 47.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Thaddeus J Wadas
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd., Campus Box 8225 St. Louis, Missouri 63110, USA.
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Stigers DJ, Ferdani R, Weisman GR, Wong EH, Anderson CJ, Golen JA, Moore C, Rheingold AL. A new phosphonate pendant-armed cross-bridged tetraaminechelator accelerates copper(ii) binding for radiopharmaceutical applications. Dalton Trans 2010; 39:1699-701. [DOI: 10.1039/b920871b] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Svobodová I, Havlíčková J, Plutnar J, Lubal P, Kotek J, Hermann P. Metal Complexes of 4,11-Dimethyl-1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid) - Thermodynamic and Formation/Decomplexation Kinetic Studies. Eur J Inorg Chem 2009. [DOI: 10.1002/ejic.200900358] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Boswell CA, Regino CAS, Baidoo KE, Wong KJ, Milenic DE, Kelley JA, Lai CC, Brechbiel MW. A novel side-bridged hybrid phosphonate/acetate pendant cyclam: synthesis, characterization, and 64Cu small animal PET imaging. Bioorg Med Chem 2008; 17:548-52. [PMID: 19101152 DOI: 10.1016/j.bmc.2008.11.073] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2008] [Revised: 11/25/2008] [Accepted: 11/29/2008] [Indexed: 10/21/2022]
Abstract
Copper-64 (t(1/2)=12.7h; beta(+): 0.653 MeV, 17.4%; beta(-): 0.578 MeV, 39%) is produced in a biomedical cyclotron and has applications in both imaging and therapy. Macrocyclic chelators are widely used as bifunctional chelators to bind copper radionuclides to antibodies and peptides owing to their relatively high kinetic stability. A novel side-bridged cyclam featuring both pendant acetate and phosphonate groups was synthesized using a Kabachnik-Fields approach followed by hydrobromic acid deprotection. The Cu(II) complex of the novel ligand was synthesized, radiolabeling with (64)Cu was demonstrated, and in vitro (serum) stability was performed. In addition, in vivo distribution and clearance of the (64)Cu-labeled complex was visualized by positron emission tomography (PET) imaging. This novel chelate may be useful in (64)Cu-mediated diagnostic positron emission tomography (PET) imaging as well as targeted radiotherapeutic applications.
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Affiliation(s)
- C Andrew Boswell
- Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Building 10 Center Drive, Bethesda, MA 20892-1088, United States
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25
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Yang CT, Kim YS, Wang J, Wang L, Shi J, Li ZB, Chen X, Fan M, Li JJ, Liu S. 64Cu-labeled 2-(diphenylphosphoryl)ethyldiphenylphosphonium cations as highly selective tumor imaging agents: effects of linkers and chelates on radiotracer biodistribution characteristics. Bioconjug Chem 2008; 19:2008-22. [PMID: 18763821 DOI: 10.1021/bc8002056] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Radiolabeled organic cations, such as triphenylphosphonium (TPP), represents a new class of radiotracers for imaging cancers and the transport function of multidrug resistance P-glycoproteins (particularly MDR1 Pgp) by single photon emission computed tomography (SPECT) or positron emission tomography (PET). This report presents the synthesis and biological evaluation of (64)Cu-labeled 2-(diphenylphosphoryl)ethyldiphenylphosphonium (TPEP) cations as novel PET radiotracers for tumor imaging. Biodistribution studies were performed using the athymic nude mice bearing subcutaneous U87MG human glioma xenografts to explore the impact of linkers, bifunctional chelators (BFCs), and chelates on biodistribution characteristics of the (64)Cu-labeled TPEP cations. Metabolism studies were carried out using normal athymic nude mice to determine the metabolic stability of four (64)Cu radiotracers. It was found that most (64)Cu radiotracers described in this study have significant advantages over (99m)Tc-Sestamibi for their high tumor/heart and tumor/muscle ratios. Both BFCs and linkers have significant impact on biological properties of (64)Cu-labeled TPEP cations. For example, (64)Cu(DO3A-xy-TPEP) has much lower liver uptake and better tumor/liver ratios than (64)Cu(DO3A-xy-TPP), suggesting that TPEP is a better mitochondrion-targeting molecule than TPP. Replacing DO3A with DO2A results in (64)Cu(DO2A-xy-TPEP) (+), which has a lower tumor uptake than (64)Cu(DO3A-xy-TPEP). Substitution of DO3A with NOTA-Bn leads to a significant decrease in tumor uptake for (64)Cu(NOTA-Bn-xy-TPEP). The use of DOTA-Bn to replace DO3A has little impact on the tumor uptake, but the tumor/liver ratio of (64)Cu(DOTA-Bn-xy-TPEP) (-) is not as good as that of (64)Cu(DO3A-xy-TPEP), probably due to the aromatic benzene ring in DOTA-Bn. Addition of an extra acetamido group in (64)Cu(DOTA-xy-TPEP) results in a lower liver uptake, but tumor/liver ratios of (64)Cu(DOTA-xy-TPEP) and (64)Cu(DO3A-xy-TPEP) are comparable due to a faster tumor washout of (64)Cu(DOTA-xy-TPEP). Substitution of xylene with the PEG 2 linker also leads to a significant reduction in both tumor and liver uptake. MicroPET imaging studies on (64)Cu(DO3A-xy-TPEP) in athymic nude mice bearing U87MG glioma xenografts showed that the tumor was clearly visualized as early as 1 h postinjection with very high T/B contrast. There was very little metabolite (<2%) detectable in the urine and feces samples for (64)Cu(DO3A-xy-TPEP), (64)Cu(DOTA-Bn-xy-TPEP)(-), and (64)Cu(NOTA-Bn-xy-TPEP). Considering both tumor uptake and T/B ratios (particularly tumor/heart, tumor/liver, and tumor/muscle), it was concluded that (64)Cu(DO3A-xy-TPEP) is a promising PET radiotracer for imaging the MDR-negative tumors.
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Affiliation(s)
- Chang-Tong Yang
- School of Health Sciences, Purdue University, West Lafayette, Indiana, USA
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26
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Liu S. Bifunctional coupling agents for radiolabeling of biomolecules and target-specific delivery of metallic radionuclides. Adv Drug Deliv Rev 2008; 60:1347-70. [PMID: 18538888 PMCID: PMC2539110 DOI: 10.1016/j.addr.2008.04.006] [Citation(s) in RCA: 299] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 04/16/2008] [Indexed: 11/23/2022]
Abstract
Receptor-based radiopharmaceuticals are of great current interest in molecular imaging and radiotherapy of cancers, and provide a unique tool for target-specific delivery of radionuclides to the diseased tissues. In general, a target-specific radiopharmaceutical can be divided into four parts: targeting biomolecule (BM), pharmacokinetic modifying (PKM) linker, bifunctional coupling or chelating agent (BFC), and radionuclide. The targeting biomolecule serves as a "carrier" for specific delivery of the radionuclide. PKM linkers are used to modify radiotracer excretion kinetics. BFC is needed for radiolabeling of biomolecules with a metallic radionuclide. Different radiometals have significant difference in their coordination chemistry, and require BFCs with different donor atoms and chelator frameworks. Since the radiometal chelate can have a significant impact on physical and biological properties of the target-specific radiopharmaceutical, its excretion kinetics can be altered by modifying the coordination environment with various chelators or coligand, if needed. This review will focus on the design of BFCs and their coordination chemistry with technetium, copper, gallium, indium, yttrium and lanthanide radiometals.
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Affiliation(s)
- Shuang Liu
- School of Health Sciences, Purdue University, West Lafayette, USA.
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Boswell CA, Regino CAS, Baidoo KE, Wong KJ, Bumb A, Xu H, Milenic DE, Kelley JA, Lai CC, Brechbiel MW. Synthesis of a cross-bridged cyclam derivative for peptide conjugation and 64Cu radiolabeling. Bioconjug Chem 2008; 19:1476-84. [PMID: 18597510 DOI: 10.1021/bc800039e] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The increased use of copper radioisotopes in radiopharmaceutical applications has created a need for bifunctional chelators (BFCs) that form stable radiocopper complexes and allow covalent attachment to biological molecules. Previous studies have established that 4,11-bis-(carbo- tert-butoxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (H 2CB-TE2A), a member of the ethylene "cross-bridged" cyclam (CB-cyclam) class of bicyclic tetraaza macrocycles, forms highly kinetically stable complexes with Cu(II) and is less susceptible to in vivo transchelation than its nonbridged analogue, 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA). Herein, we report a convenient synthesis of a novel cross-bridged BFC that is structurally analogous to CB-TE2A in that it possesses two coordinating acetate arms, but in addition possesses a third orthogonally protected arm for conjugation to peptides and other targeting agents. Application of this strategy to cross-bridged chelators may also enable the development of even further improved agents for (64)Cu-mediated diagnostic positron emission tomography (PET) imaging as well as for targeted radiotherapeutic applications.
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Affiliation(s)
- C Andrew Boswell
- Radioimmune and Inorganic Chemistry Section, Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1088, UAS
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28
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Kim YS, Yang CT, Wang J, Wang L, Li ZB, Chen X, Liu S. Effects of Targeting Moiety, Linker, Bifunctional Chelator, and Molecular Charge on Biological Properties of 64Cu-Labeled Triphenylphosphonium Cations. J Med Chem 2008; 51:2971-84. [PMID: 18419113 DOI: 10.1021/jm7015045] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Young-Seung Kim
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
| | - Chang-Tong Yang
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
| | - Jianjun Wang
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
| | - Lijun Wang
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
| | - Zi-Bo Li
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
| | - Xiaoyuan Chen
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
| | - Shuang Liu
- School of Health Sciences, Purdue University, West Lafayette, Indiana, and Molecular Imaging Program at Stanford, Department of Radiology & Bio-X, Stanford University, Stanford, California
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29
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He HT, Yin G, Hiler G, Kitko D, Carter JD, Scheper WM, Day V, Busch DH. Manganese complexes with a lengthy o -xylylene cross-bridged cyclam ligand: synthesis, characterization and catalytic hydrogen abstraction by dioxygen activation. J COORD CHEM 2007. [DOI: 10.1080/00958970701730331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Henry T. He
- a Department of Chemistry , The University of Kansas , Lawrence, KS 66045
| | - Guochuan Yin
- a Department of Chemistry , The University of Kansas , Lawrence, KS 66045
| | - George Hiler
- b The Procter and Gamble Company , Cincinnati, OH 45202
| | - David Kitko
- b The Procter and Gamble Company , Cincinnati, OH 45202
| | | | | | - Victor Day
- a Department of Chemistry , The University of Kansas , Lawrence, KS 66045
| | - Daryle H. Busch
- a Department of Chemistry , The University of Kansas , Lawrence, KS 66045
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30
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Li L, Bading J, Yazaki PJ, Ahuja AH, Crow D, Colcher D, Williams LE, Wong JYC, Raubitschek A, Shively JE. A versatile bifunctional chelate for radiolabeling humanized anti-CEA antibody with In-111 and Cu-64 at either thiol or amino groups: PET imaging of CEA-positive tumors with whole antibodies. Bioconjug Chem 2007; 19:89-96. [PMID: 17988078 DOI: 10.1021/bc700161p] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Radiolabeled anti-carcinoembryonic antigen (CEA) antibodies have the potential to give excellent images of a wide variety of human tumors, including tumors of the colon, breast, lung, and medullar thyroid. In order to realize the goals of routine and repetitive clinical imaging with anti-CEA antibodies, it is necessary that the antibodies have a high affinity for CEA, low cross reactivity and uptake in normal tissues, and low immunogenicity. The humanized anti-CEA antibody hT84.66-M5A (M5A) fulfills these criteria with an affinity constant of >10 (10) M (-1), no reactivity with CEA cross-reacting antigens found in normal tissues, and >90% human protein sequence. A further requirement for routine clinical use of radiolabeled antibodies is a versatile method of radiolabeling that allows the use of multiple radionuclides that differ in their radioemissions and half-lives. We describe a versatile bifunctional chelator, DO3A-VS (1,4,7-tris(carboxymethyl)-10-(vinylsulfone)-1,4,7,10-tetraazacyclododecane) that binds a range of radiometals including 111 In for gamma-ray imaging and 64Cu for positron emission tomography (PET), and which can be conjugated with negligible loss of immunoreactivity either to sulfhydryls (SH) in the hinge region of lightly reduced immunoglobulins or surface lysines (NH) of immunoglobulins. Based on our correlative studies comparing the kinetics of radiolabeled anti-CEA antibodies in murine models with those in man, we predict that 64Cu-labeled intact, humanized antibodies can be used to image CEA positive tumors in the clinic.
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Affiliation(s)
- Lin Li
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA
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31
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Ly SY, Jung YS, Kim SK, Lee HK. Trace Analysis of Lead and Copper Ions in Fish Tissue Using Paste Electrodes. ANAL LETT 2007. [DOI: 10.1080/00032710701588184] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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32
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Sprague JE, Peng Y, Fiamengo AL, Woodin KS, Southwick EA, Weisman GR, Wong EH, Golen JA, Rheingold AL, Anderson CJ. Synthesis, characterization and in vivo studies of Cu(II)-64-labeled cross-bridged tetraazamacrocycle-amide complexes as models of peptide conjugate imaging agents. J Med Chem 2007; 50:2527-35. [PMID: 17458949 DOI: 10.1021/jm070204r] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Copper-64, a positron emitter suitable for positron emission tomography (PET), demonstrates improved in vivo clearance when chelated by the cross-bridged tetraazamacrocycle CB-TE2A compared to TETA. Good in vivo clearance was also observed for 64Cu-CB-TE2A conjugated to a peptide, which converts one coordinating carboxylate pendant arm to an amide. To better understand the in vivo stability of peptide- conjugated CB-TE2A, cross-bridged monoamides were synthesized. Crystal structures of natCu(II)-CB-TEAMA and natCu(II)-CB-PhTEAMA revealed hexadentate, distorted octahedral coordination geometry. In vivo biodistribution showed clearance of all 64Cu-radiolabeled cross-bridged monoamides from liver and bone marrow such that uptake at 24 h was <10% of uptake at 30 min. In contrast, >60% of 30 min uptake from 64Cu-TETA was retained in these tissues at 24 h. Clearance of 64Cu-cross-bridged monoamides from nontarget organs suggests good in vivo stability, thus supporting the use of CB-TE2A as a bifunctional chelator without modifications to the macrocycle backbone.
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Affiliation(s)
- Jennifer E Sprague
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri 63110, USA
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33
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Lubal P, Maleček J, Hermann P, Kotek J, Havel J. Capillary electrophoretic separation and kinetic study of inert copper(II) complexes of 1,8-bis(methylphosphonate) derivative of cyclam. Polyhedron 2006. [DOI: 10.1016/j.poly.2005.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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34
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35
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2005; 40:1390-401. [PMID: 16237664 DOI: 10.1002/jms.811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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36
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Shen X, Boswell CA, Wong EH, Weisman GR, Anderson CJ, Tomellini SA. Investigation of copper-azamacrocyclic complexes by high-performance liquid chromatography. Biomed Chromatogr 2005; 20:37-47. [PMID: 15954159 DOI: 10.1002/bmc.525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The use of copper radioisotopes in imaging and therapy has prompted an increased interest in chelators which form stable copper complexes, such as Cu(II)-azamacrocyclic complexes. The effects of charge, stability and the size of the macrocyclic backbone of the Cu(II)-azamacrocyclic complexes on biological behavior have been evaluated. Here we report a reversed-phase high-performance liquid chromatography (HPLC) method to separate several Cu(II)-azamacrocyclic complexes, including Cu(II) complexes of 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA), 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (CB-TE2A) and 4,10-bis(carboxymethyl)-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (CB-DO2A). Absorbance at 280 nm was used to monitor the complexes as they eluted from the reversed-phase column. The effects of the concentration of the buffer, the pH of the buffered mobile phase and the concentration of the organic modifier, methanol, on the separation were investigated. Separation of these copper complexes by ion-pair HPLC with the use of a mass spectrometry-compatible ion-pair reagent, triethylammonium acetate, in the mobile phase at pH 6.3 is also presented. The reversed-phase chromatographic conditions utilized also allow the pK(a)s of Cu-TETA and the log(k'w) values of Cu-CB-TE2A, Cu-TETA and Cu-CB-DO2A to be estimated.
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Affiliation(s)
- Xiaoxuan Shen
- Department of Chemistry, University of New Hampshire, Durham, NH 03824, USA
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