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Lee KK, Chakraborty M, Hu A, Kanagasundaram T, Thorek DLJ, Wilson JJ. Chelation of [ 111In]In 3+ with the dual-size-selective macrocycles py-macrodipa and py 2-macrodipa. Dalton Trans 2024; 53:14634-14647. [PMID: 39163366 DOI: 10.1039/d4dt02146k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Indium-111 (111In) is a diagnostic radiometal that is important in nuclear medicine for single-photon emission computed tomography (SPECT). In order to apply this radiometal, it needs to be stably chelated and conjugated to a targeting vector that delivers it to diseased tissue. Identifying effective chelators that are capable of binding and retaining [111In]In3+in vivo is an important research area. In this study, two 18-membered macrocyclic chelators, py-macrodipa and py2-macrodipa, were investigated for their ability to form stable coordination complexes with In3+ and to be effectively radiolabeled with [111In]In3+. The In3+ complexes of these two chelators were characterized by NMR spectroscopy, X-ray crystallography, and density functional theory calculations. These studies show that both py-macrodipa and py2-macrodipa form 8-coordinate In3+ complexes and attain an asymmetric conformation, consistent with prior studies on this ligand class with small rare earth metal ions. Spectrophotometric titrations were carried out to determine the thermodynamic stability constants (log KML) of [In(py-macrodipa)]+ and [In(py2-macrodipa)]+, which were found to be 18.96(6) and 19.53(5), respectively, where the values in parentheses are the errors of the last significant figures obtained from the standard deviation from three independent replicates. Radiolabeling studies showed that py-macrodipa and py2-macrodipa can quantitatively be radiolabeled with [111In]In3+ at 25 °C within 5 min, even at ligand concentrations as low as 1 μM. The in vitro stability of the radiolabeled complexes was investigated in human serum at 37 °C, revealing that ∼90% of [111In][In(py-macrodipa)]+ and [111In][In(py2-macrodipa)]+ remained intact after 7 days. The biodistribution of these radiolabeled complexes in mice was investigated, showing lower uptake in the kidneys, liver, and blood at the 24 h mark compared to [111In]InCl3. These results demonstrate the potential of py-macrodipa and py2-macrodipa as chelators for [111In]In3+, suggesting their value for SPECT radiopharmaceuticals.
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Affiliation(s)
- Kevin K Lee
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, 14853, USA.
| | - Mou Chakraborty
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
- Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
| | - Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, 14853, USA.
| | - Thines Kanagasundaram
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, 14853, USA.
| | - Daniel L J Thorek
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
- Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri, 63110, USA
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri, 63110, USA
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, 14853, USA.
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2
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Simms ME, Li Z, Sibley MM, Ivanov AS, Lara CM, Johnstone TC, Kertesz V, Fears A, White FD, Thorek DLJ, Thiele NA. PYTA: a universal chelator for advancing the theranostic palette of nuclear medicine. Chem Sci 2024; 15:11279-11286. [PMID: 39055008 PMCID: PMC11268510 DOI: 10.1039/d3sc06854d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 06/05/2024] [Indexed: 07/27/2024] Open
Abstract
To clinically advance the growing arsenal of radiometals available to image and treat cancer, chelators with versatile binding properties are needed. Herein, we evaluated the ability of the py2[18]dieneN6 macrocycle PYTA to interchangeably bind and stabilize 225Ac3+, [177Lu]Lu3+, [111In]In3+ and [44Sc]Sc3+, a chemically diverse set of radionuclides that can be used complementarily for targeted alpha therapy, beta therapy, single-photon emission computed tomography (SPECT) imaging, and positron emission tomography (PET) imaging, respectively. Through NMR spectroscopy and X-ray diffraction, we show that PYTA possesses an unusual degree of flexibility for a macrocyclic chelator, undergoing dramatic conformational changes that enable it to optimally satisfy the disparate coordination properties of each metal ion. Subsequent radiolabeling studies revealed that PYTA quantitatively binds all 4 radiometals at room temperature in just minutes at pH 6. Furthermore, these complexes were found to be stable in human serum over 2 half-lives. These results surpass those obtained for 2 state-of-the-art chelators for nuclear medicine, DOTA and macropa. The stability of 225Ac-PYTA and [44Sc]Sc-PYTA, the complexes having the most disparity with respect to metal-ion size, was further probed in mice. The resulting PET images (44Sc) and ex vivo biodistribution profiles (44Sc and 225Ac) of the PYTA complexes differed dramatically from those of unchelated [44Sc]Sc3+ and 225Ac3+. These differences provide evidence that PYTA retains this size-divergent pair of radionuclides in vivo. Collectively, these studies establish PYTA as a new workhorse chelator for nuclear medicine and warrant its further investigation in targeted constructs.
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Affiliation(s)
- Megan E Simms
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Zhiyao Li
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
| | - Megan M Sibley
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Alexander S Ivanov
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Caroline M Lara
- Department of Biological Sciences, University of Notre Dame Notre Dame IN 46556 USA
| | - Timothy C Johnstone
- Department of Chemistry and Biochemistry, University of California Santa Cruz Santa Cruz CA 95064 USA
| | - Vilmos Kertesz
- Biosciences Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Amanda Fears
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
| | - Frankie D White
- Radioisotope Science and Technology Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
| | - Daniel L J Thorek
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Department of Biomedical Engineering, Washington University in St. Louis St. Louis MO 63110 USA
- Oncologic Imaging Program, Siteman Cancer Center, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
| | - Nikki A Thiele
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge TN 37831 USA
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3
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Franchi S, Madabeni A, Tosato M, Gentile S, Asti M, Orian L, Di Marco V. Navigating through the coordination preferences of heavy alkaline earth metals: Laying the foundations for 223Ra- and 131/135mBa-based targeted alpha therapy and theranostics of cancer. J Inorg Biochem 2024; 256:112569. [PMID: 38701687 DOI: 10.1016/j.jinorgbio.2024.112569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/04/2024] [Accepted: 04/18/2024] [Indexed: 05/05/2024]
Abstract
The clinical success of [223Ra]RaCl2 (Xofigo®) for the palliative treatment of bone metastases in patients with prostate cancer has highlighted the therapeutic potential of α-particle emission. Expanding the applicability of radium-223 in Targeted Alpha Therapy of non-osseous tumors is followed up with significant interest, as it holds the potential to unveil novel treatment options in the comprehensive management of cancer. Moreover, the use of barium radionuclides, like barium-131 and -135m, is still unfamiliar in nuclear medicine applications, although they can be considered as radium-223 surrogates for imaging purposes. Enabling these applications requires the establishment of chelators able to form stable complexes with radium and barium radionuclides. Until now, only a limited number of ligands have been suggested and these molecules have been primarily inspired by existing structures known for their ability to complex large metal cations. However, a systematic inspection of chelators specifically tailored to Ra2+ and Ba2+ has yet to be conducted. This work delves into a comprehensive investigation of a series of small organic ligands, aiming to unveil the coordination preferences of both radium-223 and barium-131/135m. Electronic binding energies of both metal cations to each ligand were theoretically computed via Density Functional Theory calculations (COSMO-ZORA-PBE-D3/TZ2P), while thermodynamic stability constants were experimentally determined for Ba2+-ligand complexes by potentiometry, NMR and UV-Vis spectroscopies. The outcomes revealed malonate, 2-hydroxypyridine 1-oxide and picolinate as the most favorable building blocks to design multidentate chelators. These findings serve as foundation guidelines, propelling the development of cutting-edge radium-223- and barium-131/135m-based radiopharmaceuticals for Targeted Alpha Therapy and theranostics of cancer.
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Affiliation(s)
- Sara Franchi
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.
| | - Andrea Madabeni
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.
| | - Marianna Tosato
- Radiopharmaceutical Chemistry Section, Nuclear Medicine Unit, AUSL-IRCCS Reggio Emilia, 42122 Reggio Emilia, Italy.
| | - Silvia Gentile
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.
| | - Mattia Asti
- Radiopharmaceutical Chemistry Section, Nuclear Medicine Unit, AUSL-IRCCS Reggio Emilia, 42122 Reggio Emilia, Italy.
| | - Laura Orian
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy; National Institute of Nuclear Physics, National Laboratories of Legnaro (INFN-LNL), 35020 Legnaro, Padova, Italy.
| | - Valerio Di Marco
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.
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Vizier R, Adumeau P, Moreau M, Goncalves V, Denat F. Moving Beyond Isothiocyanates: A Look at the Stability of Conjugation Links Toward Radiolysis in 89Zr-Labeled Immunoconjugates. Bioconjug Chem 2024; 35:633-637. [PMID: 38656148 DOI: 10.1021/acs.bioconjchem.4c00105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Zirconium-89 is the most widely used radioisotope for immunoPET because its physical half-life (78.2 h) suits the one of antibodies. Desferrioxamine B (DFO) is the standard chelator for the complexation of zirconium(IV), and its bifunctional version, containing a phenylisothiocyanate function, is the most commonly used for the conjugation of DFO to proteins. However, preliminary results have shown that the thiourea link obtained from the conjugation of isothiocyanate and lysines is sensitive to the ionizing radiation generated by the radioisotope, leading to the rupture of the link and the release of the chelator/radiometal complex. This radiolysis phenomenon could produce nonspecific signal and prevent the detection of bone metastasis, as free zirconium accumulates into the bones. The aim of this work was to study the stability of a selection of conjugation linkers in 89Zr-labeled immunoconjugates. We have synthesized several DFO-based bifunctional chelators appended with an isothiocyanate moiety, a bicyclononyne, or a squaramate ester. Two antibodies (trastuzumab and rituximab) were conjugated and radiolabeled with zirconium-89. The effect of increasing activities of zirconium-89 on the integrity of the bioconjugate bearing thiourea links was evaluated as well as the impact of the presence of a radioprotectant. The stability of the radiolabeled antibodies was studied over 7 days in PBS and human plasma. Radioconjugates' integrity was evaluated using iTLC and size-exclusion chromatography. This study shows that the nature of the linker between the chelator and biomolecule can have a strong impact on the stability of the 89Zr-labeled conjugates, as well as on the aggregation of the conjugates.
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Affiliation(s)
- Romane Vizier
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR 6302, CNRS, Université de Bourgogne, Dijon 21000, France
| | - Pierre Adumeau
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR 6302, CNRS, Université de Bourgogne, Dijon 21000, France
| | - Mathieu Moreau
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR 6302, CNRS, Université de Bourgogne, Dijon 21000, France
| | - Victor Goncalves
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR 6302, CNRS, Université de Bourgogne, Dijon 21000, France
| | - Franck Denat
- Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR 6302, CNRS, Université de Bourgogne, Dijon 21000, France
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5
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Stepanov AV, Xie J, Zhu Q, Shen Z, Su W, Kuai L, Soll R, Rader C, Shaver G, Douthit L, Zhang D, Kalinin R, Fu X, Zhao Y, Qin T, Baran PS, Gabibov AG, Bushnell D, Neri D, Kornberg RD, Lerner RA. Control of the antitumour activity and specificity of CAR T cells via organic adapters covalently tethering the CAR to tumour cells. Nat Biomed Eng 2024; 8:529-543. [PMID: 37798444 DOI: 10.1038/s41551-023-01102-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 08/25/2023] [Indexed: 10/07/2023]
Abstract
On-target off-tumour toxicity limits the anticancer applicability of chimaeric antigen receptor (CAR) T cells. Here we show that the tumour-targeting specificity and activity of T cells with a CAR consisting of an antibody with a lysine residue that catalytically forms a reversible covalent bond with a 1,3-diketone hapten can be regulated by the concentration of a small-molecule adapter. This adapter selectively binds to the hapten and to a chosen tumour antigen via a small-molecule binder identified via a DNA-encoded library. The adapter therefore controls the formation of a covalent bond between the catalytic antibody and the hapten, as well as the tethering of the CAR T cells to the tumour cells, and hence the cytotoxicity and specificity of the cytotoxic T cells, as we show in vitro and in mice with prostate cancer xenografts. Such small-molecule switches of T-cell cytotoxicity and specificity via an antigen-independent 'universal' CAR may enhance the control and safety profile of CAR-based cellular immunotherapies.
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Affiliation(s)
- Alexey V Stepanov
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA.
| | - Jia Xie
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | | | | | - Wenji Su
- WuXi AppTec Co., Ltd, Shanghai, China
| | | | | | - Christoph Rader
- Department of Immunology and Microbiology, UF Scripps Biomedical Research, University of Florida, Jupiter, FL, USA
| | - Geramie Shaver
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Lacey Douthit
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Ding Zhang
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Roman Kalinin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Xiang Fu
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Yingying Zhao
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Tian Qin
- The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Phil S Baran
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Alexander G Gabibov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - David Bushnell
- Structural Biology, School of Medicine, Stanford University, Stanford, CA, USA
| | - Dario Neri
- Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zurich), Zurich, Switzerland
| | - Roger D Kornberg
- Structural Biology, School of Medicine, Stanford University, Stanford, CA, USA.
| | - Richard A Lerner
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
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6
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Miederer M, Benešová-Schäfer M, Mamat C, Kästner D, Pretze M, Michler E, Brogsitter C, Kotzerke J, Kopka K, Scheinberg DA, McDevitt MR. Alpha-Emitting Radionuclides: Current Status and Future Perspectives. Pharmaceuticals (Basel) 2024; 17:76. [PMID: 38256909 PMCID: PMC10821197 DOI: 10.3390/ph17010076] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 01/24/2024] Open
Abstract
The use of radionuclides for targeted endoradiotherapy is a rapidly growing field in oncology. In particular, the focus on the biological effects of different radiation qualities is an important factor in understanding and implementing new therapies. Together with the combined approach of imaging and therapy, therapeutic nuclear medicine has recently made great progress. A particular area of research is the use of alpha-emitting radionuclides, which have unique physical properties associated with outstanding advantages, e.g., for single tumor cell targeting. Here, recent results and open questions regarding the production of alpha-emitting isotopes as well as their chemical combination with carrier molecules and clinical experience from compassionate use reports and clinical trials are discussed.
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Affiliation(s)
- Matthias Miederer
- Department of Translational Imaging in Oncology, National Center for Tumor Diseases (NCT/UCC), 01307 Dresden, Germany
- Medizinische Fakultät and University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany
| | - Martina Benešová-Schäfer
- Research Group Molecular Biology of Systemic Radiotherapy, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany;
| | - Constantin Mamat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstr, 400, 01328 Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany
| | - David Kästner
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; (D.K.); (C.B.)
| | - Marc Pretze
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; (D.K.); (C.B.)
| | - Enrico Michler
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; (D.K.); (C.B.)
| | - Claudia Brogsitter
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; (D.K.); (C.B.)
| | - Jörg Kotzerke
- Medizinische Fakultät and University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany; (D.K.); (C.B.)
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstr, 400, 01328 Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany
- National Center for Tumor Diseases (NCT) Dresden, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307 Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - David A. Scheinberg
- Molecular Pharmacology Program, Sloan Kettering Institute, New York, NY 10065, USA;
| | - Michael R. McDevitt
- Molecular Imaging and Therapy Service, Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Department of Radiology, Weill Cornell Medical College, New York, NY 10065, USA
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7
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Simms ME, Sibley MM, Driscoll DM, Kertesz V, Damron JT, Ivanov AS, White FD, Thiele NA. Reining in Radium for Nuclear Medicine: Extra-Large Chelator Development for an Extra-Large Ion. Inorg Chem 2023; 62:20834-20843. [PMID: 37811965 DOI: 10.1021/acs.inorgchem.3c02985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Targeted α therapy (TAT) of soft-tissue cancers using the α particle-emitting radionuclide 223Ra holds great potential because of its favorable nuclear properties, adequate availability, and established clinical use for treating metastatic prostate cancer of the bone. Despite these advantages, the use of 223Ra has been largely overshadowed by other α emitters due to its challenging chelation chemistry. A key criterion that needs to be met for a radionuclide to be used in TAT is its stable attachment to a targeting vector via a bifunctional chelator. The low charge density of Ra2+ arising from its large ionic radius weakens its electrostatic binding interactions with chelators, leading to insufficient complex stability in vivo. In this study, we synthesized and evaluated macropa-XL as a novel chelator for 223Ra. It bears a large 21-crown-7 macrocyclic core and two picolinate pendent groups, which we hypothesized would effectively saturate the large coordination sphere of the Ra2+ ion. The structural chemistry of macropa-XL was first established with the nonradioactive Ba2+ ion using X-ray diffraction and X-ray absorption spectroscopy, which revealed the formation of an 11-coordinate complex in a rare anti pendent-arm configuration. Subsequently, the stability constant of the [Ra(macropa-XL)] complex was determined via competitive cation exchange with 223Ra and 224Ra radiotracers and compared with that of macropa, the current state-of-the-art chelator for Ra2+. A moderate log KML value of 8.12 was measured for [Ra(macropa-XL)], which is approximately 1.5 log K units lower than the stability constant of [Ra(macropa)]. This relative decrease in Ra2+ complex stability for macropa-XL versus macropa was further probed using density functional theory calculations. Additionally, macropa-XL was radiolabeled with 223Ra, and the kinetic stability of the resulting complex was evaluated in human serum. Although macropa-XL could effectively bind 223Ra under mild conditions, the complex appeared to be unstable to transchelation. Collectively, this study sheds additional light on the chelation chemistry of the exotic Ra2+ ion and contributes to the small, but growing, number of chelator development efforts for 223Ra-based TAT.
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Affiliation(s)
- Megan E Simms
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Megan M Sibley
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Darren M Driscoll
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Vilmos Kertesz
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Joshua T Damron
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Alexander S Ivanov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Frankie D White
- Radioisotope Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Nikki A Thiele
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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8
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Carbo-Bague I, Li C, McNeil BL, Gao Y, McDonagh AW, Van de Voorde M, Ooms M, Kunz P, Yang H, Radchenko V, Schreckenbach G, Ramogida CF. Comparative Study of a Decadentate Acyclic Chelate, HOPO-O 10, and Its Octadentate Analogue, HOPO-O 8, for Radiopharmaceutical Applications. Inorg Chem 2023; 62:20549-20566. [PMID: 36608341 DOI: 10.1021/acs.inorgchem.2c03671] [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: 01/07/2023]
Abstract
Radiolanthanides and actinides are aptly suited for the diagnosis and treatment of cancer via nuclear medicine because they possess unique chemical and physical properties (e.g., radioactive decay emissions). These rare radiometals have recently shown the potential to selectively deliver a radiation payload to cancer cells. However, their clinical success is highly dependent on finding a suitable ligand for stable chelation and conjugation to a disease-targeting vector. Currently, the commercially available chelates exploited in the radiopharmaceutical design do not fulfill all of the requirements for nuclear medicine applications, and there is a need to further explore their chemistry to rationally design highly specific chelates. Herein, we describe the rational design and chemical development of a novel decadentate acyclic chelate containing five 1,2-hydroxypyridinones, 3,4,3,3-(LI-1,2-HOPO), referred to herein as HOPO-O10, based on the well-known octadentate ligand 3,4,3-(LI-1,2-HOPO), referred to herein as HOPO-O8, a highly efficient chelator for 89Zr[Zr4+]. Analysis by 1H NMR spectroscopy and mass spectrometry of the La3+ and Tb3+ complexes revealed that HOPO-O10 forms bimetallic complexes compared to HOPO-O8, which only forms monometallic species. The radiolabeling properties of both chelates were screened with [135La]La3+, [155/161Tb]Tb3+, [225Ac]Ac3+ and, [227Th]Th4+. Comparable high specific activity was observed for the [155/161Tb]Tb3+ complexes, outperforming the gold-standard 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, yet HOPO-O10 surpassed HOPO-O8 with higher [227Th]Th4+ affinity and improved complex stability in a human serum challenge assay. A comprehensive analysis of the decadentate and octadentate chelates was performed with density functional theory for the La3+, Ac3+, Eu3+, Tb3+, Lu3+, and Th4+ complexes. The computational simulations demonstrated the enhanced stability of Th4+-HOPO-O10 over Th4+-HOPO-O8. This investigation reveals the potential of HOPO-O10 for the stable chelation of large tetravalent radioactinides for nuclear medicine applications and provides insight for further chelate development.
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Affiliation(s)
- Imma Carbo-Bague
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | - Cen Li
- Department of Chemistry, University of Manitoba, Winnipeg, ManitobaR3T 2N2, Canada
| | - Brooke L McNeil
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
- Life Sciences Division, TRIUMF, Vancouver, British ColumbiaV6T 2A3, Canada
| | - Yang Gao
- Department of Chemistry, University of Manitoba, Winnipeg, ManitobaR3T 2N2, Canada
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan610054, China
| | - Anthony W McDonagh
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | | | - Maarten Ooms
- NURA Research Group, Belgian Nuclear Research Center, SCK CEN, 2400Mol, Belgium
| | - Peter Kunz
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
- Accelerator Division, TRIUMF, Vancouver, British ColumbiaV6T 2A3, Canada
| | - Hua Yang
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
- Life Sciences Division, TRIUMF, Vancouver, British ColumbiaV6T 2A3, Canada
| | - Valery Radchenko
- Life Sciences Division, TRIUMF, Vancouver, British ColumbiaV6T 2A3, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British ColumbiaV6T 1Z1, Canada
| | - Georg Schreckenbach
- Department of Chemistry, University of Manitoba, Winnipeg, ManitobaR3T 2N2, Canada
| | - Caterina F Ramogida
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
- Life Sciences Division, TRIUMF, Vancouver, British ColumbiaV6T 2A3, Canada
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9
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Hu A, Martin KE, Śmiłowicz D, Aluicio-Sarduy E, Cingoranelli SJ, Lapi SE, Engle JW, Boros E, Wilson JJ. Construction of the Bioconjugate Py-Macrodipa-PSMA and Its In Vivo Investigations with Large 132/135La 3+ and Small 47Sc 3+ Radiometal Ions. Eur J Inorg Chem 2023; 26:e202300457. [PMID: 38495596 PMCID: PMC10939043 DOI: 10.1002/ejic.202300457] [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: 07/21/2023] [Indexed: 03/19/2024]
Abstract
To harness radiometals in clinical settings, a chelator forming a stable complex with the metal of interest and targets the desired pathological site is needed. Toward this goal, we previously reported a unique set of chelators that can stably bind to both large and small metal ions, via a conformational switch. Within this chelator class, py-macrodipa is particularly promising based on its ability to stably bind several medicinally valuable radiometals including large 132/135La3+, 213Bi3+, and small 44Sc3+. Here, we report a 10-step organic synthesis of its bifunctional analogue py-macrodipa-NCS, which contains an amine-reactive -NCS group that is amenable for bioconjugation reactions to targeting vectors. The hydrolytic stability of py-macordipa-NCS was assessed, revealing a half-life of 6.0 d in pH 9.0 aqueous buffer. This bifunctional chelator was then conjugated to a prostate-specific membrane antigen (PSMA)-binding moiety, yielding the bioconjugate py-macrodipa-PSMA, which was subsequently radiolabeled with large 132/135La3+ and small 47Sc3+, revealing efficient and quantitative complex formation. The resulting radiocomplexes were injected into mice bearing both PSMA-expressing and PSMA-non-expressing tumor xenografts to determine their biodistribution patterns, revealing delivery of both 132/135La3+ and 47Sc3+ to PSMA+ tumor sites. However, partial radiometal dissociation was observed, suggesting that py-macrodipa-PSMA needs further structural optimization.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Kirsten E Martin
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Dariusz Śmiłowicz
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Eduardo Aluicio-Sarduy
- Department of Medical Physics and Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Shelbie J Cingoranelli
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Suzanne E Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Jonathan W Engle
- Department of Medical Physics and Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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10
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Nelson BJB, Wilson J, Andersson JD, Wuest F. Theranostic Imaging Surrogates for Targeted Alpha Therapy: Progress in Production, Purification, and Applications. Pharmaceuticals (Basel) 2023; 16:1622. [PMID: 38004486 PMCID: PMC10674391 DOI: 10.3390/ph16111622] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/08/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
This article highlights recent developments of SPECT and PET diagnostic imaging surrogates for targeted alpha particle therapy (TAT) radiopharmaceuticals. It outlines the rationale for using imaging surrogates to improve diagnostic-scan accuracy and facilitate research, and the properties an imaging-surrogate candidate should possess. It evaluates the strengths and limitations of each potential imaging surrogate. Thirteen surrogates for TAT are explored: 133La, 132La, 134Ce/134La, and 226Ac for 225Ac TAT; 203Pb for 212Pb TAT; 131Ba for 223Ra and 224Ra TAT; 123I, 124I, 131I and 209At for 211At TAT; 134Ce/134La for 227Th TAT; and 155Tb and 152Tb for 149Tb TAT.
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Affiliation(s)
- Bryce J. B. Nelson
- Department of Oncology, University of Alberta, 11560 University Ave., Edmonton, AB T6G 1Z2, Canada; (B.J.B.N.); (J.W.); (J.D.A.)
| | - John Wilson
- Department of Oncology, University of Alberta, 11560 University Ave., Edmonton, AB T6G 1Z2, Canada; (B.J.B.N.); (J.W.); (J.D.A.)
| | - Jan D. Andersson
- Department of Oncology, University of Alberta, 11560 University Ave., Edmonton, AB T6G 1Z2, Canada; (B.J.B.N.); (J.W.); (J.D.A.)
- Edmonton Radiopharmaceutical Center, Alberta Health Services, 11560 University Ave., Edmonton, AB T6G 1Z2, Canada
| | - Frank Wuest
- Department of Oncology, University of Alberta, 11560 University Ave., Edmonton, AB T6G 1Z2, Canada; (B.J.B.N.); (J.W.); (J.D.A.)
- Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, AB T6G 2E1, Canada
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11
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Franchi S, Asti M, Di Marco V, Tosato M. The Curies' element: state of the art and perspectives on the use of radium in nuclear medicine. EJNMMI Radiopharm Chem 2023; 8:38. [PMID: 37947909 PMCID: PMC10638329 DOI: 10.1186/s41181-023-00220-4] [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: 09/27/2023] [Accepted: 10/19/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND The alpha-emitter radium-223 (223Ra) is presently used in nuclear medicine for the palliative treatment of bone metastases from castration-resistant prostate cancer. This application arises from its advantageous decay properties and its intrinsic ability to accumulate in regions of high bone turnover when injected as a simple chloride salt. The commercial availability of [223Ra]RaCl2 as a registered drug (Xofigo®) is a further additional asset. MAIN BODY The prospect of extending the utility of 223Ra to targeted α-therapy of non-osseous cancers has garnered significant interest. Different methods, such as the use of bifunctional chelators and nanoparticles, have been explored to incorporate 223Ra in proper carriers designed to precisely target tumor sites. Nevertheless, the search for a suitable scaffold remains an ongoing challenge, impeding the diffusion of 223Ra-based radiopharmaceuticals. CONCLUSION This review offers a comprehensive overview of the current role of radium radioisotopes in nuclear medicine, with a specific focus on 223Ra. It also critically examines the endeavors conducted so far to develop constructs capable of incorporating 223Ra into cancer-targeting drugs. Particular emphasis is given to the chemical aspects aimed at providing molecular scaffolds for the bifunctional chelator approach.
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Affiliation(s)
- Sara Franchi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padua, Italy
| | - Mattia Asti
- Radiopharmaceutical Chemistry Section, Nuclear Medicine Unit, AUSL di Reggio Emilia: Azienda Unità Sanitaria Locale - IRCCS Tecnologie Avanzate e Modelli Assistenziali in Oncologia di Reggio Emilia, Via Amendola 2, 42122, Reggio Emilia, Italy
| | - Valerio Di Marco
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padua, Italy
| | - Marianna Tosato
- Radiopharmaceutical Chemistry Section, Nuclear Medicine Unit, AUSL di Reggio Emilia: Azienda Unità Sanitaria Locale - IRCCS Tecnologie Avanzate e Modelli Assistenziali in Oncologia di Reggio Emilia, Via Amendola 2, 42122, Reggio Emilia, Italy.
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12
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Martin KE, Mattocks JA, Śmiłowicz D, Aluicio-Sarduy E, Whetter JN, Engle JW, Cotruvo JA, Boros E. Radiolabeling and in vivo evaluation of lanmodulin with biomedically relevant lanthanide isotopes. RSC Chem Biol 2023; 4:414-421. [PMID: 37292057 PMCID: PMC10246553 DOI: 10.1039/d3cb00020f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/04/2023] [Indexed: 06/10/2023] Open
Abstract
Short-lived, radioactive lanthanides comprise an emerging class of radioisotopes attractive for biomedical imaging and therapy applications. To deliver such isotopes to target tissues, they must be appended to entities that target antigens overexpressed on the target cell's surface. However, the thermally sensitive nature of biomolecule-derived targeting vectors requires the incorporation of these isotopes without the use of denaturing temperatures or extreme pH conditions; chelating systems that can capture large radioisotopes under mild conditions are therefore highly desirable. Herein, we demonstrate the successful radiolabeling of the lanthanide-binding protein, lanmodulin (LanM), with medicinally relevant radioisotopes: 177Lu, 132/135La and 89Zr. Radiolabeling of the endogenous metal-binding sites of LanM, as well exogenous labeling of a protein-appended chelator, was successfully conducted at 25 °C and pH 7 with radiochemical yields ranging from 20-82%. The corresponding radiolabeled constructs possess good formulation stability in pH 7 MOPS buffer over 24 hours (>98%) in the presence of 2 equivalents of natLa carrier. In vivo experiments with [177Lu]-LanM, [132/135La]-LanM, and a prostate cancer targeting-vector linked conjugate, [132/135La]-LanM-PSMA, reveal that endogenously labeled constructs produce bone uptake in vivo. Exogenous, chelator-tag mediated radiolabeling to produce [89Zr]-DFO-LanM enables further study of the protein's in vivo behavior, demonstrating low bone and liver uptake, and renal clearance of the protein itself. While these results indicate that additional stabilization of LanM is required, this study establishes precedence for the radiochemical labeling of LanM with medically relevant lanthanide radioisotopes.
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Affiliation(s)
- Kirsten E Martin
- Department of Chemistry, Stony Brook University, Stony Brook New York 11794 USA
| | - Joseph A Mattocks
- Department of Chemistry, The Pennsylvania State University, University Park Pennsylvania 16802 USA
| | - Dariusz Śmiłowicz
- Department of Chemistry, Stony Brook University, Stony Brook New York 11794 USA
| | - Eduardo Aluicio-Sarduy
- Department of Medical Physics, University of Wisconsin Madison Wisconsin 53705 USA
- Department of Radiology, University of Wisconsin Madison Wisconsin 53705 USA
| | - Jennifer N Whetter
- Department of Chemistry, Stony Brook University, Stony Brook New York 11794 USA
| | - Jonathan W Engle
- Department of Medical Physics, University of Wisconsin Madison Wisconsin 53705 USA
- Department of Radiology, University of Wisconsin Madison Wisconsin 53705 USA
| | - Joseph A Cotruvo
- Department of Chemistry, The Pennsylvania State University, University Park Pennsylvania 16802 USA
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, Stony Brook New York 11794 USA
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13
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Pedersen KS, Deville C, Søndergaard U, Jensen M, Jensen AI. Improved procedures for production and purification of 135La from enriched [ 135Ba]BaCO 3 on a 16.5 MeV cyclotron. Appl Radiat Isot 2023; 192:110612. [PMID: 36521259 DOI: 10.1016/j.apradiso.2022.110612] [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: 09/19/2022] [Revised: 11/19/2022] [Accepted: 12/08/2022] [Indexed: 12/13/2022]
Abstract
Lanthanum-135 (135La) is a favorable Auger electron emitter with a high Auger electron yield and low gamma emission, making it promising for Auger electron radiotherapy. However, successful application requires reliable and scalable 135La production. Up to now, metallic natural barium (natBa) is a commonly used target material, but this material is sensitive to moisture and oxidation. BaCO3 has also been tested, due to its higher chemical stability. However, BaCO3 has poor thermal conductivity, limiting the applicable current and making high yield production challenging. In this study, we pressed a mixture of enriched [135Ba]BaCO3 and fine aluminum (Al) powder to provide a stable target with improved thermal conductivity compared to pure BaCO3. After 4 h of irradiation with a 16.5 MeV proton beam at 20 μA current, 1.62 ± 0.18 GBq was produced from a 200 mg [135Ba]BaCO3:Al (1:2, w/w) target. This corresponded to a saturation yield of 11.91 ± 1.31 GBq (or 596 ± 66 MBq/μA). A purification procedure involving initial precipitation, followed by a single composite column containing a layer of TK200 resin and a second layer of branched DGA resin was developed, with 97.1 ± 3.6 % decay corrected 135La recovery. [135La]LaCl3 was obtained in an effective molar activity of 79.6 ± 25.3 MBq/nmol (DOTA titration), 104.0 ± 40.4 MBq/nmol (DTPA titration) and 186.5 ± 83.8 MBq/nmol (CHX-A″-DTPA titration), and a radionuclidic purity (RNP) of >99.9 % at end of purification, hereby demonstrating a purity suitable for radiopharmaceutical use.
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Affiliation(s)
- Kristina Søborg Pedersen
- The Hevesy Laboratory, Department of Health Technology, Technical University of Denmark, Frederiksborgvej 399, Building 202, 4000, Roskilde, Denmark
| | - Claire Deville
- The Hevesy Laboratory, Department of Health Technology, Technical University of Denmark, Frederiksborgvej 399, Building 202, 4000, Roskilde, Denmark
| | - Ursula Søndergaard
- University Hospital of North Norway, Sykehusvegen 38, 9019, Tromsø, Norway; Arctic University of Norway, Hansine Hansens veg 18, 9019, Tromsø, Norway
| | - Mikael Jensen
- The Hevesy Laboratory, Department of Health Technology, Technical University of Denmark, Frederiksborgvej 399, Building 202, 4000, Roskilde, Denmark.
| | - Andreas I Jensen
- The Hevesy Laboratory, Department of Health Technology, Technical University of Denmark, Frederiksborgvej 399, Building 202, 4000, Roskilde, Denmark.
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14
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Keot N, Sarma M. Computational insight into a mechanistic overview of water exchange kinetics and thermodynamic stabilities of bis and tris-aquated complexes of lanthanides. RSC Adv 2023; 13:1516-1529. [PMID: 36688060 PMCID: PMC9816859 DOI: 10.1039/d2ra05810c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 12/08/2022] [Indexed: 01/09/2023] Open
Abstract
A thorough investigation of Ln3+ complexes with more than one inner-sphere water molecule is crucial for designing high relaxivity contrast agents (CAs) used in magnetic resonance imaging (MRI). This study accomplished a comparative stability analysis of two hexadentate (H3cbda and H3dpaa) and two heptadentate (H4peada and H3tpaa) ligands with Ln3+ ions. The higher stability of the hexadentate H3cbda and heptadentate H4peada ligands has been confirmed by the binding affinity and Gibbs free energy analysis in aqueous solution. In addition, energy decomposition analysis (EDA) reveals the higher binding affinity of the peada4- ligand than the cbda3- ligand towards Ln3+ ions due to the higher charge density of the peada4- ligand. Moreover, a mechanistic overview of water exchange kinetics has been carried out based on the strength of the metal-water bond. The strength of the metal-water bond follows the trend Gd-O47 (w) > Gd-O39 (w) > Gd-O36 (w) in the case of the tris-aquated [Gd(cbda)(H2O)3] and Gd-O43 (w) > Gd-O40 (w) for the bis-aquated [Gd(peada)(H2O)2]- complex, which was confirmed by bond length, electron density (ρ), and electron localization function (ELF) at the corresponding bond critical points. Our analysis also predicts that the activation energy barrier decreases with the decrease in bond strength; hence k ex increases. The 17O and 1H hyperfine coupling constant values of all the coordinated water molecules were different, calculated by using the second-order Douglas-Kroll-Hess (DKH2) approach. Furthermore, the ionic nature of the bonding in the metal-ligand (M-L) bond was confirmed by the Quantum Theory of Atoms-In-Molecules (QTAIM) and ELF along with energy decomposition analysis (EDA). We hope that the results can be used as a basis for the design of highly efficient Gd(iii)-based high relaxivity MRI contrast agents for medical applications.
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Affiliation(s)
- Niharika Keot
- Department of Chemistry, Indian Institute of Technology GuwahatiAssam781039India+91 361 2582318
| | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology GuwahatiAssam781039India+91 361 2582318
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15
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Nelson BJB, Wilson J, Schultz MK, Andersson JD, Wuest F. High-yield cyclotron production of 203Pb using a sealed 205Tl solid target. Nucl Med Biol 2023; 116-117:108314. [PMID: 36708660 DOI: 10.1016/j.nucmedbio.2023.108314] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/15/2022] [Accepted: 01/02/2023] [Indexed: 01/15/2023]
Abstract
INTRODUCTION 203Pb (t1/2 = 51.9 h, 279 keV (81 %)) is a diagnostic SPECT imaging radionuclide ideally suited for theranostic applications in combination with 212Pb for targeted alpha particle therapy. Our objectives were to develop a high-yield solid target 203Pb cyclotron production route using isotopically enriched 205Tl target material and the 205Tl(p,3n)203Pb reaction as an alternative to lower energy production via the 203Tl(p,n)203Pb reaction. METHODS 250 mg 205Tl metal (99.9 % isotopic enrichment) was pressed using a hardened stainless steel die. Aluminum target discs were machined with a central depression and annulus groove. The flattened 205Tl pellet was placed into the central depression of the Al disc and a circle of indium wire was laid in the machined annulus surrounding the pellet. An aluminum foil cover was then pressed onto the target disc to create an airtight bond. Targets were irradiated at 23.3 MeV for up to 516 min on a TR-24 cyclotron at currents up to 60 μA to produce 203Pb via the 205Tl(p,3n)203Pb nuclear reaction. Following a cool-down period of >12 h, the target was removed and 205Tl dissolved in 4 M HNO3. A NEPTIS Mosaic-LC synthesis unit performed automated separation using Eichrom Pb resin, and 203Pb was eluted using 8 M HCl or 1 M NH4OAc. 205Tl was diverted to a vial for recovery in an electrolytic cell. 203Pb product radionuclidic purity was assessed by HPGe gamma spectroscopy, while elemental purity was assessed by ICP-OES. Radiolabeling and stability studies were performed with PSC, TCMC, and DOTA chelators, and 203Pb incorporation was verified by radio-TLC analysis. RESULTS Cyclotron irradiations performed at 60 μA proton beam current and 23.3 MeV (205Tl incident energy) had a 203Pb saturated yield of 4658 ± 62 MBq/μA (n = 3). Automated NEPTIS separation took <4 h from the start of target dissolution to product elution, yielding >85 % decay-corrected [203Pb]PbCl2 with a radionuclidic purity of >99.9 %. Purified [203Pb]PbCl2 yields of up to 12 GBq 203Pb were attained (15.8 GBq at EOB). The [203Pb]PbCl2 and [203Pb]Pb(OAc)2 products contained no detectable radionuclidic impurities besides 201Pb (<0.1 %), and <0.4 ppm stable Pb. 205Tl metal was recovered with a 92 % batch yield. Aliquots of 100 μL [203Pb]Pb(OAc)2 were used for radiolabeling PSC-Bn-NCS, TCMC-NCS, and DOTA-NCS chelators at pH 4.5 and 22 °C for 30 min, with maximum respective molar activities of 461 ± 30 GBq/μmol, 195 ± 37 GBq/μmol, and 83 ± 12 GBq/μmol. PSC, TCMC, and DOTA chelators exhibited >99.9 % incorporation after a 120-hour incubation in human serum at 37 °C. CONCLUSIONS Nuclear medicine centers with access to higher energy cyclotrons can produce large 203Pb activities sufficient for clinical applications, with a convenient separation technique producing highly pure [203Pb]PbCl2 or [203Pb]Pb(OAc)2 for direct radiolabeling. This represents an attractive route to produce 203Pb for diagnostic SPECT imaging alongside 212Pb targeted alpha particle therapy. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE Our high-yield 203Pb production technique significantly enhances 203Pb production capabilities to meet the growing preclinical and clinical demand for 203Pb radiopharmaceuticals alongside 212Pb target alpha particle therapy.
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Affiliation(s)
- Bryce J B Nelson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada
| | - John Wilson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada
| | - Michael K Schultz
- Viewpoint Molecular Targeting, Inc., Coralville, IA 52241, USA; Department of Radiology, The University of Iowa, Iowa City, IA 52240, USA
| | - Jan D Andersson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada; Edmonton Radiopharmaceutical Center, Alberta Health Services, Edmonton, Alberta T6G 1Z2, Canada
| | - Frank Wuest
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada; Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
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16
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Wharton L, Zhang C, Zeisler J, Rodríguez-Rodríguez C, Osooly M, Radchenko V, Yang H, Lin KS, Bénard F, Schaffer P, Orvig C. H 3TPAN-Triazole-Bn-NH 2: Tripicolinate Clicked-Bifunctional Chelate for [ 225Ac]/[ 111In] Theranostics. Bioconjug Chem 2022; 33:2381-2397. [PMID: 36378809 DOI: 10.1021/acs.bioconjchem.2c00465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A new, high-denticity, bifunctional ligand─H3TPAN-triazole-Bn-NH2─has been synthesized and studied in complexation with [225Ac]Ac3+ and [111In]In3+ for radiopharmaceutical applications. The bifunctional chelator is readily synthesized, using a high-yielding four-step prep, which is highly adaptable and allows for straightforward incorporation of different covalent linkers using CuI-catalyzed alkyne-azide cycloaddition (click) chemistry. Nuclear magnetic resonance (NMR) studies of H3TPAN-triazole-Bn-NH2 with La3+ and In3+ metal ions show the formation of a single, asymmetric complex with each ion in solution, corroborated by density functional theory (DFT) calculations. Radiolabeling studies with [225Ac]Ac3+ and [111In]In3+ showed highly effective complexation, achieving quantitative radiochemical conversions at low ligand concentrations (<10-6 M) under mild conditions (RT, 10 min), which is further accompanied by high stability in human serum. The bioconjugate─H3TPAN-triazole-Bn-Aoc-Pip-Nle-CycMSHhex─was prepared for targeting of MC1R-positive tumors, and the corresponding 111In-radiolabeled tracer was studied in vivo. SPECT/CT and biodistribution studies in C57BL/6J mice bearing B16-F10 tumors were performed, with the radiotracer showing good in vivo stability; tumor uptake was achieved. This work highlights a new promising and versatile bifunctional chelator, easily prepared and encouraging for 225Ac/111In theranostics.
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Affiliation(s)
- Luke Wharton
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.,Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - Chengcheng Zhang
- Department of Molecular Oncology, BC Cancer Research Institute, Vancouver, British Columbia V5Z 1L3, Canada
| | - Jutta Zeisler
- Department of Molecular Oncology, BC Cancer Research Institute, Vancouver, British Columbia V5Z 1L3, Canada
| | - Cristina Rodríguez-Rodríguez
- Faculty of Pharmaceutical Sciences, University of British Columbia, 2405 Wesbrook Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Physics and Astronomy, University of British Columbia, 6224 Agronomy Road, Vancouver, British Columbia V6T 1Z1, Canada
| | - Maryam Osooly
- Faculty of Pharmaceutical Sciences, University of British Columbia, 2405 Wesbrook Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Valery Radchenko
- Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.,Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Hua Yang
- Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.,Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Kuo-Shyan Lin
- Department of Molecular Oncology, BC Cancer Research Institute, Vancouver, British Columbia V5Z 1L3, Canada.,Department of Radiology, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
| | - François Bénard
- Department of Molecular Oncology, BC Cancer Research Institute, Vancouver, British Columbia V5Z 1L3, Canada.,Department of Radiology, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
| | - Paul Schaffer
- Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.,Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Department of Radiology, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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17
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Abdelshafy MS, Ali BM, Elmageed KEA, Nafie HO, Hassan HE, Al-Abyad M. Study of activation cross sections of proton induced reactions on natBa and natCe near their threshold energy regions. RADIOCHIM ACTA 2022. [DOI: 10.1515/ract-2022-0048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Abstract
Activation cross-sections of the nuclear reactions natBa(p,x)135,132gLa, 135mBa and natCe(p,x)142,139,138mPr, 141,139,137mCe have been measured experimentally at the MGC-20 cyclotron, Cairo, Egypt, from their respective threshold energies up to about 14.7 MeV. Stacked foil irradiation technique and high-resolution gamma-ray spectroscopy were used. A comparison between the experimental and theoretical data derived from the nuclear model codes EMPIRE and TALYS (in the form of the TENDL library) was performed. The agreement in the low-energy region is fairly good. Integral yields of the produced radioisotopes were estimated from the present cross-section data and the results are discussed in terms of their production possibilities.
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Affiliation(s)
| | - Bahaa Mohamed Ali
- Experimental Nuclear Physics Department , Cyclotron Facility, Nuclear Research Centre, Egyptian Atomic Energy Authority , Cairo 13759 , Egypt
| | | | - Hassan Omar Nafie
- Department of Physics , Faculty of Science, Benha University , Benha 13518 , Egypt
| | - H. Ebrahim Hassan
- Experimental Nuclear Physics Department , Cyclotron Facility, Nuclear Research Centre, Egyptian Atomic Energy Authority , Cairo 13759 , Egypt
| | - Mogahed Al-Abyad
- Experimental Nuclear Physics Department , Cyclotron Facility, Nuclear Research Centre, Egyptian Atomic Energy Authority , Cairo 13759 , Egypt
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18
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Ivanov AS, Simms ME, Bryantsev VS, Benny PD, Griswold JR, Delmau LH, Thiele NA. Elucidating the coordination chemistry of the radium ion for targeted alpha therapy. Chem Commun (Camb) 2022; 58:9938-9941. [PMID: 35983753 DOI: 10.1039/d2cc03156f] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The coordination chemistry of Ra2+ is poorly defined, hampering efforts to design effective chelators for 223Ra-based targeted alpha therapy. Here, we report the complexation thermodynamics of Ra2+ with the biomedically-relevant chelators DOTA and macropa. Our work reveals the highest affinity chelator to date for Ra2+ and advances our understanding of key factors underlying complex stability and selectivity for this underexplored ion.
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Affiliation(s)
- Alexander S Ivanov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Megan E Simms
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Vyacheslav S Bryantsev
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Paul D Benny
- Radioisotope Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Justin R Griswold
- Radioisotope Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Laetitia H Delmau
- Radioisotope Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Nikki A Thiele
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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19
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Sadler AWE, Hogan L, Fraser B, Rendina LM. Cutting edge rare earth radiometals: prospects for cancer theranostics. EJNMMI Radiopharm Chem 2022; 7:21. [PMID: 36018527 PMCID: PMC9418400 DOI: 10.1186/s41181-022-00173-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 07/22/2022] [Indexed: 11/10/2022] Open
Abstract
Background With recent advances in novel approaches to cancer therapy and imaging, the application of theranostic techniques in personalised medicine has emerged as a very promising avenue of research inquiry in recent years. Interest has been directed towards the theranostic potential of Rare Earth radiometals due to their closely related chemical properties which allow for their facile and interchangeable incorporation into identical bifunctional chelators or targeting biomolecules for use in a diverse range of cancer imaging and therapeutic applications without additional modification, i.e. a “one-size-fits-all” approach. This review will focus on recent progress and innovations in the area of Rare Earth radionuclides for theranostic applications by providing a detailed snapshot of their current state of production by means of nuclear reactions, subsequent promising theranostic capabilities in the clinic, as well as a discussion of factors that have impacted upon their progress through the theranostic drug development pipeline. Main body In light of this interest, a great deal of research has also been focussed towards certain under-utilised Rare Earth radionuclides with diverse and favourable decay characteristics which span the broad spectrum of most cancer imaging and therapeutic applications, with potential nuclides suitable for α-therapy (149Tb), β−-therapy (47Sc, 161Tb, 166Ho, 153Sm, 169Er, 149Pm, 143Pr, 170Tm), Auger electron (AE) therapy (161Tb, 135La, 165Er), positron emission tomography (43Sc, 44Sc, 149Tb, 152Tb, 132La, 133La), and single photon emission computed tomography (47Sc, 155Tb, 152Tb, 161Tb, 166Ho, 153Sm, 149Pm, 170Tm). For a number of the aforementioned radionuclides, their progression from ‘bench to bedside’ has been hamstrung by lack of availability due to production and purification methods requiring further optimisation. Conclusions In order to exploit the potential of these radionuclides, reliable and economical production and purification methods that provide the desired radionuclides in high yield and purity are required. With more reactors around the world being decommissioned in future, solutions to radionuclide production issues will likely be found in a greater focus on linear accelerator and cyclotron infrastructure and production methods, as well as mass separation methods. Recent progress towards the optimisation of these and other radionuclide production and purification methods has increased the feasibility of utilising Rare Earth radiometals in both preclinical and clinical settings, thereby placing them at the forefront of radiometals research for cancer theranostics.
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Affiliation(s)
| | - Leena Hogan
- ANSTO Life Sciences, Australian Nuclear Science and Technology Organisation (ANSTO), Kirrawee, NSW, 2232, Australia
| | - Benjamin Fraser
- ANSTO Life Sciences, Australian Nuclear Science and Technology Organisation (ANSTO), Kirrawee, NSW, 2232, Australia
| | - Louis M Rendina
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia.
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20
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Hu A, Simms ME, Kertesz V, Wilson JJ, Thiele NA. Chelating Rare-Earth Metals (Ln 3+) and 225Ac 3+ with the Dual-Size-Selective Macrocyclic Ligand Py 2-Macrodipa. Inorg Chem 2022; 61:12847-12855. [PMID: 35914099 DOI: 10.1021/acs.inorgchem.2c01998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Radioisotopes of metallic elements, or radiometals, are widely employed in both therapeutic and diagnostic nuclear medicine. For this application, chelators that efficiently bind the radiometal of interest and form a stable metal-ligand complex with it are required. Toward the development of new chelators for nuclear medicine, we recently reported a novel class of 18-membered macrocyclic chelators that is characterized by their ability to form stable complexes with both large and small rare-earth metals (Ln3+), a property referred to as dual size selectivity. A specific chelator in this class called py-macrodipa, which contains one pyridyl group within its macrocyclic core, was established as a promising candidate for 135La3+, 213Bi3+, and 44Sc3+ chelation. Building upon this prior work, here we report the synthesis and characterization of a new chelator called py2-macrodipa with two pyridyl units fused into the macrocyclic backbone. Its coordination chemistry with the Ln3+ series was investigated by NMR spectroscopy, X-ray crystallography, density functional theory (DFT) calculations, analytical titrations, and transchelation assays. These studies reveal that py2-macrodipa retains the expected dual size selectivity and possesses an enhanced thermodynamic affinity for all Ln3+ compared to py-macrodipa. By contrast, the kinetic stability of Ln3+ complexes with py2-macrodipa is only improved for the light, large Ln3+ ions. Based upon these observations, we further assessed the suitability of py2-macrodipa for use with 225Ac3+, a large radiometal with valuable properties for targeted α therapy. Radiolabeling and stability studies revealed py2-macrodipa to efficiently incorporate 225Ac3+ and to form a complex that is inert in human serum over 3 weeks. Although py2-macrodipa does not surpass the state-of-the-art chelator macropa for 225Ac3+ chelation, it does provide another effective 225Ac3+ chelator. These studies shed light on the fundamental coordination chemistry of the Ln3+ series and may inspire future chelator design efforts.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Megan E Simms
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Vilmos Kertesz
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Nikki A Thiele
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
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21
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Ingham A, Wharton L, El Sayed T, Southcott L, McNeil BL, Ezhova MB, Patrick BO, Jaraquemada-Peláez MDG, Orvig C. H 2ampa─Versatile Chelator for [ 203Pb]Pb 2+, [ 213Bi]Bi 3+, and [ 225Ac]Ac 3. Inorg Chem 2022; 61:9119-9137. [PMID: 35678752 DOI: 10.1021/acs.inorgchem.2c00636] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A new decadentate chelator, H2ampa, was designed to be a potential radiopharmaceutical chelator component. The chelator involves both amide and picolinate functional groups on a large non-macrocyclic, ether-bridged backbone. With its large scaffold, H2ampa was paired with [nat/203Pb]Pb2+, [nat/213Bi]Bi3+, and natLa3+/[225Ac]Ac3+ ions. Nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry were used to study the non-radioactive metal complexes. A single crystal of [Bi(ampa)](NO3) was obtained; its asymmetric, 10-coordinate complex structure was revealed by X-ray diffraction. Optimal conformations of the metal complexes were assessed by density functional theory studies to provide further structural information. Solution studies providing thermodynamic insights into metal complex formation revealed H2ampa coordinated Bi3+, Pb2+, and La3+ ions to obtain pM values of 26, 14.8, and 15.1, respectively. Preliminary concentration-dependent radiolabeling experiments were carried out between H2ampa and three different radiometals to evaluate their compatibility for radiopharmaceutical applications. The chelator radiolabeled [203Pb]Pb2+, [213Bi]Bi3+, and [225Ac]Ac3+ in short reaction times (7-30 min), at dilute concentrations, and under mild conditions. Thus, H2ampa was proven to be a versatile chelator able to well coordinate a small range of radiometals frequently considered to be alpha therapeutic candidates.
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Affiliation(s)
- Aidan Ingham
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.,Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - Luke Wharton
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.,Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - Tarek El Sayed
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Lily Southcott
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.,Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
| | - Brooke L McNeil
- Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.,Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby V5A 1S6, Canada
| | - Maria B Ezhova
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Brian O Patrick
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - María de Guadalupe Jaraquemada-Peláez
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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22
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Kadassery KJ, King AP, Fayn S, Baidoo KE, MacMillan SN, Escorcia FE, Wilson JJ. H 2BZmacropa-NCS: A Bifunctional Chelator for Actinium-225 Targeted Alpha Therapy. Bioconjug Chem 2022; 33:1222-1231. [PMID: 35670495 PMCID: PMC9362842 DOI: 10.1021/acs.bioconjchem.2c00190] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Actinium-225 (225Ac) is one of the most promising radionuclides for targeted alpha therapy (TAT). With a half-life of 9.92 days and a decay chain that emits four high-energy α particles, 225Ac is well-suited for TAT when conjugated to macromolecular targeting vectors that exhibit extended in vivo circulation times. The implementation of 225Ac in these targeted constructs, however, requires a suitable chelator that can bind and retain this radionuclide in vivo. Previous work has demonstrated the suitability of a diaza-18-crown-6 macrocyclic chelator H2macropa for this application. Building upon these prior efforts, in this study, two rigid variants of H2macropa, which contain either one (H2BZmacropa) or two (H2BZ2macropa) benzene rings within the macrocyclic core, were synthesized and investigated for their potential use for 225Ac TAT. The coordination chemistry of these ligands with La3+, used as a nonradioactive model for Ac3+, was carried out. Both NMR spectroscopic and X-ray crystallographic studies of the La3+ complexes of these ligands revealed similar structural features to those found for the related complex of H2macropa. Thermodynamic stability constants of the La3+ complexes, however, were found to be 1 and 2 orders of magnitude lower than those of H2macropa for H2BZmacropa and H2BZ2macropa, respectively. The decrease in thermodynamic stability was rationalized via the use of density functional theory calculations. 225Ac radiolabeling and serum stability studies with H2BZmacropa showed that this chelator compares favorably with H2macropa. Based on these promising results, a bifunctional version of this chelator, H2BZmacropa-NCS, was synthesized and conjugated to the antibody codrituzumab (GC33), which targets the liver cancer biomarker glypican-3 (GPC3). The resulting GC33-BZmacropa conjugate and an analogous GC33-macropa conjugate were evaluated for their 225Ac radiolabeling efficiencies, antigen-binding affinities, and in vivo biodistribution in HepG2 liver cancer tumor-bearing mice. Although both conjugates were comparably effective in their radiolabeling efficiencies, [225Ac]Ac-GC33-BZmacropa showed slightly poorer serum stability and biodistribution than [225Ac]Ac-GC33-macropa. Together, these results establish H2BZmacropa-NCS as a new bifunctional chelator for the preparation of 225Ac radiopharmaceuticals.
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Affiliation(s)
- Karthika J. Kadassery
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - A. Paden King
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Stanley Fayn
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Kwamena E. Baidoo
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Freddy E. Escorcia
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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23
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Nelson BJB, Ferguson S, Wuest M, Wilson J, Duke MJM, Richter S, Soenke-Jans H, Andersson JD, Juengling F, Wuest F. First In Vivo and Phantom Imaging of Cyclotron-Produced 133La as a Theranostic Radionuclide for 225Ac and 135La. J Nucl Med 2022; 63:584-590. [PMID: 34385334 PMCID: PMC8973294 DOI: 10.2967/jnumed.121.262459] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 07/16/2021] [Indexed: 01/18/2023] Open
Abstract
Theranostic isotope pairs have gained recent clinical interest because they can be labeled to the same tracer and applied for diagnostic and therapeutic purposes. The goals of this study were to investigate cyclotron production of clinically relevant 133La activities using natural and isotopically enriched barium target material, compare fundamental PET phantom imaging characteristics of 133La with those of common PET radionuclides, and demonstrate in vivo preclinical PET tumor imaging using 133La-PSMA-I&T. Methods:133La was produced on a 24-MeV cyclotron using an aluminum-indium sealed target with 150-200 mg of isotopically enriched 135BaCO3, natBaCO3, and natBa metal. A synthesis unit performed barium/lanthanum separation. DOTA, PSMA-I&T, and macropa were radiolabeled with 133La. Derenzo and National Electrical Manufacturers Association phantom imaging was performed with 133La, 132La, and 89Zr and compared with 18F, 68Ga, 44Sc, and 64Cu. In vivo preclinical imaging was performed with 133La-PSMA-I&T on LNCaP tumor-bearing mice. Results: Proton irradiations for 100 µA·min at 23.3 MeV yielded 214 ± 7 MBq of 133La and 28 ± 1 MBq of 135La using 135BaCO3, 59 ± 2 MBq of 133La and 35 ± 1 MBq of 135La using natBaCO3, and 81 ± 3 MBq of 133La and 48 ± 1 MBq of 135La using natBa metal. At 11.9 MeV, 135La yields were 81 ± 2 MBq, 6.8 ± 0.4 MBq, and 9.9 ± 0.5 MBq for 135BaCO3, natBaCO3, and natBa metal. BaCO3 target material recovery was 95.4% ± 1.7%. National Electrical Manufacturers Association and Derenzo phantom imaging demonstrated that 133La PET spatial resolution and scanner recovery coefficients were superior to those of 68Ga and 132La and comparable to those of 89Zr. The apparent molar activity was 130 ± 15 GBq/µmol with DOTA, 73 ± 18 GBq/µmol with PSMA-I&T, and 206 ± 31 GBq/µmol with macropa. Preclinical PET imaging with 133La-PSMA-I&T provided high-resolution tumor visualization with an SUV of 0.97 ± 0.17 at 60 min. Conclusion: With high-yield 133La cyclotron production, recovery of BaCO3 target material, and fundamental imaging characteristics superior to those of 68Ga and 132La, 133La represents a promising radiometal candidate to provide high-resolution PET imaging as a PET/α-therapy theranostic pair with 225Ac or as a PET/Auger electron therapy theranostic pair with 135La.
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Affiliation(s)
- Bryce J B Nelson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Simon Ferguson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Melinda Wuest
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
- Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada; and
| | - John Wilson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - M John M Duke
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Susan Richter
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
- Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada; and
| | - Hans Soenke-Jans
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
- Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada; and
| | - Jan D Andersson
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
- Edmonton Radiopharmaceutical Center, Cross Cancer Institute, Alberta Health Services, Edmonton, Alberta, Canada
| | - Freimut Juengling
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Frank Wuest
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada;
- Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada; and
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24
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Radiolanthanum: Promising theranostic radionuclides for PET, alpha, and Auger-Meitner therapy. Nucl Med Biol 2022; 110-111:59-66. [DOI: 10.1016/j.nucmedbio.2022.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/06/2022] [Accepted: 04/11/2022] [Indexed: 01/18/2023]
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25
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Hu A, Wilson JJ. Advancing Chelation Strategies for Large Metal Ions for Nuclear Medicine Applications. Acc Chem Res 2022; 55:904-915. [PMID: 35230803 DOI: 10.1021/acs.accounts.2c00003] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nuclear medicine leverages radioisotopes of a wide range of elements, a significant portion of which are metals, for the diagnosis and treatment of disease. To optimally use radioisotopes of the metal ions, or radiometals, for these applications, a chelator that efficiently forms thermodynamically and kinetically stable complexes with them is required. The chelator also needs to attach to a biological targeting vector that locates pathological tissues. Numerous chelators suitable for small radiometals have been established to date, but chelators that work well for large radiometals are significantly less common. In this Account, we describe recent progress by us and others in the advancement of ligands for large radiometal chelation with emerging applications in nuclear medicine.First, we discuss and analyze the coordination chemistry of the chelator macropa, a macrocyclic ligand that contains the 18-crown-6 backbone and two picolinate pendent arms, with large metal ions in the context of nuclear medicine. This ligand is known for its unusual reverse size selectivity, the preference for binding large over small metal ions. The radiolabeling properties of macropa with large radiometals 225Ac3+, 132/135La3+, 131Ba2+, 223Ra2+, 213Bi3+, and related in vivo investigations are described. The development of macropa derivatives containing different pendent donors or rigidifying groups in the macrocyclic core is also briefly reviewed.Next, efforts to transform macropa into a radiopharmaceutical agent via covalent conjugation to biological targeting vectors are summarized. In this discussion, two types of bifunctional analogues of macropa reported in the literature, macropa-NCS and mcp-click, are presented. Their implementation in different radiopharmaceutical agents is discussed. Bioconjugates containing macropa attached to small-molecule targeting vectors or macromolecular antibodies are presented. The in vitro and in vivo evaluations of these constructs are also discussed.Lastly, chelators with dual size selectivity are described. This class of ligands exhibits good affinities for both large and small metal ions. This property is valuable for nuclear medicine applications that require the simultaneous chelation of both large and small radiometals with complementary therapeutic and diagnostic properties. Recently, we reported an 18-membered macrocyclic ligand called macrodipa that attains this selectivity pattern. This chelator, its second-generation analogue py-macrodipa, and their applications for chelating the medicinally relevant large 135La3+, 225Ac3+, 213Bi3+, and small 44Sc3+ ions are also presented. Studies with these radiometals show that py-macrodipa can effectively radiolabel and stably retain both large and small radiometals. Overall, this Account makes the case for innovative ligand design approaches for novel emerging radiometal ions with unusual coordination chemistry properties.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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26
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Hu A, Brown V, MacMillan SN, Radchenko V, Yang H, Wharton L, Ramogida CF, Wilson JJ. Chelating the Alpha Therapy Radionuclides 225Ac 3+ and 213Bi 3+ with 18-Membered Macrocyclic Ligands Macrodipa and Py-Macrodipa. Inorg Chem 2022; 61:801-806. [PMID: 34965102 PMCID: PMC9372718 DOI: 10.1021/acs.inorgchem.1c03670] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The radionuclides 225Ac3+ and 213Bi3+ possess favorable physical properties for targeted alpha therapy (TAT), a therapeutic approach that leverages α radiation to treat cancers. A chelator that effectively binds and retains these radionuclides is required for this application. The development of ligands for this purpose, however, is challenging because the large ionic radii and charge-diffuse nature of these metal ions give rise to weaker metal-ligand interactions. In this study, we evaluated two 18-membered macrocyclic chelators, macrodipa and py-macrodipa, for their ability to complex 225Ac3+ and 213Bi3+. Their coordination chemistry with Ac3+ was probed computationally and with Bi3+ experimentally via NMR spectroscopy and X-ray crystallography. Furthermore, radiolabeling studies were conducted, revealing the efficient incorporation of both 225Ac3+ and 213Bi3+ by py-macrodipa that matches or surpasses the well-known chelators macropa and DOTA. Incubation in human serum at 37 °C showed that ∼90% of the 225Ac3+-py-macrodipa complex dissociates after 1 d. The Bi3+-py-macrodipa complex possesses remarkable kinetic inertness reflected by an EDTA transchelation challenge study, surpassing that of Bi3+-macropa. This work establishes py-macrodipa as a valuable candidate for 213Bi3+ TAT, providing further motivation for its implementation within new radiopharmaceutical agents.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Victoria Brown
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Valery Radchenko
- Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Hua Yang
- Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
| | - Luke Wharton
- Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Caterina F. Ramogida
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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27
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Vaughn BA, Loveless CS, Cingoranelli SJ, Schlyer D, Lapi SE, Boros E. Evaluation of 177Lu and 47Sc Picaga-Linked, Prostate-Specific Membrane Antigen-Targeting Constructs for Their Radiotherapeutic Efficacy and Dosimetry. Mol Pharm 2021; 18:4511-4519. [PMID: 34714082 DOI: 10.1021/acs.molpharmaceut.1c00711] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lu-177-based, targeted radiotherapeutics/endoradiotherapies are an emerging clinical tool for the management of various cancers. The chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) remains the workhorse for such applications but can limit apparent molar activity or efficient charge modulation, which can impact target binding and, as a consequence, target efficacy. Previously, our lab had developed the small, rare earth selective bifunctional chelator, picaga, as an efficient bifunctional chelator for scandium and lutetium isotopes. Here, we assess the performance of these constructs for therapy in prostate-specific membrane antigen (PSMA)-expressing tumor xenografts. To assess the viability of picaga conjugates in conjunction with long in vivo circulation, a picaga conjugate functionalized with a serum albumin binding moiety, 177Lu-picaga-Alb53-PSMA, was also synthesized. A directly comparative, low, single 3.7 MBq dose treatment study with Lu-PSMA-617 was conducted. Treatment with 177Lu-picaga-Alb53-PSMA resulted in tumor regression and lengthened median survival (54 days) when compared with the vehicle (16 days), 47Sc-picaga-DUPA-, 177Lu-picaga-DUPA-, and 177Lu-PSMA-617-treated cohorts (21, 23, and 21 days, respectively).
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Affiliation(s)
- Brett A Vaughn
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
| | - C Shaun Loveless
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Shelbie J Cingoranelli
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - David Schlyer
- Brookhaven National Laboratory, Upton, New York 11973, United States.,Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Suzanne E Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
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28
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George KJH, Borjian S, Cross MC, Hicks JW, Schaffer P, Kovacs MS. Expanding the PET radioisotope universe utilizing solid targets on small medical cyclotrons. RSC Adv 2021; 11:31098-31123. [PMID: 35498914 PMCID: PMC9041346 DOI: 10.1039/d1ra04480j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/25/2021] [Indexed: 12/17/2022] Open
Abstract
Molecular imaging with medical radioisotopes enables the minimally-invasive monitoring of aberrant biochemical, cellular and tissue-level processes in living subjects. The approach requires the administration of radiotracers composed of radioisotopes attached to bioactive molecules, the pairing of which considers several aspects of the radioisotope in addition to the biological behavior of the targeting molecule to which it is attached. With the advent of modern cellular and biochemical techniques, there has been a virtual explosion in potential disease recognition antigens as well as targeting moieties, which has subsequently opened new applications for a host of emerging radioisotopes with well-matched properties. Additionally, the global radioisotope production landscape has changed rapidly, with reactor-based production and its long-defined, large-scale centralized manufacturing and distribution paradigm shifting to include the manufacture and distribution of many radioisotopes via a worldwide fleet of cyclotrons now in operation. Cyclotron-based radioisotope production has become more prevalent given the commercial availability of instruments, coupled with the introduction of new target hardware, process automation and target manufacturing methods. These advances enable sustained, higher-power irradiation of solid targets that allow hospital-based radiopharmacies to produce a suite of radioisotopes that drive research, clinical trials, and ultimately clinical care. Over the years, several different radioisotopes have been investigated and/or selected for radiolabeling due to favorable decay characteristics (i.e. a suitable half-life, high probability of positron decay, etc.), well-elucidated chemistry, and a feasible production framework. However, longer-lived radioisotopes have surged in popularity given recent regulatory approvals and incorporation of radiopharmaceuticals into patient management within the medical community. This review focuses on the applications, nuclear properties, and production and purification methods for some of the most frequently used/emerging positron-emitting, solid-target-produced radioisotopes that can be manufactured using small-to-medium size cyclotrons (≤24 MeV).
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Affiliation(s)
- K J H George
- Lawson Health Research Institute 268 Grosvenor Street London ON N6A 4V2 Canada
- Medical Biophysics, Western University 1151 Richmond Street N. London ON N6A 5C1 Canada
| | - S Borjian
- ARTMS 301-4475 Wayburn Drive Burnaby BC V5G 4X4 Canada
| | - M C Cross
- ARTMS 301-4475 Wayburn Drive Burnaby BC V5G 4X4 Canada
| | - J W Hicks
- Lawson Health Research Institute 268 Grosvenor Street London ON N6A 4V2 Canada
- Medical Biophysics, Western University 1151 Richmond Street N. London ON N6A 5C1 Canada
| | - P Schaffer
- Life Sciences, TRIUMF 4004 Wesbrook Mall Vancouver BC V6T 2A3 Canada
- ARTMS 301-4475 Wayburn Drive Burnaby BC V5G 4X4 Canada
- Radiology, University of British Columbia 2775 Laurel St Vancouver BC V5Z 1M9 Canada
- Chemistry, Simon Fraser University 8888 University Dr Burnaby BC V5A 1S6 Canada
| | - M S Kovacs
- Lawson Health Research Institute 268 Grosvenor Street London ON N6A 4V2 Canada
- Medical Biophysics, Western University 1151 Richmond Street N. London ON N6A 5C1 Canada
- Medical Imaging, Western University 1151 Richmond Street N. London ON N6A 5C1 Canada
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29
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Hu A, Aluicio-Sarduy E, Brown V, MacMillan SN, Becker KV, Barnhart TE, Radchenko V, Ramogida CF, Engle JW, Wilson JJ. Py-Macrodipa: A Janus Chelator Capable of Binding Medicinally Relevant Rare-Earth Radiometals of Disparate Sizes. J Am Chem Soc 2021; 143:10429-10440. [PMID: 34190542 DOI: 10.1021/jacs.1c05339] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Nuclear medicine leverages different types of radiometals for disease diagnosis and treatment, but these applications usually require them to be stably chelated. Given the often-disparate chemical properties of these radionuclides, it is challenging to find a single chelator that binds all of them effectively. Toward addressing this problem, we recently reported a macrocyclic chelator macrodipa with an unprecedented "dual-size-selectivity" pattern for lanthanide (Ln3+) ions, characterized by its high affinity for both the large and the small Ln3+ ( J. Am. Chem. Soc, 2020, 142, 13500). Here, we describe a second-generation "macrodipa-type" ligand, py-macrodipa. Its coordination chemistry with Ln3+ was thoroughly investigated experimentally and computationally. These studies reveal that the Ln3+-py-macrodipa complexes exhibit enhanced thermodynamic and kinetic stabilities compared to Ln3+-macrodipa, while retaining the unusual dual-size selectivity. Nuclear medicine applications of py-macrodipa for chelating radiometals with disparate chemical properties were assessed using the therapeutic 135La3+ and diagnostic 44Sc3+ radiometals representing the two size extremes within the rare-earth series. Radiolabeling and stability studies demonstrate that the rapidly formed complexes of these radionuclides with py-macrodipa are highly stable in human serum. Thus, in contrast to gold standard chelators like DOTA and macropa, py-macrodipa can be harnessed for the simultaneous, efficient binding of radiometals with disparate ionic radii like La3+ and Sc3+, signifying a substantial achievement in nuclear medicine. This concept could enable the facile incorporation of a breadth of medicinally relevant radiometals into chemically identical radiopharmaceutical agents. The fundamental coordination chemistry learned from py-macrodipa provides valuable insight for future chelator development.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Eduardo Aluicio-Sarduy
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Victoria Brown
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Kaelyn V Becker
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.,Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Todd E Barnhart
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Valery Radchenko
- Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada.,Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Caterina F Ramogida
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Life Sciences Division, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada
| | - Jonathan W Engle
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.,Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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30
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Pretze M, Kunkel F, Runge R, Freudenberg R, Braune A, Hartmann H, Schwarz U, Brogsitter C, Kotzerke J. Ac-EAZY! Towards GMP-Compliant Module Syntheses of 225Ac-Labeled Peptides for Clinical Application. Pharmaceuticals (Basel) 2021; 14:652. [PMID: 34358076 PMCID: PMC8308848 DOI: 10.3390/ph14070652] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 12/24/2022] Open
Abstract
The application of 225Ac (half-life T1/2 = 9.92 d) dramatically reduces the activity used for peptide receptor radionuclide therapy by a factor of 1000 in comparison to 90Y, 177Lu or 188Re while maintaining the therapeutic outcome. Additionally, the range of alpha particles of 225Ac and its daughter nuclides in tissue is much lower (47-85 μm for alpha energies Eα = 5.8-8.4 MeV), which results in a very precise dose deposition within the tumor. DOTA-conjugated commercially available peptides used for endoradiotherapy, which can readily be labeled with 177Lu or 90Y, can also accommodate 225Ac. The benefits are lower doses in normal tissue for the patient, dose reduction of the employees and environment and less shielding material. The low availability of 225Ac activity is preventing its application in clinical practice. Overcoming this barrier would open a broad field of 225Ac therapy. Independent which production pathway of 225Ac proves the most feasible, the use of automated synthesis and feasible and reproducible patient doses are needed. The Modular-Lab EAZY is one example of a GMP-compliant system, and the cassettes used for synthesis are small. Therefore, also the waste after the synthesis can be minimized. In this work, two different automated setups with different purification systems are presented. In its final configuration, three masterbatches were performed on the ML EAZY for DOTA-TATE and PSMA-I&T, respectively, fulfilling all quality criteria with final radiochemical yields of 80-90% for the 225Ac-labeled peptides.
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Affiliation(s)
- Marc Pretze
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
- Molecular Imaging and Radiochemistry, Department of Radiology and Nuclear Medicine, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Falk Kunkel
- Eckert & Ziegler Eurotope, 13125 Berlin, Germany;
| | - Roswitha Runge
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
| | - Robert Freudenberg
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
| | - Anja Braune
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
| | - Holger Hartmann
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
| | - Uwe Schwarz
- Eckert & Ziegler Radiopharma, 38110 Braunschweig, Germany;
| | - Claudia Brogsitter
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
| | - Jörg Kotzerke
- Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany; (R.R.); (R.F.); (A.B.); (H.H.); (C.B.)
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31
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Aluicio-Sarduy E, Barnhart TE, Weichert J, Hernandez R, Engle JW. Cyclotron-Produced 132La as a PET Imaging Surrogate for Therapeutic 225Ac. J Nucl Med 2021; 62:1012-1015. [PMID: 33127622 PMCID: PMC8882879 DOI: 10.2967/jnumed.120.255794] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/14/2020] [Indexed: 11/16/2022] Open
Abstract
The aim of this work was to explore 132La as a PET imaging surrogate for 225Ac using a DOTA-based, tumor-targeting alkylphosphocholine (NM600). Methods:132La was produced on a biomedical cyclotron. For in vivo experiments, mice bearing 4T1 tumors were administered 132La-NM600, and PET/CT scans were acquired up to 24 h after injection. After the last time point, the ex vivo tissue distribution was measured to corroborate the in vivo PET data. The ex vivo tissue distribution in mice was determined at 4 and 24 h after injection of 225Ac-NM600. Results: PET/CT images showed elevated, persistent 132La-NM600 uptake in the tumor. Low bone accumulation confirmed the in vivo stability of the conjugate. Ex vivo biodistribution studies validated the image-derived quantitative data, and the comparison of the 132La-NM600 and 225Ac-NM600 tissue distributions revealed a similar biodistribution for the 2 radiotracers. Conclusion: These findings suggest that 132La is a suitable imaging surrogate to probe the in vivo biodistribution of 225Ac radiotherapeutics.
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Affiliation(s)
| | - Todd E Barnhart
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin; and
| | - Jamey Weichert
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Reinier Hernandez
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin; and
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Jonathan W Engle
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin; and
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin
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32
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Martin KE, Cosby AG, Boros E. Multiplex and In Vivo Optical Imaging of Discrete Luminescent Lanthanide Complexes Enabled by In Situ Cherenkov Radiation Mediated Energy Transfer. J Am Chem Soc 2021; 143:9206-9214. [PMID: 34114809 DOI: 10.1021/jacs.1c04264] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recently, we pioneered the application of Cherenkov radiation (CR) of radionuclides for the in situ excitation of discrete Eu(III) and Tb(III) complexes. CR is produced by isotopes decaying under emission of charged particles in dielectric media and exhibits a maximum intensity below 400 nm. We have demonstrated that luminescent lanthanide antenna complexes are ideal acceptors for Cherenkov radiation-mediated energy transfer (CRET). Here, we develop and assess peptide-functionalized Tb(III) and Eu(III) complexes in conjunction with CRET excitation by the positron emissive radioisotope 18F for simultaneous, multiplexed imaging and in vivo optical imaging. This work demonstrates, for the first time, that the detection of the luminescence emission of a discrete Eu(III) complex in vivo is feasible. Our results open possibilities for discrete luminescent lanthanide complexes to be used as diagnostic, optical tools for the intrasurgical guidance of tumor resection.
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Affiliation(s)
- Kirsten E Martin
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
| | - Alexia G Cosby
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
| | - Eszter Boros
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794, United States
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33
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Fiszbein DJ, Brown V, Thiele NA, Woods JJ, Wharton L, MacMillan SN, Radchenko V, Ramogida CF, Wilson JJ. Tuning the Kinetic Inertness of Bi 3+ Complexes: The Impact of Donor Atoms on Diaza-18-Crown-6 Ligands as Chelators for 213Bi Targeted Alpha Therapy. Inorg Chem 2021; 60:9199-9211. [PMID: 34102841 DOI: 10.1021/acs.inorgchem.1c01269] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The radionuclide 213Bi can be applied for targeted α therapy (TAT): a type of nuclear medicine that harnesses α particles to eradicate cancer cells. To use this radionuclide for this application, a bifunctional chelator (BFC) is needed to attach it to a biological targeting vector that can deliver it selectively to cancer cells. Here, we investigated six macrocyclic ligands as potential BFCs, fully characterizing the Bi3+ complexes by NMR spectroscopy, mass spectrometry, and elemental analysis. Solid-state structures of three complexes revealed distorted coordination geometries about the Bi3+ center arising from the stereochemically active 6s2 lone pair. The kinetic properties of the Bi3+ complexes were assessed by challenging them with a 1000-fold excess of the chelating agent diethylenetriaminepentaacetic acid (DTPA). The most kinetically inert complexes contained the most basic pendent donors. Density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) calculations were employed to investigate this trend, suggesting that the kinetic inertness is not correlated with the extent of the 6s2 lone pair stereochemical activity, but with the extent of covalency between pendent donors. Lastly, radiolabeling studies of 213Bi (30-210 kBq) with three of the most promising ligands showed rapid formation of the radiolabeled complexes at room temperature within 8 min for ligand concentrations as low as 10-7 M, corresponding to radiochemical yields of >80%, thereby demonstrating the promise of this ligand class for use in 213Bi TAT.
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Affiliation(s)
- David J Fiszbein
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Victoria Brown
- Department of Chemistry, Simon Fraser University, 8888 University Dr, Burnaby, BC V5A 1S6 Canada
| | - Nikki A Thiele
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Joshua J Woods
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.,Robert F. Smith School for Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Luke Wharton
- Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 Canada.,Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Valery Radchenko
- Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 Canada.,Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Caterina F Ramogida
- Department of Chemistry, Simon Fraser University, 8888 University Dr, Burnaby, BC V5A 1S6 Canada.,Life Sciences Division, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 Canada
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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34
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Cantu DC. Predicting lanthanide coordination structures in solution with molecular simulation. Methods Enzymol 2021; 651:193-233. [PMID: 33888204 DOI: 10.1016/bs.mie.2021.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The chemical and physical properties of lanthanide coordination complexes can significantly change with small variations in their molecular structure. Further, in solution, coordination structures (e.g., lanthanide-ligand complexes) are dynamic. Resolving solution structures, computationally or experimentally, is challenging because structures in solution have limited spatial restrictions and are responsive to chemical or physical changes in their surroundings. To determine structures of lanthanide-ligand complexes in solution, a molecular simulation approach is presented in this chapter, which concurrently considers chemical reactions and molecular dynamics. Lanthanide ion, ligand, solvent, and anion molecules are explicitly included to identify, in atomic resolution, lanthanide coordination structures in solution. The computational protocol described is applicable to determining the molecular structure of lanthanide-ligand complexes, particularly with ligands known to bind lanthanides but whose structures have not been resolved, as well as with ligands not previously known to bind lanthanide ions. The approach in this chapter is also relevant to elucidating lanthanide coordination in more intricate structures, such as in the active site of enzymes.
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Affiliation(s)
- David C Cantu
- Department of Chemical and Materials Engineering, University of Nevada, Reno, Reno, NV, United States.
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35
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Filosofov D, Kurakina E, Radchenko V. Potent candidates for Targeted Auger Therapy: Production and radiochemical considerations. Nucl Med Biol 2021; 94-95:1-19. [PMID: 33461040 DOI: 10.1016/j.nucmedbio.2020.12.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/18/2020] [Accepted: 12/03/2020] [Indexed: 12/14/2022]
Abstract
Targeted Auger Therapy represents great potential for the therapy of diseases which require a high degree of selectivity on the cellular level (e.g. for therapy of metastatic cancers). Due to their high Linear Energy Transfer (LET), Auger emitters, combined with selective biological systems which enable delivery of radionuclides close to the DNA of the targeting cell, can be extremely selective and powerful treatment tools. There are two main aspects associated with the development of efficient radiopharmaceuticals based on Auger Emitters: a) the availability of suitable Auger-emitting radionuclides for therapy and b) the design of targeting vectors which can deliver Auger emitters into/close to the nucleus. In the present review, we address the first aspect by defining important parameters for the selection of radionuclides for application to Targeted Auger Therapy and form a categorized list of the most promising radionuclides, their possible production routes, and their use in the synthesis of radiopharmaceuticals.
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Affiliation(s)
- Dmitry Filosofov
- Dzhelepov Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russian Federation
| | - Elena Kurakina
- Dzhelepov Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, Dubna, Moscow Region, Russian Federation; Department of High-Energy Chemistry and Radioecology, D. Mendeleev University of Chemical Technology of Russia, Moscow, Russian Federation
| | - Valery Radchenko
- Life Sciences Division, TRIUMF, Vancouver, BC, Canada; Chemistry Department, University of British Columbia, Vancouver, BC, Canada.
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36
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Abou DS, Thiele NA, Gutsche NT, Villmer A, Zhang H, Woods JJ, Baidoo KE, Escorcia FE, Wilson JJ, Thorek DLJ. Towards the stable chelation of radium for biomedical applications with an 18-membered macrocyclic ligand. Chem Sci 2021; 12:3733-3742. [PMID: 34163647 PMCID: PMC8179459 DOI: 10.1039/d0sc06867e] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 01/19/2021] [Indexed: 12/13/2022] Open
Abstract
Targeted alpha therapy is an emerging strategy for the treatment of disseminated cancer. [223Ra]RaCl2 is the only clinically approved alpha particle-emitting drug, and it is used to treat castrate-resistant prostate cancer bone metastases, to which [223Ra]Ra2+ localizes. To specifically direct [223Ra]Ra2+ to non-osseous disease sites, chelation and conjugation to a cancer-targeting moiety is necessary. Although previous efforts to stably chelate [223Ra]Ra2+ for this purpose have had limited success, here we report a biologically stable radiocomplex with the 18-membered macrocyclic chelator macropa. Quantitative labeling of macropa with [223Ra]Ra2+ was accomplished within 5 min at room temperature with a radiolabeling efficiency of >95%, representing a significant advancement over conventional chelators such as DOTA and EDTA, which were unable to completely complex [223Ra]Ra2+ under these conditions. [223Ra][Ra(macropa)] was highly stable in human serum and exhibited dramatically reduced bone and spleen uptake in mice in comparison to bone-targeted [223Ra]RaCl2, signifying that [223Ra][Ra(macropa)] remains intact in vivo. Upon conjugation of macropa to a single amino acid β-alanine as well as to the prostate-specific membrane antigen-targeting peptide DUPA, both constructs retained high affinity for 223Ra, complexing >95% of Ra2+ in solution. Furthermore, [223Ra][Ra(macropa-β-alanine)] was rapidly cleared from mice and showed low 223Ra bone absorption, indicating that this conjugate is stable under biological conditions. Unexpectedly, this stability was lost upon conjugation of macropa to DUPA, which suggests a role of targeting vectors in complex stability in vivo for this system. Nonetheless, our successful demonstration of efficient radiolabeling of the β-alanine conjugate with 223Ra and its subsequent stability in vivo establishes for the first time the possibility of delivering [223Ra]Ra2+ to metastases outside of the bone using functionalized chelators, marking a significant expansion of the therapeutic utility of this radiometal in the clinic.
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Affiliation(s)
- Diane S Abou
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Radiology Cyclotron Facility, Mallinckrodt Institute of Radiology, Washington University in St. Louis St. Louis MO 63110 USA
| | - Nikki A Thiele
- Department of Chemistry and Chemical Biology, Cornell University Ithaca NY 14853 USA
- Chemical Sciences Division, Oak Ridge National Laboratory Oak Ridge TN 37830 USA
| | - Nicholas T Gutsche
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health Bethesda MD 20892 USA
| | - Alexandria Villmer
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
| | - Hanwen Zhang
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
| | - Joshua J Woods
- Department of Chemistry and Chemical Biology, Cornell University Ithaca NY 14853 USA
- Robert F. Smith School for Chemical and Biomolecular Engineering, Cornell University Ithaca NY 14853 USA
| | - Kwamena E Baidoo
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health Bethesda MD 20892 USA
| | - Freddy E Escorcia
- Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health Bethesda MD 20892 USA
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University Ithaca NY 14853 USA
| | - Daniel L J Thorek
- Department of Radiology, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Program in Quantitative Molecular Therapeutics, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
- Department of Biomedical Engineering, Washington University in St. Louis St. Louis MO 63110 USA
- Oncologic Imaging Program, Siteman Cancer Center, Washington University in St. Louis School of Medicine St. Louis MO 63110 USA
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37
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Kaliakin DS, Sobrinho JA, Monteiro JHSK, de Bettencourt-Dias A, Cantu DC. Solution structure of a europium–nicotianamine complex supports that phytosiderophores bind lanthanides. Phys Chem Chem Phys 2021; 23:4287-4299. [DOI: 10.1039/d0cp06150f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The structures of europium–EDTA (known lanthanide chelator) and europium–nicotianamine (biochemical precursor of phytosiderophores) complexes are resolved, in solution, with ab initio molecular dynamics as well as excitation and emission spectroscopy.
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Affiliation(s)
- Danil S. Kaliakin
- Department of Chemical and Materials Engineering
- University of Nevada
- Reno
- USA
| | | | | | | | - David C. Cantu
- Department of Chemical and Materials Engineering
- University of Nevada
- Reno
- USA
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38
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High yield cyclotron production of a novel 133/135La theranostic pair for nuclear medicine. Sci Rep 2020; 10:22203. [PMID: 33335271 PMCID: PMC7747723 DOI: 10.1038/s41598-020-79198-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/02/2020] [Indexed: 11/30/2022] Open
Abstract
This study reports the high-yield production of a novel 133/135La theranostic pair at a 22 MeV proton beam energy as an attractive alternative to the recently introduced 132/135La pair, demonstrating over an order of magnitude production increase of 133/135La (231 ± 8 MBq 133La and 166 ± 5 MBq 135La at End of Bombardment (EOB)) compared to 11.9 MeV production of 132/135La (0.82 ± 0.06 MBq 132La and 19.0 ± 1.2 MBq 135La) for 500 µA·min irradiations. A new sealed solid cyclotron target is introduced, which is fast to assemble, easy to handle, storable, and contains reusable components. Radiolabeling with macrocyclic chelators DOTA and macropa achieved full incorporation, with respective apparent 133La molar activites of 33 ± 5 GBq/µmol and 30 ± 4 GBq/µmol. PET centers with access to a 22 MeV capable cyclotron could produce clinically-relevant doses of 133/135La, via natBa irradiation, as a standalone theranostic agent for PET imaging and Auger electron therapy. With lower positron energies and less energetic and abundant gamma rays than 68Ga, 44Sc and 132La, 133La appears to be an attractive radiometal candidate for PET applications requiring a higher scanning resolution, a relatively long isotopic half-life, ease of handling, and a low patient dose.
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Thiele NA, Fiszbein DJ, Woods JJ, Wilson JJ. Tuning the Separation of Light Lanthanides Using a Reverse-Size Selective Aqueous Complexant. Inorg Chem 2020; 59:16522-16530. [DOI: 10.1021/acs.inorgchem.0c02413] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Nikki A. Thiele
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - David J. Fiszbein
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Joshua J. Woods
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Robert F. Smith School for Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Justin J. Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Hu A, MacMillan SN, Wilson JJ. Macrocyclic Ligands with an Unprecedented Size-Selectivity Pattern for the Lanthanide Ions. J Am Chem Soc 2020; 142:13500-13506. [PMID: 32697907 PMCID: PMC8084257 DOI: 10.1021/jacs.0c05217] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Lanthanides (Ln3+) are critical materials used for many important applications, often in the form of coordination compounds. Tuning the thermodynamic stability of these compounds is a general concern, which is not readily achieved due to the similar coordination chemistry of lanthanides. Herein, we report two 18-membered macrocyclic ligands called macrodipa and macrotripa that show for the first time a dual selectivity toward both the light, large Ln3+ ions and the heavy, small Ln3+ ions, as determined by potentiometric titrations. The lanthanide complexes of these ligands were investigated by NMR spectroscopy and X-ray crystallography, which revealed the occurrence of a significant conformational toggle between a 10-coordinate Conformation A and an 8-coordinate Conformation B that accommodates Ln3+ ions of different sizes. The origin of this selectivity pattern was further supported by density functional theory (DFT) calculations, which show the complementary effects of ligand strain energy and metal-ligand binding energy that contribute to this conformational switch. This work demonstrates how novel ligand design strategies can be applied to tune the selectivity pattern for the Ln3+ ions.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Abstract
Immuno-positron emission tomography (immunoPET) is a paradigm-shifting molecular imaging modality combining the superior targeting specificity of monoclonal antibody (mAb) and the inherent sensitivity of PET technique. A variety of radionuclides and mAbs have been exploited to develop immunoPET probes, which has been driven by the development and optimization of radiochemistry and conjugation strategies. In addition, tumor-targeting vectors with a short circulation time (e.g., Nanobody) or with an enhanced binding affinity (e.g., bispecific antibody) are being used to design novel immunoPET probes. Accordingly, several immunoPET probes, such as 89Zr-Df-pertuzumab and 89Zr-atezolizumab, have been successfully translated for clinical use. By noninvasively and dynamically revealing the expression of heterogeneous tumor antigens, immunoPET imaging is gradually changing the theranostic landscape of several types of malignancies. ImmunoPET is the method of choice for imaging specific tumor markers, immune cells, immune checkpoints, and inflammatory processes. Furthermore, the integration of immunoPET imaging in antibody drug development is of substantial significance because it provides pivotal information regarding antibody targeting abilities and distribution profiles. Herein, we present the latest immunoPET imaging strategies and their preclinical and clinical applications. We also emphasize current conjugation strategies that can be leveraged to develop next-generation immunoPET probes. Lastly, we discuss practical considerations to tune the development and translation of immunoPET imaging strategies.
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Affiliation(s)
- Weijun Wei
- Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
- Departments of Radiology and Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Room 7137, Madison, Wisconsin 53705, United States
| | - Zachary T Rosenkrans
- Department of Pharmaceutical Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Jianjun Liu
- Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Gang Huang
- Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
- Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai 201318, China
| | - Quan-Yong Luo
- Department of Nuclear Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Weibo Cai
- Departments of Radiology and Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Room 7137, Madison, Wisconsin 53705, United States
- Department of Pharmaceutical Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
- University of Wisconsin Carbone Cancer Center, Madison, Wisconsin 53705, United States
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Hu A, Keresztes I, MacMillan SN, Yang Y, Ding E, Zipfel WR, DiStasio RA, Babich JW, Wilson JJ. Oxyaapa: A Picolinate-Based Ligand with Five Oxygen Donors that Strongly Chelates Lanthanides. Inorg Chem 2020; 59:5116-5132. [PMID: 32216281 DOI: 10.1021/acs.inorgchem.0c00372] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Coordination compounds of the lanthanide ions (Ln3+) have important applications in medicine due to their photophysical, magnetic, and nuclear properties. To effectively use the Ln3+ ions for these applications, chelators that stably bind them in vivo are required to prevent toxic side effects that arise from localization of these ions in off-target tissue. In this study, two new picolinate-containing chelators, a heptadentate ligand OxyMepa and a nonadentate ligand Oxyaapa, were prepared, and their coordination chemistries with Ln3+ ions were thoroughly investigated to evaluate their suitability for use in medicine. Protonation constants of these chelators and stability constants for their Ln3+ complexes were evaluated. Both ligands exhibit a thermodynamic preference for small Ln3+ ions. The log KLuL = 12.21 and 21.49 for OxyMepa and Oxyaapa, respectively, indicating that the nonadentate Oxyaapa forms complexes of significantly higher stability than the heptadentate OxyMepa. X-ray crystal structures of the Lu3+ complexes were obtained, revealing that Oxyaapa saturates the coordination sphere of Lu3+, whereas OxyMepa leaves an additional open coordination site for a bound water ligand. Solution structural studies carried out with NMR spectroscopy revealed the presence of two possible conformations for these ligands upon Ln3+ binding. Density functional theory (DFT) calculations were applied to probe the geometries and energies of these conformations. Energy differences obtained by DFT are small but consistent with experimental data. The photophysical properties of the Eu3+ and Tb3+ complexes were characterized, revealing modest photoluminescent quantum yields of <2%. Luminescence lifetime measurements were carried out in H2O and D2O, showing that the Eu3+ and Tb3+ complexes of OxyMepa have two inner-sphere water ligands, whereas the Eu3+ and Tb3+ complexes of Oxyaapa have zero. Lastly, variable-temperature 17O NMR spectroscopy was performed for the Gd-OxyMepa complex to determine its water exchange rate constant of kex298 = (2.8 ± 0.1) × 106 s-1. Collectively, this comprehensive characterization of these Ln3+ chelators provides valuable insight for their potential use in medicine and garners additional understanding of ligand design strategies.
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Affiliation(s)
- Aohan Hu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Ivan Keresztes
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Yang Yang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Erdong Ding
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Warren R Zipfel
- Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Robert A DiStasio
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - John W Babich
- Department of Radiology, Weill Cornell Medicine, New York, New York 10065, United States
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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