1
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Schlein E, Rokka J, Odell LR, van den Broek SL, Herth MM, Battisti UM, Syvänen S, Sehlin D, Eriksson J. Synthesis and evaluation of fluorine-18 labelled tetrazines as pre-targeting imaging agents for PET. EJNMMI Radiopharm Chem 2024; 9:21. [PMID: 38446356 PMCID: PMC10917718 DOI: 10.1186/s41181-024-00250-6] [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: 02/04/2024] [Accepted: 02/28/2024] [Indexed: 03/07/2024] Open
Abstract
BACKGROUND The brain is a challenging target for antibody-based positron emission tomography (immunoPET) imaging due to the restricted access of antibody-based ligands through the blood-brain barrier (BBB). To overcome this physiological obstacle, we have previously developed bispecific antibody ligands that pass through the BBB via receptor-mediated transcytosis. While these radiolabelled ligands have high affinity and specificity, their long residence time in the blood and brain, typical for large molecules, poses another challenge for PET imaging. A viable solution could be a two-step pre-targeting approach which involves the administration of a tagged antibody that accumulates at the target site in the brain and then clears from the blood, followed by administration of a small radiolabelled molecule with fast kinetics. This radiolabelled molecule can couple to the tagged antibody and thereby make the antibody localisation visible by PET imaging. The in vivo linkage can be achieved by using the inverse electron demand Diels-Alder reaction (IEDDA), with trans-cyclooctene (TCO) and tetrazine groups participating as reactants. In this study, two novel 18F-labelled tetrazines were synthesized and evaluated for their potential use as pre-targeting imaging agents, i.e., for their ability to rapidly enter the brain and, if unbound, to be efficiently cleared with minimal background retention. RESULTS The two compounds, a methyl tetrazine [18F]MeTz and an H-tetrazine [18F]HTz were radiolabelled using a two-step procedure via [18F]F-Py-TFP synthesized on solid support followed by amidation with amine-bearing tetrazines, resulting in radiochemical yields of 24% and 22%, respectively, and a radiochemical purity of > 96%. In vivo PET imaging was performed to assess their suitability for in vivo pre-targeting. Time-activity curves from PET-scans showed [18F]MeTz to be the more pharmacokinetically suitable agent, given its fast and homogenous distribution in the brain and rapid clearance. However, in terms of rection kinetics, H-tetrazines are advantageous, exhibiting faster reaction rates in IEDDA reactions with dienophiles like trans-cyclooctenes, making [18F]HTz potentially more beneficial for pre-targeting applications. CONCLUSION This study demonstrates a significant potential of [18F]MeTz and [18F]HTz as agents for pre-targeted PET brain imaging due to their efficient brain uptake, swift clearance and appropriate chemical stability.
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Affiliation(s)
- Eva Schlein
- Department of Public Health and Caring Sciences, Uppsala University, 751 85, Uppsala, Sweden
| | - Johanna Rokka
- Department of Public Health and Caring Sciences, Uppsala University, 751 85, Uppsala, Sweden
| | - Luke R Odell
- Department of Medicinal Chemistry, Uppsala University, 751 23, Uppsala, Sweden
| | | | - Matthias M Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100, Copenhagen, Denmark
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark
| | - Umberto M Battisti
- Department of Drug Design and Pharmacology, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Stina Syvänen
- Department of Public Health and Caring Sciences, Uppsala University, 751 85, Uppsala, Sweden
| | - Dag Sehlin
- Department of Public Health and Caring Sciences, Uppsala University, 751 85, Uppsala, Sweden
| | - Jonas Eriksson
- Department of Medicinal Chemistry, Uppsala University, 751 23, Uppsala, Sweden.
- PET Centre, Uppsala University Hospital, 751 85, Uppsala, Sweden.
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2
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Mc Veigh M, Bellan LM. Microfluidic synthesis of radiotracers: recent developments and commercialization prospects. LAB ON A CHIP 2024; 24:1226-1243. [PMID: 38165824 DOI: 10.1039/d3lc00779k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Positron emission tomography (PET) is a powerful diagnostic tool that holds incredible potential for clinicians to track a wide variety of biological processes using specialized radiotracers. Currently, however, a single radiotracer accounts for over 95% of procedures, largely due to the cost of radiotracer synthesis. Microfluidic platforms provide a solution to this problem by enabling a dose-on-demand pipeline in which a single benchtop platform would synthesize a wide array of radiotracers. In this review, we will explore the field of microfluidic production of radiotracers from early research to current development. Furthermore, the benefits and drawbacks of different microfluidic reactor designs will be analyzed. Lastly, we will discuss the various engineering considerations that must be addressed to create a fully developed, commercially effective platform that can usher the field from research and development to commercialization.
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Affiliation(s)
- Mark Mc Veigh
- Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, TN, 37235, USA
| | - Leon M Bellan
- Department of Mechanical Engineering, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
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3
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Ghosh S, Lee SJ, Hsu JC, Chakraborty S, Chakravarty R, Cai W. Cancer Brachytherapy at the Nanoscale: An Emerging Paradigm. CHEMICAL & BIOMEDICAL IMAGING 2024; 2:4-26. [PMID: 38274040 PMCID: PMC10806911 DOI: 10.1021/cbmi.3c00092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/09/2023] [Accepted: 11/01/2023] [Indexed: 01/27/2024]
Abstract
Brachytherapy is an established treatment modality that has been globally utilized for the therapy of malignant solid tumors. However, classic therapeutic sealed sources used in brachytherapy must be surgically implanted directly into the tumor site and removed after the requisite period of treatment. In order to avoid the trauma involved in the surgical procedures and prevent undesirable radioactive distribution at the cancerous site, well-dispersed radiolabeled nanomaterials are now being explored for brachytherapy applications. This emerging field has been coined "nanoscale brachytherapy". Despite present-day advancements, an ongoing challenge is obtaining an advanced, functional nanomaterial that concurrently incorporates features of high radiolabeling yield, short labeling time, good radiolabeling stability, and long tumor retention time without leakage of radioactivity to the nontargeted organs. Further, attachment of suitable targeting ligands to the nanoplatforms would widen the nanoscale brachytherapy approach to tumors expressing various phenotypes. Molecular imaging using radiolabeled nanoplatforms enables noninvasive visualization of cellular functions and biological processes in vivo. In vivo imaging also aids in visualizing the localization and retention of the radiolabeled nanoplatforms at the tumor site for the requisite time period to render safe and effective therapy. Herein, we review the advancements over the last several years in the synthesis and use of functionalized radiolabeled nanoplatforms as a noninvasive substitute to standard brachytherapy sources. The limitations of present-day brachytherapy sealed sources are analyzed, while highlighting the advantages of using radiolabeled nanoparticles (NPs) for this purpose. The recent progress in the development of different radiolabeling methods, delivery techniques and nanoparticle internalization mechanisms are discussed. The preclinical studies performed to date are summarized with an emphasis on the current challenges toward the future translation of nanoscale brachytherapy in routine clinical practices.
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Affiliation(s)
- Sanchita Ghosh
- Radiopharmaceuticals
Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Sophia J. Lee
- Departments
of Radiology and Medical Physics, University
of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Jessica C. Hsu
- Departments
of Radiology and Medical Physics, University
of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Sudipta Chakraborty
- Radiopharmaceuticals
Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Rubel Chakravarty
- Radiopharmaceuticals
Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi
Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Weibo Cai
- Departments
of Radiology and Medical Physics, University
of Wisconsin-Madison, Madison, Wisconsin 53705, United States
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4
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McNeil BL, Mastroianni SA, McNeil SW, Zeisler S, Kumlin J, Borjian S, McDonagh AW, Cross M, Schaffer P, Ramogida CF. Optimized production, purification, and radiolabeling of the 203Pb/ 212Pb theranostic pair for nuclear medicine. Sci Rep 2023; 13:10623. [PMID: 37391445 PMCID: PMC10313663 DOI: 10.1038/s41598-023-37313-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 06/20/2023] [Indexed: 07/02/2023] Open
Abstract
TRIUMF is one of the only laboratories in the world able to produce both lead-203 (203Pb, t1/2 = 51.9 h) and 212Pb (t1/2 = 10.6 h) onsite via its 13 and 500 MeV cyclotrons, respectively. Together, 203Pb and 212Pb form an element-equivalent theranostic pair that potentiate image-guided, personalized cancer treatment, using 203Pb as a single-photon emission computed tomography (SPECT) source, and 212Pb for targeted alpha therapy. In this study, improvements to 203Pb production were accomplished by manufacturing electroplated, silver-backed thallium (Tl) targets to improve target thermal stability, which allow for higher currents during irradiation. We implemented a novel, two-column purification method that employs selective Tl precipitation (203Pb only) alongside extraction and anion exchange chromatography to elute high specific activity and chemical purity 203/212Pb in a minimal volume of dilute acid, without the need for evaporation. Optimization of the purification method translated to improvements in radiolabeling yields and apparent molar activity of lead chelators TCMC (S-2-(4-Isothiocyanatobenzyl)-1,4,7,10-tetraaza-1,4,7,10-tetra(2-carbamoylmethyl)cyclododecane) and Crypt-OH, a derivative of a [2.2.2]-cryptand.
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Affiliation(s)
- Brooke L McNeil
- Life Sciences Division, TRIUMF, Vancouver, BC, V6T 2A3, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | | | - Scott W McNeil
- Life Sciences Division, TRIUMF, Vancouver, BC, V6T 2A3, Canada
| | | | | | | | - Anthony W McDonagh
- Department of Chemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | | | - Paul Schaffer
- Life Sciences Division, TRIUMF, Vancouver, BC, V6T 2A3, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
- ARTMS Inc., Burnaby, BC, V5A 4N5, Canada
- Department of Radiology, University of British Columbia, 2775 Laurel St, Vancouver, BC, V5Z 1M9, Canada
| | - Caterina F Ramogida
- Life Sciences Division, TRIUMF, Vancouver, BC, V6T 2A3, Canada.
- Department of Chemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
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5
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Chochevska M, Velichkovska M, Atanasova Lazareva M, Kolevska K, Jolevski F, Razmoska J, Filipovski Z, Nikolovski S, Zdraveska Kocovska M, Ugrinska A. Evaluation of factors with potential influence on [ 18F]FDG radiochemical synthesis yield. Appl Radiat Isot 2023; 199:110900. [PMID: 37348257 DOI: 10.1016/j.apradiso.2023.110900] [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: 02/10/2023] [Revised: 05/30/2023] [Accepted: 06/13/2023] [Indexed: 06/24/2023]
Abstract
[18F]FDG radiopharmaceutical production is performed with automatic synthesis modules, which enables to carry out the production process safely, reliably and reproducibly. This study aimed to investigate the factors which may influence and give inconsistent radiochemical synthesis yield, as well as common pitfalls in the synthesis process which can occur. We evaluated more than 500 batches in the overall study. The results confirmed that irradiation parameter affect the production yield of the final product, also transport capillary capability and some synthesis factors have an impact on [18F]FDG radiochemical synthesis yield.
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Affiliation(s)
- Maja Chochevska
- University Institute of Positron Emission Tomography, Skopje, Macedonia; Faculty of Medical Science, University "Goce Delchev", Shtip, Macedonia.
| | - Maja Velichkovska
- University Institute of Positron Emission Tomography, Skopje, Macedonia; Faculty of Medical Science, University "Goce Delchev", Shtip, Macedonia
| | - Marija Atanasova Lazareva
- University Institute of Positron Emission Tomography, Skopje, Macedonia; Faculty of Medical Science, University "Goce Delchev", Shtip, Macedonia
| | - Katerina Kolevska
- University Institute of Positron Emission Tomography, Skopje, Macedonia; Faculty of Medical Science, University "Goce Delchev", Shtip, Macedonia
| | - Filip Jolevski
- University Institute of Positron Emission Tomography, Skopje, Macedonia
| | - Jasmina Razmoska
- University Institute of Positron Emission Tomography, Skopje, Macedonia
| | - Zlatko Filipovski
- University Institute of Positron Emission Tomography, Skopje, Macedonia
| | - Sasho Nikolovski
- University Institute of Positron Emission Tomography, Skopje, Macedonia; Faculty of Medical Science, University "Goce Delchev", Shtip, Macedonia; Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, Skopje, Macedonia
| | | | - Ana Ugrinska
- University Institute of Positron Emission Tomography, Skopje, Macedonia; Faculty of Medicine, Ss. Cyril and Methodius University, Skopje, Macedonia
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6
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Goel M, Mackeyev Y, Krishnan S. Radiolabeled nanomaterial for cancer diagnostics and therapeutics: principles and concepts. Cancer Nanotechnol 2023; 14:15. [PMID: 36865684 PMCID: PMC9968708 DOI: 10.1186/s12645-023-00165-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 02/13/2023] [Indexed: 03/01/2023] Open
Abstract
In the last three decades, radiopharmaceuticals have proven their effectiveness for cancer diagnosis and therapy. In parallel, the advances in nanotechnology have fueled a plethora of applications in biology and medicine. A convergence of these disciplines has emerged more recently with the advent of nanotechnology-aided radiopharmaceuticals. Capitalizing on the unique physical and functional properties of nanoparticles, radiolabeled nanomaterials or nano-radiopharmaceuticals have the potential to enhance imaging and therapy of human diseases. This article provides an overview of various radionuclides used in diagnostic, therapeutic, and theranostic applications, radionuclide production through different techniques, conventional radionuclide delivery systems, and advancements in the delivery systems for nanomaterials. The review also provides insights into fundamental concepts necessary to improve currently available radionuclide agents and formulate new nano-radiopharmaceuticals.
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Affiliation(s)
- Muskan Goel
- Amity School of Applied Sciences, Amity University, Gurugram, Haryana 122413 India
| | - Yuri Mackeyev
- Vivian L. Smith Department of Neurosurgery, University of Texas Health Science Center, Houston, TX 77030 USA
| | - Sunil Krishnan
- Vivian L. Smith Department of Neurosurgery, University of Texas Health Science Center, Houston, TX 77030 USA
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7
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Singh P, Singh D, Srivastava P, Mishra G, Tiwari AK. Evaluation of advanced, pathophysiologic new targets for imaging of CNS. Drug Dev Res 2023; 84:484-513. [PMID: 36779375 DOI: 10.1002/ddr.22040] [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: 10/23/2022] [Revised: 12/12/2022] [Accepted: 12/31/2022] [Indexed: 02/14/2023]
Abstract
The inadequate information about the in vivo pathological, physiological, and neurological impairments, as well as the absence of in vivo tools for assessing brain penetrance and the efficiency of newly designed drugs, has hampered the development of new techniques for the treatment for variety of new central nervous system (CNS) diseases. The searching sites such as Science Direct and PubMed were used to find out the numerous distinct tracers across 16 CNS targets including tau, synaptic vesicle glycoprotein, the adenosine 2A receptor, the phosphodiesterase enzyme PDE10A, and the purinoceptor, among others. Among the most encouraging are [18 F]FIMX for mGluR imaging, [11 C]Martinostat for Histone deacetylase, [18 F]MNI-444 for adenosine 2A imaging, [11 C]ER176 for translocator protein, and [18 F]MK-6240 for tau imaging. We also reviewed the findings for each tracer's features and potential for application in CNS pathophysiology and therapeutic evaluation investigations, including target specificity, binding efficacy, and pharmacokinetic factors. This review aims to present a current evaluation of modern positron emission tomography tracers for CNS targets, with a focus on recent advances for targets that have newly emerged for imaging in humans.
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Affiliation(s)
- Priya Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Deepika Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Pooja Srivastava
- Division of Cyclotron and Radiopharmaceuticals Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Gauri Mishra
- Department of Zoology, Swami Shraddhananad College, University of Delhi, Alipur, Delhi, India
| | - Anjani K Tiwari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
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8
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Migliari S, Scarlattei M, Baldari G, Silva C, Ruffini L. A Specific HPLC Method to Determine Residual HEPES in [ 68Ga]Ga-Radiopharmaceuticals: Development and Validation. Molecules 2022; 27:molecules27144477. [PMID: 35889351 PMCID: PMC9323806 DOI: 10.3390/molecules27144477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 01/25/2023] Open
Abstract
Background: Nowadays, in Nuclear Medicine, clinically applied radiopharmaceuticals must meet quality release criteria such as high radiochemical purity and radiochemical yield. Many radiopharmaceuticals do not have marketing authorization and have no dedicated monograph within European Pharmacopeia (Ph. Eur.); therefore, general monographs on quality controls (QCs) have to be applied for clinical application. These criteria require standardization and validation in labeling and preparation, including quality controls measurements, according to well defined standard operation procedures. However, QC measurements are often based on detection techniques that are specific to a certain chromatographic system. Several radiosyntheses of [68Ga]Ga-radiopharmaceuticals are more efficient and robust when they are performed with 2-[4-(2-hydroxyethyl)piperazin-1-yl] ethanesulfonic acid (HEPES) buffer, which is considered as an impurity to be assessed in the QC procedure, prior to clinical use. Thus, Ph. Eur. has introduced a thin-layer chromatography (TLC) method to quantify the HEPES amount that is present in [68Ga]Ga-radiopharmaceuticals. However, this is only qualitative and has proven to be unreliable. Here we develop and validate a new high-performance liquid chromatography (UV-Radio-HPLC) method to quantify the residual amount of HEPES in 68Ga-based radiopharmaceuticals. Method: To validate the proposed UV-Radio-HPLC method, a stepwise approach was used, as defined in the guidance document that was adopted by the European Medicines Agency (CMP/ICH/381/95 2014). The assessed parameters are specificity, linearity, precision (repeatability), accuracy, and limit of quantification. A range of concentrations of HEPES (100, 80, 60, 40, 20, 10, 5, 3 μg/mL) were analyzed. Moreover, to test the validity and pertinence of our new HPLC method, we analyzed samples of [68Ga]Ga-DOTATOC; [68Ga]Ga-PSMA; [68Ga]Ga-DOTATATE; [68Ga]Ga-Pentixafor; and [68Ga]Ga-NODAGA-Exendin-4 from different batches that were prepared for clinical use. Results: In the assessed samples, HEPES could not be detected by the TLC method that was described in Ph. Eur. within 4 min incubation in an iodine-saturated chamber. Our developed HPLC method showed excellent linearity between 3 and 100 μg/mL for HEPES, with a correlation coefficient (R2) for calibration curves that was equal to 0.999, coefficients of variation (CV%) < 2%, and percent deviation value of bias from 100% to 5%, in accordance with acceptance criteria. The intra-day and inter-day precision of our method was statistically confirmed and the limit-of-quantification (LOQ) was 3 μg/mL, confirming the high sensitivity of the method. The amount of HEPES that was detected with our developed HPLC method in the tested [68Ga]Ga-radiopharmaceuticals resulted well below the Ph. Eur. limit, especially for [68Ga]Ga-NODAGA-Exendin-4. Conclusions: The TLC method that is described in Ph. Eur. to assess residual HEPES in [68Ga]-based radiopharmaceuticals may not be sufficiently sensitive and thus unsuitable for QC release. Our new HPLC method was sensitive, quantitative, reproducible, and rapid for QCs, allowing us to exactly determine the residual HEPES amount in [68Ga]Ga-radiopharmaceuticals for safe patient administration.
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Affiliation(s)
- Silvia Migliari
- Nuclear Medicine and Molecular Imaging Department, Azienda Ospedaliero-Universitaria di Parma, Via Gramsci 14, 43126 Parma, Italy; (M.S.); (G.B.); (L.R.)
- Correspondence: ; Tel.: +39-3335939138
| | - Maura Scarlattei
- Nuclear Medicine and Molecular Imaging Department, Azienda Ospedaliero-Universitaria di Parma, Via Gramsci 14, 43126 Parma, Italy; (M.S.); (G.B.); (L.R.)
| | - Giorgio Baldari
- Nuclear Medicine and Molecular Imaging Department, Azienda Ospedaliero-Universitaria di Parma, Via Gramsci 14, 43126 Parma, Italy; (M.S.); (G.B.); (L.R.)
| | - Claudia Silva
- Food and Drug Sciences Department, Parco Area delle Scienze 27/A, University of Parma, 43124 Parma, Italy;
| | - Livia Ruffini
- Nuclear Medicine and Molecular Imaging Department, Azienda Ospedaliero-Universitaria di Parma, Via Gramsci 14, 43126 Parma, Italy; (M.S.); (G.B.); (L.R.)
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9
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Peukert C, Langer LNB, Wegener SM, Tutov A, Bankstahl JP, Karge B, Bengel FM, Ross TL, Brönstrup M. Optimization of Artificial Siderophores as 68Ga-Complexed PET Tracers for In Vivo Imaging of Bacterial Infections. J Med Chem 2021; 64:12359-12378. [PMID: 34370949 DOI: 10.1021/acs.jmedchem.1c01054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The diagnosis of bacterial infections at deep body sites benefits from noninvasive imaging of molecular probes that can be traced by positron emission tomography (PET). We specifically labeled bacteria by targeting their iron transport system with artificial siderophores. The cyclen-based probes contain different binding sites for iron and the PET nuclide gallium-68. A panel of 11 siderophores with different iron coordination numbers and geometries was synthesized in up to 8 steps, and candidates with the best siderophore potential were selected by a growth recovery assay. The probes [68Ga]7 and [68Ga]15 were found to be suitable for PET imaging based on their radiochemical yield, radiochemical purity, and complex stability in vitro and in vivo. Both showed significant uptake in mice infected with Escherichia coli and were able to discern infection from lipopolysaccharide-triggered, sterile inflammation. The study qualifies cyclen-based artificial siderophores as readily accessible scaffolds for the in vivo imaging of bacteria.
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Affiliation(s)
- Carsten Peukert
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Laura N B Langer
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Sophie M Wegener
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Anna Tutov
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Bianka Karge
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
| | - Frank M Bengel
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Tobias L Ross
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Mark Brönstrup
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany
- German Center for Infection Research (DZIF), Site Hannover-Braunschweig, 38124 Braunschweig, Germany
- Center for Biomolecular Drug Research (BMWZ), Schneiderberg 38, 30167 Hannover, Germany
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10
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Labelling via [Al 18F] 2+ Using Precomplexed Al-NODA Moieties. Pharmaceuticals (Basel) 2021; 14:ph14080818. [PMID: 34451915 PMCID: PMC8399807 DOI: 10.3390/ph14080818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 12/02/2022] Open
Abstract
Over the past 20 years, 68Ga-labelled radiopharmaceuticals have become an important part in clinical routine. However, the worldwide supply with 68Ge/68Ga generators is limited as well as the number of patient doses per batch of 68Ga radiopharmaceutical. In the recent years, a new technique appeared, making use of the ease of aqueous labelling via chelators as with 68Ga but using 18F instead. This technique takes advantage of the strong coordinative bond between aluminium and fluoride, realized in the aqueous cation [Al18F]2+. Most applications to date make use of one-pot syntheses with free Al(III) ions in the system. In contrast, we investigated the labelling approach split into two steps: generating the Al-bearing precursor in pure form and using this Al compound as a precursor in the labelling step with aqueous [18F]fluoride. Hence, no free Al3+ ions are present in the labelling step. We investigated the impact of parameters: temperature, pH, addition of organic solvent, and reaction time using the model chelator NH2-MPAA-NODA. With optimized parameters we could stably achieve a 80% radiochemical yield exerting a 30-min reaction time at 100 °C. This technique has the potential to become an important approach in radiopharmaceutical syntheses.
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11
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Migliari S, Sammartano A, Scarlattei M, Baldari G, Janota B, Bonadonna RC, Ruffini L. Feasibility of a scale-down production of [68Ga]Ga-NODAGA-Exendin-4 in a hospital based radiopharmacy. Curr Radiopharm 2021; 15:63-75. [PMID: 33687908 DOI: 10.2174/1874471014666210309151930] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/14/2021] [Accepted: 01/19/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Glucagon-like peptide 1 receptor (GLP-1R) is preferentially expressed in β-cells, but it is highly expressed in human insulinomas and gastrinomas. Several GLP-1 receptor-avid radioligands have been developed to image insulin-secreting tumors or to provide a quantitative in vivo biomarker of pancreatic β-cell mass. Exendin-4 is a high affinity ligand of the GLP1-R, which is a candidate for being labeled with a PET isotope and used for imaging purposes. OBJECTIVE Here, we report the development and validation results of a semi manual procedure to label [Lys40,Nle14(Ahx-NODAGA)NH2]exendin-4, with Ga-68. METHODS A 68Ge/68Ga Generator (GalliaPharma®,Eckert and Ziegler) was eluted with 0.1M HCl on an automated synthesis module (Scintomics GRP®). The peptide contained in the kit vial (Radioisotope Center POLATOM) in different amounts (10-20-30 µg) was reconstituted with 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethansulfonic acid (HEPES) solution and 68GaCl3 (400-900 MBq), followed by 10 min incubation at 95°C. The reaction solution was then purified through an Oasis HLB column. The radiopharmaceutical product was tested for quality controls (CQs), in accordance with the European Pharmacopoeia standards. RESULTS The synthesis of 68Ga]Ga-NODAGA-Exendin-4 provided optimal results with 10 µg of peptide, getting the best radiochemical yield (23.53 ± 2.4 %), molar activity (100 GBq/µmol) and radiochemical purity (91.69 %). CONCLUSION The study developed an imaging tool [68Ga]Ga-NODAGA-Exendin-4, avoiding pharmacological effects of exendin-4, for the clinical community.
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Affiliation(s)
- Silvia Migliari
- Nuclear Medicine and Molecular Imaging Department, University Hospital of Parma, via Gramsci 14, 43126 Parma. Italy
| | - Antonino Sammartano
- Nuclear Medicine and Molecular Imaging Department, University Hospital of Parma, via Gramsci 14, 43126 Parma. Italy
| | - Maura Scarlattei
- Nuclear Medicine and Molecular Imaging Department, University Hospital of Parma, via Gramsci 14, 43126 Parma. Italy
| | - Giorgio Baldari
- Nuclear Medicine and Molecular Imaging Department, University Hospital of Parma, via Gramsci 14, 43126 Parma. Italy
| | - Barbara Janota
- National Centre for Nuclear Research Radioisotope Centre POLATOM, Otwock. Poland
| | - Riccardo C Bonadonna
- Division of Endocrinology and Metabolic Diseases, Department of Medicine and Surgery, University of Parma School of Medicine and University Hospital of Parma, Parma. Italy
| | - Livia Ruffini
- Nuclear Medicine and Molecular Imaging Department, University Hospital of Parma, via Gramsci 14, 43126 Parma. Italy
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12
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Pellico J, Gawne PJ, T M de Rosales R. Radiolabelling of nanomaterials for medical imaging and therapy. Chem Soc Rev 2021; 50:3355-3423. [PMID: 33491714 DOI: 10.1039/d0cs00384k] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nanomaterials offer unique physical, chemical and biological properties of interest for medical imaging and therapy. Over the last two decades, there has been an increasing effort to translate nanomaterial-based medicinal products (so-called nanomedicines) into clinical practice and, although multiple nanoparticle-based formulations are clinically available, there is still a disparity between the number of pre-clinical products and those that reach clinical approval. To facilitate the efficient clinical translation of nanomedicinal-drugs, it is important to study their whole-body biodistribution and pharmacokinetics from the early stages of their development. Integrating this knowledge with that of their therapeutic profile and/or toxicity should provide a powerful combination to efficiently inform nanomedicine trials and allow early selection of the most promising candidates. In this context, radiolabelling nanomaterials allows whole-body and non-invasive in vivo tracking by the sensitive clinical imaging techniques positron emission tomography (PET), and single photon emission computed tomography (SPECT). Furthermore, certain radionuclides with specific nuclear emissions can elicit therapeutic effects by themselves, leading to radionuclide-based therapy. To ensure robust information during the development of nanomaterials for PET/SPECT imaging and/or radionuclide therapy, selection of the most appropriate radiolabelling method and knowledge of its limitations are critical. Different radiolabelling strategies are available depending on the type of material, the radionuclide and/or the final application. In this review we describe the different radiolabelling strategies currently available, with a critical vision over their advantages and disadvantages. The final aim is to review the most relevant and up-to-date knowledge available in this field, and support the efficient clinical translation of future nanomedicinal products for in vivo imaging and/or therapy.
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Affiliation(s)
- Juan Pellico
- School of Biomedical Engineering & Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, UK.
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13
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Guibbal F, Isenegger PG, Wilson TC, Pacelli A, Mahaut D, Sap JBI, Taylor NJ, Verhoog S, Preshlock S, Hueting R, Cornelissen B, Gouverneur V. Manual and automated Cu-mediated radiosynthesis of the PARP inhibitor [ 18F]olaparib. Nat Protoc 2020; 15:1525-1541. [PMID: 32111986 DOI: 10.1038/s41596-020-0295-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 01/06/2020] [Indexed: 02/04/2023]
Abstract
Positron emission tomography (PET) is a diagnostic nuclear imaging modality that relies on automated protocols to prepare agents labeled with a positron-emitting radionuclide (e.g., 18F). In recent years, new reactions have appeared for the 18F-labeling of agents that are difficult to access by applying traditional radiochemistry, for example those requiring 18F incorporation into unactivated (hetero)arenes. However, automation of these new methods for translation to the clinic has progressed slowly because extensive modification of manual protocols is typically required when implementing novel 18F-labeling methodologies within automated modules. Here, we describe the workflow that led to the automated radiosynthesis of the poly(ADP-ribose) polymerase (PARP) inhibitor [18F]olaparib. First, we established a robust manual protocol to prepare [18F]olaparib from the protected N-[2-(trimethylsilyl)ethoxy]methyl (SEM) arylboronate ester precursor in a 17% ± 5% (n = 15; synthesis time, 135 min) non-decay-corrected (NDC) activity yield, with molar activity (Am) up to 34.6 GBq/µmol. Automation of the process, consisting of copper-mediated 18F-fluorodeboronation followed by deprotection, was achieved on an Eckert & Ziegler Modular-Lab radiosynthesis platform, affording [18F]olaparib in a 6% ± 5% (n = 3; synthesis time, 120 min) NDC activity yield with Am up to 319 GBq/µmol.
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Affiliation(s)
- Florian Guibbal
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
- Radiobiology Research Institute, Department of Oncology, Churchill Hospital, University of Oxford, Headington, UK
| | | | - Thomas C Wilson
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | - Anna Pacelli
- Radiobiology Research Institute, Department of Oncology, Churchill Hospital, University of Oxford, Headington, UK
| | - Damien Mahaut
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | - Jeroen B I Sap
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | | | - Stefan Verhoog
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | - Sean Preshlock
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | - Rebekka Hueting
- Radiobiology Research Institute, Department of Oncology, Churchill Hospital, University of Oxford, Headington, UK
| | - Bart Cornelissen
- Radiobiology Research Institute, Department of Oncology, Churchill Hospital, University of Oxford, Headington, UK.
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14
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McCluskey SP, Plisson C, Rabiner EA, Howes O. Advances in CNS PET: the state-of-the-art for new imaging targets for pathophysiology and drug development. Eur J Nucl Med Mol Imaging 2020; 47:451-489. [PMID: 31541283 PMCID: PMC6974496 DOI: 10.1007/s00259-019-04488-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/15/2019] [Indexed: 02/07/2023]
Abstract
PURPOSE A limit on developing new treatments for a number of central nervous system (CNS) disorders has been the inadequate understanding of the in vivo pathophysiology underlying neurological and psychiatric disorders and the lack of in vivo tools to determine brain penetrance, target engagement, and relevant molecular activity of novel drugs. Molecular neuroimaging provides the tools to address this. This article aims to provide a state-of-the-art review of new PET tracers for CNS targets, focusing on developments in the last 5 years for targets recently available for in-human imaging. METHODS We provide an overview of the criteria used to evaluate PET tracers. We then used the National Institute of Mental Health Research Priorities list to identify the key CNS targets. We conducted a PubMed search (search period 1st of January 2013 to 31st of December 2018), which yielded 40 new PET tracers across 16 CNS targets which met our selectivity criteria. For each tracer, we summarised the evidence of its properties and potential for use in studies of CNS pathophysiology and drug evaluation, including its target selectivity and affinity, inter and intra-subject variability, and pharmacokinetic parameters. We also consider its potential limitations and missing characterisation data, but not specific applications in drug development. Where multiple tracers were present for a target, we provide a comparison of their properties. RESULTS AND CONCLUSIONS Our review shows that multiple new tracers have been developed for proteinopathy targets, particularly tau, as well as the purinoceptor P2X7, phosphodiesterase enzyme PDE10A, and synaptic vesicle glycoprotein 2A (SV2A), amongst others. Some of the most promising of these include 18F-MK-6240 for tau imaging, 11C-UCB-J for imaging SV2A, 11C-CURB and 11C-MK-3168 for characterisation of fatty acid amide hydrolase, 18F-FIMX for metabotropic glutamate receptor 1, and 18F-MNI-444 for imaging adenosine 2A. Our review also identifies recurrent issues within the field. Many of the tracers discussed lack in vivo blocking data, reducing confidence in selectivity. Additionally, late-stage identification of substantial off-target sites for multiple tracers highlights incomplete pre-clinical characterisation prior to translation, as well as human disease state studies carried out without confirmation of test-retest reproducibility.
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Affiliation(s)
- Stuart P McCluskey
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK.
| | - Christophe Plisson
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Eugenii A Rabiner
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Oliver Howes
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK
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15
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Yang BY, Telu S, Haskali MB, Morse CL, Pike VW. A Gas Phase Route to [ 18F]fluoroform with Limited Molar Activity Dilution. Sci Rep 2019; 9:14835. [PMID: 31619702 PMCID: PMC6795885 DOI: 10.1038/s41598-019-50747-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/12/2019] [Indexed: 01/03/2023] Open
Abstract
Positron emission tomography (PET) is an important imaging modality for biomedical research and drug development. PET requires biochemically selective radiotracers to realize full potential. Fluorine-18 (t1/2 = 109.8 min) is a major radionuclide for labeling such radiotracers but is only readily available in high activities from cyclotrons as [18F]fluoride ion. [18F]fluoroform has emerged for labeling tracers in trifluoromethyl groups. Prior methods of [18F]fluoroform synthesis used difluoro precursors in solution and led to high dilution with carrier and low molar activity (Am). We explored a new approach for the synthesis of [18F]fluoroform based on the radiosynthesis of [18F]fluoromethane from [18F]fluoride ion and then cobaltIII fluoride mediated gas phase fluorination. We estimate that carrier dilution in this process is limited to about 3-fold and find that moderate to high Am values can be achieved. We show that [18F]fluoroform so produced is highly versatile for rapidly and efficiently labeling various chemotypes that carry trifluoromethyl groups, thereby expanding prospects for developing new PET radiotracers.
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Affiliation(s)
- Bo Yeun Yang
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Sanjay Telu
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Mohammad B Haskali
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3 C346A, 10 Center Drive, Bethesda, MD, 20892-1003, USA.
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16
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O'Hara MJ, Murray NJ, Carter JC, Kellogg CM, Link JM. Tandem column isolation of zirconium-89 from cyclotron bombarded yttrium targets using an automated fluidic platform: Anion exchange to hydroxamate resin columns. J Chromatogr A 2018; 1567:37-46. [PMID: 30054129 DOI: 10.1016/j.chroma.2018.06.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/07/2018] [Accepted: 06/14/2018] [Indexed: 12/23/2022]
Abstract
The development of a tandem column purification method for the preparation of high-purity 89Zr(IV) oxalate is presented. The primary column was a macroporous strongly basic anion exchange resin on styrene divinylbenzene co-polymer. The secondary column, with an internal volume of 33 μL, was packed with hydroxamate resin. A condition of inverted selectivity was developed, whereby the 89Zr eluent solution for the primary column is equivalent to the 89Zr load solution for the secondary column. The ability to transfer 89Zr from one column to the next allows two sequential column clean-up methods to be performed prior to the final elution of the 89Zr(IV) oxalate. This approach assures delivery of high purity 89Zr product and assures a 89Zr product that is eluted in a substantially smaller volume than is possible when using the traditionally-employed single hydroxamate resin column method. The tandem column purification process has been implemented into a prototype automated fluidic system. The system is configured with on-line gamma detection so column effluents can be monitored in near-real time. The automated method was tested using seven cyclotron bombarded Y foil targets. It was found that 95.1 ± 1.3% of the 89Zr present in the foils was recovered in the secondary column elution fraction. Furthermore, elution peak analysis of several 89Zr elution profile radiochromatograms made possible the determination of 89Zr recovery as a function of volume; a 89Zr product volume that contains 90% of the mean secondary column elution peak can be obtained in 0.29 ± 0.06 mL (representing 86 ± 5% of the 89Zr activity in the target). This product volume represents a significant improvement in radionuclide product concentration over the predominant method used in the field. In addition to the reduced 89Zr product elution volume, titrations of the 89Zr product with deferoxamine mesylate salt across two preparatory methods resulted in mean effective specific activity (ESA) values of 279 and 340 T Bq·mmole-1 and mean bindable metals concentrations ([MB]) of 13.5 and 16.7 nmole·g-1. These ESA and [MB] values infer that the 89Zr(IV) oxalate product resulting from this tandem column isolation method has the highest purity reported to date.
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Affiliation(s)
- Matthew J O'Hara
- Nuclear Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, WA 99352, United States.
| | - Nathaniel J Murray
- Nuclear Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, WA 99352, United States
| | - Jennifer C Carter
- Nuclear Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, WA 99352, United States
| | - Cynthia M Kellogg
- Nuclear Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd., PO Box 999, Richland, WA 99352, United States
| | - Jeanne M Link
- Center for Radiochemistry Research, Department of Diagnostic Radiology, Oregon Health & Science University, 3181 Sam Jackson Park Rd., Portland, OR 97239, United States
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17
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Reliable radiosynthesis of 4-[ 10B]borono-2-[ 18F]fluoro-L-phenylalanine with quality assurance for boron neutron capture therapy-oriented diagnosis. Ann Nucl Med 2018; 32:463-473. [PMID: 29869193 PMCID: PMC6061177 DOI: 10.1007/s12149-018-1268-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/31/2018] [Indexed: 11/18/2022]
Abstract
Objective The aim of this study was to establish a reliable and routine method for the preparation of 4-[10B]borono-2-[18F]fluoro-l-phenylalanine (l-[18F]FBPA) for boron neutron capture therapy-oriented diagnosis using positron emission tomography. Methods To produce l-[18F]FBPA by electrophilic fluorination of 4-[10B]borono-l-phenylalanine (l-BPA) with [18F]acetylhypofluorite ([18F]AcOF) via [18F]F2 derived from the 20Ne(d,α)18F nuclear reaction, several preparation parameters and characteristics of l-[18F]FBPA were investigated, including: pre-irradiation for [18F]F2 production, the carrier F2 content in the Ne target, l-BPA-to-F2 ratios, separation with high-performance liquid chromatography (HPLC) using 10 different eluents, enantiomeric purity, and residual trifluoroacetic acid used as the reaction solvent by gas chromatography-mass spectrometry. Results The activity yields and molar activities of l-[18F]FBPA (n = 38) were 1200 ± 160 MBq and 46–113 GBq/mmol, respectively, after deuteron-irradiation for 2 h. Two 5 min pre-irradiations prior to [18F]F2 production for 18F-labeling were preferable. For l-[18F]FBPA synthesis, 0.15–0.2% of carrier F2 in Ne and l-BPA-to-F2 ratios > 2 were preferable. HPLC separations with five of the 10 eluents provided injectable l-[18F]FBPA without any further formulation processing, which resulted in a synthesis time of 32 min. Among the five eluents, 1 mM phosphate-buffered saline was the eluent of choice. The l-[18F]FBPA injection was sterile and pyrogen-free, and contained very small amounts of D-enantiomer (< 0.1% of l-[18F]FBPA), l-BPA (< 1% of l-FBPA), and trifluoroacetic acid (< 0.5 ppm). Conclusions l-[18F]FBPA injection was reliably prepared by the electrophilic fluorination of l-BPA with [18F]AcOF followed by HPLC separation with 1 mM phosphate-buffered saline.
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Pérez-Malo M, Szabó G, Eppard E, Vagner A, Brücher E, Tóth I, Maiocchi A, Suh EH, Kovács Z, Baranyai Z, Rösch F. Improved Efficacy of Synthesizing *M III-Labeled DOTA Complexes in Binary Mixtures of Water and Organic Solvents. A Combined Radio- and Physicochemical Study. Inorg Chem 2018; 57:6107-6117. [PMID: 29746106 DOI: 10.1021/acs.inorgchem.8b00669] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Typically, the synthesis of radiometal-based radiopharmaceuticals is performed in buffered aqueous solutions. We found that the presence of organic solvents like ethanol increased the radiolabeling yields of [68Ga]Ga-DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacatic acid). In the present study, the effect of organic cosolvents [ethanol (EtOH), isopropyl alcohol, and acetonitrile] on the radiolabeling yields of the macrocyclic chelator DOTA with several trivalent radiometals (gallium-68, scandium-44, and lutetium-177) was systematically investigated. Various binary water (H2O)/organic solvent mixtures allowed the radiolabeling of DOTA at a significantly lower temperature than 95 °C, which is relevant for the labeling of sensitive biological molecules. Simultaneously, much lower amounts of the chelators were required. This strategy may have a fundamental impact on the formulation of trivalent radiometal-based radiopharmaceuticals. The equilibrium properties and formation kinetics of [M(DOTA)]- (MIII= GaIII, CeIII, EuIII, YIII, and LuIII) complexes were investigated in H2O/EtOH mixtures (up to 70 vol % EtOH). The protonation constants of DOTA were determined by pH potentiometry in H2O/EtOH mixtures (0-70 vol % EtOH, 0.15 M NaCl, 25 °C). The log K1H and log K2H values associated with protonation of the ring N atoms decreased with an increase of the EtOH content. The formation rates of [M(DOTA)]- complexes increase with an increase of the pH and [EtOH]. Complexation occurs through rapid formation of the diprotonated [M(H2DOTA)]+ intermediates, which are in equilibrium with the kinetically active monoprotonated [M(HDOTA)] intermediates. The rate-controlling step is deprotonation (and rearrangement) of the monoprotonated intermediate, which occurs through H2O (*M(HL) kH2O) and OH- (*M(HL) kOH) assisted reaction pathways. The rate constants are essentially independent of the EtOH concentration, but the M(HL) kH2O values increase from CeIII to LuIII. However, the log KM(HL)H protonation constants, analogous to the log KH2 value, decrease with increasing [EtOH], which increases the concentration of the monoprotonated M(HDOTA) intermediate and accelerates formation of the final complexes. The overall rates of complex formation calculated by the obtained rate constants at different EtOH concentrations show a trend similar to that of the complexation rates determined with the use of radioactive isotopes.
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Affiliation(s)
- Marylaine Pérez-Malo
- Institute of Nuclear Chemistry , Johannes Gutenberg-University of Mainz , Fritz-Strassmann-Weg 2 , D-55128 Mainz , Germany
| | - Gergely Szabó
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology , University of Debrecen , Egyetem tér 1 , H-4032 Debrecen , Hungary
| | - Elisabeth Eppard
- Institute of Nuclear Chemistry , Johannes Gutenberg-University of Mainz , Fritz-Strassmann-Weg 2 , D-55128 Mainz , Germany
| | - Adrienn Vagner
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology , University of Debrecen , Egyetem tér 1 , H-4032 Debrecen , Hungary
| | - Ernő Brücher
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology , University of Debrecen , Egyetem tér 1 , H-4032 Debrecen , Hungary
| | - Imre Tóth
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology , University of Debrecen , Egyetem tér 1 , H-4032 Debrecen , Hungary
| | - Alessandro Maiocchi
- Bracco Research Centre , Bracco Imaging , Via Ribes 5 , 10010 Colleretto Giacosa (TO) , Italy
| | - Eul Hyun Suh
- Advanced Imaging Research Center , University of Texas Southwestern Medical Center , 5323 Harry Hines Boulevard , Dallas , Texas 75390 , United States
| | - Zoltán Kovács
- Advanced Imaging Research Center , University of Texas Southwestern Medical Center , 5323 Harry Hines Boulevard , Dallas , Texas 75390 , United States
| | - Zsolt Baranyai
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology , University of Debrecen , Egyetem tér 1 , H-4032 Debrecen , Hungary.,Bracco Research Centre , Bracco Imaging , Via Ribes 5 , 10010 Colleretto Giacosa (TO) , Italy
| | - Frank Rösch
- Institute of Nuclear Chemistry , Johannes Gutenberg-University of Mainz , Fritz-Strassmann-Weg 2 , D-55128 Mainz , Germany
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