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Jahan M, Amir A, Das A, Kihlström J, Nag S. Automated radiosynthesis of mGluR5 PET tracer [ 18F]FPEB from aryl-chloro precursor and validation for clinical application. J Labelled Comp Radiopharm 2024; 67:155-164. [PMID: 38369901 DOI: 10.1002/jlcr.4088] [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: 10/09/2023] [Revised: 12/11/2023] [Accepted: 01/29/2024] [Indexed: 02/20/2024]
Abstract
The radioligand [18F]FPEB, used for PET imaging of the brain's metabotropic glutamate receptor subtype 5 (mGluR5), undergoes a thorough validation process to ensure its safety, efficacy, and quality for clinical use. The process starts by optimizing the synthesis of [18F]FPEB to achieve high radiochemical yield and purity. This study focuses on optimizing the radiolabeling process using an aryl-chloro precursor and validating the GMP production for clinical applications. Fully automated radiolabeling was achieved via one-step nucleophilic substitution reaction. [18F]FPEB was produced and isolated in high radioactivity and radiochemical purity. Throughout the validation process, thorough quality control measures are implemented. Radiopharmaceutical batch release criteria are established, including testing for physical appearance, filter integrity, pH, radiochemical purity, molar activity, radiochemical identity, chemical impurity, structural identity, stability, residual solvent, sterility, and endotoxin levels. In conclusion, the validation of [18F]FPEB involved a comprehensive process of synthesis optimization, quality control, which ensure the safety, efficacy, and quality of [18F]FPEB, enabling its reliable use in clinical PET. Here, we successfully radiolabeled and validated [18F]FPEB using aryl-chloro precursor according to GMP production for clinical application.
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Affiliation(s)
- Mahabuba Jahan
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Arsalan Amir
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Arindam Das
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Jacob Kihlström
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Sangram Nag
- Department of Clinical Neuroscience, Centre for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, 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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Laferriere-Holloway TS, Rios A, Lu Y, Okoro CC, van Dam RM. A rapid and systematic approach for the optimization of radio thin-layer chromatography resolution. J Chromatogr A 2023; 1687:463656. [PMID: 36463649 PMCID: PMC9894532 DOI: 10.1016/j.chroma.2022.463656] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022]
Abstract
Radiopharmaceutical analysis is limited by conventional methods. Radio-HPLC may be inaccurate for some compounds (e.g., 18F-radiopharmaceuticals) due to radionuclide sequester. Radio-TLC is simpler, faster, and detects all species but has limited resolution. Imaging-based readout of TLC plates (e.g., using Cerenkov luminescence imaging) can improve readout resolution, but the underlying chromatographic separation efficiency may be insufficient to resolve chemically similar species such as product and precursor-derived impurities. This study applies a systematic mobile phase optimization method, PRISMA, to improve radio-TLC resolution. The PRISMA method optimizes the mobile phase by selecting the correct solvent, optimizing solvent polarity, and optimizing composition. Without prior knowledge of impurities and by simply observing the separation resolution between a radiopharmaceutical and its nearest radioactive or non-radioactive impurities (observed via UV imaging) for different mobile phases, the PRISMA method enabled the development of high-resolution separation conditions for a wide range of 18F-radiopharmaceuticals ( [18F]PBR-06, [18F]FEPPA, [18F]Fallypride, [18F]FPEB, and [18F]FDOPA). Each optimization required a single batch of crude radiopharmaceutical and a few hours. Interestingly, the optimized TLC method provided greater accuracy (compared to other published TLC methods) in determining the product abundance of one radiopharmaceutical studied in more depth ( [18F]Fallypride) and was capable of resolving a comparable number of species as isocratic radio-HPLC. We used the PRISMA-optimized mobile phase for [18F]FPEB in combination with multi-lane radio-TLC techniques to evaluate reaction performance during high-throughput synthesis optimization of [18F]FPEB. The PRISMA methodology, in combination with high-resolution radio-TLC readout, enables a rapid and systematic approach to achieving high-resolution and accurate analysis of radiopharmaceuticals without the need for radio-HPLC.
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Affiliation(s)
- Travis S Laferriere-Holloway
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA.
| | - Alejandra Rios
- Physics and Biology in Medicine Interdepartmental Graduate Program, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA
| | - Yingqing Lu
- Physics and Biology in Medicine Interdepartmental Graduate Program, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA
| | - Chelsea C Okoro
- Institute for Society and Genetics, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA
| | - R Michael van Dam
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA; Physics and Biology in Medicine Interdepartmental Graduate Program, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA.
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Production of [ 11C]Carbon Labelled Flumazenil and L-Deprenyl Using the iMiDEV™ Automated Microfluidic Radiosynthesizer. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27248843. [PMID: 36557975 PMCID: PMC9788284 DOI: 10.3390/molecules27248843] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
In the last decade, microfluidic techniques have been explored in radiochemistry, and some of them have been implemented in preclinical production. However, these are not suitable and reliable for preparing different types of radiotracers or dose-on-demand production. A fully automated iMiDEV™ microfluidic radiosynthesizer has been introduced and this study is aimed at using of the iMiDEV™ radiosynthesizer with a microfluidic cassette to produce [11C]flumazenil and [11C]L-deprenyl. These two are known PET radioligands for benzodiazepine receptors and monoamine oxidase-B (MAO-B), respectively. Methods were successfully developed to produce [11C]flumazenil and [11C]L-deprenyl using [11C]methyl iodide and [11C]methyl triflate, respectively. The final products 1644 ± 504 MBq (n = 7) and 533 ± 20 MBq (n = 3) of [11C]flumazenil and [11C]L-deprenyl were produced with radiochemical purities were over 98% and the molar activity for [11C]flumazenil and [11C]L-deprenyl was 1912 ± 552 GBq/µmol, and 1463 ± 439 GBq/µmol, respectively, at the end of synthesis. All the QC tests complied with the European Pharmacopeia. Different parameters, such as solvents, bases, methylating agents, precursor concentration, and different batches of cassettes, were explored to increase the radiochemical yield. Synthesis methods were developed using 3-5 times less precursor than conventional methods. The fully automated iMiDEV™ microfluidic radiosynthesizer was successfully applied to prepare [11C]flumazenil and [11C]L-deprenyl.
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Microliter-scale reaction arrays for economical high-throughput experimentation in radiochemistry. Sci Rep 2022; 12:10263. [PMID: 35715457 PMCID: PMC9205965 DOI: 10.1038/s41598-022-14022-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 05/31/2022] [Indexed: 01/14/2023] Open
Abstract
The increasing number of positron-emission tomography (PET) tracers being developed to aid drug development and create new diagnostics has led to an increased need for radiosynthesis development and optimization. Current radiosynthesis instruments are designed to produce large-scale clinical batches and are often limited to performing a single synthesis before they must be decontaminated by waiting for radionuclide decay, followed by thorough cleaning or disposal of synthesizer components. Though with some radiosynthesizers it is possible to perform a few sequential radiosyntheses in a day, none allow for parallel radiosyntheses. Throughput of one or a few experiments per day is not well suited for rapid optimization experiments. To combat these limitations, we leverage the advantages of droplet-radiochemistry to create a new platform for high-throughput experimentation in radiochemistry. This system contains an array of 4 heaters, each used to heat a set of 16 reactions on a small chip, enabling 64 parallel reactions for the rapid optimization of conditions in any stage of a multi-step radiosynthesis process. As examples, we study the syntheses of several 18F-labeled radiopharmaceuticals ([18F]Flumazenil, [18F]PBR06, [18F]Fallypride, and [18F]FEPPA), performing > 800 experiments to explore the influence of parameters including base type, base amount, precursor amount, solvent, reaction temperature, and reaction time. The experiments were carried out within only 15 experiment days, and the small volume (~ 10 μL compared to the ~ 1 mL scale of conventional instruments) consumed ~ 100 × less precursor per datapoint. This new method paves the way for more comprehensive optimization studies in radiochemistry and substantially shortening PET tracer development timelines.
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Lisova K, Wang J, Hajagos TJ, Lu Y, Hsiao A, Elizarov A, van Dam RM. Economical droplet-based microfluidic production of [ 18F]FET and [ 18F]Florbetaben suitable for human use. Sci Rep 2021; 11:20636. [PMID: 34667246 PMCID: PMC8526601 DOI: 10.1038/s41598-021-99111-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/26/2021] [Indexed: 01/22/2023] Open
Abstract
Current equipment and methods for preparation of radiopharmaceuticals for positron emission tomography (PET) are expensive and best suited for large-scale multi-doses batches. Microfluidic radiosynthesizers have been shown to provide an economic approach to synthesize these compounds in smaller quantities, but can also be scaled to clinically-relevant levels. Batch microfluidic approaches, in particular, offer significant reduction in system size and reagent consumption. Here we show a simple and rapid technique to concentrate the radioisotope, prior to synthesis in a droplet-based radiosynthesizer, enabling production of clinically-relevant batches of [18F]FET and [18F]FBB. The synthesis was carried out with an automated synthesizer platform based on a disposable Teflon-silicon surface-tension trap chip. Up to 0.1 mL (4 GBq) of radioactivity was used per synthesis by drying cyclotron-produced aqueous [18F]fluoride in small increments directly inside the reaction site. Precursor solution (10 µL) was added to the dried [18F]fluoride, the reaction chip was heated for 5 min to perform radiofluorination, and then a deprotection step was performed with addition of acid solution and heating. The product was recovered in 80 µL volume and transferred to analytical HPLC for purification. Purified product was formulated via evaporation and resuspension or a micro-SPE formulation system. Quality control testing was performed on 3 sequential batches of each tracer. The method afforded production of up to 0.8 GBq of [18F]FET and [18F]FBB. Each production was completed within an hour. All batches passed quality control testing, confirming suitability for human use. In summary, we present a simple and efficient synthesis of clinically-relevant batches of [18F]FET and [18F]FBB using a microfluidic radiosynthesizer. This work demonstrates that the droplet-based micro-radiosynthesizer has a potential for batch-on-demand synthesis of 18F-labeled radiopharmaceuticals for human use.
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Affiliation(s)
- Ksenia Lisova
- Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA, USA
- Physics in Biology and Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA, USA
| | - Jia Wang
- Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA, USA
- Bioengineering Department, University of California Los Angeles, Los Angeles, CA, USA
| | | | - Yingqing Lu
- Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA, USA
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA, USA
- Physics in Biology and Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA, USA
| | | | | | - R Michael van Dam
- Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA, USA.
- Physics in Biology and Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA, USA.
- Bioengineering Department, University of California Los Angeles, Los Angeles, CA, USA.
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7
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Varlow C, Murrell E, Holland JP, Kassenbrock A, Shannon W, Liang SH, Vasdev N, Stephenson NA. Revisiting the Radiosynthesis of [ 18F]FPEB and Preliminary PET Imaging in a Mouse Model of Alzheimer's Disease. Molecules 2020; 25:molecules25040982. [PMID: 32098347 PMCID: PMC7070414 DOI: 10.3390/molecules25040982] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/19/2020] [Accepted: 02/20/2020] [Indexed: 11/24/2022] Open
Abstract
[18F]FPEB is a positron emission tomography (PET) radiopharmaceutical used for imaging the abundance and distribution of mGluR5 in the central nervous system (CNS). Efficient radiolabeling of the aromatic ring of [18F]FPEB has been an ongoing challenge. Herein, five metal-free precursors for the radiofluorination of [18F]FPEB were compared, namely, a chloro-, nitro-, sulfonium salt, and two spirocyclic iodonium ylide (SCIDY) precursors bearing a cyclopentyl (SPI5) and a new adamantyl (SPIAd) auxiliary. The chloro- and nitro-precursors resulted in a low radiochemical yield (<10% RCY), whereas both SCIDY precursors and the sulfonium salt precursor produced [18F]FPEB in the highest RCYs of 25% and 36%, respectively. Preliminary PET/CT imaging studies with [18F]FPEB were conducted in a transgenic model of Alzheimer’s Disease (AD) using B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J (APP/PS1) mice, and data were compared with age-matched wild-type (WT) B6C3F1/J control mice. In APP/PS1 mice, whole brain distribution at 5 min post-injection showed a slightly higher uptake (SUV = 4.8 ± 0.4) than in age-matched controls (SUV = 4.0 ± 0.2). Further studies to explore mGluR5 as an early biomarker for AD are underway.
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Affiliation(s)
- Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Institute of Medical Science, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Emily Murrell
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
| | - Jason P. Holland
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
- Department of Chemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Alina Kassenbrock
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
| | - Whitney Shannon
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N OX2, Canada
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
- Department of Psychiatry, University of Toronto, Toronto, ON M5T-1R8, Canada
- Correspondence: (N.V.); (N.A.S.); Tel.: +416-535-8501 (ext. 30988) (N.V.); +1-876-927-1910 (N.A.S.)
| | - Nickeisha A. Stephenson
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada; (C.V.); (E.M.); (W.S.)
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; (J.P.H.); (A.K.); (S.H.L.)
- Department of Chemistry, The University of West Indies at Mona, Kingston 7, Jamaica
- Correspondence: (N.V.); (N.A.S.); Tel.: +416-535-8501 (ext. 30988) (N.V.); +1-876-927-1910 (N.A.S.)
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8
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The chemistry of labeling heterocycles with carbon-11 or fluorine-18 for biomedical imaging. ADVANCES IN HETEROCYCLIC CHEMISTRY 2020. [DOI: 10.1016/bs.aihch.2019.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Frank C, Winter G, Rensei F, Samper V, Brooks AF, Hockley BG, Henderson BD, Rensch C, Scott PJH. Development and implementation of ISAR, a new synthesis platform for radiopharmaceutical production. EJNMMI Radiopharm Chem 2019; 4:24. [PMID: 31659546 PMCID: PMC6751239 DOI: 10.1186/s41181-019-0077-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 08/30/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND PET radiopharmaceutical development and the implementation of a production method on a synthesis module is a complex and time-intensive task since new synthesis methods must be adapted to the confines of the synthesis platform in use. Commonly utilized single fluid bus architectures put multiple constraints on synthesis planning and execution, while conventional microfluidic solutions are limited by compatibility at the macro-to-micro interface. In this work we introduce the ISAR synthesis platform and custom-tailored fluid paths leveraging up to 70 individually addressable valves on a chip-based consumable. The ISAR synthesis platform replaces traditional stopcock valve manifolds with a fluidic chip that integrates all fluid paths (tubing) and valves into one consumable and enables channel routing without the single fluid bus constraint. ISAR can scale between the macro- (10 mL), meso- (0.5 mL) and micro- (≤0.05 mL) domain seamlessly, addressing the macro-to-micro interface challenge and enabling custom tailored fluid circuits for a given application. In this paper we demonstrate proof-of-concept by validating a single chip design to address the challenge of synthesizing multiple batches of [13N]NH3 for clinical use throughout the workday. RESULTS ISAR was installed at an academic PET Center and used to manufacture [13N]NH3 in > 96% radiochemical yield. Up to 9 batches were manufactured with a single consumable chip having parallel paths without the need to open the hot-cell. Quality control testing confirmed the ISAR-based [13N]NH3 met existing clinical release specifications, and utility was demonstrated by imaging a rodent with [13N]NH3 produced on ISAR. CONCLUSIONS ISAR represents a new paradigm in radiopharmaceutical production. Through a new system architecture, ISAR integrates the principles of microfluidics with the standard volumes and consumables established in PET Centers all over the world. Proof-of-concept has been demonstrated through validation of a chip design for the synthesis of [13N]NH3 suitable for clinical use.
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Affiliation(s)
| | - Georg Winter
- GE Healthcare, Oskar-Schlemmer-Str. 11, 80807 Munich, Germany
| | | | | | - Allen F. Brooks
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI 48109 USA
| | - Brian G. Hockley
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI 48109 USA
| | - Bradford D. Henderson
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI 48109 USA
| | | | - Peter J. H. Scott
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI 48109 USA
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10
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Knapp KA, Nickels ML, Manning HC. The Current Role of Microfluidics in Radiofluorination Chemistry. Mol Imaging Biol 2019; 22:463-475. [DOI: 10.1007/s11307-019-01414-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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11
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Facile 18F labeling of non-activated arenes via a spirocyclic iodonium(III) ylide method and its application in the synthesis of the mGluR 5 PET radiopharmaceutical [ 18F]FPEB. Nat Protoc 2019; 14:1530-1545. [PMID: 30980032 DOI: 10.1038/s41596-019-0149-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 02/12/2019] [Indexed: 01/08/2023]
Abstract
Non-activated (electron-rich and/or sterically hindered) arenes are prevalent chemical scaffolds in pharmaceuticals and positron emission tomography (PET) diagnostics. Despite substantial efforts to develop a general method to introduce 18F into these moieties for molecular imaging by PET, there is an urgent and unmet need for novel radiofluorination strategies that result in sufficiently labeled tracers to enable human imaging. Herein, we describe an efficient method that relies on spirocyclic iodonium ylide (SCIDY) precursors for one-step and regioselective radiofluorination, as well as proof-of-concept translation to the radiosynthesis of a clinically useful PET tracer, 3-[18F]fluoro-5-[(pyridin-3-yl)ethynyl] benzonitrile ([18F]FPEB). The protocol begins with the preparation of a SCIDY precursor for FPEB, followed by radiosynthesis of [18F]FPEB, by either manual operation or an automated synthesis module. [18F]FPEB can be obtained in quantities >7.4 GBq (200 mCi), ready for injection (20 ± 5%, non-decay corrected), and has excellent chemical and radiochemical purity (>98%) as well as high molar activity (666 ± 51.8 GBq/μmol; 18 ± 1.4 Ci/μmol). The total time for the synthesis and purification of the corresponding labeling SCIDY precursor is 10 h. The subsequent radionuclide production, experimental setup, 18F labeling, and formulation of a product that is ready for injection require 2 h.
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12
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Xu Y, Li Z. Imaging metabotropic glutamate receptor system: Application of positron emission tomography technology in drug development. Med Res Rev 2019; 39:1892-1922. [DOI: 10.1002/med.21566] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Youwen Xu
- Independent Consultant and Contractor, Radiopharmaceutical Development, Validation and Bio-Application; Philadelphia Pennsylvania
| | - Zizhong Li
- Pharmaceutical Research and Development, SOFIE Biosciences; Somerset New Jersey
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13
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Kang Y, Henchcliffe C, Verma A, Vallabhajosula S, He B, Kothari PJ, Pryor KO, Mozley PD. 18F-FPEB PET/CT Shows mGluR5 Upregulation in Parkinson's Disease. J Neuroimaging 2018; 29:97-103. [DOI: 10.1111/jon.12563] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 11/28/2022] Open
Affiliation(s)
- Yeona Kang
- Department of Radiology; Weill Cornell Medicine; New York NY
| | | | | | | | - Bin He
- Department of Radiology; Weill Cornell Medicine; New York NY
| | | | - Kane O. Pryor
- Department of Anesthesiology; Weill Cornell Medicine; New York NY
| | - P. David Mozley
- Department of Radiology; Weill Cornell Medicine; New York NY
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14
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Collier TL, Liang SH, Mann JJ, Vasdev N, Kumar JSD. Microfluidic radiosynthesis of [ 18F]FEMPT, a high affinity PET radiotracer for imaging serotonin receptors. Beilstein J Org Chem 2017; 13:2922-2927. [PMID: 29564020 PMCID: PMC5753126 DOI: 10.3762/bjoc.13.285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 12/18/2017] [Indexed: 01/04/2023] Open
Abstract
Continuous-flow microfluidics has shown increased applications in radiochemistry over the last decade, particularly for both pre-clinical and clinical production of fluorine-18 labeled radiotracers. The main advantages of microfluidics are the reduction in reaction times and consumption of reagents that often result in increased radiochemical yields and rapid optimization of reaction parameters for 18F-labeling. In this paper, we report on the two-step microfluidic radiosynthesis of the high affinity partial agonist of the serotonin 1A receptor, [18F]FEMPT (pKi = 9. 79; Ki = 0.16 nM) by microfluidic radiochemistry. [18F]FEMPT was obtained in ≈7% isolated radiochemical yield and in >98% radiochemical and chemical purity. The molar activity of the final product was determined to be >148 GBq/µmol (>4 Ci/µmol).
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Affiliation(s)
- Thomas Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Harvard Medical School, Boston, MA, USA
- Advion, Inc., Ithaca, NY, USA
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Harvard Medical School, Boston, MA, USA
| | - J John Mann
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, NY, USA
| | | | - J S Dileep Kumar
- Molecular Imaging and Neuropathology Division, New York State Psychiatric Institute, New York, NY, USA
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15
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Bernard-Gauthier V, Collier TL, Liang SH, Vasdev N. Discovery of PET radiopharmaceuticals at the academia-industry interface. DRUG DISCOVERY TODAY. TECHNOLOGIES 2017; 25:19-26. [PMID: 29233263 DOI: 10.1016/j.ddtec.2017.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/18/2017] [Indexed: 01/24/2023]
Abstract
Project-specific collaborations between academia and pharmaceutical partners are a growing phenomenon within molecular imaging and in particular in the positron emission tomography (PET) radiopharmaceutical community. This cultural shift can be attributed in part to decreased public funding in academia in conjunction with the increased reliance on outsourcing of chemistry, radiochemistry, pharmacology and molecular imaging studies by the pharmaceutical industry. This account highlights some of our personal experiences working with industrial partners to develop new PET radiochemistry methodologies for drug discovery and neuro-PET research studies. These symbiotic academic-industrial partnerships have not only led to novel radiotracers for new targets but also to the application of new carbon-11 and fluorine-18 labeling methodologies and technologies to label previously unprecedented compounds for in vivo evaluations.
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Affiliation(s)
- Vadim Bernard-Gauthier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA
| | - Thomas L Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA; Advion Inc., Research and Development, Ithaca, NY 14850, USA
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114, USA.
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16
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Production of diverse PET probes with limited resources: 24 18F-labeled compounds prepared with a single radiosynthesizer. Proc Natl Acad Sci U S A 2017; 114:11309-11314. [PMID: 29073049 DOI: 10.1073/pnas.1710466114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
New radiolabeled probes for positron-emission tomography (PET) are providing an ever-increasing ability to answer diverse research and clinical questions and to facilitate the discovery, development, and clinical use of drugs in patient care. Despite the high equipment and facility costs to produce PET probes, many radiopharmacies and radiochemistry laboratories use a dedicated radiosynthesizer to produce each probe, even if the equipment is idle much of the time, to avoid the challenges of reconfiguring the system fluidics to switch from one probe to another. To meet growing demand, more cost-efficient approaches are being developed, such as radiosynthesizers based on disposable "cassettes," that do not require reconfiguration to switch among probes. However, most cassette-based systems make sacrifices in synthesis complexity or tolerated reaction conditions, and some do not support custom programming, thereby limiting their generality. In contrast, the design of the ELIXYS FLEX/CHEM cassette-based synthesizer supports higher temperatures and pressures than other systems while also facilitating flexible synthesis development. In this paper, the syntheses of 24 known PET probes are adapted to this system to explore the possibility of using a single radiosynthesizer and hot cell for production of a diverse array of compounds with wide-ranging synthesis requirements, alongside synthesis development efforts. Most probes were produced with yields and synthesis times comparable to literature reports, and because hardware modification was unnecessary, it was convenient to frequently switch among probes based on demand. Although our facility supplies probes for preclinical imaging, the same workflow would be applicable in a clinical setting.
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17
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Matesic L, Kallinen A, Greguric I, Pascali G. Dose-on-demand production of diverse 18 F-radiotracers for preclinical applications using a continuous flow microfluidic system. Nucl Med Biol 2017; 52:24-31. [DOI: 10.1016/j.nucmedbio.2017.05.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 05/08/2017] [Accepted: 05/10/2017] [Indexed: 12/30/2022]
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18
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Rotstein BH, Liang SH, Placzek MS, Hooker JM, Gee AD, Dollé F, Wilson AA, Vasdev N. (11)C[double bond, length as m-dash]O bonds made easily for positron emission tomography radiopharmaceuticals. Chem Soc Rev 2016; 45:4708-26. [PMID: 27276357 PMCID: PMC5000859 DOI: 10.1039/c6cs00310a] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The positron-emitting radionuclide carbon-11 ((11)C, t1/2 = 20.3 min) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [(11)C]methyl iodide or [(11)C]methyl triflate (generated from [(11)C]carbon dioxide or [(11)C]methane). Consequently, small molecules that lack an easily substituted (11)C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [(11)C]Carbon dioxide itself, [(11)C]carbon monoxide, [(11)C]cyanide, and [(11)C]phosgene represent alternative reactants to enable (11)C-carbonylation. Methodologies developed for preparation of (11)C-carbonyl groups have had a tremendous impact on the development of novel PET tracers and provided key tools for clinical research. (11)C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility and practicality of the underlying radiochemistry.
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Affiliation(s)
| | - Steven H Liang
- Massachusetts General Hospital, Harvard Medical School, Boston, USA.
| | - Michael S Placzek
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, HMS, Charlestown, USA and McLean Hospital, Belmont, USA
| | - Jacob M Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, HMS, Charlestown, USA
| | | | - Frédéric Dollé
- CEA - Institut d'imagerie biomédicale, Service hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Alan A Wilson
- Centre for Addiction and Mental Health, Toronto, Canada
| | - Neil Vasdev
- Massachusetts General Hospital, Harvard Medical School, Boston, USA.
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19
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Kimura H, Tomatsu K, Saiki H, Arimitsu K, Ono M, Kawashima H, Iwata R, Nakanishi H, Ozeki E, Kuge Y, Saji H. Continuous-Flow Synthesis of N-Succinimidyl 4-[18F]fluorobenzoate Using a Single Microfluidic Chip. PLoS One 2016; 11:e0159303. [PMID: 27410684 PMCID: PMC4943714 DOI: 10.1371/journal.pone.0159303] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/30/2016] [Indexed: 11/30/2022] Open
Abstract
In the field of positron emission tomography (PET) radiochemistry, compact microreactors provide reliable and reproducible synthesis methods that reduce the use of expensive precursors for radiolabeling and make effective use of the limited space in a hot cell. To develop more compact microreactors for radiosynthesis of 18F-labeled compounds required for the multistep procedure, we attempted radiosynthesis of N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) via a three-step procedure using a microreactor. We examined individual steps for [18F]SFB using a batch reactor and microreactor and developed a new continuous-flow synthetic method with a single microfluidic chip to achieve rapid and efficient radiosynthesis of [18F]SFB. In the synthesis of [18F]SFB using this continuous-flow method, the three-step reaction was successfully completed within 6.5 min and the radiochemical yield was 64 ± 2% (n = 5). In addition, it was shown that the quality of [18F]SFB synthesized on this method was equal to that synthesized by conventional methods using a batch reactor in the radiolabeling of bovine serum albumin with [18F]SFB.
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Affiliation(s)
- Hiroyuki Kimura
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
- Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Kyoto, Kyoto, Japan
- * E-mail: (HS); (HK)
| | - Kenji Tomatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
| | - Hidekazu Saiki
- Technology Research Laboratory, Shimadzu Corporation, Souraku-gun, Kyoto, Japan
| | - Kenji Arimitsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
- School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women’s University, Nishinomiya, Hyogo, Japan
| | - Masahiro Ono
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
| | - Hidekazu Kawashima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
- Radioisotope Research Center, Kyoto Pharmaceutical University, Kyoto, Kyoto, Japan
| | - Ren Iwata
- CYRIC, Tohoku University, Sendai, Miyagi, Japan
| | - Hiroaki Nakanishi
- Technology Research Laboratory, Shimadzu Corporation, Souraku-gun, Kyoto, Japan
| | - Eiichi Ozeki
- Technology Research Laboratory, Shimadzu Corporation, Souraku-gun, Kyoto, Japan
| | - Yuji Kuge
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
- Central Institute of Isotope Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hideo Saji
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Kyoto, Japan
- * E-mail: (HS); (HK)
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20
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Leurquin-Sterk G, Van den Stock J, Crunelle CL, de Laat B, Weerasekera A, Himmelreich U, Bormans G, Van Laere K. Positive Association Between Limbic Metabotropic Glutamate Receptor 5 Availability and Novelty-Seeking Temperament in Humans: An 18F-FPEB PET Study. J Nucl Med 2016; 57:1746-1752. [PMID: 27283933 DOI: 10.2967/jnumed.116.176032] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 05/06/2016] [Indexed: 11/16/2022] Open
Abstract
Heritable temperament traits have been linked to several neuropsychiatric illnesses, including disorders associated with metabotropic glutamate receptor 5 (mGluR5) and dopaminergic dysfunctions. Considering its modulating effect on neurotransmission, we hypothesized that cerebral mGluR5 availability is associated with temperament traits in healthy humans. METHODS Forty-four nonsmoking healthy volunteers (mean age ± SD, 40 ± 14 y; age range, 22-66 y; 22 women) were included in this cross-sectional investigation. Brain mGluR5 availability was quantified on both a voxel-by-voxel and a volume-of-interest basis using the total distribution volume of the radioligand 18F-3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile (18F-FPEB) with 90-min dynamic PET and arterial input function. Moreover, glutamate-glutamine concentrations in the anterior cingulate cortex were measured using MR spectroscopy. These measures were related to the temperament traits of the 240-item Cloninger temperament and character inventory using a regression analysis with age and sex as nuisance variables. RESULTS High novelty-seeking temperament was robustly associated with increased mGluR5 availability in various regions including the thalamus (r = 0.71; the strongest association), amygdala, parahippocampus, insula, anterior and posterior cingulate cortex, and several primary sensory areas (all r > 0.58; P < 0.05, corrected for familywise error). These associations were specific because no correlations were found with other temperament scales or with spectroscopic measures of glutamatergic transmission. CONCLUSION Overall, these data posit mGluR5 in key paralimbic areas as a strong determinant of the temperament trait novelty seeking. These data add to our understanding of how brain neurochemistry accounts for the variation in human behavior and strongly support further research on mGluR5 as a potential therapeutic target in neuropsychiatric disorders associated with abnormal novelty-seeking behaviors.
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Affiliation(s)
- Gil Leurquin-Sterk
- Department of Nuclear Medicine and Molecular Imaging, University Hospitals Leuven, Leuven, Belgium
| | - Jan Van den Stock
- Laboratory for Translational Neuropsychiatry, Department of Neurosciences, KU Leuven and Department of Old Age Psychiatry, University Hospitals Leuven, Leuven, Belgium
| | | | - Bart de Laat
- Department of Nuclear Medicine and Molecular Imaging, University Hospitals Leuven, Leuven, Belgium.,MoSAIC, Molecular Small Animal Imaging Center, KU Leuven, Leuven, Belgium
| | - Akila Weerasekera
- Biomedical MRI/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; and
| | - Uwe Himmelreich
- Biomedical MRI/MoSAIC, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium; and
| | - Guy Bormans
- Laboratory for Radiopharmacy, KU Leuven, Leuven, Belgium
| | - Koen Van Laere
- Department of Nuclear Medicine and Molecular Imaging, University Hospitals Leuven, Leuven, Belgium.,MoSAIC, Molecular Small Animal Imaging Center, KU Leuven, Leuven, Belgium
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21
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Rehm TH. Photochemical Fluorination Reactions - A Promising Research Field for Continuous-Flow Synthesis. Chem Eng Technol 2015. [DOI: 10.1002/ceat.201500195] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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22
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Mossine AV, Brooks AF, Makaravage KJ, Miller JM, Ichiishi N, Sanford MS, Scott PJH. Synthesis of [18F]Arenes via the Copper-Mediated [18F]Fluorination of Boronic Acids. Org Lett 2015; 17:5780-3. [PMID: 26568457 PMCID: PMC4672358 DOI: 10.1021/acs.orglett.5b02875] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
A copper-mediated
radiofluorination of aryl- and vinylboronic acids
with K18F is described. This method exhibits high functional
group tolerance and is effective for the radiofluorination of a range
of electron-deficient, -neutral, and -rich aryl-, heteroaryl-, and
vinylboronic acids. This method has been applied to the synthesis
of [18F]FPEB, a PET radiotracer for quantifying metabotropic
glutamate 5 receptors.
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Affiliation(s)
- Andrew V Mossine
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
| | - Allen F Brooks
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States
| | - Katarina J Makaravage
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jason M Miller
- Department of Medicinal Chemistry, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109, United States
| | - Naoko Ichiishi
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Peter J H Scott
- Department of Radiology, University of Michigan Medical School , 1301 Catherine Street, Ann Arbor, Michigan 48109, United States.,Department of Medicinal Chemistry, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109, United States
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23
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Calderwood S, Collier TL, Gouverneur V, Liang SH, Vasdev N. Synthesis of 18F-Arenes from Spirocyclic Iodonium(III) Ylides via Continuous-Flow Microfluidics. J Fluor Chem 2015; 178:249-253. [PMID: 27512233 PMCID: PMC4976495 DOI: 10.1016/j.jfluchem.2015.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Spirocyclic hypervalent iodine(III) ylides have proven to be synthetically versatile precursors for efficient radiolabelling of a diverse range of non-activated (hetero)arenes, highly functionalised small molecules, building blocks and radiopharmaceuticals from [18F]fluoride ion. Herein, we report the implementation of these reactions onto a continuous-flow microfluidic platform, thereby offering an alterative and automated synthetic procedure of a radiopharmaceutical, 3-[18F]fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ([18F]FPEB) and a routinely used building block for click-radiochemistry, 4-[18F]fluorobenzyl azide. This new protocol was applied to the synthesis of [18F]FPEB (radiochemical conversion (RCC) = 68 ± 5%) and 4-[18F]fluorobenzyl azide (RCC=68 ± 5%; isolated radiochemical yield = 24±0%). We anticipate that the high throughput microfluidic platform will accelerate the discovery and applications of 18F-labelled building blocks and labelled compounds prepared by iodonium ylide precursors as well as the production of radiotracers for preclinical imaging studies.
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Affiliation(s)
- Samuel Calderwood
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, UK
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
| | - Thomas Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, USA
- Advion BioSystems, 10 Brown Road, Suite 101, Ithaca, New York, USA
| | - Véronique Gouverneur
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, UK
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, USA
- Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, USA
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24
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Abstract
The logic of total synthesis transformed a stagnant state of medicinal and synthetic organic chemistry when there was a paucity of methods and reagents to synthesize drug molecules and/or natural products. Molecular imaging by positron emission tomography (PET) is now experiencing a renaissance in the way radiopharmaceuticals for molecular imaging are synthesized, however, a paradigm shift is desperately needed in the discovery pipeline to accelerate in vivo imaging studies. A significant challenge in radiochemistry is the limited choice of labeled reagents (or building blocks) available for the synthesis of novel radiopharmaceuticals with the most commonly used short-lived radionuclides carbon-11 (11C; half-life ~20 minutes) and fluorine-18 (18F; half-life ~2 hours). In fact, most drugs cannot be labeled with 11C or 18F due to a lack of efficient and diverse radiosynthetic methods. In general, routine radiopharmaceutical production relies on the incorporation of the isotope at the last or penultimate step of synthesis, ideally within one half-life of the radionuclide, to maximize radiochemical yields and specific activities thereby reducing losses due to radioactive decay. Reliance on radiochemistry conducted within the constraints of an automated synthesis unit ("box") has stifled the exploration of multi-step reactions with short-lived radionuclides. Radiopharmaceutical synthesis can be transformed by considering logic of total synthesis to develop novel approaches for 11C- and 18F-radiolabeling complex molecules via retrosynthetic analysis and multi-step reactions. As a result of such exploration, new methods, reagents and radiopharmaceuticals for in vivo imaging studies are discovered. A new avenue to develop radiotracers that were previously unattainable due to the lack of efficient radiosynthetic methods is necessary to work towards our ultimate, albeit impossible goal - the concept we term total radiosynthesis - to radiolabel virtually any molecule. As with the vast majority of drugs, most radiotracers also fail, therefore expeditious evaluation of tracers in preclinical models prior to optimization or derivatization of the lead molecules/drugs is necessary. Furthermore the exact position of the 11C and 18F radionuclide in tracers is often critical for metabolic considerations, and flexible methodologies to introduce the radiolabel are needed. Using the principles of total synthesis our laboratory and others have shown that multi-step radiochemical reactions are indeed suitable for preclinical and even clinical use. As the goal of total synthesis is to be concise, we have also simplified the syntheses of radiopharmaceuticals. We are presently developing new strategies via [11C]CO2 fixation which has enabled library radiosynthesis as well as labeling non-activated arenes using [18F]fluoride via iodonium ylides. Both of which have proven to be suitable for human PET imaging. We concurrently utilize state-of-the-art automation technologies including microfluidic flow chemistry and rapid purification strategies for radiopharmaceutical production. In this account we highlight how total radiosynthesis has impacted our radiochemistry program, with prominent examples from others, focusing on its impact towards preclinical and clinical research studies.
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Affiliation(s)
- Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, 55 Fruit St., Boston, MA, 02114, USA
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25
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Liang SH, Yokell DL, Normandin MD, Rice PA, Jackson RN, Shoup TM, Brady TJ, El Fakhri G, Collier TL, Vasdev N. First human use of a radiopharmaceutical prepared by continuous-flow microfluidic radiofluorination: proof of concept with the tau imaging agent [18F]T807. Mol Imaging 2015; 13. [PMID: 25248283 DOI: 10.2310/7290.2014.00025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite extensive preclinical imaging with radiotracers developed by continuous-flow microfluidics, a positron emission tomographic (PET) radiopharmaceutical has not been reported for human imaging studies by this technology. The goal of this study was to validate the synthesis of the tau radiopharmaceutical 7-(6-fluoropyridin-3-yl)-5H-pyrido[4,3-b]indole ([18F]T807) and perform first-in-human PET scanning enabled by microfluidic flow chemistry. [18F]T807 was synthesized by our modified one-step method and adapted to suit a commercial microfluidic flow chemistry module. For this proof of concept, the flow system was integrated to a GE Tracerlab FXFN unit for high-performance liquid chromatography purification and formulation. Three consecutive productions of [18F]T807 were conducted to validate this radiopharmaceutical. Uncorrected radiochemical yields of 17 ± 1% of crude [18F]T807 (≈ 500 mCi, radiochemical purity 95%) were obtained from the microfluidic device. The crude material was then purified, and > 100 mCi of the final product was obtained in an overall uncorrected radiochemical yield of 5 ± 1% (n = 3), relative to starting [18F]fluoride (end of bombardment), with high radiochemical purity (≥ 99%) and high specific activities (6 Ci/μmol) in 100 minutes. A clinical research study was carried out with [18F]T807, representing the first reported human imaging study with a radiopharmaceutical prepared by this technology.
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26
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Stephenson NA, Holland JP, Kassenbrock A, Yokell DL, Livni E, Liang SH, Vasdev N. Iodonium ylide-mediated radiofluorination of 18F-FPEB and validation for human use. J Nucl Med 2015; 56:489-92. [PMID: 25655630 DOI: 10.2967/jnumed.114.151332] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Translation of new methodologies for labeling nonactivated aromatic molecules with (18)F remains a challenge. Here, we report a one-step, regioselective, metal-free (18)F-labeling method that uses a hypervalent iodonium(III) ylide precursor, to prepare the radiopharmaceutical (18)F-3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ((18)F-FPEB). METHODS Automated radiosynthesis of (18)F-FPEB was achieved by reaction of the ylide precursor (4 mg) with (18)F-Et4NF in dimethylformamide at 80°C for 5 min and formulated for injection within 1 h. RESULTS (18)F-FPEB was synthesized in 20% ± 5% (n = 3) uncorrected radiochemical yields relative to (18)F-fluoride, with specific activities of 666 ± 51.8 GBq (18 ± 1.4 Ci)/μmol at the end of synthesis and was validated for human use. CONCLUSION Radiofluorination of iodonium (III) ylides proved to be an efficient radiosynthetic strategy for synthesis of (18)F-labeled radiopharmaceuticals.
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Affiliation(s)
- Nickeisha A Stephenson
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Jason P Holland
- Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Alina Kassenbrock
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and
| | - Daniel L Yokell
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and
| | - Eli Livni
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, Boston, Massachusetts; and Department of Radiology, Harvard Medical School, Boston, Massachusetts
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