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Edwards R, Greenwood HE, McRobbie G, Khan I, Witney TH. Robust and Facile Automated Radiosynthesis of [ 18F]FSPG on the GE FASTlab. Mol Imaging Biol 2021; 23:854-864. [PMID: 34013395 PMCID: PMC8578107 DOI: 10.1007/s11307-021-01609-w] [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: 12/22/2020] [Revised: 03/19/2021] [Accepted: 04/18/2021] [Indexed: 01/18/2023]
Abstract
Purpose (S)-4-(3-18F-Fluoropropyl)-ʟ-Glutamic Acid ([18F]FSPG) is a radiolabeled non-natural amino acid that is used for positron emission tomography (PET) imaging of the glutamate/cystine antiporter, system xC-, whose expression is upregulated in many cancer types. To increase the clinical adoption of this radiotracer, reliable and facile automated procedures for [18F]FSPG production are required. Here, we report a cassette-based method to produce [18F]FSPG at high radioactivity concentrations from low amounts of starting activity. Procedures An automated synthesis and purification of [18F]FSPG was developed using the GE FASTlab. Optimization of the reaction conditions and automated manipulations were performed by measuring the isolated radiochemical yield of [18F]FSPG and by assessing radiochemical purity using radio-HPLC. Purification of [18F]FSPG was conducted by trapping and washing of the radiotracer on Oasis MCX SPE cartridges, followed by a reverse elution of [18F]FSPG in phosphate-buffered saline. Subsequently, the [18F]FSPG obtained from the optimized process was used to image an animal model of non-small cell lung cancer. Results The optimized protocol produced [18F]FSPG in 38.4 ± 2.6 % radiochemical yield and >96 % radiochemical purity with a molar activity of 11.1 ± 7.7 GBq/μmol. Small alterations, including the implementation of a reverse elution and an altered Hypercarb cartridge, led to significant improvements in radiotracer concentration from <10 MBq/ml to >100 MBq/ml. The improved radiotracer concentration allowed for the imaging of up to 20 mice, starting with just 1.5 GBq of [18F]Fluoride. Conclusions We have developed a robust and facile method for [18F]FSPG radiosynthesis in high radiotracer concentration, radiochemical yield, and radiochemical purity. This cassette-based method enabled the production of [18F]FSPG at radioactive concentrations sufficient to facilitate large-scale preclinical experiments with a single prep of starting activity. The use of a cassette-based radiosynthesis on an automated synthesis module routinely used for clinical production makes the method amenable to rapid and widespread clinical translation. Supplementary Information The online version contains supplementary material available at 10.1007/s11307-021-01609-w.
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Affiliation(s)
- Richard Edwards
- School of Biomedical Engineering & Imaging Sciences, King's College London, St. Thomas' Hospital, London, SE1 7EH, UK
| | - Hannah E Greenwood
- School of Biomedical Engineering & Imaging Sciences, King's College London, St. Thomas' Hospital, London, SE1 7EH, UK
| | - Graeme McRobbie
- Pharmaceutical Diagnostics, Life Sciences, GE Healthcare, Pollards Wood, Nightingales Lane, Chalfont St. Giles, Buckinghamshire, HP8 4SP, UK
| | - Imtiaz Khan
- Pharmaceutical Diagnostics, Life Sciences, GE Healthcare, Pollards Wood, Nightingales Lane, Chalfont St. Giles, Buckinghamshire, HP8 4SP, UK
| | - Timothy H Witney
- School of Biomedical Engineering & Imaging Sciences, King's College London, St. Thomas' Hospital, London, SE1 7EH, UK.
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Zhang Z, Liu S, Ma H, Xiang X, Nie D, Hu P, Tang G. Propionic Acid-Based PET Imaging of Prostate Cancer. Mol Imaging Biol 2021; 23:836-845. [PMID: 33876336 DOI: 10.1007/s11307-021-01608-x] [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: 10/16/2020] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE This study aimed to evaluate the potential value of 2-[18F]fluoropropionic acid ([18F]FPA) for PET imaging of prostate cancer (PCa) and to explore the relationship between [18F]FPA accumulation and fatty acid synthase (FASN) levels in PCa models. The results of the first [18F]FPA PET study of a PCa patient are reported. PROCEDURES The LNCaP, PC-3 cell lines with high FASN expression, and DU145 cell lines with low FASN expression were selected for cell culture. A PET imaging comparison of [18F]FDG and [18F]FPA was performed in LNCaP, PC-3, and DU145 tumors. Additionally, in vivo inhibition experiments in those models were conducted with orlistat. In a human PET study, a patient with PCa before surgery was examined with [18F]FPA PET and [18F]FDG PET. RESULTS The uptake of [18F]FPA in the LNCaP and PC-3 tumors was higher than that of [18F]FDG (P<0.05 and P<0.05), but was lower in DU145 tumors (P<0.05). The accumulation (% ID/g) of [18F]FPA in the LNCaP, PC-3, and DU145 tumors decreased by 27.6, 40.5, and 11.7 %, respectively, after treatment with orlistat. The [18F]FPA showed higher radioactive uptake than [18F]FDG in the first PCa patient. CONCLUSIONS The [18F]FPA uptake in PCa models may be varies with fatty acid synthase activity and could be reduced after administration of a single FASN inhibitor, albeit the activity that is not measured directly. The [18F]FPA seems to be a potential broad-spectrum PET imaging agent and may serve as a valuable tool in the diagnosis of PCa in humans.
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Affiliation(s)
- Zhanwen Zhang
- Department of Nuclear Medicine, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510655, China.,Department of Nuclear Medicine and Medical Imaging, Guangdong Engineering Research Center for Translational Application of Medical Radiopharmaceuticals, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Shaoyu Liu
- Department of Nuclear Medicine and Medical Imaging, Guangdong Engineering Research Center for Translational Application of Medical Radiopharmaceuticals, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China.,Department of Nuclear Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China
| | - Hui Ma
- Department of Nuclear Medicine and Medical Imaging, Guangdong Engineering Research Center for Translational Application of Medical Radiopharmaceuticals, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China.,Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xianhong Xiang
- Department of Nuclear Medicine and Medical Imaging, Guangdong Engineering Research Center for Translational Application of Medical Radiopharmaceuticals, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Dahong Nie
- Department of Nuclear Medicine and Medical Imaging, Guangdong Engineering Research Center for Translational Application of Medical Radiopharmaceuticals, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Ping Hu
- Department of Nuclear Medicine, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510655, China.
| | - Ganghua Tang
- Department of Nuclear Medicine and Medical Imaging, Guangdong Engineering Research Center for Translational Application of Medical Radiopharmaceuticals, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China. .,Nanfang PET Center and Department of Nuclear Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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Application of chiral chromatography in radiopharmaceutical fields: A review. J Chromatogr A 2020; 1632:461611. [PMID: 33086153 DOI: 10.1016/j.chroma.2020.461611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/07/2020] [Accepted: 10/08/2020] [Indexed: 01/20/2023]
Abstract
Chiral column chromatography (CCC) is a revolutionary analytical methodology for the enantioseparation of novel positron emission tomography (PET) tracers in the primary stages of drug development. Due to the different behaviors of tracer enantiomers (e.g. toxicity, metabolism and side effects) in administrated subjects, their separation and purification is a challenging endeavor. Over the last three decades, different commercial chiral columns have been applied for the enantioseparation of PET-radioligand (PET-RL) or radiotracers (PET-RT), using high-performance liquid chromatography (HPLC). The categorization and reviewing of them is a vital topic. This review presents a brief overview of advances, applications, and future prospectives of CCC in radiopharmaceutical approaches. In addition, the effective chromatographic parameters and degravitation trends to enhance enantioseparation resolution are addressed. Moreover, the application and potential of chiral super fluidical chromatography (CSFC) as an alternative for enantioseparation in the field of radiopharmaceutical is discussed. Finally, the crucial application challenges of CCC are explained and imminent tasks are suggested.
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One-step radiosynthesis of the MCTs imaging agent [ 18F]FACH by aliphatic 18F-labelling of a methylsulfonate precursor containing an unprotected carboxylic acid group. Sci Rep 2019; 9:18890. [PMID: 31827199 PMCID: PMC6906299 DOI: 10.1038/s41598-019-55354-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 11/27/2019] [Indexed: 02/07/2023] Open
Abstract
Monocarboxylate transporters 1 and 4 (MCT1 and MCT4) are involved in tumour development and progression. Their level of expression is particularly upregulated in glycolytic cancer cells and accordingly MCTs are considered as promising drug targets for treatment of a variety of human cancers. The non-invasive imaging of these transporters in cancer patients via positron emission tomography (PET) is regarded to be valuable for the monitoring of therapeutic effects of MCT inhibitors. Recently, we developed the first 18F-radiolabelled MCT1/MCT4 inhibitor [18F]FACH and reported on a two-step one-pot radiosynthesis procedure. We herein describe now a unique one-step radiosynthesis of this radiotracer which is based on the approach of using a methylsulfonate (mesylate) precursor bearing an unprotected carboxylic acid function. With the new procedure unexpected high radiochemical yields of 43 ± 8% at the end of the radiosynthesis could be obtained in a strongly reduced total synthesis time. Moreover, the radiosynthesis was successfully transferred to a TRACERlab FX2 N synthesis module ready for future preclinical applications of [18F]FACH.
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