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K Nazar A, Basu S. Radiolabeled Somatostatin Analogs for Cancer Imaging. Semin Nucl Med 2024:S0001-2998(24)00058-8. [PMID: 39122608 DOI: 10.1053/j.semnuclmed.2024.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Accepted: 07/01/2024] [Indexed: 08/12/2024]
Abstract
Somatostatin receptors (SSTR) are expressed by many tumours especially those related to neuro-endocrine origin and molecular functional imaging of SSTR expression using radiolabelled somatostatin analogs have revolutionized imaging of patients with these group of malignancies. Coming a long way from the first radiolabelled somatostatin analog 123I-Tyr-3-octreotide, there has been significant developments in terms of radionuclides used, the ligands and somatostatin derivatives. 111In-Pentetreotide extensively employed for imaging NETs at the beginning has now been replaced by 68Ga-SSA based PET-CT. SSA-PET/CT performs superior to conventional imaging modalities and has evolved in the mainframe for NET imaging. The advantages were multiple: (i) superior spatial resolution of PET versus SPECT, (ii) quantitative capabilities of PET aiding in disease activity and treatment response monitoring with better precision, (iii) shorter scan time and (iv) less patient exposure to radiation. The modality is indicated for staging, detecting the primary in CUP-NETs, restaging, treatment planning (along with FDG: the concept of dual-tracer PET-CT) as well as treatment response evaluation and follow-up of NETs. SSA PET/CT has also been incorporated in the guidelines for imaging of Pheochromocytoma-Paraganglioma, Medullary carcinoma thyroid, Meningioma and Tumor induced osteomalacia. At present, there is rising interest on (a) 18F-labelled SSA, (b) 64Cu-labelled SSA, and (c) somatostatin antagonists. 18F offers excellent imaging properties, 64Cu makes delayed imaging feasible which has implications in dosimetry and SSTR antagonists bind with the SST receptors with high affinity and specificity, providing high contrast images with less background, which can be translated to theranostics effectively. SSTR have been demonstrated in non-neuroendocrine tumours as well in the peer-reviewed literature, with studies demonstrating the potential of SSA PET/CT in Neuroblastoma, Nasopharyngeal carcinoma, carcinoma prostate (neuroendocrine differentiation) and lymphoma. This review will focus on the currently available SSAs and their history, different SPECT/PET agents, SSTR antagonists, comparison between the various imaging tracers, and their utility in both neuroendocrine and non-neuroendocrine tumors.
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Affiliation(s)
- Aamir K Nazar
- Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Mumbai; Homi Bhabha National Institute, Mumbai
| | - Sandip Basu
- Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Mumbai; Homi Bhabha National Institute, Mumbai.
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2
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Dubash S, Barwick TD, Kozlowski K, Rockall AG, Khan S, Khan S, Yusuf S, Lamarca A, Valle JW, Hubner RA, McNamara MG, Frilling A, Tan T, Wernig F, Todd J, Meeran K, Pratap B, Azeem S, Huiban M, Keat N, Lozano-Kuehne JP, Aboagye EO, Sharma R. Somatostatin Receptor Imaging with [ 18F]FET-βAG-TOCA PET/CT and [ 68Ga]Ga-DOTA-Peptide PET/CT in Patients with Neuroendocrine Tumors: A Prospective, Phase 2 Comparative Study. J Nucl Med 2024; 65:jnumed.123.266601. [PMID: 38331457 PMCID: PMC10924162 DOI: 10.2967/jnumed.123.266601] [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: 09/22/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 02/10/2024] Open
Abstract
There is a clinical need for 18F-labeled somatostatin analogs for the imaging of neuroendocrine tumors (NET), given the limitations of using [68Ga]Ga-DOTA-peptides, particularly with regard to widespread accessibility. We have shown that [18F]fluoroethyl-triazole-[Tyr3]-octreotate ([18F]FET-βAG-TOCA) has favorable dosimetry and biodistribution. As a step toward clinical implementation, we conducted a prospective, noninferiority study of [18F]FET-βAG-TOCA PET/CT compared with [68Ga]Ga-DOTA- peptide PET/CT in patients with NET. Methods: Forty-five patients with histologically confirmed NET, grades 1 and 2, underwent PET/CT imaging with both [18F]FET-βAG-TOCA and [68Ga]Ga-peptide performed within a 6-mo window (median, 77 d; range, 6-180 d). Whole-body PET/CT was conducted 50 min after injection of 165 MBq of [18F]FET-βAG-TOCA. Tracer uptake was evaluated by comparing SUVmax and tumor-to-background ratios at both lesion and regional levels by 2 unblinded, experienced readers. A randomized, blinded reading of both scans was also then undertaken by 3 experienced readers, and consensus was assessed at a regional level. The ability of both tracers to visualize liver metastases was also assessed. Results: A total of 285 lesions were detected on both imaging modalities. An additional 13 tumor deposits were seen in 8 patients on [18F]FET-βAG-TOCA PET/CT, and [68Ga]Ga-DOTA-peptide PET/CT detected an additional 7 lesions in 5 patients. Excellent correlation in SUVmax was observed between both tracers (r = 0.91; P < 0.001). No difference was observed between median SUVmax across regions, except in the liver, where the median tumor-to-background ratio of [18F]FET-βAG-TOCA was significantly lower than that of [68Ga]Ga-DOTA-peptide (2.5 ± 1.9 vs. 3.5 ± 2.3; P < 0.001). Conclusion: [18F]FET-βAG-TOCA was not inferior to [68Ga]Ga-DOTA-peptide in visualizing NET and may be considered in routine clinical practice given the longer half-life and availability of the cyclotron-produced fluorine radioisotope.
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Affiliation(s)
- Suraiya Dubash
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Tara D Barwick
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
- Department of Imaging, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Kasia Kozlowski
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Andrea G Rockall
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Sairah Khan
- Department of Imaging, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Sameer Khan
- Department of Imaging, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Siraj Yusuf
- Radiology and Nuclear Medicine Department, Royal Marsden NHS Foundation Trust, London, United Kingdom
| | - Angela Lamarca
- Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom
- Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Juan W Valle
- Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom
- Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Richard A Hubner
- Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom
- Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Mairéad G McNamara
- Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom
- Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Andrea Frilling
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Tricia Tan
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Florian Wernig
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Jeannie Todd
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Karim Meeran
- Department of Endocrinology, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Bhavesh Pratap
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Saleem Azeem
- Invicro-London, Imperial College London, London, United Kingdom; and
| | - Michael Huiban
- Invicro-London, Imperial College London, London, United Kingdom; and
| | - Nicholas Keat
- Invicro-London, Imperial College London, London, United Kingdom; and
| | - Jingky P Lozano-Kuehne
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
- Population Health Sciences Institute, Faculty of Medical Sciences, University of Newcastle, Newcastle, United Kingdom
| | - Eric O Aboagye
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Rohini Sharma
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom;
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Ullrich M, Brandt F, Löser R, Pietzsch J, Wodtke R. Comparative Saturation Binding Analysis of 64Cu-Labeled Somatostatin Analogues Using Cell Homogenates and Intact Cells. ACS OMEGA 2023; 8:24003-24009. [PMID: 37426243 PMCID: PMC10324063 DOI: 10.1021/acsomega.3c02755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/09/2023] [Indexed: 07/11/2023]
Abstract
The development of novel ligands for G-protein-coupled receptors (GPCRs) typically entails the characterization of their binding affinity, which is often performed with radioligands in a competition or saturation binding assay format. Since GPCRs are transmembrane proteins, receptor samples for binding assays are prepared from tissue sections, cell membranes, cell homogenates, or intact cells. As part of our investigations on modulating the pharmacokinetics of radiolabeled peptides for improved theranostic targeting of neuroendocrine tumors with a high abundance of the somatostatin receptor sub-type 2 (SST2), we characterized a series of 64Cu-labeled [Tyr3]octreotate (TATE) derivatives in vitro in saturation binding assays. Herein, we report on the SST2 binding parameters measured toward intact mouse pheochromocytoma cells and corresponding cell homogenates and discuss the observed differences taking the physiology of SST2 and GPCRs in general into account. Furthermore, we point out method-specific advantages and limitations.
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Affiliation(s)
- Martin Ullrich
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany
| | - Florian Brandt
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany
- School
of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, Dresden 01069, Germany
| | - Reik Löser
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany
- School
of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, Dresden 01069, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany
- School
of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, Dresden 01069, Germany
| | - Robert Wodtke
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, Dresden 01328, Germany
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4
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Adnan A, Basu S. Somatostatin Receptor Targeted PET-CT and Its Role in the Management and Theranostics of Gastroenteropancreatic Neuroendocrine Neoplasms. Diagnostics (Basel) 2023; 13:2154. [PMID: 37443548 DOI: 10.3390/diagnostics13132154] [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: 05/01/2023] [Revised: 06/18/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Somatostatin receptor (SSTR) agonist-based Positron Emission Tomography-Computed Tomography (PET-CT) imaging is nowadays the mainstay for the assessment and diagnostic imaging of neuroendocrine neoplasms (NEN), especially in well-differentiated neuroendocrine tumors (NET) (World Health Organization (WHO) grade I and II). Major clinical indications for SSTR imaging are primary staging and metastatic workup, especially (a) before surgery, (b) detection of unknown primary in metastatic NET, (c) patient selection for theranostics and appropriate therapy, especially peptide receptor radionuclide therapy (PRRT), while less major indications include treatment response evaluation on and disease prognostication. Dual tracer PET-CT imaging using SSTR targeted PET tracers, viz. [68Ga]Ga-DOTA-Tyr3-Octreotate (DOTA-TATE) and [68Ga]Ga-DOTA-NaI3-Octreotide (DOTA-NOC), and fluorodeoxyglucose (FDG), have recently gained widespread acceptance for better assessment of whole-body tumor biology compared to single-site histopathology, in terms of being non-invasive and the ability to assess inter- and intra-tumoral heterogeneity on a global scale. FDG uptake has been identified as independent adverse risk factor in various studies. Recently, somatostatin receptor antagonists have been shown to be more sensitive and specific in detecting the disease. The aim of this review article is to summarize the clinical importance of SSTR-based imaging in the clinical management of neuroendocrine and related tumors.
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Affiliation(s)
- Aadil Adnan
- Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, JerbaiWadia Road, Parel, Mumbai 400012, India
- Homi Bhabha National Institute, Mumbai 400094, India
| | - Sandip Basu
- Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, JerbaiWadia Road, Parel, Mumbai 400012, India
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Al[ 18F]F-NOTA-Octreotide Is Comparable to [ 68Ga]Ga-DOTA-TATE for PET/CT Imaging of Neuroendocrine Tumours in the Latin-American Population. Cancers (Basel) 2023; 15:cancers15020439. [PMID: 36672388 PMCID: PMC9856643 DOI: 10.3390/cancers15020439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/12/2023] Open
Abstract
PET imaging of neuroendocrine tumours (NET) is well established for staging and therapy follow-up. The short half-life, increasing costs, and regulatory issues significantly limit the availability of approved imaging agents, such as [68Ga]Ga-DOTA-TATE. Al[18F]F-NOTA-Octreotide provides a similar biodistribution and tumour uptake, can be produced on a large scale and may improve access to precision imaging. Here we prospectively compared the clinical utility of [68Ga]Ga-DOTA-TATE and Al[18F]F-NOTA-Octreotide in the Latin-American population. Our results showed that in patients with stage IV NETs [68Ga]Ga-DOTA-TATE presents higher physiological uptake than Al[18F]F-NOTA-Octreotide in the liver, hypophysis, salivary glands, adrenal glands (all p < 0.001), pancreatic uncinated process, kidneys, and small intestine (all p < 0.05). Nevertheless, despite the lower background uptake of Al[18F]F-NOTA-Octreotide, comparative analysis of tumour-to-liver (TLR) and tumour-to-spleen (TSR) showed no statistically significant difference for lesions in the liver, bone, lymph nodes, and other tissues. Only three discordant lesions in highly-metastases livers were detected by [68Ga]Ga-DOTA-TATE but not by Al[18F]F-NOTA-Octreotide and only one discordant lesion was detected by Al[18F]F-NOTA-Octreotide but not by [68Ga]Ga-DOTA-TATE. Non-inferiority analysis showed that Al[18F]F-NOTA-Octreotide is comparable to [68Ga]Ga-DOTA-TATE. Hence, our results demonstrate that Al[18F]F-NOTA-Octreotide provided excellent image quality, visualized NET lesions with high sensitivity and represents a highly promising, clinical alternative to [68Ga]Ga-DOTA-TATE.
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6
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Epigenetic potentiation of somatostatin-2 by guadecitabine in neuroendocrine neoplasias as a novel method to allow delivery of peptide receptor radiotherapy. Eur J Cancer 2022; 176:110-120. [PMID: 36208569 DOI: 10.1016/j.ejca.2022.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 09/08/2022] [Indexed: 12/15/2022]
Abstract
BACKGROUND Somatostatin receptor-2 (SSTR2) is expressed on cell surface of neuroendocrine neoplasias; its presence is exploited for the delivery of peptide receptor radionuclide therapy (PRRT). Patients with no or low expression of SSTR2 are not candidates for PRRT. SSTR2 promotor undergoes epigenetic modification, known to regulate gene expression. We investigated whether the demethylation agent, guadecitabine, could enhance the expression of SSTR2 in NET models, using radioligand uptake/PET imaging as a biomarker of epigenetic modification. METHODS The effects of guadecitabine on the transcriptional, translational, and functional regulation of SSTR2 both in vitro and in vivo using low (QGP-1) and high (BON-1) methylated neuroendocrine neoplasia models was characterised. Promotor region methylation profiling of clinical samples (n = 61) was undertaken. Safety of combination guadecitabine and PRRT was assessed in vivo. RESULTS Pyrosequencing of cell lines illustrated differential methylation indices - BON: 1 94%, QGP: 1 21%. Following guadecitabine treatment, a dose-dependent increase in SSTR2 in BON-1 at a transcriptional, translational, and functional levels using the SSTR2-directed radioligand, 18F-FET-βAG-TOCA ([18F]-FETO) (150% increase [18F]-FETO uptake, p < 0.05) was observed. In vivo, guadecitabine treatment resulted in a 70% increase in [18F]-FETO uptake in BON-1 tumour models compared models with low baseline percentage methylation (p < 0.05). No additive toxicity was observed with the combination treatment of PRRT and guadecitabine in vivo. Methylation index in clinical samples was 10.5% compared to 5.2% in controls (p = 0.03) and correlated with SSTR2 expression (Wilcoxon rank sign -3.75,p < 0.01). CONCLUSION Guadecitabine increases SSTR2 expression both in vitro and in vivo. The combination of demethylation agents with PRRT warrants further investigation.
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7
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Otaru S, Paulus A, Imlimthan S, Kuurne I, Virtanen H, Liljenbäck H, Tolvanen T, Auchynnikava T, Roivainen A, Helariutta K, Sarparanta M, Airaksinen AJ. Development of [ 18F]AmBF 3 Tetrazine for Radiolabeling of Peptides: Preclinical Evaluation and PET Imaging of [ 18F]AmBF 3-PEG 7-Tyr 3-Octreotide in an AR42J Pancreatic Carcinoma Model. Bioconjug Chem 2022; 33:1393-1404. [PMID: 35709482 PMCID: PMC9305971 DOI: 10.1021/acs.bioconjchem.2c00231] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Radiolabeled peptides have emerged as highly specific agents for targeting receptors expressed in tumors for therapeutic and diagnostic purposes. Peptides developed for positron emission tomography (PET) are typically radiolabeled using prosthetic groups or bifunctional chelators for fast "kit-like" incorporation of the radionuclide into the structure. A novel [18F]alkylammoniomethyltrifluoroborate ([18F]AmBF3) tetrazine (Tz), [18F]AmBF3-Tz, was developed for the [18F]fluorination of trans-cyclooctene (TCO)-modified biomolecules using Tyr3-octreotides (TOCs) as model peptides. [18F]AmBF3-Tz (Am = 15.4 ± 9.2 GBq/μmol, n = 14) was evaluated in healthy mice by ex vivo biodistribution and PET/computed tomography (CT), where the radiolabel in the prosthetic group was found stable in vivo, indicated by the low bone uptake in tibia (0.4 ± 0.1% ID/g, t = 270 min). TCO-TOCs tailored with polyethylene glycol (PEG) linkers were radiolabeled with [18F]AmBF3-Tz, forming two new tracers, [18F]AmBF3-PEG4-TOC (Am = 2.8 ± 1.8 GBq/μmol, n = 3) and [18F]AmBF3-PEG7-TOC (Am of 6.0 ± 3.4 GBq/μmol, n = 13), which were evaluated by cell uptake studies and ex vivo biodistribution in subcutaneous AR42J rat pancreatic carcinoma tumor-bearing nude mice. The tracer demonstrating superior behavior ex vivo, the [18F]AmBF3-PEG7-TOC, was further evaluated with PET/CT, where the tracer provided clear tumor visualization (SUVbaseline = 1.01 ± 0.07, vs SUVblocked = 0.76 ± 0.04) at 25 min post injection. The novel AmBF3-Tz demonstrated that it offers potential as a prosthetic group for rapid radiolabeling of biomolecules in mild conditions using bioorthogonal chemistry.
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Affiliation(s)
- Sofia Otaru
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Andreas Paulus
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Surachet Imlimthan
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Iida Kuurne
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Helena Virtanen
- Turku
PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland
| | - Heidi Liljenbäck
- Turku
PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland
- Turku
Center for Disease Modeling, Institute of Biomedicine, University of Turku, FI-20520 Turku, Finland
| | - Tuula Tolvanen
- Turku
PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland
- Department
of Medical Physics, Turku University Hospital, FI-20521 Turku, Finland
| | - Tatsiana Auchynnikava
- Turku
PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland
- Department
of Chemistry, University of Turku, FI-20014 Turku, Finland
| | - Anne Roivainen
- Turku
PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland
- Turku
Center for Disease Modeling, Institute of Biomedicine, University of Turku, FI-20520 Turku, Finland
| | - Kerttuli Helariutta
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Mirkka Sarparanta
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Anu J. Airaksinen
- Radiochemistry,
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
- Turku
PET Centre, University of Turku, Kiinamyllynkatu 4-8, FI-20520 Turku, Finland
- Department
of Chemistry, University of Turku, FI-20014 Turku, Finland
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8
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Methods to radiolabel somatostatin analogs with [18F]fluoride: current status, challenges, and progress in clinical applications. J Radioanal Nucl Chem 2020. [DOI: 10.1007/s10967-020-07437-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Allott L, Aboagye EO. Chemistry Considerations for the Clinical Translation of Oncology PET Radiopharmaceuticals. Mol Pharm 2020; 17:2245-2259. [DOI: 10.1021/acs.molpharmaceut.0c00328] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Louis Allott
- Comprehensive Cancer Imaging Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, United Kingdom
| | - Eric O. Aboagye
- Comprehensive Cancer Imaging Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, United Kingdom
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10
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Allott L, Dubash S, Aboagye EO. [ 18F]FET-βAG-TOCA: The Design, Evaluation and Clinical Translation of a Fluorinated Octreotide. Cancers (Basel) 2020; 12:cancers12040865. [PMID: 32252406 PMCID: PMC7226534 DOI: 10.3390/cancers12040865] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 01/17/2023] Open
Abstract
The success of Lutathera™ ([177Lu]Lu-DOTA-TATE) in the NETTER-1 clinical trial as a peptide receptor radionuclide therapy (PRRT) for somatostatin receptor expressing (SSTR) neuroendocrine tumours (NET) is likely to increase the demand for patient stratification by positron emission tomography (PET). The current gold standard of gallium-68 radiolabelled somatostatin analogues (e.g., [68Ga]Ga-DOTA-TATE) works effectively, but access is constrained by the limited availability and scalability of gallium-68 radiopharmaceutical production. The aim of this review is three-fold: firstly, we discuss the peptide library design, biological evaluation and clinical translation of [18F]fluoroethyltriazole-βAG-TOCA ([18F]FET-βAG-TOCA), our fluorine-18 radiolabelled octreotide; secondly, to exemplify the potential of the 2-[18F]fluoroethylazide prosthetic group and copper-catalysed azide-alkyne cycloaddition (CuAAC) chemistry in accessing good manufacturing practice (GMP) compatible radiopharmaceuticals; thirdly, we aim to illustrate a framework for the translation of similarly radiolabelled peptides, in which in vivo pharmacokinetics drives candidate selection, supported by robust radiochemistry methodology and a route to GMP production. It is hoped that this review will continue to inspire the development and translation of fluorine-18 radiolabelled peptides into clinical studies for the benefit of patients.
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11
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Sharma R, Wang WM, Yusuf S, Evans J, Ramaswami R, Wernig F, Frilling A, Mauri F, Al-Nahhas A, Aboagye EO, Barwick TD. 68Ga-DOTATATE PET/CT parameters predict response to peptide receptor radionuclide therapy in neuroendocrine tumours. Radiother Oncol 2019; 141:108-115. [PMID: 31542317 DOI: 10.1016/j.radonc.2019.09.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 08/25/2019] [Accepted: 09/02/2019] [Indexed: 12/18/2022]
Abstract
PURPOSE [177Lu]DOTATATE prolongs progression free survival (PFS) in metastatic neuroendocrine tumours (NETs). However, objective response rate is low. This, coupled with long duration of therapy and expense suggest need for better selection. We aim to assess whether baseline [68Ga]DOTATATE-PET/CT parameters, and whether response assessment by PET accurately predicts clinical outcome to [177Lu]DOTATATE. EXPERIMENTAL DESIGN Retrospective study of patients receiving [177Lu]DOTATATE was conducted. Patients were followed 3-monthly until disease progression. Four [68Ga]DOTATATE-PET parameters (single lesion SUVmax, tumour to spleen and liver SUV ratios, and SUVmax-av using up to five target lesions in multiple organ sites) were determined at baseline and follow-up. The association between these PET parameters either at baseline, or any changes following treatment, and PET response criteria (PERCIST and modified PERCIST) to predict PFS were determined. Patients were followed 3-monthly until disease progression. Response was determined using RECIST 1.1. Baseline SSTR2 expression was assessed and compared with PET parameters. RESULTS 55 patients with metastatic NETs were identified predominantly small bowel (N = 18) and pancreatic (N = 8) in origin. 16 were low grade, 15 intermediate and 3 high grade. Response to PRRT (N = 47): partial response (PR) 28%, stable disease (SD) 60% progressive disease (PD) 13%. Response to PRRT predicted PFS: PR 71.8 months (95%CI: not achieved), SD 29.1 months (95%CI: 15.2-43.1), and PD 9.7 months (95%CI: 0-21.02). Baseline, single lesion SUVmax predicted both response and PFS with SUV cut-off of 13.0 giving high sensitivity and specificity. Tumoural SUVmax correlated with SSTR2 expression, Spearman's rho - 0.69, p < 0.01. CONCLUSIONS Baseline single lesion SUVmax and SUVmax-av predicts response to [177Lu]DOTATATE. Objective response following PRRT defines a subset of patients with markedly improved PFSBaseline SUVmax 13.0 defines a threshold below which patients have poor response to PRRT and worse PFS. SUV threshold analysis should be taken forward into prospective studies.
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Affiliation(s)
- Rohini Sharma
- Department of Surgery and Cancer, Imperial College London, UK.
| | - Wai Meng Wang
- Department of Surgery and Cancer, Imperial College London, UK
| | - Siraj Yusuf
- Department of Nuclear Medicine, Imperial College NHS Trust, UK
| | - Joanne Evans
- Department of Surgery and Cancer, Imperial College London, UK
| | - Ramya Ramaswami
- Department of Surgery and Cancer, Imperial College London, UK
| | - Florian Wernig
- Department of Endocrinology, Imperial College London, UK
| | - Andrea Frilling
- Department of Surgery and Cancer, Imperial College London, UK
| | - Francesco Mauri
- Department of Surgery and Cancer, Imperial College London, UK
| | - Adil Al-Nahhas
- Department of Nuclear Medicine, Imperial College NHS Trust, UK
| | - Eric O Aboagye
- Department of Surgery and Cancer, Imperial College London, UK
| | - Tara D Barwick
- Department of Surgery and Cancer, Imperial College London, UK; Department of Nuclear Medicine, Imperial College NHS Trust, UK
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Pretargeted Nuclear Imaging and Radioimmunotherapy Based on the Inverse Electron-Demand Diels-Alder Reaction and Key Factors in the Pretargeted Synthetic Design. CONTRAST MEDIA & MOLECULAR IMAGING 2019; 2019:9182476. [PMID: 31531006 PMCID: PMC6732628 DOI: 10.1155/2019/9182476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 06/20/2019] [Accepted: 08/01/2019] [Indexed: 11/18/2022]
Abstract
The exceptional speed and biorthogonality of the inverse electron-demand Diels-Alder (IEDDA) click chemistry between 1,2,4,5-tetrazines and strained alkene dienophiles have made it promising in the realm of pretargeted imaging and therapy. During the past 10 years, the IEDDA-pretargeted strategies have been tested and have already proven capable of producing images with high tumor-to-background ratios and improving therapeutic effect. This review will focus on recent applications of click chemistry ligations in the pretargeted imaging studies of single photon emission computed tomography (SPECT), positron emission tomography (PET), and pretargeted radioimmunotherapy investigations. Additionally, the influence factors of stability, reactivity, and pharmacokinetic properties of TCO tag modified immunoconjugates and radiolabeled Tz derivatives were also summarized in this article, which should be carefully considered in the system design in order to develop a successful pretargeted methodology. We hope that this review will not only equip readers with a knowledge of pretargeted methodology based on IEDDA click chemistry but also inspire synthetic chemists and radiochemists to develop pretargeted radiopharmaceutical components in a more innovative way with various influence factors considered.
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13
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Manufacturing and preclinical validation of CAR T cells targeting ICAM-1 for advanced thyroid cancer therapy. Sci Rep 2019; 9:10634. [PMID: 31337787 PMCID: PMC6650612 DOI: 10.1038/s41598-019-46938-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/28/2019] [Indexed: 12/13/2022] Open
Abstract
While the majority of thyroid cancer patients are easily treatable, those with anaplastic or poorly differentiated recurrent thyroid carcinomas have a very poor prognosis with a median survival of less than a year. Previously, we have shown a significant correlation between ICAM-1 overexpression and malignancy in thyroid cancer, and have pioneered the use of ICAM-1 targeted CAR T cells as a novel treatment modality. For clinical translation of this novel modality, we designed CAR T cells possessing micromolar rather than nanomolar affinity to ICAM-1 to avoid cytotoxicity in normal cells with basal levels of ICAM-1 expression. Herein, we report the automated process of CAR T cell manufacturing with CliniMACS Prodigy (Miltenyi Biotec) using cryopreserved peripheral blood leukocytes from apheresis collections. Using Prodigy, thawed leukopak cells were enriched for CD4+ and CD8+ T cells, subjected to double transduction using lentiviral vector, and expanded in culture for a total of 10 days with a final yield of 2–4 × 109 cells. The resulting CAR T cells were formulated for cryopreservation to be used directly for infusion into patients after thawing with no further processing. We examined cross-reactivity of CAR T cells toward both human and murine ICAM-1 and ICAM-1 expression in human and mouse tissues to demonstrate that both efficacy and on-target, off-tumor toxicity can be studied in our preclinical model. Selective anti-tumor activity in the absence of toxicity provides proof-of-concept that micromolar affinity tuned CAR T cells can be used to target tumors expressing high levels of antigen while avoiding normal tissues expressing basal levels of the same antigen. These studies support the initiation of a phase I study to evaluate the safety and potential efficacy of micromolar affinity tuned CAR T cells against newly diagnosed anaplastic and refractory or recurrent thyroid cancers.
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Clinical Application of 18F-AlF-NOTA-Octreotide PET/CT in Combination With 18F-FDG PET/CT for Imaging Neuroendocrine Neoplasms. Clin Nucl Med 2019; 44:452-458. [DOI: 10.1097/rlu.0000000000002578] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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15
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Ferris T, Carroll L, Mease RC, Spivey AC, Aboagye EO. Iodination of terminal alkynes using KI/CuSO 4 - A facile method with potential for radio-iodination. Tetrahedron Lett 2019; 60:936-939. [PMID: 31217642 PMCID: PMC6562058 DOI: 10.1016/j.tetlet.2019.02.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 02/22/2019] [Indexed: 12/19/2022]
Abstract
Herein, we report an efficient new method for the iodination of terminal alkynes using stoichiometric KI and CuSO4 in a mix of acetonitrile and acetate buffer that holds promise for further development into a method for radio-iodination.
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Affiliation(s)
- Trevor Ferris
- Comprehensive Cancer Imaging Centre, Department of Surgery & Cancer, Hammersmith Campus, Imperial College, London W12 0NN, UK
| | - Laurence Carroll
- Comprehensive Cancer Imaging Centre, Department of Surgery & Cancer, Hammersmith Campus, Imperial College, London W12 0NN, UK
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA
| | - Ronnie C. Mease
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA
| | - Alan C. Spivey
- Department of Chemistry, Molecular Sciences Research Hub, 80 Wood Lane, White City Campus, Imperial College, London W12 0BZ, UK
| | - Eric O. Aboagye
- Comprehensive Cancer Imaging Centre, Department of Surgery & Cancer, Hammersmith Campus, Imperial College, London W12 0NN, UK
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16
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Waldmann CM, Stuparu AD, van Dam RM, Slavik R. The Search for an Alternative to [ 68Ga]Ga-DOTA-TATE in Neuroendocrine Tumor Theranostics: Current State of 18F-labeled Somatostatin Analog Development. Theranostics 2019; 9:1336-1347. [PMID: 30867834 PMCID: PMC6401503 DOI: 10.7150/thno.31806] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 01/14/2019] [Indexed: 02/06/2023] Open
Abstract
The trend to inform personalized molecular radiotherapy with molecular imaging diagnostics, a concept referred to as theranostics, has transformed the field of nuclear medicine in recent years. The development of theranostic pairs comprising somatostatin receptor (SSTR)-targeting nuclear imaging probes and therapeutic agents for the treatment of patients with neuroendocrine tumors (NETs) has been a driving force behind this development. With the Neuroendocrine Tumor Therapy (NETTER-1) phase 3 trial reporting encouraging results in the treatment of well-differentiated, metastatic midgut NETs, peptide radioligand therapy (RLT) with the 177Lu-labeled somatostatin analog (SSA) [177Lu]Lu-DOTA-TATE is now anticipated to become the standard of care. On the diagnostics side, the field is currently dominated by 68Ga-labeled SSAs for the molecular imaging of NETs with positron emission tomography-computed tomography (PET/CT). PET/CT imaging with SSAs such as [68Ga]Ga-DOTA-TATE, [68Ga]Ga-DOTA-TOC, and [68Ga]Ga-DOTA-NOC allows for NET staging with high accuracy and is used to qualify patients for RLT. Driven by the demand for PET/CT imaging of NETs, a commercial kit for the production of [68Ga]Ga-DOTA-TATE (NETSPOT) was approved by the U.S. Food and Drug Administration (FDA). The synthesis of 68Ga-labeled SSAs from a 68Ge/68Ga-generator is straightforward and allows for a decentralized production, but there are economic and logistic difficulties associated with these approaches that warrant the search for a viable, generator-independent alternative. The clinical introduction of an 18F-labeled SSTR-imaging probe can help mitigate the shortcomings of the generator-based synthesis approach, but despite extensive research efforts, none of the proposed 18F-labeled SSAs has been translated past prospective first-in-humans studies so far. Here, we review the current state of probe-development from a translational viewpoint and make a case for a clinically viable, 18F-labeled alternative to the current standard [68Ga]Ga-DOTA-TATE.
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Affiliation(s)
- Christopher M. Waldmann
- Ahmanson Translational Imaging Division, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Andreea D. Stuparu
- Ahmanson Translational Imaging Division, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - R. Michael van Dam
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Roger Slavik
- Ahmanson Translational Imaging Division, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
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17
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Allott L, Barnes C, Brickute D, Aboagye EO. An improved automated radiosynthesis of [18F]FET-βAG-TOCA. REACT CHEM ENG 2019. [DOI: 10.1039/c8re00279g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The fluorine-18 radiolabelled octreotide [18F]FET-βAG-TOCA has been evaluated clinically for positron emission tomography (PET) imaging of neuroendocrine tumours (NETs). An improved automated radiosynthesis using “click” chemistry (CuAAC) and the 2-[18F]fluoroethylazide prosthetic group is reported and with minimal adaptation, may be used for radiolabelling other peptides.
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Affiliation(s)
- Louis Allott
- Comprehensive Cancer Imaging Centre
- Imperial College London
- Hammersmith Hospital
- London
- UK
| | - Chris Barnes
- Comprehensive Cancer Imaging Centre
- Imperial College London
- Hammersmith Hospital
- London
- UK
| | - Diana Brickute
- Comprehensive Cancer Imaging Centre
- Imperial College London
- Hammersmith Hospital
- London
- UK
| | - Eric O. Aboagye
- Comprehensive Cancer Imaging Centre
- Imperial College London
- Hammersmith Hospital
- London
- UK
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18
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Liu F, Liu T, Xu X, Guo X, Li N, Xiong C, Li C, Zhu H, Yang Z. Design, Synthesis, and Biological Evaluation of 68Ga-DOTA-PA1 for Lung Cancer: A Novel PET Tracer for Multiple Somatostatin Receptor Imaging. Mol Pharm 2018; 15:619-628. [PMID: 29278911 DOI: 10.1021/acs.molpharmaceut.7b00963] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Most of the radiolabeled somatostatin analogues (SSAs) are specific for subtype somatostatin receptor 2 (SSTR2). Lack of ligands targeting other subtypes of SSTRs, especially SSTR1, SSTR3, and SSTR5, limited their applications in tumors of low SSTR2 expression, including lung tumor. In this study, we aimed to design and synthesize a positron emission tomography (PET) radiotracer targeting multi-subtypes of SSTRs for PET imaging. PA1 peptide and its conjugate with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelator or fluorescein isothiocyanate (FITC) at the N-terminal of the lysine position were synthesized. 68Ga was chelated to DOTA-PA1 to obtain 68Ga-DOTA-PA1 radiotracer. The stability, lipophilicity, binding affinity, and binding specificity of 68Ga-DOTA-PA1 and FITC-PA1 were evaluated by various in vitro experiments. Micro-PET imaging of 68Ga-DOTA-PA1 was performed in nude mice bearing A549 lung adenocarcinoma, as compared with 68Ga-DOTA-(Tyr3)-octreotate (68Ga-DOTA-TATE). Histological analysis of SSTR expression in A549 tumor tissues and human tumor tissues was conducted using immunofluorescence staining and immunohistochemical assay. 68Ga-DOTA-PA1 had high radiochemical yield and radiochemical purity of over 95% and 99%, respectively. The radiotracer was stable in vitro in different buffers over a 2 h incubation period. Cell uptake of 68Ga-DOTA-PA1 was 1.31-, 1.33-, and 1.90-fold that of 68Ga-DOTA-TATE, which has high binding affinity only for SSTR2, after 2 h incubation in H520, PG, and A549 lung cancer cell lines, respectively. Micro-PET images of 68Ga-DOTA-PA1 showed that the PET imaging signal correlated with the total expression of SSTRs, instead of SSTR2 only, which was measured by Western blotting and immunofluorescence analysis in mice bearing A549 tumors. In summary, a novel PET radiotracer, 68Ga-DOTA-PA1, targeting multi-subtypes of SSTRs, was successfully synthesized and was confirmed to be useful for PET imaging. It may have potential as a noninvasive PET radiotracer for imaging SSTR-positive tumors.
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Affiliation(s)
- Fei Liu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Teli Liu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Xiaoxia Xu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Xiaoyi Guo
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Nan Li
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Chiyi Xiong
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center , Houston, Texas 77030, United States
| | - Chun Li
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center , Houston, Texas 77030, United States
| | - Hua Zhu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
| | - Zhi Yang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute , Beijing 100142, P. R. China
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19
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Meyer JP, Adumeau P, Lewis JS, Zeglis BM. Click Chemistry and Radiochemistry: The First 10 Years. Bioconjug Chem 2016; 27:2791-2807. [PMID: 27787983 DOI: 10.1021/acs.bioconjchem.6b00561] [Citation(s) in RCA: 166] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The advent of click chemistry has had a profound influence on almost all branches of chemical science. This is particularly true of radiochemistry and the synthesis of agents for positron emission tomography (PET), single photon emission computed tomography (SPECT), and targeted radiotherapy. The selectivity, ease, rapidity, and modularity of click ligations make them nearly ideally suited for the construction of radiotracers, a process that often involves working with biomolecules in aqueous conditions with inexorably decaying radioisotopes. In the following pages, our goal is to provide a broad overview of the first 10 years of research at the intersection of click chemistry and radiochemistry. The discussion will focus on four areas that we believe underscore the critical advantages provided by click chemistry: (i) the use of prosthetic groups for radiolabeling reactions, (ii) the creation of coordination scaffolds for radiometals, (iii) the site-specific radiolabeling of proteins and peptides, and (iv) the development of strategies for in vivo pretargeting. Particular emphasis will be placed on the four most prevalent click reactions-the Cu-catalyzed azide-alkyne cycloaddition (CuAAC), the strain-promoted azide-alkyne cycloaddition (SPAAC), the inverse electron demand Diels-Alder reaction (IEDDA), and the Staudinger ligation-although less well-known click ligations will be discussed as well. Ultimately, it is our hope that this review will not only serve to educate readers but will also act as a springboard, inspiring synthetic chemists and radiochemists alike to harness click chemistry in even more innovative and ambitious ways as we embark upon the second decade of this fruitful collaboration.
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Affiliation(s)
| | - Pierre Adumeau
- Department of Chemistry, Hunter College of the City University of New York , 413 East 69th Street, New York, New York 10028, United States
| | - Jason S Lewis
- Department of Radiology, Weill Cornell Medical College , 520 East 70th Street, New York, New York 10065, United States
| | - Brian M Zeglis
- Department of Chemistry, Hunter College of the City University of New York , 413 East 69th Street, New York, New York 10028, United States.,Department of Radiology, Weill Cornell Medical College , 520 East 70th Street, New York, New York 10065, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York , 365 5th Avenue, New York, New York 10016, United States
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20
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Maschauer S, Heilmann M, Wängler C, Schirrmacher R, Prante O. Radiosynthesis and Preclinical Evaluation of 18F-Fluoroglycosylated Octreotate for Somatostatin Receptor Imaging. Bioconjug Chem 2016; 27:2707-2714. [PMID: 27715017 DOI: 10.1021/acs.bioconjchem.6b00472] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Short synthetic octapeptide analogs derived from the native somatostatin peptides SST-14 and SST-28, namely, octreotate (TATE) or octreotide (TOC), bind with high affinity to somatostatin receptors (sstr), mainly to subtypes 2 and 5, which are expressed in high density on neuroendocrine tumors (NET). Therefore, radiolabeled TATE or TOC derivatives represent highly valuable imaging probes for NET diagnosis by positron emission tomography (PET). The aim of our study was the development of an 18F-labeled octreotate analog as an alternative radiotracer for the clinically established 68Ga-DOTATOC and 68Ga-DOTATATE. We applied our previously developed method based on copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) to the radiosynthesis of 18F-fluoroglycosylated TATE ([18F]FGlc-TATE). [18F]FGlc-TATE was obtained in high yields of 19-22% (non-decay-corrected, referred to [18F]fluoride) and in high specific activities of 32-106 GBq/μmol. [18F]FGlc-TATE showed high affinity to sstr expressed on AR42J cells (IC50 = 4.2 nM) with fast and high internalization, and a beneficial logD7.4 of -1.8. In AR42J tumor bearing nude mice, [18F]FGlc-TATE showed high and specific tumor uptake of 5.6%ID/g at 60 min post-injection, as determined by blocking experiments using octreotide, and fast clearance from other organs, resulting in excellent tumor-to-blood ratios increasing from 9 to 17 from 30 to 60 min post-injection. Small animal PET studies revealed high uptake of [18F]FGlc-TATE in the tumor which could be blocked with octreotide by >99%. Overall, [18F]FGlc-TATE revealed excellent in vitro and in vivo properties and is therefore a viable alternative 18F-labeled radiopeptide for imaging somatostatin receptor-positive tumors by PET.
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Affiliation(s)
- Simone Maschauer
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University Erlangen-Nürnberg (FAU) , Schwabachanlage 6, 91054 Erlangen, Germany
| | - Marcus Heilmann
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University Erlangen-Nürnberg (FAU) , Schwabachanlage 6, 91054 Erlangen, Germany
| | - Carmen Wängler
- Biomedical Chemistry, Department of Clinical Radiology and Nuclear Medicine Medical Faculty Mannheim of Heidelberg University , Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Ralf Schirrmacher
- Medical Isotope Cyclotron Facility, Department of Oncology, University of Alberta , 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Olaf Prante
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University Erlangen-Nürnberg (FAU) , Schwabachanlage 6, 91054 Erlangen, Germany
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21
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Charron CL, Farnsworth AL, Roselt PD, Hicks RJ, Hutton CA. Recent developments in radiolabelled peptides for PET imaging of cancer. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.07.083] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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22
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Dubash SR, Keat N, Mapelli P, Twyman F, Carroll L, Kozlowski K, Al-Nahhas A, Saleem A, Huiban M, Janisch R, Frilling A, Sharma R, Aboagye EO. Clinical Translation of a Click-Labeled 18F-Octreotate Radioligand for Imaging Neuroendocrine Tumors. J Nucl Med 2016; 57:1207-13. [PMID: 27173162 DOI: 10.2967/jnumed.115.169532] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/29/2016] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED We conducted the first-in-human study of (18)F-fluoroethyl triazole [Tyr(3)] octreotate ((18)F-FET-βAG-TOCA) in patients with neuroendocrine tumors (NETs) to evaluate biodistribution, dosimetry, and safety. Despite advances in clinical imaging, detection and quantification of NET activity remains a challenge, with no universally accepted imaging standard. METHODS Nine patients were enrolled. Eight patients had sporadic NETs, and 1 had multiple endocrine neoplasia type 1 syndrome. Patients received 137-163 MBq (mean ± SD, 155.7 ± 8 MBq) of (18)F-FET-βAG-TOCA. Safety data were obtained during and 24 h after radioligand administration. Patients underwent detailed whole-body PET/CT multibed scanning over 4 h with sampling of venous bloods for radioactivity and radioactive metabolite quantification. Regions of interest were defined to derive individual and mean organ residence times; effective dose was calculated with OLINDA 1.1. RESULTS All patients tolerated (18)F-FET-βAG-TOCA with no adverse events. Over 60% parent radioligand was present in plasma at 60 min. High tumor (primary and metastases)-to-background contrast images were observed. Physiologic distribution was seen in the pituitary, salivary glands, thyroid, and spleen, with low background distribution in the liver, an organ in which metastases commonly occur. The organs receiving highest absorbed dose were the gallbladder, spleen, stomach, liver, kidneys, and bladder. The calculated effective dose over all subjects (mean ± SD) was 0.029 ± 0.004 mSv/MBq. CONCLUSION The favorable safety, imaging, and dosimetric profile makes (18)F-FET-βAG-TOCA a promising candidate radioligand for staging and management of NETs. Clinical studies in an expanded cohort are ongoing to clinically qualify this agent.
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Affiliation(s)
- Suraiya R Dubash
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Nicholas Keat
- Imanova Centre for Imaging Sciences, London, United Kingdom
| | - Paola Mapelli
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Frazer Twyman
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Laurence Carroll
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Kasia Kozlowski
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Adil Al-Nahhas
- Department of Radiology/Nuclear Medicine, Imperial College Healthcare NHS Trust, London, United Kingdom; and
| | - Azeem Saleem
- Imanova Centre for Imaging Sciences, London, United Kingdom
| | - Mickael Huiban
- Imanova Centre for Imaging Sciences, London, United Kingdom
| | - Ryan Janisch
- Imanova Centre for Imaging Sciences, London, United Kingdom
| | - Andrea Frilling
- Department of Surgery, Imperial College Healthcare NHS Trust, London, United Kingdom
| | - Rohini Sharma
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Eric O Aboagye
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
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Litau S, Niedermoser S, Vogler N, Roscher M, Schirrmacher R, Fricker G, Wängler B, Wängler C. Next Generation of SiFAlin-Based TATE Derivatives for PET Imaging of SSTR-Positive Tumors: Influence of Molecular Design on In Vitro SSTR Binding and In Vivo Pharmacokinetics. Bioconjug Chem 2015; 26:2350-9. [PMID: 26420336 DOI: 10.1021/acs.bioconjchem.5b00510] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Silicon-Fluoride-Acceptor (SiFA)-(18)F-labeling strategy has been shown before to enable the straightforward and efficient (18)F-labeling of complex biologically active substances such as proteins and peptides. Especially in the case of peptides, the radiolabeling proceeds kit-like in short reaction times and without the need of complex product workup. SiFA-derivatized, (18)F-labeled Tyr(3)-octreotate (TATE) derivatives demonstrated, besides strong somatostatin receptor (SSTR) binding, favorable in vivo pharmacokinetics as well as excellent tumor visualization by PET imaging. In this study, we intended to determine the influence of the underlying molecular design and used molecular scaffolds of SiFAlin-TATE derivatives on SSTR binding as well as on the in vivo pharmacokinetics of the resulting (18)F-labeled peptides. For this purpose, new SiFAlin-(Asp)n-PEG1-TATE analogs (where n = 1-4) were synthesized, efficiently radiolabeled with (18)F in a kit-like manner and obtained in radiochemical yields of 70-80%, radiochemical purities of ≥97%, and nonoptimized specific activities of 20.1-45.2 GBq/μmol within 20-25 min starting from 0.7-1.5 GBq of (18)F. In the following, the radiotracer's lipophilicities and stabilities in human serum were determined. Furthermore, the SSTR-specific binding affinities were evaluated by a competitive displacement assay on SSTR-positive AR42J cells. The obtained in vitro results support the assumption that aspartic acids are able to considerably increase the radiotracer's hydrophilicity and that their number does not affect the SSTR binding potential of the TATE derivatives. The most promising tracer (18)F-SiFAlin-Asp3-PEG1-TATE [(18)F]6 (LogD = -1.23 ± 0.03, IC50 = 20.7 ± 2.5 nM) was further evaluated in vivo in AR42J tumor-bearing nude mice via PET/CT imaging against the clinical gold standard (68)Ga-DOTATATE as well as the previously developed SiFAlin-TATE derivative [(18)F]3. The results of these evaluations showed that [(18)F]6-although showing very similar chemical and in vitro properties to [(18)F]3-exhibits not only a slowed renal clearance compared to [(18)F]3, but also a higher absolute tumor uptake compared to (68)Ga-DOTATATE, and furthermore enables excellent tumor visualization with high image resolution. These results emphasize the importance of systematic study of the influence of molecular design and applied structure elements of peptidic radiotracers, as these may considerably influence in vivo pharmacokinetics while not affecting other parameters such as radiochemistry, lipophilicity, serum stability, or receptor binding potential.
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Affiliation(s)
| | | | | | | | - R Schirrmacher
- Department of Oncology, Division of Oncological Imaging, University of Alberta , Edmonton T6G 2R3, Canada
| | - G Fricker
- Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg , 69117 Heidelberg, Germany
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Zeglis BM, Brand C, Abdel-Atti D, Carnazza KE, Cook BE, Carlin S, Reiner T, Lewis JS. Optimization of a Pretargeted Strategy for the PET Imaging of Colorectal Carcinoma via the Modulation of Radioligand Pharmacokinetics. Mol Pharm 2015; 12:3575-87. [PMID: 26287993 PMCID: PMC4696756 DOI: 10.1021/acs.molpharmaceut.5b00294] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pretargeted PET imaging has emerged as an effective strategy for merging the exquisite selectivity of antibody-based targeting vectors with the rapid pharmacokinetics of radiolabeled small molecules. We previously reported the development of a strategy for the pretargeted PET imaging of colorectal cancer based on the bioorthogonal inverse electron demand Diels-Alder reaction between a tetrazine-bearing radioligand and a transcyclooctene-modified huA33 immunoconjugate. Although this method effectively delineated tumor tissue, its clinical potential was limited by the somewhat sluggish clearance of the radioligand through the gastrointestinal tract. Herein, we report the development and in vivo validation of a pretargeted strategy for the PET imaging of colorectal carcinoma with dramatically improved pharmacokinetics. Two novel tetrazine constructs, Tz-PEG7-NOTA and Tz-SarAr, were synthesized, characterized, and radiolabeled with (64)Cu in high yield (>90%) and radiochemical purity (>99%). PET imaging and biodistribution experiments in healthy mice revealed that although (64)Cu-Tz-PEG7-NOTA is cleared via both the gastrointestinal and urinary tracts, (64)Cu-Tz-SarAr is rapidly excreted by the renal system alone. On this basis, (64)Cu-Tz-SarAr was selected for further in vivo evaluation. To this end, mice bearing A33 antigen-expressing SW1222 human colorectal carcinoma xenografts were administered huA33-TCO, and the immunoconjugate was given 24 h to accumulate at the tumor and clear from the blood, after which (64)Cu-Tz-SarAr was administered via intravenous tail vein injection. PET imaging and biodistribution experiments revealed specific uptake of the radiotracer in the tumor at early time points (5.6 ± 0.7 %ID/g at 1 h p.i.), high tumor-to-background activity ratios, and rapid elimination of unclicked radioligand. Importantly, experiments with longer antibody accumulation intervals (48 and 120 h) yielded slight decreases in tumoral uptake but also concomitant increases in tumor-to-blood activity concentration ratios. This new strategy offers dosimetric benefits as well, yielding a total effective dose of 0.041 rem/mCi, far below the doses produced by directly labeled (64)Cu-NOTA-huA33 (0.133 rem/mCi) and (89)Zr-DFO-huA33 (1.54 rem/mCi). Ultimately, this pretargeted PET imaging strategy boasts a dramatically improved pharmacokinetic profile compared to our first generation system and is capable of clearly delineating tumor tissue with high image contrast at only a fraction of the radiation dose created by directly labeled radioimmunoconjugates.
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Affiliation(s)
- Brian M. Zeglis
- Department of Chemistry and Biochemistry, Hunter College and the Graduate Center of the City University of New York, New York, New York 10021, United States
| | - Christian Brand
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Dalya Abdel-Atti
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Kathryn E. Carnazza
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Brendon E. Cook
- Department of Chemistry and Biochemistry, Hunter College and the Graduate Center of the City University of New York, New York, New York 10021, United States
| | - Sean Carlin
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Thomas Reiner
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
| | - Jason S. Lewis
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
- Program in Molecular Pharmacology and Chemistry, Memorial Sloan Kettering Cancer Center, New York, New York 10065, United States
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25
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Amouroux G, Pan J, Jenni S, Zhang C, Zhang Z, Hundal-Jabal N, Colpo N, Liu Z, Bénard F, Lin KS. Imaging Bradykinin B1 Receptor with 68Ga-Labeled [des-Arg10]Kallidin Derivatives: Effect of the Linker on Biodistribution and Tumor Uptake. Mol Pharm 2015; 12:2879-88. [DOI: 10.1021/acs.molpharmaceut.5b00070] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Guillaume Amouroux
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Jinhe Pan
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Silvia Jenni
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Chengcheng Zhang
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Zhengxing Zhang
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Navjit Hundal-Jabal
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Nadine Colpo
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Zhibo Liu
- Chemistry
Department, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - François Bénard
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
- Department
of Radiology, University of British Columbia, Vancouver, BC V5Z 4E3, Canada
| | - Kuo-Shyan Lin
- Department
of Molecular Oncology, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
- Department
of Radiology, University of British Columbia, Vancouver, BC V5Z 4E3, Canada
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26
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Li G, Low PS. Synthesis and evaluation of a ligand targeting the somatostatin-2 receptor for drug delivery to neuroendocrine cancers. Bioorg Med Chem Lett 2015; 25:1792-1798. [PMID: 25791453 DOI: 10.1016/j.bmcl.2015.02.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 02/11/2015] [Accepted: 02/16/2015] [Indexed: 11/16/2022]
Abstract
Over-expression of the somatostatin-2 (SST2) receptor on plasma membranes of neuroendocrine cancer cells renders it attractive for use in targeting both imaging and therapeutic agents to neuroendocrine tumors. Peptide analogs of somatostatin have dominated this approach to date, however, many peptide analogs are either unstable in vivo or exhibit unwanted non-specific uptake in the liver and kidneys. The purpose of this Letter is to describe the preparation and evaluation of a non-peptide SST2 agonist for use in targeting drugs to neuroendocrine cancers. A non-peptide ligand for the SST2 receptor was identified from the literature as a candidate for development of targeted pharmaceuticals for neuroendocrine tumors, based on its SST2 binding affinity and selectivity for SST2 over other somatostatin receptors. It also offered a multiplicity of possible conjugation sites. Rhodamine conjugates in two positions were used for optical imaging and two compounds were internalized in an SST2 receptor transduced cell line (C6-SST2) via SST2 receptor-mediated endocytosis. Radionuclide conjugates were prepared for in vivo imaging and biodistribution studies in mice. The in vitro binding affinity of (99m)Tc conjugates ranged from a Kd of 37-494. Of these, one (99m)Tc conjugate was selected and dosed by IV injection into mice bearing C6-SST2 tumor xenografts. The highest uptake was into tumor, intestine and skin four hours after IV injection. Competition studies with octreotide, a synthetic peptide and SST2 agonist, confirmed that uptake was SST2 receptor mediated. While relatively high uptake in intestine, liver, kidneys and skin discouraged further development of the conjugate for delivery of chemotherapeutic agents, the conjugate may still be worthy of further development for neuroendocrine tumor imaging.
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Affiliation(s)
- Guo Li
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, United States
| | - Philip S Low
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907-2084, United States.
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27
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Liu Z, Pourghiasian M, Bénard F, Pan J, Lin KS, Perrin DM. Preclinical Evaluation of a High-Affinity 18F-Trifluoroborate Octreotate Derivative for Somatostatin Receptor Imaging. J Nucl Med 2014; 55:1499-505. [DOI: 10.2967/jnumed.114.137836] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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28
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Zlatopolskiy BD, Krapf P, Richarz R, Frauendorf H, Mottaghy FM, Neumaier B. Synthesis of ¹⁸F-labelled β-lactams by using the Kinugasa reaction. Chemistry 2014; 20:4697-703. [PMID: 24615842 DOI: 10.1002/chem.201304056] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 01/13/2014] [Indexed: 11/10/2022]
Abstract
Owing to their broad spectrum of biological activities and low toxicity, β-lactams are attractive lead structures for the design of novel molecular probes. However, the synthesis of positron emission tomography (PET)-isotope-labelled β-lactams has not yet been reported. Herein, we describe the simple preparation of radiofluorinated β-lactams by using the fast Kinugasa reaction between (18)F-labelled nitrone [(18)F]-1 and alkynes of different reactivity. Additionally, (18)F-labelled fused β-lactams were obtained through the reaction of a cyclic nitrone 7 with radiofluorinated alkynes [(18)F]-6 a,b. Radiochemical yields of the Kinugasa reaction products could be significantly increased by the use of different Cu(I) ligands, which additionally allowed a reduction in the amount of precursor and/or reaction time. Model radiofluorinated β-lactam-peptide and protein conjugates ([(18)F]-10 and (18)F-labelled BSA conjugate) were efficiently obtained in high yield under mild conditions (aq. MeCN, ambient temperature) within a short reaction time, demonstrating the suitability of the developed method for radiolabelling of sensitive molecules such as biopolymers.
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Affiliation(s)
- Boris D Zlatopolskiy
- Institute of Radiochemistry and Experimental Molecular Imaging, University Clinic Cologne, Kerpener Strasse 62, 50937 Cologne (Germany), Fax: (+49) 221-478-86851; Max Planck Institute of Neurological Research, Gleueler Strasse 50, 50931 Cologne (Germany); Clinic of Nuclear Medicine, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen (Germany)
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29
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Theodoropoulou M, Stalla GK. Somatostatin receptors: from signaling to clinical practice. Front Neuroendocrinol 2013; 34:228-52. [PMID: 23872332 DOI: 10.1016/j.yfrne.2013.07.005] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/13/2013] [Accepted: 07/12/2013] [Indexed: 02/08/2023]
Abstract
Somatostatin is a peptide with a potent and broad antisecretory action, which makes it an invaluable drug target for the pharmacological management of pituitary adenomas and neuroendocrine tumors. Somatostatin receptors (SSTR1, 2A and B, 3, 4 and 5) belong to the G protein coupled receptor family and have a wide expression pattern in both normal tissues and solid tumors. Investigating the function of each SSTR in several tumor types has provided a wealth of information about the common but also distinct signaling cascades that suppress tumor cell proliferation, survival and angiogenesis. This provided the rationale for developing multireceptor-targeted somatostatin analogs and combination therapies with signaling-targeted agents such as inhibitors of the mammalian (or mechanistic) target of rapamycin (mTOR). The ability of SSTR to internalize and the development of rabiolabeled somatostatin analogs have improved the diagnosis and treatment of neuroendocrine tumors.
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Affiliation(s)
- Marily Theodoropoulou
- Department of Endocrinology, Max Planck Institute of Psychiatry, Kraepelinstrasse 10, 80804 Munich, Germany.
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30
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Abstract
Targeted agents are increasingly used for treating cancer and other diseases, but patients may need to be carefully selected to maximize the potential for therapeutic benefit. One way to select patients is to bind an imaging radionuclide to a targeting agent of interest, so that its uptake in specific sites of disease can be visualized by positron-emission tomography (PET) or single-photon emission computed tomography.18F is the most commonly used radionuclide for PET imaging. Its half-life of approximately 2 h is suited for same-day imaging of many compounds that clear quickly from the body to allow visualization of uptake in the intended target. A significant impediment to its use, however, is the challenging coupling of 18F to a carbon atom of the targeting agent. Because fluorine binds to aluminum, we developed a procedure where the Al18F complex could be captured by a chelate, thereby greatly simplifying the way that imaging agents can be fluorinated for PET imaging. This article reviews our experience with this technology.
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Inkster J, Lin KS, Ait-Mohand S, Gosselin S, Bénard F, Guérin B, Pourghiasian M, Ruth T, Schaffer P, Storr T. 2-Fluoropyridine prosthetic compounds for the 18F labeling of bombesin analogues. Bioorg Med Chem Lett 2013; 23:3920-6. [PMID: 23683595 DOI: 10.1016/j.bmcl.2013.04.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/12/2013] [Accepted: 04/22/2013] [Indexed: 12/28/2022]
Abstract
Acetylene-bearing 2-[(18)F]fluoropyridines [(18)F]FPy5yne and PEG-[(18)F]FPyKYNE were prepared via efficient nucleophilic heteroaromatic [(18)F]fluorination of their corresponding 2-trimethylammoniumpyrdinyl precursors. The prosthetic groups were conjugated to azide- and PEG3-modified bombesin(6-14) analogues via copper-catalyzed azide-alkyne cycloaddition couplings to yield mono- and di-mini-PEGylated ligands for PET imaging of the gastrin- releasing peptide receptor. The PEG3- and PEG2/PEG3-bearing (18)F peptides showed decreased lipophilicity relative to an analogous non-mini-PEGylated (18)F peptide. Assessment of water-soluble peptide pharmacokinetics and tumour-targeting capabilities in a mouse model of prostate cancer is currently underway.
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Affiliation(s)
- James Inkster
- TRIUMF, Nuclear Medicine Division, 4004 Wesbrook Mall, Vancouver, Canada BC V6T 2A3.
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32
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Current world literature. Curr Opin Endocrinol Diabetes Obes 2012; 19:328-37. [PMID: 22760515 DOI: 10.1097/med.0b013e3283567080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Fani M, Maecke HR. Radiopharmaceutical development of radiolabelled peptides. Eur J Nucl Med Mol Imaging 2012; 39 Suppl 1:S11-30. [PMID: 22388624 DOI: 10.1007/s00259-011-2001-z] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Receptor targeting with radiolabelled peptides has become very important in nuclear medicine and oncology in the past few years. The overexpression of many peptide receptors in numerous cancers, compared to their relatively low density in physiological organs, represents the molecular basis for in vivo imaging and targeted radionuclide therapy with radiolabelled peptide-based probes. The prototypes are analogs of somatostatin which are routinely used in the clinic. More recent developments include somatostatin analogs with a broader receptor subtype profile or with antagonistic properties. Many other peptide families such as bombesin, cholecystokinin/gastrin, glucagon-like peptide-1 (GLP-1)/exendin, arginine-glycine-aspartic acid (RGD) etc. have been explored during the last few years and quite a number of potential radiolabelled probes have been derived from them. On the other hand, a variety of strategies and optimized protocols for efficient labelling of peptides with clinically relevant radionuclides such as (99m)Tc, M(3+) radiometals ((111)In, (86/90)Y, (177)Lu, (67/68)Ga), (64/67)Cu, (18)F or radioisotopes of iodine have been developed. The labelling approaches include direct labelling, the use of bifunctional chelators or prosthetic groups. The choice of the labelling approach is driven by the nature and the chemical properties of the radionuclide. Additionally, chemical strategies, including modification of the amino acid sequence and introduction of linkers/spacers with different characteristics, have been explored for the improvement of the overall performance of the radiopeptides, e.g. metabolic stability and pharmacokinetics. Herein, we discuss the development of peptides as radiopharmaceuticals starting from the choice of the labelling method and the conditions to the design and optimization of the peptide probe, as well as some recent developments, focusing on a selected list of peptide families, including somatostatin, bombesin, cholecystokinin/gastrin, GLP-1/exendin and RGD.
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Affiliation(s)
- Melpomeni Fani
- Department of Nuclear Medicine, University Hospital Freiburg, Hugstetterstrasse 55, 79106 Freiburg, Germany.
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34
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Smith TAD. [18F]Fluoride labelling of macromolecules in aqueous conditions: silicon and boroaryl-based [18F]fluorine acceptors, [18F]FDG conjugation and Al18F chelation. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.2940] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tim A. D. Smith
- Biomedical Physics Building, Division of Applied Medicine; University of Aberdeen; Foresterhill; Aberdeen; AB; 25 2TN, 01224 553481; UK
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Zhou D, Chu W, Dence CS, Mach RH, Welch MJ. Highly efficient click labeling using 2-[¹⁸F]fluoroethyl azide and synthesis of an ¹⁸FN-hydroxysuccinimide ester as conjugation agent. Nucl Med Biol 2012; 39:1175-81. [PMID: 22770647 DOI: 10.1016/j.nucmedbio.2012.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 05/21/2012] [Accepted: 06/02/2012] [Indexed: 10/28/2022]
Abstract
INTRODUCTION Click labeling using 2-[¹⁸F]fluoroethyl azide has been proven to be promising methods of radiolabeling small molecules and peptides, some of which are undergoing clinical evaluations. However, the previously reported method afforded low yield, poor purities and under desirable reproducibility. METHODS A vacuum distillation method was used to isolate 2-[¹⁸F]fluoroethyl azide, and the solvent effect of acetonitrile and dimethylformamide (DMF) on the click labeling using Cu(I) from copper sulfate/sodium ascorbate was studied. The labeling conditions were optimized to radiosynthesize a hydroxysuccinimide ester (N-hydroxysuccinimide, or NHS). RESULTS 2-[¹⁸F]fluoroethyl azide was isolated by the vacuum distillation method with >80% yield within 10min in a "pure" and click-ready form. It was found that the amount of DMF was critical for maintaining high levels of Cu(I) from copper sulfate/sodium ascorbate in order to rapidly complete the click labeling reaction. The addition of bathophenanthrolinedisulfonic acid disodium salt to the mixture of copper sulfate/sodium ascorbate also greatly improved the click labeling efficiency. Through exploiting these optimizations, a base-labile NHS ester was rapidly radiosynthesized in 90% isolated yield with good chemical and radiochemical purities. CONCLUSIONS We have developed a general method to click-label small molecules efficiently using [¹⁸F]2 for research and clinical use. This NHS ester can be used for conjugation chemistry to label antibodies, peptides and small molecules as positron emission tomography tracers.
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Affiliation(s)
- Dong Zhou
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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36
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Zlatopolskiy BD, Kandler R, Kobus D, Mottaghy FM, Neumaier B. Beyond azide-alkyne click reaction: easy access to 18F-labelled compounds via nitrile oxide cycloadditions. Chem Commun (Camb) 2012; 48:7134-6. [PMID: 22531279 DOI: 10.1039/c2cc31335a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Radiofluorinated 4-fluorobenzonitrile oxide and N-hydroxy-4-fluorobenzimidoyl chloride rapidly react with different alkenes and alkynes under mild conditions. These cycloadditions are suitable for the preparation of low-molecular weight radiopharmaceuticals and, in a strain-promoted variant, can enable easy labelling of sensitive biopolymers.
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Affiliation(s)
- Boris D Zlatopolskiy
- Klinik für Nuklearmedizin, Aachen University, RWTH, Pauwelsstr. 30, 52074 Aachen, Germany
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37
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McBride WJ, D'Souza CA, Karacay H, Sharkey RM, Goldenberg DM. New lyophilized kit for rapid radiofluorination of peptides. Bioconjug Chem 2012; 23:538-47. [PMID: 22273147 DOI: 10.1021/bc200608e] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Radiolabeling compounds with positron-emitting radionuclides often involves a time-consuming, customized process. Herein, we report a simple lyophilized kit formulation for labeling peptides with (18)F, based on the aluminum-fluoride procedure. The prototype kit contains IMP485, a NODA (1,4,7-triazacyclononane-1,4-diacetate)-MPAA (methyl phenylacetic acid)-di-HSG (histamine-succinyl-glycine) hapten-peptide, [NODA-MPAA-D-Lys(HSG)-D-Tyr-D-Lys(HSG)-NH(2)], used for pretargeting, but we also examined a similar kit formulation for a somatostatin-binding peptide [IMP466, NOTA-D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Throl] bearing a NOTA ligand to determine if the benefits of using a kit can be extended to other AlF-binding peptides. The NODA-MPAA ligand forms a single stable complex with (AlF)(2+) in high yields. In order to establish suitable conditions for a facile kit, the formulation was optimized for pH, peptide to Al(3+) ratio, bulking agent, radioprotectant, and the buffer. For optimal labeling, the kit was reconstituted with an aqueous solution of (18)F(-) and ethanol (1:1), heated at 100-110 °C for 15 min, and then simply and rapidly purified using one of two equally effective solid-phase extraction (SPE) methods. Al(18)F-IMP485 was isolated as a single isomer complex, in high yield (45-97%) and high specific activity (up to 223 GBq/μmol), within 20 min. The labeled product was stable in human serum at 37 °C for 4 h and in vivo, urine samples showed the intact product was eliminated. Tumor targeting of the Al(18)F-IMP485 in nude mice bearing human colon cancer xenografts pretargeted with an anti-CEACAM5 bispecific antibody showed very low uptake (0.06% ± 0.02 ID/g) in bone, further illustrating its stability. At 1 h, pretargeted animals had high Al(18)F-IMP485 tumor uptake (28.1% ± 4.5 ID/g), with ratios of 9 ± 4, 123 ± 38, 110 ± 43, and 120 ± 108 for kidney, liver, blood and bone, respectively. Tumor uptake remained high at 3 h postinjection, with increased tumor/nontumor ratios. The NOTA-somatostatin-binding peptide also was fluorinated with good yield and high specific activity in the same kit formulation. However, yields were somewhat lower than those achieved with IMP485 containing the NODA-MPAA ligand, likely reflecting this ligand's superior binding properties over the simple NOTA. These studies indicate that (18)F-labeled peptides can be reproducibly prepared as stable Al-F complexes with good radiochemical yield and high specific activity using a simple, one-step, lyophilized kit followed by a rapid purification by SPE that provides the (18)F-peptide ready for patient injection within 30 min.
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