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Liu N, Wan Q, Wu X, Zhao T, Jakobsson V, Yuan H, Chen X, Zhang J, Zhang W. A comparison of [ 18F]AlF- and 68Ga-labeled dual targeting heterodimer FAPI-RGD in malignant tumor: preclinical evaluation and pilot clinical PET/CT imaging. Eur J Nucl Med Mol Imaging 2024; 51:1685-1697. [PMID: 38246909 DOI: 10.1007/s00259-023-06587-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 12/12/2023] [Indexed: 01/23/2024]
Abstract
Due to the heterogeneity of tumors, strategies to improve the effectiveness of dual-targeting tracers in tumor diagnostics have been intensively practiced. In this study, the radiolabeled [18F]AlF-NOTA-FAPI-RGD (denoted as [18F]AlF-LNC1007), a dual-targeting heterodimer tracer targeting both fibroblast activation protein (FAP) and integrin αvβ3 to enhance specific tumor uptake and retention, was synthesized and evaluated. The tracer was compared with [68Ga]Ga-LNC1007 in preclinical and clinical settings. METHODS The preparation of [18F]AlF- and 68Ga-labeled FAPI-RGD was carried out with an optimized protocol. The stability was tested in PBS and fetal bovine serum (FBS). Cellular uptake and in vivo distribution of the two products were compared and carried out on the U87MG cell line and its xenograft model. The safety and dosimetry of [18F]AlF-LNC1007 PET/CT scan were evaluated in six patients with malignant tumors. RESULTS Two radiolabeling protocols of [18F]AlF-/[68Ga]Ga-LNC1007 were developed and optimized to give a high yield of tracers with good stability. In vivo microPET images showed that the two tracers exhibited comparable pharmacokinetic characteristics, with high tumor uptake and prolonged tumor retention. In vivo distribution data showed that the target-to-non-target ratios of [18F]AlF-LNC1007 were similar to[68Ga]Ga-LNC1007. A total of six patients underwent [18F]AlF-LNC1007 PET/CT evaluation while two had head-to-head [18F]FDG PET/CT scans. The total body effective dose was 9.94E-03 mSv/MBq. The biodistribution curve showed optimal normal organ uptake with high tumor uptake and long retention of up to 3h p.i., and notably, the tumor-to-background ratio increased over time. CONCLUSION We successfully prepared an [18F]AlF-LNC1007 dual-targeting PET probe with comparable performances as [68Ga]Ga-LNC1007. With prolonged tumor retention and tumor specificity, it produced good imaging quality in preclinical and clinical translational studies, indicating that [18F]AlF-LNC1007 is a promising non-invasive tracer for detecting tumors expressing FAP and/or integrin avβ3, with the prospect of clinical implementation.
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Affiliation(s)
- Nan Liu
- Department of Nuclear Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Qiang Wan
- Department of Nuclear Medicine, Affiliated Hospital of Southwest Medical University, Luzhou, 646000, China
| | - Xiaoming Wu
- College of Nuclear Science and Technology, Harbin Engineering University, Harbin, 150001, China
| | - Tianzhi Zhao
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119074, Singapore
- Clinical Imaging Research Centre, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117599, Singapore
- Nanomedicine Translational Research Program, NUS Center for Nanomedicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore
| | - Vivianne Jakobsson
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119074, Singapore
- Clinical Imaging Research Centre, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117599, Singapore
- Nanomedicine Translational Research Program, NUS Center for Nanomedicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore
| | - Hongmei Yuan
- Department of Pharmaceutics, School of Pharmacy, Southwest Medical University, Jiangyang District, Luzhou, 646000, China
| | - Xiaoyuan Chen
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119074, Singapore.
- Clinical Imaging Research Centre, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117599, Singapore.
- Nanomedicine Translational Research Program, NUS Center for Nanomedicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore.
- Departments of Surgery, Chemical and Biomolecular Engineering, and Biomedical Engineering, Yong Loo Lin School of Medicine and College of Design and Engineering, National University of Singapore, Singapore, 119074, Singapore.
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research (A*STAR), National University of Singapore, 61 Biopolis Drive, Proteos, Singapore, 138673, Singapore.
| | - Jingjing Zhang
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119074, Singapore.
- Clinical Imaging Research Centre, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117599, Singapore.
- Nanomedicine Translational Research Program, NUS Center for Nanomedicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597, Singapore.
| | - Wei Zhang
- Department of Nuclear Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, 610072, China.
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Schreck MV, Burgard C, Schmidtke A, Hierlmeier I, Stemler T, Maus S, Rosar F, Jung M, Speicher A, Ezziddin S, Holland JP, Bartholomä MD. Radiometal Complexes as Pharmacokinetic Modifiers: A Potent 68Ga-Labeled Gastrin-Releasing Peptide Receptor Antagonist Based on the Macrocyclic Metal Chelator NODIA-Me. Mol Pharm 2023; 20:6463-6473. [PMID: 37978936 DOI: 10.1021/acs.molpharmaceut.3c00852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The gastrin-releasing peptide receptor (GRPr) is overexpressed in various cancer types including prostate and breast carcinomas, making it an attractive target for molecular imaging and therapy. In this work, we designed a novel GRPr antagonistic probe comprising metal chelator NODIA-Me. This 1,4,7-triazacyclononane-based chelator forms positively charged metal complexes due to its neutral methylimidazole arms. Because a positive charge at the N-terminus of GRPr conjugates is responsible for high receptor affinity as exemplified by the current gold standard DOTA-RM2, we investigated if a positively charged radiometal complex can be used as a pharmacokinetic modifier to also produce high-affinity GRPr conjugates. In this respect, the bioconjugate NODIA-Me-Ahx-JMV594 was prepared by a combination of solid-phase peptide synthesis and solution-based reactions in a 94% yield. Radiolabeling provided the 68Ga-labeled conjugate in radiochemical yields of >95% and radiochemical purities of >98% with mean molar activities of Am ∼17 MBq nmol-1. The competitive GRPr affinity of the metal-free and 69/71Ga-labeled conjugate was determined to be IC50 = 0.41 ± 0.06 and 1.45 ± 0.06 nM, respectively. The metal-free GRPr antagonist DOTA-RM2 and its corresponding 69/71Ga complex had IC50 values of 1.42 ± 0.07 and 0.98 ± 0.19 nM, respectively. Small-animal PET imaging of mice bearing GRPr(+) PC-3 tumors revealed high radioactivity accumulation in the tumors and in the pancreas as an organ with high levels of GRPr expression. These findings were corroborated by the corresponding ex vivo biodistribution data, in which the tumors and the pancreas exhibited the highest radioactivity accumulation. By coinjection of an excess of NODIA-Me-Ahx-JMV594, uptake in the tumors and GRPr(+) organs was significantly reduced, confirming specific receptor-mediated uptake. The estrogen receptor-positive tumor of a female breast cancer patient was clearly visualized by PET imaging using 68Ga-labeled NODIA-Me-Ahx-JMV594. To summarize, the positive charge at the N-terminus of the conjugate induced by the Ga(NODIA-Me) complex resulted in high GRPr affinity comparable to that of the potent antagonist DOTA-RM2. The conjugate NODIA-Me-Ahx-JMV594 is a promising probe for imaging of GRPr tumors that warrants further evaluation in larger patient cohorts as well as in combination with other radiometals.
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Affiliation(s)
- Moritz-Valentin Schreck
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Caroline Burgard
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Alexander Schmidtke
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Ina Hierlmeier
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Tobias Stemler
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Stephan Maus
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Florian Rosar
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Martin Jung
- Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66421 Homburg, Germany
| | - Andreas Speicher
- Department of Organic Chemistry, Saarland University, D-66123 Saarbrücken, Germany
| | - Samer Ezziddin
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
| | - Jason P Holland
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Mark D Bartholomä
- Department of Nuclear Medicine, Saarland University-Medical Center, Kirrbergerstrasse, D-66421 Homburg, Germany
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Höltke C, Alsibai W, Grewer M, Stölting M, Geyer C, Eisenblätter M, Wildgruber M, Helfen A. How Different Albumin-Binders Drive Probe Distribution of Fluorescent RGD Mimetics. Front Chem 2021; 9:689850. [PMID: 34504831 PMCID: PMC8421774 DOI: 10.3389/fchem.2021.689850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 08/09/2021] [Indexed: 11/13/2022] Open
Abstract
The biodistribution of medical imaging probes depends on the chemical nature of the probe and the preferred metabolization and excretion routes. Especially targeted probes, which have to reach a certain (sub)cellular destination, have to be guided to the tissue of interest. Therefore, small molecular probes need to exhibit a well-balanced polarity and lipophilicity to maintain an advantageous bioavailability. Labelled antibodies circulate for several days due to their size. To alter the biodistribution behavior of probes, different strategies have been pursued, including utilizing serum albumin as an inherent transport mechanism for small molecules. We describe here the modification of an existing fluorescent RGD mimetic probe targeted to integrin αvβ3 with three different albumin binding moieties (ABMs): a diphenylcyclohexyl (DPCH) group, a p-iodophenyl butyric acid (IPBA) and a fatty acid (FA) group with the purpose to identify an optimal ABM for molecular imaging applications. All three modifications result in transient albumin binding and a preservation of the target binding capability. Spectrophotometric measurements applying variable amounts of bovine serum albumin (BSA) reveal considerable differences between the compounds concerning their absorption and emission characteristics and hence their BSA binding mode. In vivo the modified probes were investigated in a murine U87MG glioblastoma xenograft model over the course of 1 wk by fluorescence reflectance imaging (FRI) and fluorescence mediated tomography (FMT). While the unmodified probe was excreted rapidly, the albumin-binding probes were accumulating in tumor tissue for at least 5 days. Considerable differences between the three probes in biodistribution and excretion characteristics were proved, with the DPCH-modified probe showing the highest overall signal intensities, while the FA-modified probe exhibits a low but more specific fluorescent signal. In conclusion, the modification of small molecular RGD mimetics with ABMs can precisely fine-tune probe distribution and offers potential for future clinical applications.
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Affiliation(s)
- Carsten Höltke
- Clinic for Radiology, University Hospital Münster, Münster, Germany
| | - Wael Alsibai
- Clinic for Radiology, University Hospital Münster, Münster, Germany
| | - Martin Grewer
- Clinic for Radiology, University Hospital Münster, Münster, Germany
| | - Miriam Stölting
- Clinic for Radiology, University Hospital Münster, Münster, Germany
| | - Christiane Geyer
- Clinic for Radiology, University Hospital Münster, Münster, Germany
| | - Michel Eisenblätter
- Clinic for Radiology, University Hospital Münster, Münster, Germany.,Department of Radiology, University Hospital Freiburg, Freiburg, Germany
| | - Moritz Wildgruber
- Clinic for Radiology, University Hospital Münster, Münster, Germany.,Department of Radiology, University Hospital, LMU Munich, Munich, Germany
| | - Anne Helfen
- Clinic for Radiology, University Hospital Münster, Münster, Germany
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