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Peng L, Yang T, Zhang D, Wu R, Wen F, Liu J, He X, Zhang X, Zha Z. Optimization and automation of the radiosynthesis of [ 18F]Lu-LuFL as a clinically useful PET ligand targeting FAP for tumor imaging. Appl Radiat Isot 2024; 207:111247. [PMID: 38432032 DOI: 10.1016/j.apradiso.2024.111247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 02/08/2024] [Accepted: 02/22/2024] [Indexed: 03/05/2024]
Abstract
Recently, a novel radiohybrid tracer [18F]Lu-LuFL targeting the fibroblast activation protein (FAP) has been developed for PET imaging of solid tumors. This tracer has shown promising results, prompting us to conduct a first-in-human study to evaluate its efficacy for PET imaging of FAP in human body. In order to facilitate the routine production and clinical application of [18F]Lu-LuFL, a straightforward and efficient automated synthesis is described. The optimum labeling parameters were determined at laboratory scale, and subsequently incorporated into an automated production process. Further studies have demonstrated that clinical doses of [18F]Lu-LuFL can be prepared within 19 min, with excellent radio chemical purity (>99%) and activity yield (23.58% ± 2.20%, non-decay corrected), coupled with solid phase extraction (SPE) purification method. All the quality control results satisfy the required criteria for release. In conclusion, we have successfully synthesized [18F]Lu-LuFL with sufficient radioactivity and superior quality, thereby establishing its potential for further clinical application.
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Affiliation(s)
- Lei Peng
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Tianhong Yang
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Dake Zhang
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Renbo Wu
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Fuhua Wen
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Jianbo Liu
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Xingjin He
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Xiangsong Zhang
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China.
| | - Zhihao Zha
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-sen University, 58# Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China.
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Holzleitner N, Fischer S, Maniyankerikalam I, Beck R, Lapa C, Wester HJ, Günther T. Significant reduction of activity retention in the kidneys via optimized linker sequences in radiohybrid-based minigastrin analogs. EJNMMI Res 2024; 14:23. [PMID: 38429609 PMCID: PMC10907560 DOI: 10.1186/s13550-024-01087-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/26/2024] [Indexed: 03/03/2024] Open
Abstract
BACKGROUND We recently introduced radiohybrid (rh)-based minigastrin analogs e.g., DOTA-rhCCK-18 (DOTA-D-Dap(p-SiFA)-(D-γ-Glu)8-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2), that revealed substantially increased activity retention in the tumor. However, one major drawback of these first generation rh-based cholecystokinin-2 receptor (CCK-2R) ligands is their elevated activity levels in the kidneys, especially at later time points (24 h p.i.). Therefore, this study aimed to reduce kidney retention with regard to a therapeutic use via substitution of negatively charged D-glutamic acid moieties by hydrophilic uncharged polyethylene glycol (PEG) linkers of various length ((PEG)4 to (PEG)11). Furthermore, the influence of differently charged silicon-based fluoride acceptor (SiFA)-moieties (p-SiFA: neutral, SiFA-ipa: negatively charged, and SiFAlin: positively charged) on in vitro properties of minigastrin analogs was evaluated. Out of all compounds evaluated in vitro, the two most promising minigastrin analogs were further investigated in vivo. RESULTS CCK-2R affinity of most compounds evaluated was found to be in a range of 8-20 nM (by means of apparent IC50), while ligands containing a SiFA-ipa moiety displayed elevated IC50 values. Lipophilicity was noticeably lower for compounds containing a D-γ-glutamate (D-γ-Glu) moiety next to the D-Dap(SiFA) unit as compared to their counterparts lacking the additional negative charge. Within this study, combining the most favorable CCK-2R affinity and lipophilicity, [177/natLu]Lu-DOTA-rhCCK-70 (DOTA-D-Dap(p-SiFA)-D-γ-Glu-(PEG)7-D-γ-Glu-(PEG)3-Trp-(N-Me)Nle-Asp-1-Nal-NH2; IC50: 12.6 ± 2.0 nM; logD7.4: - 1.67 ± 0.08) and [177/natLu]Lu-DOTA-rhCCK-91 (DOTA-D-Dap(SiFAlin)-D-γ-Glu-(PEG)4-D-γ-Glu-(PEG)3-Trp-(N-Me)Nle-Asp-1-Nal-NH2; IC50: 8.6 ± 0.7 nM; logD7.4 = - 1.66 ± 0.07) were further evaluated in vivo. Biodistribution data of both compounds revealed significantly reduced (p < 0.0001) activity accumulation in the kidneys compared to [177Lu]Lu-DOTA-rhCCK-18 at 24 h p.i., leading to enhanced tumor-to-kidney ratios despite lower tumor uptake. However, overall tumor-to-background ratios of the novel compounds were lower than those of [177Lu]Lu-DOTA-rhCCK-18. CONCLUSION We could show that the reduction of negative charges within the linker section of radiohybrid-based minigastrin analogs led to decreased activity levels in the kidneys at 24 h p.i., while maintaining a good tumor uptake. Thus, favorable tumor-to-kidney ratios were accomplished in vivo. However, further optimization has to be done in order to improve tumor retention and general biodistribution profile.
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Affiliation(s)
- Nadine Holzleitner
- TUM School of Natural Sciences, Department of Chemistry, Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany.
| | - Sebastian Fischer
- TUM School of Natural Sciences, Department of Chemistry, Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany
| | - Isabel Maniyankerikalam
- TUM School of Natural Sciences, Department of Chemistry, Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany
| | - Roswitha Beck
- TUM School of Natural Sciences, Department of Chemistry, Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany
| | - Constantin Lapa
- Nuclear Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
- Bavarian Cancer Research Center (BZKF), Bavaria, Germany
| | - Hans-Jürgen Wester
- TUM School of Natural Sciences, Department of Chemistry, Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany
| | - Thomas Günther
- TUM School of Natural Sciences, Department of Chemistry, Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany.
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Wurzer A, De Rose F, Fischer S, Schwaiger M, Weber W, Nekolla S, Wester HJ, Eiber M, D'Alessandria C. Preclinical comparison of [ 177Lu]Lu-rhPSMA-10.1 and [ 177Lu]Lu-rhPSMA-10.2 for endoradiotherapy of prostate cancer: biodistribution and dosimetry studies. EJNMMI Radiopharm Chem 2024; 9:18. [PMID: 38407630 PMCID: PMC10897098 DOI: 10.1186/s41181-024-00246-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 02/20/2024] [Indexed: 02/27/2024] Open
Abstract
BACKGROUND Radiohybrid PSMA-targeted ligands (rhPSMA) have been introduced as a novel platform for theranostic applications. Among a variety of rhPSMA-ligands developed for radioligand therapy, two stereoisomers [177Lu]Lu-rhPSMA-10.1 and -10.2 have been synthesized and initially characterized in preclinical experiments with the aim to provide an optimized binding profile to human serum albumin, a reduction of charge, and thus accelerated kidney excretion, and unaffected or even improved tumor uptake. As both isomers showed similar in vitro characteristics and tumor uptake at 24 h post injection in tumor bearing mice and in order to identify the isomer with the most favorable pharmacokinetics for radioligand therapy, we carried out in-depth biodistribution and dosimetry studies in tumor-bearing and healthy mice. RESULTS rhPSMA-10.1 and -10.2 were radiolabeled with lutetium-177 according to the established procedures of other DOTA-based PSMA ligands and displayed a high and comparable stability in all buffers and human serum (> 97%, 24 h). Biodistribution studies revealed fast clearance from the blood pool (0.3-0.6%ID/g at 1 h) and other background tissues within 48 h. Distinctive differences were found in the kidneys, where [177Lu]Lu-rhPSMA-10.1 displayed lower initial uptake and faster excretion kinetics compared to [177Lu]Lu-rhPSMA-10.2 expressed by a 1.5-fold and ninefold lower uptake value at 1 h and 24 h in healthy animals, respectively. Tumor uptake was comparable and in the range of 8.6-11.6%ID/g for both isomers over 24 h and was maintained up to 168 h at a level of 2.2 ± 0.8 and 4.1 ± 1.4%ID/g for [177Lu]Lu-rhPSMA-10.1 and [177Lu]Lu-rhPSMA-10.2, respectively. CONCLUSION Our preclinical data on biodistribution and dosimetry indicate a more favorable profile of [177Lu]Lu-rhPSMA-10.1 compared to [177Lu]Lu-rhPSMA-10.2 for PSMA-targeted radioligand therapy. [177Lu]Lu-rhPSMA-10.1 shows fast kidney clearance kinetics resulting in excellent tumor-to-organ ratios over a therapy relevant time course. Meanwhile, [177Lu]Lu-rhPSMA-10.1 is currently being investigated in clinical phase I/II studies in patients with mCRPC (NCT05413850), in patients with high-risk localized PC (NCT06066437, Nautilus Trial) and after external beam radiotherapy (NCT06105918).
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Affiliation(s)
- Alexander Wurzer
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany.
| | - Francesco De Rose
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Sebastian Fischer
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany
| | - Markus Schwaiger
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Wolfgang Weber
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Stephan Nekolla
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Hans-Jürgen Wester
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Garching, Germany
| | - Matthias Eiber
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
| | - Calogero D'Alessandria
- Department of Nuclear Medicine, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Straße 22, 81675, Munich, Germany
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Yang T, Peng L, Qiu J, He X, Zhang D, Wu R, Liu J, Zhang X, Zha Z. A radiohybrid theranostics ligand labeled with fluorine-18 and lutetium-177 for fibroblast activation protein-targeted imaging and radionuclide therapy. Eur J Nucl Med Mol Imaging 2023; 50:2331-2341. [PMID: 36864362 PMCID: PMC10250256 DOI: 10.1007/s00259-023-06169-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/19/2023] [Indexed: 03/04/2023]
Abstract
PURPOSE A series of radiotracers targeting fibroblast activation protein (FAP) with great pharmacokinetics have been developed for cancer diagnosis and therapy. Nevertheless, the use of dominant PET tracers, gallium-68-labeled FAPI derivatives, was limited by the short nuclide half-life and production scale, and the therapeutic tracers exhibited rapid clearance and insufficient tumor retention. In this study, we developed a FAP targeting ligand, LuFL, containing organosilicon-based fluoride acceptor (SiFA) and DOTAGA chelator, capable of labeling fluorine-18 and lutetium-177 in one molecular with simple and highly efficient labeling procedure, to achieve cancer theranostics. METHODS The precursor LuFL (20) and [natLu]Lu-LuFL (21) were successfully synthesized and labeled with fluorine-18 and lutetium-177 using a simple procedure. A series of cellular assays were performed to characterize the binding affinity and FAP specificity. PET imaging, SPECT imaging, and biodistribution studies were conducted to evaluate pharmacokinetics in HT-1080-FAP tumor-bearing nude mice. A comparison study of [177Lu]Lu-LuFL ([177Lu]21) and [177Lu]Lu-FAPI-04 was carried out in HT-1080-FAP xenografts to determine the cancer therapeutic efficacy. RESULTS LuFL (20) and [natLu]Lu-LuFL (21) demonstrated excellent binding affinity towards FAP (IC50: 2.29 ± 1.12 nM and 2.53 ± 1.87 nM), compared to that of FAPI-04 (IC50: 6.69 ± 0.88 nM). In vitro cellular studies showed that 18F-/177Lu-labeled 21 displayed high specific uptake and internalization in HT-1080-FAP cells. Micro-PET, SPECT imaging and biodistribution studies with [18F]/[177Lu]21 revealed higher tumor uptake and longer tumor retention than those of [68 Ga]/[177Lu]Ga/Lu-FAPI-04. The radionuclide therapy studies showed significantly greater inhibition of tumor growth for the [177Lu]21 group, than for the control group and the [177Lu]Lu-FAPI-04 group. CONCLUSION The novel FAPI-based radiotracer containing SiFA and DOTAGA was developed as a theranostics radiopharmaceutical with simple and short labeling process, and showed promising properties including higher cellular uptake, better FAP binding affinity, higher tumor uptake and prolong retention compared to FAPI-04. Preliminary experiments with 18F- and 177Lu-labeled 21 showed promising tumor imaging properties and favorable anti-tumor efficacy.
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Affiliation(s)
- Tianhong Yang
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Lei Peng
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Jia Qiu
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Xingjin He
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Dake Zhang
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Renbo Wu
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Jianbo Liu
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China
| | - Xiangsong Zhang
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China.
| | - Zhihao Zha
- Department of Nuclear Medicine, The First Affiliated Hospital of Sun Yat-Sen University, #58 Zhongshan Er Road, Guangzhou, 510080, Guangdong Province, China.
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Wurzer A, Kunert JP, Fischer S, Felber V, Beck R, De Rose F, D'Alessandria C, Weber WA, Wester HJ. Synthesis and Preclinical Evaluation of 177Lu-labeled Radiohybrid PSMA Ligands (rhPSMAs) for Endoradiotherapy of Prostate Cancer. J Nucl Med 2022; 63:1489-1495. [PMID: 35086894 PMCID: PMC9536713 DOI: 10.2967/jnumed.121.263371] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 01/18/2022] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION The prostate-specific membrane antigen (PSMA)-targeted radiohybrid (rh) ligand [177Lu]Lu-rhPSMA-7.3 has recently been assessed in a pretherapeutic dosimetry study in prostate cancer patients. In comparison to [177Lu]Lu-PSMA I&T, application of [177Lu]Lu-rhPSMA-7.3 resulted in a significantly improved tumor dose, but also higher kidney accumulation. AIM Although rhPSMA-7.3 has been initially selected as the lead compound for diagnostic application based on the characterization of its gallium complex, a systematic comparison of the most promising 177Lu-labeled rhPSMA ligands is still missing. Thus, this study aimed to identify the rhPSMA ligand with most favorable pharmacokinetics for 177Lu-radioligand therapy. Methods: The four isomers of [177Lu]Lu-rhPSMA-7 (namely [177Lu]Lu-rhPSMA-7.1, -7.2, -7.3 and -7.4), along with the novel radiohybrid ligands [177Lu]Lu-rhPSMA-10.1 and -10.2, were compared to the state-of-the-art compounds [177Lu]Lu-PSMA I&T and [177Lu]Lu-PSMA-617. The comparative evaluation comprised affinity studies (IC50) and internalization experiments on LNCaP cells, as well as lipophilicity measurements. In addition, we determined the apparent molecular weight (AMW) of each tracer as a parameter for human serum albumin (HSA) binding. Biodistribution studies and µSPECT imaging was performed in LNCaP-tumor bearing mice at 24 h post injection. Results: 177Lu-labeling of the radiohybrids was carried out according to the established procedures for the currently established PSMA-targeted ligands. All ligands showed potent binding to PSMA-expressing LNCaP cells, with affinities in the low nanomolar range and high internalization rates. Surprisingly, most pronounced differences were identified regarding the HSA-related AMW. While [177Lu]Lu-rhPSMA-7 isomers demonstrated the highest AMW and thus strongest HSA-interactions, [177Lu]Lu-rhPSMA-10.1 showed an AMW lower than [177Lu]Lu-rhPSMA-7.3 but higher than the 177Lu-labeled references PSMA I&T and PSMA-617. In biodistribution studies [177Lu]Lu-rhPSMA-10.1 exhibited the lowest kidney uptake and fastest excretion from the blood pool of all rhPSMA ligands, while preserving a high tumor accumulation. Conclusion: Clinical investigation of [177Lu]Lu-rhPSMA-10.1 is highly warranted in order to determine if the favorable pharmacokinetics observed in mice will also result in high tumor uptake and decreased absorbed dose to kidneys and other non-target tissues in patients.
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Wurzer A, Di Carlo D, Herz M, Richter A, Robu S, Schirrmacher R, Mascarin A, Weber W, Eiber M, Schwaiger M, Wester HJ. Automated synthesis of [ 18F]Ga-rhPSMA-7/ -7.3: results, quality control and experience from more than 200 routine productions. EJNMMI Radiopharm Chem 2021; 6:4. [PMID: 33484364 DOI: 10.1186/s41181-021-00120-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/11/2021] [Indexed: 12/15/2022] Open
Abstract
Introduction The radiohybrid (rh) prostate-specific membrane antigen (PSMA)-targeted ligand [18F]Ga-rhPSMA-7 has previously been clinically assessed and demonstrated promising results for PET-imaging of prostate cancer. The ligand is present as a mixture of four stereoisomers ([18F]Ga-rhPSMA-7.1, − 7.2, − 7.3 and − 7.4) and after a preclinical isomer selection process, [18F]Ga-rhPSMA-7.3 has entered formal clinical trials. Here we report on the establishment of a fully automated production process for large-scale production of [18F]Ga-rhPSMA-7/ -7.3 under GMP conditions (EudraLex). Methods [18F]Fluoride in highly enriched [18O]H2O was retained on a strong anion exchange cartridge, rinsed with anhydrous acetonitrile and subsequently eluted with a solution of [K+ ⊂ 2.2.2]OH− in anhydrous acetonitrile into a reactor containing Ga-rhPSMA ligand and oxalic acid in DMSO. 18F-for-19F isotopic exchange at the Silicon-Fluoride Acceptor (SiFA) was performed at room temperature, followed by dilution with buffer and cartridge-based purification. Optimum process parameters were determined on the laboratory scale and thereafter implemented into an automated synthesis. Data for radiochemical yield (RCY), purity and quality control were analyzed for 243 clinical productions (160 for [18F]Ga-rhPSMA-7; 83 for [18F]Ga-rhPSMA-7.3). Results The automated production of [18F]Ga-rhPSMA-7 and the single isomer [18F]Ga-rhPSMA-7.3 is completed in approx. 16 min with an average RCY of 49.2 ± 8.6% and an excellent reliability of 98.8%. Based on the different starting activities (range: 31–130 GBq, 89 ± 14 GBq) an average molar activity of 291 ± 62 GBq/μmol (range: 50–450 GBq/μmol) was reached for labeling of 150 nmol (231 μg) precursor. Radiochemical purity, as measured by radio-high performance liquid chromatography and radio-thin layer chromatography, was 99.9 ± 0.2% and 97.8 ± 1.0%, respectively. Conclusion This investigation demonstrates that 18F-for-19F isotopic exchange is well suited for the fast, efficient and reliable automated routine production of 18F-labeled PSMA-targeted ligands. Due to its simplicity, speed and robustness the development of further SiFA-based radiopharmaceuticals is highly promising and can be of far-reaching importance for future theranostic concepts. Supplementary Information The online version contains supplementary material available at 10.1186/s41181-021-00120-5.
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Wurzer A, Parzinger M, Konrad M, Beck R, Günther T, Felber V, Färber S, Di Carlo D, Wester HJ. Preclinical comparison of four [ 18F, natGa]rhPSMA-7 isomers: influence of the stereoconfiguration on pharmacokinetics. EJNMMI Res 2020; 10:149. [PMID: 33284394 PMCID: PMC7721954 DOI: 10.1186/s13550-020-00740-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/24/2020] [Indexed: 12/27/2022] Open
Abstract
Introduction Radiohybrid (rh) ligands, a novel class of prostate-specific membrane antigen (PSMA)-targeted radiopharmaceuticals, can be labeled either with [18F]fluorine via isotopic exchange or with radiometals (such as [68Ga]Gallium, [177Lu]Lutetium, [225Ac]Actinium). Among these, [18F, natGa]rhPSMA-7 has recently entered clinical assessment.
Aim Since [18F, natGa]rhPSMA-7 is composed of four stereoisomers ([18F, natGa]rhPSMA-7.1, -7.2, -7.3 and -7.4), we initiated a preclinical selection process to identify the isomer with the most favorable pharmacokinetics for further clinical investigation. Methods A synthetic protocol for enantiopure [19F, natGa]rhPSMA-7 isomers has been developed. The comparative evaluation of the four isomers comprised human serum albumin binding, lipophilicity, IC50, internalization and classical biodistribution studies and competition experiments in LNCaP tumor-bearing CB-17 SCID mice. In addition, a radio high-performance liquid chromatography-based method was developed allowing quantitative, intraindividual comparison of [18F, natGa]rhPSMA-7.1 to -7.4 in LNCaP tumor-bearing mice. Results Cell studies revealed high PSMA affinity and internalization for [18/19F, natGa]rhPSMA-7.2, -7.3 and -7.4, whereas [18/19F, natGa]rhPSMA-7.1 showed approximately twofold lower values. Although the biodistribution profile obtained was typical of PSMA inhibitors, it did not allow for selection of a lead candidate for clinical studies. Thus, an intraindividual comparison of all four isomers in LNCaP tumor-bearing mice was carried out by injection of a diastereomeric mixture, followed by analysis of the differential uptake and excretion pattern of each isomer. Based on its high tumor accumulation and low uptake in blood, liver and kidneys, [18F, natGa]rhPSMA-7.3 was identified as the preferred isomer and transferred into clinical studies. Conclusion [18F, natGa]rhPSMA-7.3 has been selected as a lead compound for clinical development of a [18F]rhPSMA-based candidate. The intraindividual differential uptake and excretion analysis in vivo allowed for an accurate comparison and assessment of radiopharmaceuticals.
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Affiliation(s)
- Alexander Wurzer
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany.
| | - Mara Parzinger
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Matthias Konrad
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Roswitha Beck
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Thomas Günther
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Veronika Felber
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Stefanie Färber
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Daniel Di Carlo
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
| | - Hans-Jürgen Wester
- Chair of Pharmaceutical Radiochemistry, Technical University of Munich, Walther-Meißner-Str. 3, 85748, Garching, Germany
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