Biological Evaluation of [18F]AlF-NOTA-NSC-GLU as a Positron Emission Tomography Tracer for Hepatocellular Carcinoma

Purpose: N-(2-[18F]fluoropropionyl)-L-glutamate ([18F]FPGLU) for hepatocellular carcinoma (HCC) imaging has been performed in our previous studies, but its radiosynthesis method and stability in vivo need to be improved. Hence, we evaluated the synthesis and biological properties of a simple [18F]-labeled glutamate analog, [18F]AlF-1,4,7-triazacyclononane-1,4,7-triacetic-acid-2-S-(4-isothiocyanatobenzyl)-l-glutamate ([18F]AlF-NOTA-NSC-GLU), for HCC imaging.Procedures: [18F]AlF-NOTA-NSC-GLU was synthesized via a one-step reaction sequence from NOTA-NSC-GLU. In order to investigate the imaging value of [18F]AlF-NOTA-NSC-GLU in HCC, we conducted positron emission tomography/computed tomography (PET/CT) imaging and competitive binding of [18F]AlF-NOTA-NSC-GLU in human Hep3B tumor-bearing mice. The transport mechanism of [18F]AlF-NOTA-NSC-GLU was determined by competitive inhibition and protein incorporation experiments in vitro.Results: [18F]AlF-NOTA-NSC-GLU was prepared with an overall radiochemical yield of 29.3 ± 5.6% (n = 10) without decay correction within 20 min. In vitro competitive inhibition experiments demonstrated that the Na+-dependent systems XAG-, B0+, ASC, and minor XC- were involved in the uptake of [18F]AlF-NOTA-NSC-GLU, with the Na+-dependent system XAG- possibly playing a more dominant role. Protein incorporation studies of the Hep3B human hepatoma cell line showed almost no protein incorporation. Micro-PET/CT imaging with [18F]AlF-NOTA-NSC-GLU showed good tumor-to-background contrast in Hep3B human hepatoma-bearing mouse models. After [18F]AlF-NOTA-NSC-GLU injection, the tumor-to-liver uptake ratio of [18F]AlF-NOTA-NSC-GLU was 2.06 ± 0.17 at 30 min post-injection. In vivo competitive binding experiments showed that the tumor-to-liver uptake ratio decreased with the addition of inhibitors to block the XAG system.Conclusions: We have successfully synthesized [18F]AlF-NOTA-NSC-GLU as a novel PET tracer with good radiochemical yield and high radiochemical purity. Our findings indicate that [18F]AlF-NOTA-NSC-GLU may be a potential candidate for HCC imaging. Also, a further biological evaluation is underway.

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Biological evaluation of [18F]AlF-NOTA-NSC-GLU as a PET tracer for hepatocellular carcinoma

10.21203/rs.3.rs-25398/v2 ◽

2020 ◽

Author(s):

Liping Lin ◽

Xianhong Xiang ◽

Shu Su ◽

Shaoyu Liu ◽

Ying Xiong ◽

...

Keyword(s):

Competitive Inhibition ◽

Radiochemical Yield ◽

Uptake Ratio ◽

Reaction Sequence ◽

Liver Uptake ◽

Pet Tracer ◽

Pet Ct ◽

One Step ◽

Protein Incorporation

Abstract Purpose 18F-labeled amino acids (AAs) as tumor-specific imaging agents play a critical role in hepatocellular carcinoma (HCC) imaging. In this work, we evaluated the synthesis and biological properties of a simple 18F-labeled glutamate analogue, [18F]AlF-1,4,7-triazacyclononane-1,4,7-triacetic-acid-2-S-(4-isothiocyanatobenzyl))-l-glutamate ([18F]AlF-NOTA-NSC-GLU) for HCC imaging via one-step reaction sequence. Methods [18F]AlF-NOTA-NSC-GLU was synthesized via the one-step reaction sequence from NOTA-NSC-GLU. In order to investigate the imaging value of [18F]AlF-NOTA-NSC-GLU in HCC, we conducted PET/CT imaging and competitive binding of [18F]AlF-NOTA-NSC-GLU in human Hep3B tumor-bearing mice. The transport mechanism of [18F]AlF-NOTA-NSC-GLU was determined by competitive inhibition and protein incorporation experiments in vitro. Results [18F]AlF-NOTA-NSC-GLU was prepared without decay-corrected radiochemical yield of 29.3 ± 5.6% (n=10) within 20 min. In vitro competitive inhibition experiments demonstrated that Na+-dependent Systems XAG-, B0+, ASC and minor XC- were involved in the uptake of [18F]AlF-NOTA-NSC-GLU, with Na+-dependent System XAG- possibly playing a more dominant role. Protein incorporation studies of the Hep3B human hepatoma cell line found almost no protein incorporation. Micro-PET/CT imaging with [18F]AlF-NOTA-NSC-GLU showed good tumor-to-background contrast in Hep3B human hepatoma-bearing mouse models. After [18F]AlF-NOTA-NSC-GLU injection, the tumor-to-liver uptake ratio of [18F]AlF-NOTA-NSC-GLU was 2.06 ± 0.17 at 30 min post-injection. In vivo competitive binding experiments exhibited that the tumor-to-liver uptake ratio decreased by the addition of the inhibitors to block the system XAG-. Conclusion We have successfully synthesized [18F]AlF-NOTA-NSC-GLU as a novel PET tracer with good radiochemical yield and high radiochemical purity. Our findings indicate that [18F]AlF-NOTA-NSC-GLU might have good clinical potential as a PET tumor-detecting agent for HCC imaging.

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Biological evaluation of [18F]AIF-NOTA-NSC-GLU as a PET tracer for hepatocellular carcinoma

10.21203/rs.3.rs-25398/v1 ◽

2020 ◽

Author(s):

Liping Lin ◽

Xianhong Xiang ◽

Shu Su ◽

Shaoyu Liu ◽

Ying Xiong ◽

...

Keyword(s):

Competitive Inhibition ◽

Radiochemical Yield ◽

Uptake Ratio ◽

Reaction Sequence ◽

Liver Uptake ◽

Pet Tracer ◽

Pet Ct ◽

One Step ◽

Protein Incorporation

Abstract Purpose 18F-labeled amino acids (AAs) as tumor-specific imaging agents play a critical role in hepatocellular carcinoma (HCC) imaging. In this work, we evaluated the synthesis and biological properties of a simple 18F-labeled glutamate analogue, [18F]AIF-1,4,7-triazacyclononane-1,4,7-triacetic-acid-2-S-(4-isothiocyanatobenzyl))-l-glutamate ([18F]AIF-NOTA-NSC-GLU) for HCC imaging via one-step reaction sequence. Methods [18F]AIF-NOTA-NSC-GLU was synthesized via the one-step reaction sequence from NOTA-NSC-GLU. In order to investigate the imaging value of [18F]AIF-NOTA-NSC-GLU in HCC, we conducted PET/CT imaging and competitive binding of [18F]AIF-NOTA-NSC-GLU in human Hep3B 2.1-7 tumor-bearing mice. The transport mechanism of [18F]AIF-NOTA-NSC-GLU was determined by competitive inhibition and protein incorporation experiments in vitro. Results [18F]AIF-NOTA-NSC-GLU was prepared with decay-corrected radiochemical yield of 29.3 ± 5.6% (n=10) within 20 min. In vitro competitive inhibition experiments demonstrated that Na+-dependent Systems XAG-, B0+, ASC and minor XC- were involved in the uptake of [18F]AIF-NOTA-NSC-GLU, with Na+-dependent System XAG- possibly playing a more dominant role. Protein incorporation studies of the Hep3B 2.1-7 human hepatoma cell line found almost no protein incorporation. Micro-PET/CT imaging with [18F]AIF-NOTA-NSC-GLU showed good tumor-to-background contrast in Hep3B 2.1-7 human hepatoma-bearing mouse models. After [18F]AIF-NOTA-NSC-GLU injection, the tumor-to-liver uptake ratio of [18F]AIF-NOTA-NSC-GLU reached the peak at 30 min post-injection (2.06 ± 0.17). In vivo competitive binding experiments exhibited that the tumor-to-liver uptake ratio decreased by the addition of the inhibitors to block the system XAG-. Conclusion We have successfully synthesized [18F]AIF-NOTA-NSC-GLU as a novel PET tracer with good radiochemical yield and high radiochemical purity. Our findings indicate that [18F]AIF-NOTA-NSC-GLU might have good clinical potential as a PET tumor-detecting agent for HCC imaging.

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Evaluation of Organo [18F]Fluorosilicon Tetrazine as a Prosthetic Group for the Synthesis of PET Radiotracers

Molecules ◽

10.3390/molecules25051208 ◽

2020 ◽

Vol 25 (5) ◽

pp. 1208 ◽

Cited By ~ 1

Author(s):

Sofia Otaru ◽

Surachet Imlimthan ◽

Mirkka Sarparanta ◽

Kerttuli Helariutta ◽

Kristiina Wähälä ◽

...

Keyword(s):

Radiochemical Yield ◽

Biological Evaluation ◽

Prosthetic Group ◽

Molar Activity ◽

Positron Emission ◽

Biological Studies ◽

Model Protein ◽

Improved Stability

Fluorine-18 is the most widely used positron emission tomography (PET) radionuclide currently in clinical application, due to its optimal nuclear properties. The synthesis of 18F-labeled radiotracers often requires harsh reaction conditions, limiting the use of sensitive bio- and macromolecules as precursors for direct radiolabeling with fluorine-18. We aimed to develop a milder and efficient in vitro and in vivo labeling method for trans-cyclooctene (TCO) functionalized proteins, through the bioorthogonal inverse-electron demand Diels-Alder (IEDDA) reaction with fluorine-18 radiolabeled tetrazine ([18F]SiFA-Tz). Here, we used TCO-modified bovine serum albumin (BSA) as the model protein, and isotopic exchange (IE) (19F/18F) chemistry as the labeling strategy. The radiolabeling of albumin-TCO with [18F]SiFA-Tz ([18F]6), providing [18F]fluoroalbumin ([18F]10) in high radiochemical yield (99.1 ± 0.2%, n = 3) and a molar activity (MA) of 1.1 GBq/µmol, confirmed the applicability of [18F]6 as a quick in vitro fluorination reagent for the TCO functionalized proteins. While the biological evaluation of [18F]6 demonstrated defluorination in vivo, limiting the utility for pretargeted applications, the in vivo stability of the radiotracer was dramatically improved when [18F]6 was used for the radiolabeling of albumin-TCO ([18F]10) in vitro, prior to administration. Due to the detected defluorination in vivo, structural optimization of the prosthetic group for improved stability is needed before further biological studies and application of pretargeted PET imaging.

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Radiosynthesis and Biological Investigation of a Novel Fluorine-18 Labeled Benzoimidazotriazine- Based Radioligand for the Imaging of Phosphodiesterase 2A with Positron Emission Tomography

Molecules ◽

10.3390/molecules24224149 ◽

2019 ◽

Vol 24 (22) ◽

pp. 4149

Author(s):

Ritawidya ◽

Wenzel ◽

Teodoro ◽

Toussaint ◽

Kranz ◽

...

Keyword(s):

Positron Emission Tomography ◽

Specific Binding ◽

Standardized Uptake Value ◽

Radiochemical Yield ◽

Biological Evaluation ◽

Emission Tomography ◽

Biological Investigation ◽

Positron Emission

A specific radioligand for the imaging of cyclic nucleotide phosphodiesterase 2A (PDE2A) via positron emission tomography (PET) would be helpful for research on the physiology and disease-related changes in the expression of this enzyme in the brain. In this report, the radiosynthesis of a novel PDE2A radioligand and the subsequent biological evaluation were described. Our prospective compound 1-(2-chloro-5-methoxy phenyl)-8-(2-fluoropyridin-4-yl)-3- methylbenzo[e]imidazo[5,1-c][1,2,4]triazine, benzoimidazotriazine (BIT1) (IC50 PDE2A = 3.33 nM; 16-fold selectivity over PDE10A) was fluorine-18 labeled via aromatic nucleophilic substitution of the corresponding nitro precursor using the K[18F]F‐K2.2.2‐carbonate complex system. The new radioligand [18F]BIT1 was obtained with a high radiochemical yield (54 ± 2%, n = 3), a high radiochemical purity (≥99%), and high molar activities (155–175 GBq/μmol, n = 3). In vitro autoradiography on pig brain cryosections exhibited a heterogeneous spatial distribution of [18F]BIT1 corresponding to the known pattern of expression of PDE2A. The investigation of in vivo metabolism of [18F]BIT1 in a mouse revealed sufficient metabolic stability. PET studies in mouse exhibited a moderate brain uptake of [18F]BIT1 with a maximum standardized uptake value of ~0.7 at 5 minutes p.i. However, in vivo blocking studies revealed a non-target specific binding of [18F]BIT1. Therefore, further structural modifications are needed to improve target selectivity.

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Development of 18F-Labeled Radiotracers for PET Imaging of the Adenosine A2A Receptor: Synthesis, Radiolabeling and Preliminary Biological Evaluation

International Journal of Molecular Sciences ◽

10.3390/ijms22052285 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2285

Author(s):

Thu Hang Lai ◽

Susann Schröder ◽

Magali Toussaint ◽

Sladjana Dukić-Stefanović ◽

Mathias Kranz ◽

...

Keyword(s):

Specific Binding ◽

Brain Slices ◽

Total Activity ◽

Biological Evaluation ◽

Adenosine A2a Receptor ◽

Positron Emission ◽

A2a Receptor ◽

Adenosine A2a

The adenosine A2A receptor (A2AR) represents a potential therapeutic target for neurodegenerative diseases. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor changes of receptor density and/or occupancy during the A2AR-tailored therapy, we designed a library of fluorinated analogs based on a recently published lead compound (PPY). Among those, the highly affine 4-fluorobenzyl derivate (PPY1; Ki(hA2AR) = 5.3 nM) and the 2-fluorobenzyl derivate (PPY2; Ki(hA2AR) = 2.1 nM) were chosen for 18F-labeling via an alcohol-enhanced copper-mediated procedure starting from the corresponding boronic acid pinacol ester precursors. Investigations of the metabolic stability of [18F]PPY1 and [18F]PPY2 in CD-1 mice by radio-HPLC analysis revealed parent fractions of more than 76% of total activity in the brain. Specific binding of [18F]PPY2 on mice brain slices was demonstrated by in vitro autoradiography. In vivo PET/magnetic resonance imaging (MRI) studies in CD-1 mice revealed a reasonable high initial brain uptake for both radiotracers, followed by a fast clearance.

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New 55Co-labeled Albumin-Binding Folate Derivatives as Potential PET Agents for Folate Receptor Imaging

Pharmaceuticals ◽

10.3390/ph12040166 ◽

2019 ◽

Vol 12 (4) ◽

pp. 166 ◽

Cited By ~ 4

Author(s):

Lauren L. Radford ◽

Solana Fernandez ◽

Rebecca Beacham ◽

Retta El Sayed ◽

Renata Farkas ◽

...

Keyword(s):

Folate Receptor ◽

Small Animal ◽

Small Animal Pet ◽

Receptor Imaging ◽

Albumin Binding ◽

Liver Uptake ◽

Biodistribution Studies ◽

Positron Emission

Overexpression of folate receptors (FRs) on different tumor types (e.g., ovarian, lung) make FRs attractive in vivo targets for directed diagnostic/therapeutic agents. Currently, no diagnostic agent suitable for positron emission tomography (PET) has been adopted for clinical FR imaging. In this work, two 55Co-labeled albumin-binding folate derivatives-[55Co]Co-cm10 and [55Co]Co-rf42-with characteristics suitable for PET imaging have been developed and evaluated. High radiochemical yields (≥95%) and in vitro stabilities (≥93%) were achieved for both compounds, and cell assays demonstrated FR-mediated uptake. Both 55Co-labeled folate conjugates demonstrated high tumor uptake of 17% injected activity per gram of tissue (IA/g) at 4 h in biodistribution studies performed in KB tumor-bearing mice. Renal uptake was similar to other albumin-binding folate derivatives, and liver uptake was lower than that of previously reported [64Cu]Cu-rf42. Small animal PET/CT images confirmed the biodistribution results and showed the clear delineation of FR-expressing tumors.

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Synthesis and Preclinical Evaluation of [18F]PF04217903, a Selective MET PET Tracer

10.26434/chemrxiv.13095764.v1 ◽

2020 ◽

Author(s):

Vegard Torp Lien ◽

Emily Hauge ◽

Syed Nuruddin ◽

Jo Klaveness ◽

Dag Erlend Olberg

Keyword(s):

Growth Factor Receptor ◽

Radiochemical Yield ◽

Molar Activity ◽

Bioisosteric Replacement ◽

Pet Tracer ◽

Positron Emission ◽

Wide Range ◽

Hepatocyte Growth

The tyrosine kinase MET (hepatocyte growth factor receptor) is abnormally activated in a wide range of cancers and is often correlated with a poor prognosis. Precision medicine with positron emission tomography (PET) can potentially aid in the assessment of tumor biochemistry and heterogeneity, which can prompt the selection of the most effective therapeutic regimes. The selective MET inhibitor PF04217903 (1) formed the basis for a bioisosteric replacement to the deoxyfluorinated analogue [18F]2, intended as a PET tracer for MET. [18F]2 could be synthesized with a “hydrous fluoroethylation” protocol in 6.3 ± 2.6% radiochemical yield and a molar activity of >50 GBq/µmol. In vitro autoradiography indicated that [18F]2 specifically binds to MET in PC3 tumor tissue, and in vivo biodistribution in mice showed predominantly a hepatobiliary excretion along with a low retention of radiotracer in other organs.

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Radioiodination and biological evaluation of Cimetidine as a new highly selective radiotracer for peptic ulcer disorder detection

Radiochimica Acta ◽

10.1515/ract-2020-0046 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Mahmoud H. Sanad ◽

Safaa B. Challan ◽

Fawzy A. Marzook ◽

Sayed M. Abd-Elhaliem ◽

Ebtisam A. Marzook

Keyword(s):

Peptic Ulcer ◽

Nuclear Imaging ◽

Radiochemical Yield ◽

Biological Evaluation ◽

Stomach Ulcer ◽

Control Group ◽

Factors Affecting ◽

Biodistribution Studies

AbstractOne of the most famous techniques for stomach ulcer imaging is the nuclear imaging technique. We aim to focus on the synthesis of 125I-cimetidine (125I-cim) as an agent for peptic ulcer imaging. Cimetidine was labeled with Iodine-125 using a different oxidizing agent (Ch-T, NBS). All factors affecting the labeling yield were optimized. The radiochemical yield of 125I-cim was 98 ± 0.22% at optimum conditions. In vitro stability, in vivo biodistribution of 125I-cimetidine was studied in three groups: control group, pretreated group, and ulcer bearing group. In vivo biodistribution studies of 125I-cim revealed high uptake in the stomach ulcer, reaching about 75.4 ± 1.2% ID/g at 15 min post-injection, than pretreated groups compared to the control. The results showed the suitability of using 125I-cimetidine for stomach ulcer imaging.

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Synthesis and Preclinical Evaluation of [18F]PF04217903, a Selective MET PET Tracer

10.26434/chemrxiv.13095764 ◽

2020 ◽

Author(s):

Vegard Torp Lien ◽

Emily Hauge ◽

Syed Nuruddin ◽

Jo Klaveness ◽

Dag Erlend Olberg

Keyword(s):

Growth Factor Receptor ◽

Radiochemical Yield ◽

Molar Activity ◽

Bioisosteric Replacement ◽

Pet Tracer ◽

Positron Emission ◽

Wide Range ◽

Hepatocyte Growth

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ImmunoPET imaging of human CD8+ T cells with novel 68Ga-labeled nanobody companion diagnostic agents

Journal of Nanobiotechnology ◽

10.1186/s12951-021-00785-9 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Haitao Zhao ◽

Chao Wang ◽

Yanling Yang ◽

Yan Sun ◽

Weijun Wei ◽

...

Keyword(s):

T Cells ◽

T Lymphocytes ◽

Treatment Strategies ◽

Radiochemical Yield ◽

Efficacy Evaluation ◽

Positron Emission ◽

Equilibrium Dissociation ◽

Cd8 Antigen

Abstract Background Although immunotherapy has revolutionized treatment strategies for some types of cancers, most patients failed to respond or obtain long-term benefit. Tumor-infiltrating CD8+ T lymphocytes are closely related to the treatment outcome and prognosis of patients. Therefore, noninvasive elucidation of both systemic and tumor-infiltrating CD8+ T lymphocytes is of extraordinary significance for patients during cancer immunotherapy. Herein, a panel of 68Ga-labeled Nanobodies were designed and investigated to track human CD8+ T cells in vivo through immuno-positron emission tomography (immunoPET). Results Among the screened Nanobodies, SNA006a showed the highest binding affinity and specificity to both human CD8 protein and CD8+ cells in vitro, with the equilibrium dissociation constant (KD) of 6.4 × 10−10 M and 4.6 × 10−10 M, respectively. 68Ga-NOTA-SNA006 was obtained with high radiochemical yield and purity, and stayed stable for at least 1 h both in vitro and in vivo. Biodistribution and Micro-PET/CT imaging studies revealed that all tracers specifically concentrated in the CD8+ tumors with low accumulation in CD8− tumors and normal organs except the kidneys, where the tracer was excreted and reabsorbed. Notably, the high uptake of 68Ga-NOTA-SNA006a in CD8+ tumors was rapid and persistent, which reached 24.41 ± 1.00% ID/g at 1.5 h after intravenous injection, resulting in excellent target-to-background ratios (TBRs). More specifically, the tumor-to-muscle, tumor-to-liver, and CD8+ to CD8− tumor was 28.10 ± 3.68, 5.26 ± 0.86, and 19.58 ± 2.70 at 1.5 h, respectively. Furthermore, in the humanized PBMC-NSG and HSC-NPG mouse models, 68Ga-NOTA-SNA006a accumulated in both CD8+ tumors and specific tissues such as liver, spleen and lung where human CD8 antigen was overexpressed or CD8+ T cells located during immunoPET imaging. Conclusions 68Ga-NOTA-SNA006a, a novel Nanobody tracer targeting human CD8 antigen, was developed with high radiochemical purity and high affinity. Compared with other candidates, the long retention time, low background, excellent TBRs of 68Ga-NOTA-SNA006a make it precisely track the human CD8+ T cells in mice models, showing great potential for immunotherapy monitoring and efficacy evaluation.

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