| 1. |
- Mitran, Bogdan, et al.
(författare)
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Radionuclide imaging of VEGFR2 in glioma vasculature using biparatopic affibody conjugate : proof-of-principle in a murine model
- 2018
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Ingår i: Theranostics. - : Ivyspring International Publisher. - 1838-7640. ; 8:16, s. 4462-4476
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor receptor-2 (VEGFR2) is a key mediator of angiogenesis and therefore a promising therapeutic target in malignancies including glioblastoma multiforme (GBM). Molecular imaging of VEGFR2 expression may enable patient stratification for antiangiogenic therapy. The goal of the current study was to evaluate the capacity of the novel anti-VEGFR2 biparatopic affibody conjugate (Z(VEGFR2)-Bp(2)) for in vivo visualization of VEGFR2 expression in GBM. Methods: Z(VEGFR2)-Bp(2) coupled to a NODAGA chelator was generated and radiolabeled with indium-111. The VEGFR2-expressing murine endothelial cell line MS1 was used to evaluate in vitro binding specificity and affinity, cellular processing and targeting specificity in mice. Further tumor targeting was studied in vivo in GL261 glioblastoma orthotopic tumors. Experimental imaging was performed. Results: [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) bound specifically to VEGFR2 (K-D=33 +/- 18 pM). VEGFR2-mediated accumulation was observed in liver, spleen and lungs. The tumor-to-organ ratios 2 h post injection for mice bearing MS1 tumors were approximately 11 for blood, 15 for muscles and 78 for brain. Intracranial GL261 glioblastoma was visualized using SPECT/CT. The activity uptake in tumors was significantly higher than in normal brain tissue. The tumor-to-cerebellum ratios after injection of 4 mu g [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) were significantly higher than the ratios observed for the 40 mu g injected dose and for the non-VEGFR2 binding size-matched conjugate, demonstrating target specificity. Microautoradiography of cryosectioned CNS tissue was in good agreement with the SPECT/CT images. Conclusion: The anti-VEGFR2 affibody conjugate [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) specifically targeted VEGFR2 in vivo and visualized its expression in a murine GBM orthotopic model. Tumor-to-blood ratios for [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) were higher compared to other VEGFR2 imaging probes. [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) appears to be a promising probe for in vivo noninvasive visualization of tumor angiogenesis in glioblastoma.
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| 2. |
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| 3. |
- Altai, Mohamed, et al.
(författare)
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Influence of Nuclides and Chelators on Imaging Using Affibody Molecules : Comparative Evaluation of Recombinant Affibody Molecules Site-Specifically Labeled with Ga-68 and In-111 via Maleimido Derivatives of DOTA and NODAGA
- 2013
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 24:6, s. 1102-1109
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Tidskriftsartikel (refereegranskat)abstract
- Accurate detection of cancer-associated molecular abnormalities in tumors could make cancer treatment more of personalized. Affibody molecules enable high contrast imaging of tumor-associated protein expression shortly after injection. The use should increase sensitivity of HER2 imaging. The chemical nature of the generator-produced positron-emitting radionuclide Ga-68 of radionuclides and chelators influences the biodistribution of Affibody molecules, providing an opportunity to further increase the imaging contrast. The aim of the study was to compare maleimido derivatives of DOTA and NODAGA for site-specific labeling of a recombinant Z(HER2:2395) HER2-binding Affibody molecule with Ga-68. DOTA and NODAGA were site-specifically conjugated to the Z(HER2:2395) Affibody molecule having a C-terminal cysteine and labeled with Ga-68 and In-111. All labeled conjugates retained specificity to HER2 in vitro. Most of the cell-associated activity was membrane-bound with a minor difference in internalization rate. All variants demonstrated specific targeting of xenografts and a high tumor uptake. The xenografts were dearly visualized using all conjugates. The influence of chelator on the biodistribution and targeting properties was much less pronounced for Ga-68 than for In-111. The tumor uptake of Ga-68-NODAGA-Z(HER2:2395) and Ga-68-NODAGA-Z(HER2:2395) and tumor-to-blood ratios at 2 h p.i. did not differ significantly. However, the tumor-to-liver ratio was significantly higher for Ga-68-NODAGA- Z(HER2:2395) (8 +/- 2 vs 5.0 +/- 0.3) offering the advantage of better liver metastases visualization. In conclusion, influence of chelators on biodistribution of Affibody molecules depends on the radionuclides and reoptimization of labeling chemistry is required when a radionuclide label is changed.
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| 4. |
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| 5. |
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| 6. |
- Eriksson, Olof, et al.
(författare)
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In Vivo Visualization of beta-Cells by Targeting of GPR44
- 2018
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 67:2, s. 182-192
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Tidskriftsartikel (refereegranskat)abstract
- GPR44 expression has recently been described as highly beta-cell selective in the human pancreas and constitutes a tentative surrogate imaging biomarker in diabetes. A radiolabeled small-molecule GPR44 antagonist, [C-11]AZ12204657, was evaluated for visualization of beta-cells in pigs and non-human primates by positron emission tomography as well as in immunodeficient mice transplanted with human islets under the kidney capsule. In vitro autoradiography of human and animal pancreatic sections from subjects without and with diabetes, in combination with insulin staining, was performed to assess beta-cell selectivity of the radiotracer. Proof of principle of in vivo targeting of human islets by [C-11]AZ12204657 was shown in the immunodeficient mouse transplantation model. Furthermore, [C-11]AZ12204657 bound by a GPR44-mediated mechanism in pancreatic sections from humans and pigs without diabetes, but not those with diabetes. In vivo [C-11]AZ12204657 bound specifically to GPR44 in pancreas and spleen and could be competed away dose-dependently in nondiabetic pigs and nonhuman primates. [C-11]AZ12204657 is a first-in-class surrogate imaging biomarker for pancreatic beta-cells by targeting the protein GPR44.
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| 7. |
- Eriksson, Olof, et al.
(författare)
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Pancreatic imaging using an antibody fragment targeting the zinc transporter type 8 : a direct comparison with radio-iodinated Exendin-4
- 2018
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Ingår i: Acta Diabetologica. - : Springer. - 0940-5429 .- 1432-5233. ; 55:1, s. 49-57
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Tidskriftsartikel (refereegranskat)abstract
- AIM: The zinc transporter 8 (ZnT8) has been suggested as a suitable target for non-invasive visualization of the functional pancreatic beta cell mass, due to both its pancreatic beta cell restricted expression and tight involvement in insulin secretion.METHODS: In order to examine the potential of ZnT8 as a surrogate target for beta cell mass, we performed mRNA transcription analysis in pancreatic compartments. A novel ZnT8 targeting antibody fragment Ab31 was radiolabeled with iodine-125, and evaluated by in vitro autoradiography in insulinoma and pancreas as well as by in vivo biodistribution. The evaluation was performed in a direct comparison with radio-iodinated Exendin-4.RESULTS: Transcription of the ZnT8 mRNA was higher in islets of Langerhans compared to exocrine tissue. Ab31 targeted ZnT8 in the cytosol and on the plasma membrane with 108 nM affinity. Ab31 was successfully radiolabeled with iodine-125 with high yield and > 95% purity. [(125)I]Ab31 binding to insulinoma and pancreas was higher than for [(125)I]Exendin-4, but could only by partially competed away by 200 nM Ab31 in excess. The in vivo uptake of [(125)I]Ab31 was higher than [(125)I]Exendin-4 in most tissues, mainly due to slower clearance from blood.CONCLUSIONS: We report a first-in-class ZnT8 imaging ligand for pancreatic imaging. Development with respect to ligand miniaturization and radionuclide selection is required for further progress. Transcription analysis indicates ZnT8 as a suitable target for visualization of the human endocrine pancreas.
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| 8. |
- Eriksson, Olof, et al.
(författare)
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Species differences in pancreatic binding of DO3A-VS-Cys40-Exendin4
- 2017
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Ingår i: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 54:11, s. 1039-1045
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Radiolabeled Exendin-4 has been proposed as suitable imaging marker for pancreatic beta cell mass quantification mediated by Glucagon-like peptide-1 receptor (GLP-1R). However, noticeable species variations in basal pancreatic uptake as well as uptake reduction degree due to selective beta cell ablation were observed.METHODS: -Exendin4 Positron Emission Tomography (PET) in the same species. In vitro, ex vivo, and in vivo data formed the basis for calculating the theoretical in vivo contribution of each pancreatic compartment.RESULTS: -Exendin4.CONCLUSIONS: IPR as well as the exocrine GLP-1R density is the main determinants of the species variability in pancreatic uptake. Thus, the IPR in human is an important factor for assessing the potential of GLP-1R as an imaging biomarker for pancreatic beta cells.
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| 9. |
- Espes, Daniel, 1985-, et al.
(författare)
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Longitudinal Assessment of 11C-5-Hydroxytryptophan Uptake in Pancreas After Debut of Type 1 Diabetes
- 2021
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 70:4, s. 966-975
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Tidskriftsartikel (refereegranskat)abstract
- The longitudinal alterations of the pancreatic β-cell and islet mass in the progression of type 1 diabetes (T1D) are still poorly understood. The objective of this study was to repeatedly assess the endocrine volume and the morphology of the pancreas for up to 24 months after T1D diagnosis (n = 16), by 11C-5-hydroxytryptophan (11C-5-HTP) positron emission tomography (PET) and MRI. Study participants were examined four times by PET/MRI: at recruitment and then after 6, 12, and 24 months. Clinical examinations and assessment of β-cell function by a mixed-meal tolerance test and fasting blood samples were performed in connection with the imaging examination. Pancreas volume has a tendency to decrease from 50.2 ± 10.3 mL at T1D debut to 42.2 ± 14.6 mL after 24 months (P < 0.098). Pancreas uptake of 11C-5-HTP (e.g., the volume of the endocrine pancreas) did not decrease from T1D diagnosis (0.23 ± 0.10 % of injected dose) to 24-month follow-up, 0.21 ± 0.14% of injected dose, and exhibited low interindividual changes. Pancreas perfusion was unchanged from diagnosis to 24-month follow-up. The pancreas uptake of 11C-5-HTP correlated with the long-term metabolic control as estimated by HbA1c (P < 0.05). Our findings argue against a major destruction of β-cell or islet mass in the 2-year period after diagnosis of T1D.
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| 10. |
- Estrada, Sergio, et al.
(författare)
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Preclinical evaluation of [C-11]GW457427 as a tracer for neutrophil elastase
- 2022
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Ingår i: Nuclear Medicine and Biology. - : Elsevier. - 0969-8051 .- 1872-9614. ; 106-107, s. 62-71
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Neutrophils are part of the innate immune system and function as a first line of defense against invading microorganisms. Overactivity of the immune system may result in a devastating immuno-inflammation with extensive damage to tissue leading to organ damage and/or failure. The literature suggests several human diseases in which neutrophil elastase (NE) is postulated to be important in the pathophysiology including inflammatory bowel disease (IBD), chronic obstructive pulmonary disorder (COPD), abdominal aortic aneurysms (AAA), breast and lung cancer, and recently also in Sars-cov-2 virus infection (Covid-19). In particular, the lungs are affected by the destructive power of the protease neutrophil elastase (NE). In this paper, we report the pre-clinical development of a selective and specific positron emission tomography (PET) tracer, [C-11] GW457427, as an in vivo biomarker for the study of NE, now available for human studies.Methods: [C-11]GW457427 was produced by methylation of GW447631 using [C-11]methyl triflate and GMP validated production and quality control methods were developed. Chemical purity was high with no traces of the precursor GW611437 or other uv-absorbing compounds. A method for the determination of intact [C-11] GW457427 in plasma was developed and the binding characteristics were evaluated in vitro and in vivo. An animal model for lung inflammation was used to investigate the specificity and sensitivity of the [C-11]GW457427 tracer for neutrophil elastase (NE) in pulmonary inflammation, verified by blockade using two structurally different elastase inhibitors.Results: [C-11]GW457427 was obtained in approximately 45% radiochemical yield and with a radiochemical purity higher than 98%. Molar activity was in the range 130-360 GBq/mu mol. Binding to NE was shown to be highly specific both in vitro and in vivo and a significantly higher uptake of tracer was found in a lipopolysaccharide mouse model of pulmonary inflammation compared with control animals. The uptake in lung tissue measured as standardized uptake value (SUV) strongly correlated with tissue NE content as measured by ELISA. In vitro studies also showed specific tracer binding in aortic tissue of patients with abdominal aorta aneurysm (AAA). The rate of metabolism in rats was appropriate considering the critical balance between available tracer for binding and requirement for blood clearance with about 40% and 20% intact [C-11]GW457427 in plasma at 5 and 40 min, respectively. Radioactivity was cleared from blood and organs in control animals with mainly hepatobiliary excretion with distribution in the intestines and the urinary bladder; but without retention of the tracer in healthy organs of interests such as the lung, liver, kidneys or in the cardiovascular system. A dosimetry study in rat indicated that the whole-body effective dose was 2.2 mu Sv/MBq with bone marrow as the limiting organ. It is estimated that up to five PET-CT investigations could be performed in humans without exceeding a total dose of 10 mSv.Conclusion: [C-11]GW457427 is a promising in vivo PET-biomarker for NE with high specific binding demonstrated both in vitro and in vivo. A GMP validated production method including quality control has been developed and a microdosing toxicity study performed with no adverse signs. [C-11]GW457427 is currently being evaluated in a First-In-Man PET study.
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| 11. |
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| 12. |
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| 13. |
- Honarvar, Hadis, et al.
(författare)
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Position for site-specific attachment of a DOTA chelator to synthetic affibody molecules has a different influence on the targeting properties of 68Ga-Compared to 111in-labeled conjugates
- 2014
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Ingår i: Molecular Imaging. - : SAGE Publications. - 1535-3508 .- 1536-0121. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules, small (7 kDa) scaffold proteins, are a promising class of probes for radionuclide molecular imaging. Radiolabeling of Affibody molecules with the positron-emitting nuclide 68Ga would permit the use of positron emission tomography (PET), providing better resolution, sensitivity, and quantification accuracy than single-photon emission computed tomography (SPECT). The synthetic anti-HER2 ZHER2:S1 Affibody molecule was conjugated with DOTA at the N-terminus, in the middle of helix 3, or at the Cterminus. The biodistribution of 68Ga-and 111In-labeled Affibody molecules was directly compared in NMRI nu/nu mice bearing SKOV3 xenografts. The position of the chelator strongly influenced the biodistribution of the tracers, and the influence was more pronounced for 68Ga-labeled Affibody molecules than for the 111In-labeled counterparts. The best 68Ga-labeled variant was 68Ga-[DOTA-A1]-ZHER2:S1, which provided a tumor uptake of 13 ± 1 %ID/g and a tumor to blood ratio of 39 ± 12 at 2 hours after injection. 111In-[DOTA-A1]-ZHER2:S1 and 111In-[DOTA-K58]-ZHER2:S1 were equally good at this time point, providing a tumor uptake of 15 to 16 %ID/g and a tumor to blood ratio in the range of 60 to 80. In conclusion, the selection of the best position for a chelator in Affibody molecules can be used for optimization of their imaging properties. This may be important for the development of Affibody-based and other protein-based imaging probes.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Mitran, Bogdan, et al.
(författare)
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Selection of optimal chelator improves the contrast of GRPR imaging using bombesin analogue RM26.
- 2016
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Ingår i: International journal of oncology. - : Spandidos Publications. - 1791-2423 .- 1019-6439. ; 48:5, s. 2124-2134
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Tidskriftsartikel (refereegranskat)abstract
- Bombesin (BN) analogs bind with high affinity to gastrin-releasing peptide receptors (GRPRs) that are up-regulated in prostate cancer and can be used for the visualization of prostate cancer. The aim of this study was to investigate the influence of radionuclide-chelator complexes on the biodistribution pattern of the 111In-labeled bombesin antagonist PEG2-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (PEG2-RM26) and to identify an optimal construct for SPECT imaging. A series of RM26 analogs N-terminally conjugated with NOTA, NODAGA, DOTA and DOTAGA via a PEG2 spacer were radiolabeled with 111In and evaluated both in vitro and in vivo. The conjugates were successfully labeled with 111In with 100% purity and retained binding specificity to GRPR and high stability. The cellular processing of all compounds was characterized by slow internalization. The IC50 values were in the low nanomolar range, with lower IC50 values for positively charged natIn-NOTA-PEG2-RM26 (2.6±0.1 nM) and higher values for negatively charged natIn-DOTAGA-PEG2-RM26 (4.8±0.5 nM). The kinetic binding studies showed KD values in the picomolar range that followed the same pattern as the IC50 data. The biodistribution of all compounds was studied in BALB/c nu/nu mice bearing PC-3 prostate cancer xenografts. Tumor targeting and biodistribution studies displayed rapid clearance of radioactivity from the blood and normal organs via kidney excretion. All conjugates showed similar uptake in tumors at 4 h p.i. The radioactivity accumulation in GRPR-expressing organs was significantly lower for DOTA- and DOTAGA-containing constructs compared to those containing NOTA and NODAGA. 111In-NOTA-PEG2-RM26 with a positively charged complex showed the highest initial uptake and the slowest clearance of radioactivity from the liver. At 4 h p.i., DOTA- and DOTAGA-coupled analogs showed significantly higher tumor-to-organ ratios compared to NOTA- and NODAGA-containing variants. The NODAGA conjugate demonstrated the best retention of radioactivity in tumors, and, at 24 h p.i., had the highest contrast to blood, muscle and bones.
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| 18. |
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| 19. |
- Nordeman, Patrik, Docent, et al.
(författare)
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18F-Radiolabeling and Preliminary Evaluation of a HSP90 ligand
- 2021
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: With the ambition of improving the management of pancreatic neuroendocrine tumors (P-NETs), we developed and preliminary validated a novel fluorine-18 labelled HSP90 ligand.METHODS: A precursor containing methoxymethyl ethers protecting groups and a tosyl as leaving group was synthesized. The target compound was labeled with nucleophilic 18F-fluoride and the protecting groups was subsequently removed with hydrochloric acid before purification. In vitro cell- and frozen section autoradiography and in vivo animal studies were performed.RESULTS: The precursor was successfully synthesized and utilized in the 18F-radiolabeling giving 0.5-1.0 GBq of pure product with a synthesis time of 70 min. In vitro experiments indicated a high specific binding, but in vivo studies showed no tumor uptake due to fast hepatobiliary metabolism and excretion.CONCLUSIONS: Despite the unfavorable in vivo properties of the tracer, the promising results from in vitro autoradiography experiments in frozen sections of P-NETs from surgical resection encourage us to continue the project aiming the improvement of in vivo properties of the tracer.
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| 20. |
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| 21. |
- Orlova, Anna, et al.
(författare)
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Imaging of HER3-expressing xenografts in mice using a Tc-99m(CO)(3)-HEHEHE-Z(HER3:08699) affibody molecule
- 2014
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 41:7, s. 1450-1459
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Tidskriftsartikel (refereegranskat)abstract
- Human epidermal growth factor receptor type 3 (HER3) is a transmembrane receptor tyrosine kinase belonging to the HER (ErbB) receptor family. Membranous expression of HER3 is associated with trastuzumab resistance in breast cancer and the transition to androgen independence in prostate cancer. Imaging of HER3 expression in malignant tumors may provide important diagnostic information that can influence patient management. Affibody molecules with low picomolar affinity to HER3 were recently selected. The aim of this study was to investigate the feasibility of HER3 imaging using radiolabeled Affibody molecules. A HER3-binding Affibody molecule, Z(08699), with a HEHEHE-tag on N-terminus was labeled with Tc-99m(CO)(3) using an IsoLink kit. In vitro and in vivo binding specificity and the cellular processing of the labeled binder were evaluated. Biodistribution of Tc-99m(CO)(3)-HEHEHE-Z(08699) was studied over time in mice bearing HER3-expressing xenografts. HEHEHE-Z(08699) was labeled with Tc-99m(CO)(3) with an isolated yield of > 80 % and a purity of > 99 %. Binding of Tc-99m(CO)(3)-HEHEHE-Z(08699) was specific to BT474 and MCF7 (breast cancer), and LS174T (colon cancer) cells. Cellular processing showed rapid binding and relatively quick internalization of the receptor/Affibody molecule complex (70 % of cell-associated radioactivity was internalized after 24 h). The tumor targeting was receptor mediated and the excretion was predominantly renal. Receptor-mediated uptake was also found in the liver, lung, stomach, intestine, and salivary glands. At 4 h pi, tumor-to-blood ratios were 7 +/- 3 for BT474, and 6 +/- 2 for LS174T xenografts. LS174T tumors were visualized by microSPECT 4 h pi. The results of this study suggest the feasibility of HER3-imaging in malignant tumors using Affibody molecules.
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| 22. |
- Rosik, Daniel, et al.
(författare)
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Incorporation of a Triglutamyl Spacer Improves the Biodistribution of Synthetic Affibody Molecules Radiofluorinated at the N-Terminus via Oxime Formation with F-18-4-Fluorobenzaldehyde
- 2014
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 25:1, s. 82-92
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are a class of affinity agents for molecular imaging based on a non-immunoglobulin protein scaffold. Previous studies have demonstrated high contrast for in vivo imaging of cancer-associated molecular abnormalities using Affibody molecules. Using the radionuclide F-18 for labeling and PET as the imaging modality, the sensitivity of molecular imaging using Affibody molecules can be further increased. The use of oxime formation between an aminooxy-functionalized peptide and F-18-fluorobenzaldehyde (F-18-FBA) is a promising way of radiolabeling of targeting peptides. However, previous studies demonstrated that application of this method to Affibody molecules is associated with high liver uptake. We hypothesized that incorporation of a triglutamyl spacer between the aminooxy moiety and the N-terminus of a synthetic Affibody molecule would decrease the hepatic uptake of the F-18-N-(4-fluorobenzylidine)oxime) (F-18-FBO)-labeled tracer. To verify this, we have produced two variants of the HER2-targeting Z(HER2:342) Affibody molecule by peptide synthesis: OA-PEP4313, where aminooxyacetic acid was conjugated directly to the N-terminal alanine, and OA-E-3-PEP4313, where a triglutamyl spacer was introduced between the aminooxy moiety and the N-terminus. We have found that the use of the spacer is associated with a minor decrease of affinity, from K-D = 49 pM to K-D = 180 pM. Radiolabeled F-18-FBO-E-3-PEP4313 demonstrated specific binding to HER2-expressing ovarian carcinoma SKOV-3 cells and slow internalization. Biodistribution studies in mice demonstrated that the use of a triglutamyl linker decreased uptake of radioactivity in liver 2.7-fold at 2 h after injection. Interestingly, radioactivity uptake in kidneys was also reduced (2.4-fold). Experiments in BALB/C nu/nu mice bearing SKOV-3 xenografts demonstrated HER2-specific uptake of F-18-FBO-E-3-PEP4313 in tumors. At 2 h pi, the tumor uptake (20 +/- 2% ID/g) exceeded uptake in liver 5-fold and uptake in kidneys 3.6-fold. The tumor-to-blood ratio was 21 +/- 3. The microPET/CT imaging experiment confirmed the biodistribution data. In conclusion, the use of a triglutamyl spacer is a convenient way to improve the biodistribution profile of Affibody molecules labeled at the N-terminus using F-18-FBA. It provides a tracer capable of producing high-contrast images of HER2-expressing tumors.
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| 23. |
- Samanta, Sumanta, et al.
(författare)
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Heparin-Derived Theranostic Nanoprobes Overcome the Blood-Brain Barrier and Target Glioma in Murine Model
- 2022
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Ingår i: Advanced Therapeutics. - : John Wiley & Sons. - 2366-3987. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- The poor permeability of theranostic agents across the blood-brain barrier (BBB) significantly hampers the development of new treatment modalities for neurological diseases. A new biomimetic nanocarrier is discovered using heparin (HP) that effectively passes the BBB and targets glioblastoma. Specifically, HP-coated gold nanoparticles (HP-AuNPs) are designed that are labeled with three different imaging modalities namely, fluorescein (FITC-HP-AuNP), radioisotope (68)Gallium (Ga-68-HP-AuNPs), and MRI active gadolinium (Gd-HP-AuNPs). The systemic infusion of FITC-HP-AuNPs in three different mouse strains (C57BL/6JRj, FVB, and NMRI-nude) displays excellent penetration and reveals uniform distribution of fluorescent particles in the brain parenchyma (69-86%) with some accumulation in neurons (8-18%) and microglia (4-10%). Tail-vein administration of radiolabeled Ga-68-HP-AuNPs in healthy rats also show Ga-68-HP-AuNP inside the brain parenchyma and in areas containing cerebrospinal fluid, such as the lateral ventricles, the cerebellum, and brain stem. Finally, tail-vein administration of Gd-HP-AuNPs (that displays approximate to threefold higher relaxivity than that of commercial Gd-DTPA) in an orthotopic glioblastoma (U87MG xenograft) model in nude mice demonstrates enrichment of T1-contrast at the intracranial tumor with a gradual increase in the contrast in the tumor region between 1 and 3 h. It is believed, the finding offers the untapped potential of HP-derived-NPs to deliver cargo molecules for treating neurological disorders.
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| 24. |
- Sellberg, Felix, et al.
(författare)
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A novel polymer-based carbonyl scavenger for the detection of ischemic tissues
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- PurposePolyvinylalcohol-carbazate (PVAC) is a soluble functionalized polymer acting as a carbonyl scavenger. This study aimed to create a radiolabelled PVAC and investigate the pharmacokinetics and biodistribution of PVAC in naïve animals and ischemia models. MethodsPVAC was labelled using radionuclide [18F]FBA to track the substance with PET. Sprague Dawley rats underwent an ischemic event, either to the hind limb or to the kidney, while others served as controls. To study the pharmacokinetics rats were injected with radiolabelled or fluorochrome labelled PVAC. Radiolabelled PVAC was injected, and animals were followed by PET for 90 min, biodistribution ex vivo was finally examined. Injection of fluorochrome-labelled PVAC was followed by repeated blood sampling to measure the circulating concentration. ResultsIn control animals, PVAC was mainly confined to the bloodstream followed by elimination via kidneys and accumulation in the bladder. Ex vivo biodistribution of PVAC confirmed the highest uptake in urine followed by blood, kidneys and other well-perfused organs. The elimination of I.V. administered PVAC was split into a fast phase (t1/2 = 0.2 h) followed by a slow phase (t1/2 = 10.73 h), with near-complete elimination from blood after 48 h. Both the ischemic kidney (fourfold increase, p = <0.001) and limb models (threefold increase, p = <0.001) demonstrated a higher uptake of PVAC in ischemic tissues, ex vivo radioactivity detection.ConclusionLabelled PVAC, an aldehyde-carbonyl scavenger, is a promising new strategy to detect ischemic tissues. Potential therapeutic effects of PVAC on ischemic injuries should be investigated further.
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| 25. |
- Selvaraju, Ram kumar, 1987-
(författare)
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[68Ga]Exendin-4: Bench-to-Bedside : PET molecular imaging of the GLP-1 receptor for diabetes and cancer
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetes epidemic is underway. Beta cell dysfunction (BCF) and loss of beta cell mass (BCM) are known to be key events in its progression. Currently, there are no reliable techniques to estimate or follow the loss of BCM, in vivo. Non-invasive imaging and quantification of the whole BCM in the pancreas, therefore, has a great potential for understanding the progression of diabetes and the scope for early diagnosis for Type 2 diabetes.Glucagon-like peptide-1 receptor (GLP-1R) is known to be selectively expressed on the pancreatic beta cells and overexpressed on the insulinoma, a pancreatic neuroendocrine tumor (PNET). Therefore, this receptor is considered to be a selective imaging biomarker for the beta cells and the insulinoma. Exendin-4 is a naturally occurring analog of GLP-1 peptide. It binds and activates GLP-1R with same the potency and engages in the insulin synthesis, with a longer biological half-life. In this thesis, Exendin-4 precursor, DO3A-VS-Cys40-Exendin-4 labeled with [68Ga], [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 ([68Ga]Exendin-4), was evaluated in different species models, namely, immune deficient nude mice, rats, pigs, non-human primate (NHP), and clinically in one insulinoma patient by positron emission tomography (PET), for its potential in beta cell imaging and its quantification as well as for visualizing the insulinoma. From internal dosimetry, the possible number of repetitive [68Ga]Exendin-4-PET/CT scans was estimated.Pancreatic uptake and insulinoma tumor uptake of [68Ga]Exendin-4 were confirmed to be mediated by the specific binding to the GLP-1R. Pancreatic GLP-1R could be visualized and semi-quantified, for diabetic studies, except in rats. Nonetheless, we found conflicting results regarding the GLP-1R being a selective imaging biomarker for the beta cells. PET/CT scan of the patient with [68Ga]Exendin-4 has proven to be more sensitive than the clinical neuroendocrine tracer, [11C]5-HTP, as it could reveal small metastatic tumors in liver. The kidney was the dose-limiting organ in the entire species model, from absorbed dose estimation. Before reaching a yearly kidney limiting dose of 150 mGy and a whole body effective dose of 10 mSv, 2–4 [68Ga]Exendin-4 PET/CT scans be performed in an adult human, which enables longitudinal clinical PET imaging studies of the GLP-1R in the pancreas, transplanted islets, or insulinoma, as well as in healthy volunteers enrolled in the early phase of anti-diabetic drug development studies.
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| 26. |
- Selvaraju, Ram Kumar, et al.
(författare)
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Dosimetry of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in rodents, pigs, non-human primates and human - : repeated scanning in human is possible.
- 2015
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Ingår i: American journal of nuclear medicine and molecular imaging. - 2160-8407. ; 5:3, s. 259-69
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative PET imaging with [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 has potential use in diabetes and cancer. However, the radiation dose to the kidneys has been a concern for the possibility of repeated imaging studies in humans. Therefore, we investigated the dosimetry of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 based on the biodistribution data in rats, pigs, non-human primates (NHP) and a human.Organ distribution of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in rats (Male Lewis; n=12; 30, 60, and 80 min) was measured ex vivo. The dynamic uptake of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in the abdomen was assessed by PET/CT scanning of pigs (male; n = 4, 0-60 min), NHP (Female; cynomolgus; n=3; 0-90 min), and human (female; n=1; 0-40, 100, 120 min).The organ distribution data in each species were extrapolated to those of a human, assuming similar distribution between the species. Residence times were assessed by trapezoidal approximation of the kinetic data. Organ doses (mGy/MBq) and the whole body effective dose (mSv/MBq), was extrapolated by using the OLINDA/EXM 1.1 software. The extrapolated human whole body effective dose was 0.017 ± 0.004 (rats), 0.014 ± 0.004 (pigs), 0.017 ± 0.004 (NHP), and 0.016 (human) mSv/MBq. The absorbed dose to the kidneys was limiting:0.33 ± 0.06 (rats), 0.28±0.05 (pigs), 0.65 ± 0.11 (NHP), and 0.28 (human) mGy/MBq, which corresponded to the maximum yearly administered amounts of 455 (rat), 536 (pig), 231 (NHP), and 536 (human) MBq before reaching the yearly kidney limiting dose of 150 mGy. More than 200 MBq of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 can be administered yearly in a human, allowing for repeated (2-4 times) scanning. This potentially enables longitudinal clinical PET imaging studies of the GLP-1R in the pancreas, transplanted islets, or insulinoma.
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| 31. |
- Selvaraju, Ram Kumar, et al.
(författare)
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Pre-clinical evaluation of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 for imaging of insulinoma
- 2014
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Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 41:6, s. 471-476
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Insulinoma is the most common form of pancreatic endocrine tumors responsible for hyperinsulinism in adults. These tumors overexpress glucagon like peptide-1 (GLP-1) receptor, and biologically stable GLP-1 analogs have therefore been proposed as potential imaging agents. Here, we evaluate the potential of a positron emission tomography (PET) tracer, [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4, for imaging and quantification of GLP-1 receptors (GLP-1R) in insulinoma.METHODS: [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 was evaluated for binding to GLP-1R by in vitro autoradiography binding studies in INS-1 tumor from xenografts. In vivo biodistribution was investigated in healthy control mice, INS-1 xenografted and PANC1 xenografted immunodeficient mice at two different doses of peptide: 2.5μg/kg (baseline) and 100μg/kg (block). In vivo imaging of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in xenografted mice was evaluated by small animal PET/CT using a direct comparison with the clinically established insulinoma marker [(11)C]5-hydroxy-tryptophan ([(11)C]5-HTP).RESULTS: GLP-1 receptor density could be quantified in INS-1 tumor biopsies. [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 showed significant uptake (p≤0.05) in GLP1-R positive tissues such as INS-1 tumor, lungs and pancreas upon comparison between baseline and blocking studies. In vivo imaging showed concordant results with higher tumor-to-muscle ratio in INS-1 xenografted mice compared with [(11)C]5-HTP.CONCLUSION: [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 has high affinity and specificity for GLP-1R expressed on insulinoma in vitro and in vivo.
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| 32. |
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| 35. |
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| 36. |
- Strand, Joanna, et al.
(författare)
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Influence of Macrocyclic Chelators on the Targeting Properties of Ga-68-Labeled Synthetic Affibody Molecules : Comparison with In-111-Labeled Counterparts
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8, s. e70028-
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are a class of small (7 kDa) non-immunoglobulin scaffold-based affinity proteins, which have demonstrated substantial potential as probes for radionuclide molecular imaging. The use of positron emission tomography (PET) would further increase the resolution and quantification accuracy of Affibody-based imaging. The rapid in vivo kinetics of Affibody molecules permit the use of the generator-produced radionuclide Ga-68 (T-1/2 = 67.6 min). Earlier studies have demonstrated that the chemical nature of chelators has a substantial influence on the biodistribution properties of Affibody molecules. To determine an optimal labeling approach, the macrocyclic chelators 1,4,7,10-tetraazacylododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-N,N,N-triacetic acid (NOTA) and 1-(1,3-carboxypropyl)-1,4,7- triazacyclononane-4,7-diacetic acid (NODAGA) were conjugated to the N-terminus of the synthetic Affibody molecule Z(HER2:S1) targeting HER2. Affibody molecules were labeled with Ga-68, and their binding specificity and cellular processing were evaluated. The biodistribution of Ga-68-DOTA-Z(HER2:S1), Ga-68-NOTA-Z(HER2:S1) and Ga-68-NODAGA-Z(HER2:S1), as well as that of their In-111-labeled counterparts, was evaluated in BALB/C nu/nu mice bearing HER2-expressing SKOV3 xenografts. The tumor uptake for Ga-68-DOTA-Z(HER2:S1) (17.9 +/- 0.7%IA/g) was significantly higher than for both Ga-68-NODAGA-Z(HER2:S1) (16.13 +/- 0.67%IA/g) and Ga-68-NOTA-Z(HER2:S1) (13 +/- 3%IA/g) at 2 h after injection. Ga-68-NODAGA-Z(HER2:S1) had the highest tumor-to-blood ratio (60 +/- 10) in comparison with both Ga-68-DOTA-Z(HER2:S1) (28 +/- 4) and Ga-68-NOTA-Z(HER2:S1) (42 +/- 11). The tumor-to-liver ratio was also higher for Ga-68-NODAGA-Z(HER2:S1) (7 +/- 2) than the DOTA and NOTA conjugates (5.5 +/- 0.6 vs. 3.3 +/- 0.6). The influence of chelator on the biodistribution and targeting properties was less pronounced for Ga-68 than for In-111. The results of this study demonstrate that macrocyclic chelators conjugated to the N-terminus have a substantial influence on the biodistribution of HER2-targeting Affibody molecules labeled with Ga-68. This can be utilized to enhance the imaging contrast of PET imaging using Affibody molecules and improve the sensitivity of molecular imaging. The study demonstrated an appreciable difference of chelator influence for Ga-68 and In-111.
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| 37. |
- Tugues, Sònia, et al.
(författare)
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Histidine-Rich Glycoprotein Uptake and Turnover Is Mediated by Mononuclear Phagocytes.
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9, s. e107483-
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Tidskriftsartikel (refereegranskat)abstract
- Histidine-rich glycoprotein (HRG) is implicated in tumor growth and metastasis by regulation of angiogenesis and inflammation. HRG is produced by hepatocytes and carried to tissues via the circulation. We hypothesized that HRG's tissue distribution and turnover may be mediated by inflammatory cells. Biodistribution parameters were analyzed by injection of radiolabeled, bioactive HRG in the circulation of healthy and tumor-bearing mice. 125I-HRG was cleared rapidly from the blood and taken up in tissues of healthy and tumor-bearing mice, followed by degradation, to an increased extent in the tumor-bearing mice. Steady state levels of HRG in the circulation were unaffected by the tumor disease both in murine tumor models and in colorectal cancer (CRC) patients. Importantly, stromal pools of HRG, detected in human CRC microarrays, were associated with inflammatory cells. In agreement, microautoradiography identified 125I-HRG in blood vessels and on CD45-positive leukocytes in mouse tissues. Moreover, radiolabeled HRG bound in a specific, heparan sulfate-independent manner, to differentiated human monocytic U937 cells in vitro. Suppression of monocyte differentiation by systemic treatment of mice with anti-colony stimulating factor-1 neutralizing antibodies led to reduced blood clearance of radiolabeled HRG and to accumulation of endogenous HRG in the blood. Combined, our data show that mononuclear phagocytes have specific binding sites for HRG and that these cells are essential for uptake of HRG from blood and distribution of HRG in tissues. Thereby, we confirm and extend our previous report that inflammatory cells mediate the effect of HRG on tumor growth and metastatic spread.
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| 38. |
- Varasteh, Zohreh, et al.
(författare)
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Synthesis and Characterization of a High-Affinity NOTA-Conjugated Bombesin Antagonist for GRPR-Targeted Tumor Imaging
- 2013
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 24:7, s. 1144-1153
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Tidskriftsartikel (refereegranskat)abstract
- The gastrin-releasing peptide receptor (GRPR/BB2) is a molecular target for the visualization of prostate cancer. This work focused on the development of high-affinity, hydrophilic, antagonistic, bombesin-based imaging agents for PET and SPECT. The bombesin antagonist analog D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 ([D-Phe(6),Sta(13),Leu(14)]-bombesin[6-14]) was synthesized and conjugated to 1,4,7-triazacyclononane-N,N',N ''-triacetic acid (NOTA) via a diethylene glycol (PEG(2)) linker. The resulting conjugate, NOTA-PEG(2)-[D-Phe(6),Sta(13),Leu(14)]bombesin[6-14] (NOTA-P2-RM26), was labeled with Ga-68 (T-1/2 = 68 min, positron emitter) and In-111 (T-1/2 = 2.8 days, gamma emitter). The labeling stability, specificity, inhibition efficiency (IC50), and dissociation constant (K-D) of both labeled compounds as well as their cellular retention and internalization were investigated. The pharmacokinetics of the dual isotope) (In-111/Ga-68)-labeled peptide in both normal NMRI mice and PC-3 tumor-bearing Balb/c nu/nu mice was also studied. NOTA-P2-RM26 was labeled with In-111 and Ga-68 at a radiochemical yield of >98%. Both conjugates were shown to have high specificity and binding affinity for GRPR. The K-D value was determined to be 23 +/- 13 pM for the In-111-labeled compound in a saturation binding experiment. In addition, In-nat- and Ga-nat-NOTA-P2-RM26 showed low nanomolar binding inhibition concentrations (IC50 = 1.24 +/- 0.29 nM and 0.91 +/- 0.19 nM, respectively) in a competitive binding assay. The internalization rate of the radiolabeled conjugates was slow. The radiometal-labeled tracers demonstrated rapid blood clearance via the kidney and GRPR-specific uptake in the pancreas in normal mice. Tumor targeting and biodistribution studies in mice bearing PC-3 xenografts displayed high and specific uptake in tumors (8.1 +/- 0.4%ID/g for Ga-68 and 5.7 +/- 0.3%ID/g for In-111) and high tumor-to-background ratios (tumor/blood: 12 +/- 1 for Ga-68 and 10 +/- 1 for In-111) after only 1 h pi of 45 pmol of peptide. The xenografts were visualized by gamma and microPET cameras shortly after injection. In conclusion, the antagonistic bombesin analog NOTA-PEG(2)-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (NOTA-P2-RM26) is a promisindg candidate for prostate cancer imaging using PET and SPECT/CT.
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| 39. |
- Velikyan, Irina, et al.
(författare)
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Dosimetry of [(177)Lu]-DO3A-VS-Cys(40)-Exendin-4 - impact on the feasibility of insulinoma internal radiotherapy.
- 2015
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Ingår i: American journal of nuclear medicine and molecular imaging. - 2160-8407. ; 5:2, s. 109-26
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Tidskriftsartikel (refereegranskat)abstract
- [(68)Ga]-DO3A-VS-Cys(40)-Exendin-4 has been shown to be a promising imaging candidate for targeting glucagon like peptide-1 receptor (GLP-1R). In the light of radiotheranostics and personalized medicine the (177)Lu-labelled analogue is of paramount interest. In this study we have investigated the organ distribution of [(177)Lu]-DO3A-VS-Cys(40)-Exendin-4 in rat and calculated human dosimetry parameters in order to estimate the maximal acceptable administered radioactivity, and thus potential applicability of [(177)Lu]-DO3A-VS-Cys(40)-Exendin-4 for internal radiotherapy of insulinomas. Nine male and nine female Lewis rats were injected with [(177)Lu]-DO3A-VS-Cys(40)-Exendin-4 for ex vivo organ distribution study at nine time points. The estimation of human organ/total body absorbed and total effective doses was performed using Organ Level Internal Dose Assessment Code software (OLINDA/EXM 1.1). Six more rats (male: n = 3; female: n = 3) were scanned by single photon emission tomography and computed tomography (SPECT-CT). The renal function and potential cell dysfunction were monitored by creatinine ISTAT and glucose levels. The fine uptake structure of kidney and pancreas was investigated by ex vivo autoradiography. Blood clearance and washout from most of the organs was fast. The kidney was the dose-limiting organ with absorbed dose of 5.88 and 6.04 mGy/MBq, respectively for female and male. Pancreatic beta cells demonstrated radioactivity accumulation. Renal function and beta cell function remained unaffected by radiation. The absorbed dose of [(177)Lu]-DO3A-VS-Cys(40)-Exendin-4 to kidneys may limit the clinical application of the agent. However, hypothetically, kidney protection and peptidase inhibition may allow reduction of kidney absorbed dose and amplification of tumour absorbed doses.
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