| 1. |
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| 2. |
- Alhuseinalkhudhur, Ali
(författare)
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HER2-receptor quantification in breast cancer patients by imaging with ABY-025 Affibody and PET
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Breast cancer is the most common malignancy in women worldwide. Human epidermal growth factor receptor type 2 (HER2) is overexpressed in up to 20% of breast cancer cases and is considered an important prognostic factor and a therapeutic target. With the introduction of HER2-targeted therapy, it was important to recognize patients who will likely benefit from such treatment. Immunohistochemistry staining performed on a tumor biopsy, with in situ hybridization to detect gene amplification if needed, is the current gold standard method for HER2 receptor quantification. However, in cases with multiple metastases, it is both unfeasible and impractical to perform multiple biopsies without risking higher morbidity. Molecular imaging with tracers specifically targeting HER2 receptors provides a non-invasive approach, which allows full body quantification without the serious side effects associated with invasive biopsies. The molecule of focus in this thesis work is Affibody ZHER2:2891 (ABY-025) molecule that has a high affinity and selectivity towards HER2 receptors.This thesis is based on four original articles. The first part focused on the aspect of breast cancer imaging using HER2-targeting gallium-labeled tracer 68Ga-ABY-025 in positron emission tomography (PET) and its role in predicting breast cancer outcome. The second part was to investigate the effect of different risk factors on developing brain metastasis, the overall survival and the effect of HER2-targeted treatment on breast cancer brain metastasis based on Uppsala County cancer registry.We demonstrated that HER2-binding Affibody PET kinetics can be explained using a two-tissue compartment model and SUV values correlated well with the influx rates calculated using kinetic modeling, supporting its use to measure actual HER2 receptor binding. Phase II study demonstrated the potential of 68Ga-ABY-025 PET to predict the treatment outcome more accurately compared to biopsy HER2-status that uses the traditional immunohistochemistry staining and in situ hybridization techniques. 68Ga-ABY-025 PET provided accurate staging and reduced false positive 18F-FDG PET results in HER2-positive cases. HER2-positive molecular subtypes were associated with an increased risk of developing brain metastasis. Yet, longer survival times were observed in HER2-positive subtypes receiving HER2-targeted therapy.
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| 3. |
- Alhuseinalkhudhur, Ali, et al.
(författare)
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Human Epidermal Growth Factor Receptor 2-Targeting [68Ga]Ga-ABY-025 PET/CT Predicts Early Metabolic Response in Metastatic Breast Cancer.
- 2023
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 64:9, s. 1364-1370
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Tidskriftsartikel (refereegranskat)abstract
- Imaging using the human epidermal growth factor receptor 2 (HER2)-binding tracer 68Ga-labeled ZHER2:2891-Cys-MMA-DOTA ([68Ga]Ga-ABY-025) was shown to reflect HER2 status determined by immunohistochemistry and in situ hybridization in metastatic breast cancer (MBC). This single-center open-label phase II study investigated how [68Ga]Ga-ABY-025 uptake corresponds to biopsy results and early treatment response in both primary breast cancer (PBC) planned for neoadjuvant chemotherapy and MBC. Methods: Forty patients with known positive HER2 status were included: 19 with PBC and 21 with MBC (median, 3 previous treatments). [68Ga]Ga-ABY-025 PET/CT, [18F]F-FDG PET/CT, and core-needle biopsies from targeted lesions were performed at baseline. [18F]F-FDG PET/CT was repeated after 2 cycles of therapy to calculate the directional change in tumor lesion glycolysis (Δ-TLG). The largest lesions (up to 5) were evaluated in all 3 scans per patient. SUVs from [68Ga]Ga-ABY-025 PET/CT were compared with the biopsied HER2 status and Δ-TLG by receiver operating characteristic analyses. Results: Trial biopsies were HER2-positive in 31 patients, HER2-negative in 6 patients, and borderline HER2-positive in 3 patients. The [68Ga]Ga-ABY-025 PET/CT cutoff SUVmax of 6.0 predicted a Δ-TLG lower than -25% with 86% sensitivity and 67% specificity in soft-tissue lesions (area under the curve, 0.74 [95% CI, 0.67-0.82]; P = 0.01). Compared with the HER2 status, this cutoff resulted in clinically relevant discordant findings in 12 of 40 patients. Metabolic response (Δ-TLG) was more pronounced in PBC (-71% [95% CI, -58% to -83%]; P < 0.0001) than in MBC (-27% [95% CI, -16% to -38%]; P < 0.0001), but [68Ga]Ga-ABY-025 SUVmax was similar in both with a mean SUVmax of 9.8 (95% CI, 6.3-13.3) and 13.9 (95% CI, 10.5-17.2), respectively (P = 0.10). In multivariate analysis, global Δ-TLG was positively associated with the number of previous treatments (P = 0.0004) and negatively associated with [68Ga]Ga-ABY-025 PET/CT SUVmax (P = 0.018) but not with HER2 status (P = 0.09). Conclusion: [68Ga]Ga-ABY-025 PET/CT predicted early metabolic response to HER2-targeted therapy in HER2-positive breast cancer. Metabolic response was attenuated in recurrent disease. [68Ga]Ga-ABY-025 PET/CT appears to provide an estimate of the HER2 expression required to induce tumor metabolic remission by targeted therapies and might be useful as an adjunct diagnostic tool.
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| 4. |
- Alhuseinalkhudhur, Ali, et al.
(författare)
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Kinetic analysis of HER2-binding ABY-025 Affibody molecule using dynamic PET in patients with metastatic breast cancer
- 2020
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Ingår i: EJNMMI Research. - : SPRINGEROPEN. - 2191-219X. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: High expression of human epidermal growth factor receptor type 2 (HER2) represents an aggressive subtype of breast cancer. Anti-HER2 treatment requires a theragnostic approach wherein sufficiently high receptor expression in biopsy material is mandatory. Heterogeneity and discordance of HER2 expression between primary tumour and metastases, as well as within a lesion, present a complication for the treatment and require multiple biopsies. Molecular imaging using the HER2-targeting Affibody peptide ABY-025 radiolabelled with Ga-68-gallium for PET/CT is currently under investigation as a non-invasive tool for whole-body evaluation of metastatic HER2 expression. Initial studies demonstrated a high correlation between Ga-68-ABY-025 standardized uptake values (SUVs) and histopathology. However, detecting small liver lesions might be compromised by high background uptake. This study aimed to explore the applicability of kinetic modelling and parametric image analysis for absolute quantification of Ga-68-ABY-025 uptake and HER2-receptor expression and how that relates to static SUVs.Methods: Dynamic Ga-68-ABY-025 PET of the upper abdomen was performed 0-45 min post-injection in 16 patients with metastatic breast cancer. Five patients underwent two examinations to test reproducibility. Parametric images of tracer delivery (K-1) and irreversible binding (K-i) were created with an irreversible two-tissue compartment model and Patlak graphical analysis using an image-derived input function from the descending aorta. A volume of interest (VOI)-based analysis was performed to validate parametric images. SUVs were calculated from 2 h and 4 h post-injection static whole-body images and compared to K-i.Results: Characterization of HER2 expression in smaller liver metastases was improved using parametric images. K-i values from parametric images agreed very well with VOI-based gold standard (R-2 > 0.99, p < 0.001). SUVs of metastases at 2 h and 4 h post-injection were highly correlated with K-i values from both the two-tissue compartment model and Patlak method (R-2 = 0.87 and 0.95, both p < 0.001). Ga-68-ABY-025 PET yielded high test-retest reliability (relative repeatability coefficient for Patlak 30% and for the two-tissue compartment model 47%).Conclusion: Ga-68-ABY-025 binding in HER2-positive metastases was well characterized by irreversible two-tissue compartment model wherein K-i highly correlated with SUVs at 2 and 4 h. Dynamic scanning with parametric image formation can be used to evaluate metastatic HER2 expression accurately.
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| 5. |
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| 6. |
- Bergström, Sara K., et al.
(författare)
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Polyamine deactivation of integrated poly(dimethylsiloxane) structures investigated by radionuclide imaging and capillary electrophoresis experiments
- 2005
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 77:3, s. 938-942
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Tidskriftsartikel (refereegranskat)abstract
- The poly(dimethylsiloxane) (PDMS) material provides a number of advantageous features, such as flexibility, elasticity, and transparency, making it useful in integrated analytical systems. Hard fused-silica capillary structures and soft PDMS channels can easily be combined by a tight fit, which offers many alternatives for structure combinations. PDMS and fused silica are in different ways prone to adsorption of low levels of organic compounds. The need for modification of the inner wall surface of PDMS channels may often be necessary, and in this paper, we describe an easy and effective method using the amine-containing polymer PolyE-323 to deactivate both fused-silica and PDMS surfaces. The adsorption of selected peptides to untreated surfaces was compared to PolyE-323-modified surfaces, using both radionuclide imaging and capillary electrophoresis experiments. The polyamine modification displayed a substantially reduced adsorption of three hydrophobic test peptides compared to the native PDMS surface. Filling and storage of aqueous solution were also possible in PolyE-323-modified PDMS channels. In addition, hybrid microstructures of fused silica and PDMS could simultaneously be deactivated in one simple coating procedure.
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| 7. |
- Blom, Elisabeth, 1979-, et al.
(författare)
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68Ga-Labeling of Biotin Analogues and their Characterization
- 2009
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 20:6, s. 1146-1151
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Tidskriftsartikel (refereegranskat)abstract
- Biotin- and Ga-68-based tracers have been suggested as tools that could be used to monitor the survival of avidin-coated islets of Langerhans isolated from pancreas and used in transplantation, i.e., to liver. Three biotin analogues with various alkyl and poly(ethylene glycol) (PEG) chains coupled to DOTA were synthesized and labeled with Ga-68. The Ga-68 labeling was studied at room temperature as well as elevated temperature using either conventional or microwave heating. Radioactivity incorporation reached 95% within 5 and 2 min using the, respectively, conventional and microwave heating modes. The specific activity of the tracers was improved by preconcentration and purification of the generator eluate. The binding of the labeled and nonlabeled conjugates to avidin in solution was compared to the binding of native biotim. All compounds maintained good affinity for avidin, though introducing the linkers and chelator, especially the PEG-groups, somewhat decreased the binding affinity. The extent of binding of the labeled compounds to avidin was 54-91% after 5 min. Blocking experiments were performed confirming the specificity of the binding of biotin analogues to avidin. The stability of the three labeled compounds in human serum was studied. The stability of the biotin analogue 8 (65% within 30 min) and avidin-biotin complex (80% within 120 min) might be sufficient for the monitoring of the islets of Langerhans. The tracers will be evaluated in in vitro experiments of avidin-coated islets of Langerhans and in transplantation models in vivo.
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| 8. |
- Blom, Elisabeth, et al.
(författare)
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68Ga-Labeling of RGD peptides and biodistribution
- 2012
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Ingår i: International Journal of Clinical and Experimental Medicine. - 1940-5901. ; 5:2, s. 165-172
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Tidskriftsartikel (refereegranskat)abstract
- Several peptides comprising Arg-Gly-Asp (RGD) domain and macrocyclic chelator were labeled with 68Ga for the imaging of angiogenesis. The analogues varied in peptide constitution, linker and chelator type. The labeling efficiency did not vary with the peptide constitution and linker type, but depended on the chelator type. Four of the compounds containing 2,2',2'',2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) chelator were labeled at 90 ± 5°C using conventional or microwave heating reaching 90% of 68Ga incorporation after 5 and 2 min respectively, when the concentration of the precursor was 2.5 μM. The compound having 2,2',2''-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA) as the chelator could be labeled at room temperature within 5 min using 2.5 μM peptide precursor. Two of the compounds contained a poly (ethylene glycol) (PEG) linker to the chelator. The biodistribution of the analogues was studied in male rats.
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| 9. |
- Blom, Elisabeth, et al.
(författare)
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68Ga-Labelling of RGD peptides
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Several peptides comprising Arg-Gly-Asp (RGD) domain and macrocyclic chelator were labelled with 68Ga for the imaging of angiogenesis. The analogues varied in peptide constitution, linker and chelator type. The labelling efficiency did not vary with the peptide constitution and linker type, but depended on the chelator type. Four of the compounds containing 2,2',2'',2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) chelator were labelled at 90 ± 5 °C using conventional or microwave heating reaching 90% of 68Ga incorporation after 5 and 2 min respectively, when the concentration of the precursor was 2.5 mM. The compound having 2,2',2''-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA) as the chelator could be labelled at room temperature within 5 min using 2.5 mM peptide precursor. Two of the compounds contained a poly(ethylene glycol) (PEG) linker to the chelator.
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| 10. |
- Blom, Elisabeth, 1979-
(författare)
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Development of 18F- and 68Ga-Labelled Tracers : Design Perspectives and the Search for Faster Synthesis
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the design of 18F- and 68Ga-labelled positron emission tomography (PET) tracers and the development of technologies that enable faster and simpler preparation with high specific radioactivity. Techniques like microwave heating and reducing the concentrations of the precursor were investigated with this perspective. A few applications were explored using molecular design perspectives. A nucleophilic 18F-labelling strategy using perfluoro-containing leaving groups was explored. We observed that [18F]fluoride was interacting with the perfluoro alkyl chains of the substrate, preventing the nucleophilic substitution from taking place. When a perfluoroaryl group was instead used in the leaving group, the substitution took place and purification by fluorous solid-phase extraction was possible. 18F-Labelled analogues of the monoamine oxidase-A inhibitor harmine were prepared by one-step nucleophilic fluorinations and evaluated by in vitro autoradiography, showing high specific binding. Biotin analogues labelled with 18F and 68Ga were prepared and their binding to avidin evaluated. All analogues retained their binding ability and will be further evaluated in transplantation models with avidin-coated islets of Langerhans. Peptide design perspectives were used in some examples where the Arg-Gly-Asp (RGD) sequence and a single-chain version of vascular endothelial growth factor (VEGF) protein functionalized with 2,2',2'',2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) or 2,2',2''-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA) as chelators were labelled with 68Ga. The RGD motif and VEGF have high affinity for, respectively, αvβ3 integrin and VEGFR-2 receptor that are overexpressed in angiogenesis process. The 68Ga-labelled scVEGF maintained its functional activity in vitro. A polypeptide conjugate containing phosphocholine, which has affinity for the C-reactive protein released during the inflammatory process, was labelled with 68Ga for the development of an imaging agent for inflammation in vivo. Finally [18F]/19F exchange in fluorine-containing compounds was studied in order to investigate whether the exchange reaction can be of practical use for labelling.
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| 11. |
- Blom, Elisabeth, et al.
(författare)
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Ga-68-Labeling of RGD peptides and biodistribution
- 2012
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Ingår i: International Journal of Clinical and Experimental Medicine. - 1940-5901. ; 5:2, s. 165-172
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Tidskriftsartikel (refereegranskat)abstract
- Several peptides comprising Arg-Gly-Asp (RGD) domain and macrocyclic chelator were labeled with Ga-68 for the imaging of angiogenesis. The analogues varied in peptide constitution, linker and chelator type. The labeling efficiency did not vary with the peptide constitution and linker type, but depended on the chelator type. Four of the compounds containing 2,2', 2 '', 2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl) tetraacetic acid (DOTA) chelator were labeled at 90 +/- 5 degrees C using conventional or microwave heating reaching 90% of Ga-68 incorporation after 5 and 2 min respectively, when the concentration of the precursor was 2.5 mu M. The compound having 2,2', 2 ''-(1,4,7-triazonane1,4,7-triyl)triacetic acid (NOTA) as the chelator could be labeled at room temperature within 5 min using 2.5 mu M peptide precursor. Two of the compounds contained a poly (ethylene glycol) (PEG) linker to the chelator. The biodistribution of the analogues was studied in male rats.
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| 12. |
- Blom, Elisabeth, et al.
(författare)
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Synthesis and characterization of scVEGF-PEG-[68Ga]NOTA and scVEGF-PEG-[68Ga]DOTA PET tracers
- 2011
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Ingår i: Journal of labelled compounds & radiopharmaceuticals. - : Wiley. - 0362-4803 .- 1099-1344. ; 54:11, s. 685-692
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor (VEGF) signaling via vascular endothelial growth factor receptor 2 (VEGFR-2) on tumor endothelial cells is a critical driver of tumor angiogenesis. Novel anti-angiogenic drugs target VEGF/VEGFR-2 signaling and induce changes in VEGFR-2 prevalence. To monitor VEGFR-2 prevalence in the course of treatment, we are evaluating (68)Ga positron emission tomography imaging agents based on macrocyclic chelators, site-specifically conjugated via polyethylene glycol (PEG) linkers to engineered VEGFR-2 ligand, single-chain (sc) VEGF. The (68)Ga-labeling was performed at room temperature with NOTA (2,2', 2 ''-(1,4,7-triazonane-1,4,7-triyl) triacetic acid) conjugates or at 90 degrees C by using either conventional or microwave heating with NOTA and DOTA (2,2', 2 '', 2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl) tetraacetic acid) conjugates. The fastest (similar to 2min) and the highest incorporation (>90%) of (68)Ga into conjugate that resulted in the highest specific radioactivity (similar to 400MBq/nmol) was obtained with microwave heating of the conjugates. The bioactivity of the NOTA-and DOTA-containing tracers was validated in 3-D tissue culture model of 293/KDR cells engineered to express high levels of VEGFR-2. The NOTA-containing tracer also displayed a rapid accumulation (similar to 20s after intravenous injection) to steady-state level in xenograft tumor models. A combination of high specific radioactivity and maintenance of functional activity suggests that scVEGF-PEG-[(68)Ga] NOTA and scVEGF-PEG-[(68)Ga] DOTA might be promising tracers for monitoring VEGFR-2 prevalence and should be further explored.
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| 13. |
- Borges, João Batista, et al.
(författare)
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Ventilation Distribution Studies Comparing Technegas and "Gallgas" Using (GaCl3)-Ga-68 as the Label
- 2011
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 52:2, s. 206-209
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Tidskriftsartikel (refereegranskat)abstract
- Ventilation distribution can be assessed by SPECT with Technegas. This study was undertaken in piglets with different degrees of ventilation inhomogeneity to compare PET using Ga-68-labeled pseudogas or "Gallgas" with Technegas. Methods: Twelve piglets were studied in 3 groups: control, lobar obstruction, and diffuse airway obstruction. Two more piglets were assessed for lung volume (functional residual capacity). Results: In controls, SPECT and PET images showed an even distribution of radioactivity. With lobar obstruction, the absence of ventilation of the obstructed lobe was visible with both techniques. In diffuse airway obstruction, SPECT images showed an even distribution of radioactivity, and PET images showed more varied radioactivity over the lung. Conclusion: PET provides detailed ventilation distribution images and a better appreciation of ventilation heterogeneity. Gallgas with PET is a promising new diagnostic tool for the assessment of ventilation distribution.
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| 14. |
- Bossart, Martin, et al.
(författare)
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Effects on weight loss and glycemic control with SAR441255, a potent unimolecular peptide GLP-1/GIP/GCG receptor triagonist
- 2022
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Ingår i: Cell Metabolism. - : CELL PRESS. - 1550-4131 .- 1932-7420. ; 34:1, s. 59-
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Tidskriftsartikel (refereegranskat)abstract
- Unimolecular triple incretins, combining the activity of glucagon-like peptide-1 (GLP-1), glucose -dependent insulinotropic polypeptide (GIP), and glucagon (GCG), have demonstrated reduction in body weight and improved glucose control in rodent models. We developed SAR441255, a synthetic peptide agonist of the GLP-1, GCG, and GIP receptors, structurally based on the exendin-4 sequence. SAR441255 displays high potency with balanced activation of all three target receptors. In animal models, metabolic outcomes were superior to results with a dual GLP-1/GCG receptor agonist. Preclinical in vivo positron emission tomography imaging demonstrated SAR441255 binding to GLP-1 and GCG receptors. In healthy subjects, SAR441255 improved glycemic control during a mixed-meal tolerance test and impacted biomarkers for GCG and GIP receptor activation. Single doses of SAR441255 were well tolerated. The results demonstrate that integrating GIP activity into dual GLP-1 and GCG receptor agonism provides improved effects on weight loss and glycemic control while buffering the diabetogenic risk of chronic GCG receptor agonism.
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| 15. |
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| 16. |
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| 17. |
- Eriksson, Olof, et al.
(författare)
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Assessment of glucagon receptor occupancy by Positron Emission Tomography in non-human primates
- 2019
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1, s. 14960-
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Tidskriftsartikel (refereegranskat)abstract
- The glucagon receptor (GCGR) is an emerging target in anti-diabetic therapy. Reliable biomarkers for in vivo activity on the GCGR, in the setting of dual glucagon-like peptide 1/glucagon (GLP-1/GCG) receptor agonism, are currently unavailable. Here, we investigated [68Ga]Ga-DO3A-S01-GCG as a biomarker for GCGR occupancy in liver, the tissue with highest GCGR expression, in non-human primates (NHP) by PET. [68Ga]Ga-DO3A-S01-GCG was evaluated by dynamic PET in NHPs by a dose escalation study design, where up to 67 µg/kg DO3A-S01-GCG peptide mass was co-injected. The test-retest reproducibility of [68Ga]Ga-DO3A-S01-GCG binding in liver was evaluated. Furthermore, we investigated the effect of pre-treatment with acylated glucagon agonist 1-GCG on [68Ga]Ga-DO3A-S01-GCG binding in liver. [68Ga]Ga-DO3A-S01-GCG bound to liver in vivo in a dose-dependent manner. Negligible peptide mass effect was observed for DO3A-S01-GCG doses <0.2 µg/kg. In vivo Kd for [68Ga]Ga-DO3A-S01-GCG corresponded to 0.7 µg/kg, which indicates high potency. The test-retest reproducibility for [68Ga]Ga-DO3A-S01-GCG binding in liver was 5.7 ± 7.9%. Pre-treatment with 1-GCG, an acylated glucagon agonist, resulted in a GCGR occupancy of 61.5 ± 9.1% in liver. Predicted human radiation dosimetry would allow for repeated annual [68Ga]Ga-DO3A-S01-GCG PET examinations. In summary, PET radioligand [68Ga]Ga-DO3A-S01-GCG is a quantitative biomarker of in vivo GCGR occupancy.
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| 18. |
- Eriksson, Olof, et al.
(författare)
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Detection of Metastatic Insulinoma by Positron Emission Tomography with [(68)Ga]Exendin-4 - : a case report
- 2014
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 99:5, s. 1519-1524
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Tidskriftsartikel (refereegranskat)abstract
- Context: Insulinomas are the most common cause of endogenous hyperinsulinaemic hypoglycaemia in non-diabetic adult patients. They are usually benign and curative surgery is the "gold standard" treatment if they can be localized. Malignant insulinomas are seen in less than 10% and their prognosis is poor. The Glucagon Like Peptide-1 receptor (GLP-1R) is markedly upregulated in insulinomas - especially benign lesions which are difficult to localize with current imaging techniques.Objective:To assess the possibility of the detection of primary and metastatic insulinoma by PET using [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 ([(68)Ga]Exendin-4) in a patient with severe hypoglycemia.Design:Dynamic and static PET/CT examination of a patient using [68Ga]Exendin-4.Setting:Uppsala University Hospital, Uppsala, Sweden.Patients:A patient presented with hypoglycemia requiring continuous intravenous glucose infusions. A pancreatic insulinoma was suspected and an exploratory laparotomy was urgently performed. At surgery, a tumor in the pancreatic tail with an adjacent metastasis was found and a distal pancreatic resection (plus splenectomy) and removal of lymph node was performed. Histopathology showed a WHO grade II insulinoma. Postoperatively hypoglycemia persisted but a PET/CT examination using the neuroendocrine marker [(11)C]-5-hydroxy-L-tryptophan was negative.Interventions:The patient was administered with [(68)Ga]Exendin-4 and examined by dynamic PET over the liver and pancreas.Main Outcome Measures:N/AResults:The stable GLP-1 analogue Exendin-4 was labeled with (68)Ga for PET imaging of GLP-1R expressing tumors. The patient was examined by [(68)Ga]Exendin-4-PET/CT which confirmed several small GLP-1R positive lesions in the liver and a lymph node that could not be conclusively identified by other imaging techniques. The results obtained from the [(68)Ga]Exendin-4-PET/CT examination provided the basis for continued systemic treatment.Conclusion:The results of the [(68)Ga]Exendin-4-PET/CT examination governed the treatment strategy of this particular patient and demonstrated the potential of this technique for future management of patients with this rare, but potentially fatal disease.
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| 19. |
- Eriksson, Olof, et al.
(författare)
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Drug Occupancy Assessment at the Glucose-Dependent Insulinotropic Polypeptide Receptor by Positron Emission Tomography
- 2021
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Ingår i: Diabetes. - : AMER DIABETES ASSOC. - 0012-1797 .- 1939-327X. ; 70:4, s. 842-853
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Tidskriftsartikel (refereegranskat)abstract
- Targeting of the glucose-dependent insulinotropic polypeptide receptor (GIPR) is an emerging strategy in antidiabetic drug development. The aim of this study was to develop a positron emission tomography (PET) radioligand for the GIPR to enable the assessment of target distribution and drug target engagement in vivo. The GIPR-selective peptide S02-GIP was radiolabeled with Ga-68. The resulting PET tracer [Ga-68]S02-GIP-T4 was evaluated for affinity and specificity to human GIPR (huGIPR). The in vivo GIPR binding of [Ga-68]S02-GIP-T4 as well as the occupancy of a drug candidate with GIPR activity were assessed in nonhuman primates (NHPs) by PET. [Ga-68]S02-GIP-T4 bound with nanomolar affinity and high selectivity to huGIPR in overexpressing cells. In vivo, pancreatic binding in NHPs could be dose-dependently inhibited by coinjection of unlabeled S02-GIP-T4. Finally, subcutaneous pretreatment with a high dose of a drug candidate with GIPR activity led to a decreased pancreatic binding of [Ga-68]S02-GIP-T4, corresponding to a GIPR drug occupancy of almost 90%. [Ga-68]S02-GIP-T4 demonstrated a safe dosimetric profile, allowing for repeated studies in humans. In conclusion, [Ga-68]S02-GIP-T4 is a novel PET biomarker for safe, noninvasive, and quantitative assessment of GIPR target distribution and drug occupancy.
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| 20. |
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| 21. |
- Eriksson, Olof, et al.
(författare)
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Glucagonlike Peptide-1 Receptor Imaging in Individuals with Type 2 Diabetes
- 2022
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 63:5, s. 794-800
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Tidskriftsartikel (refereegranskat)abstract
- The glucagonlike peptide-1 receptor (GLP1R) is a gut hormone receptor, intricately linked to regulation of blood glucose homeostasis via several mechanisms. It is an established and emergent drug target in metabolic disease. The PET radioligand 68Ga-DO3A-VS-exendin4 (68Ga-exendin4) has the potential to enable longitudinal studies of GLP1R in the human pancreas.Methods: 68Ga-exendin4 PET/CT examinations were performed on overweight-to-obese individuals with type 2 diabetes (n = 13) as part of a larger target engagement study (NCT03350191). A scanning protocol was developed to optimize reproducibility (target amount of 0.5 MBq/kg [corresponding to peptide amount of <0.2 µg/kg], blood sampling, and tracer stability assessment). The pancreas and abdominal organs were segmented, and binding was correlated with clinical parameters.Results: Uptake of 68Ga-exendin4 in the pancreas, but not in other abdominal tissues, was high but variable between individuals. There was no evidence of self-blocking of GLP1R by the tracer in this protocol, despite the high potency of exendin4. The results showed that a full dynamic scan can be simplified to a short static scan, potentially increasing throughput and reducing patient discomfort. The 68Ga-exendin4 concentration in the pancreas (i.e., GLP1R density) correlated inversely with the age of the individual and tended to correlate positively with body mass index. However, the total GLP1R content in the pancreas did not.Conclusion: In summary, we present an optimized and simplified 68Ga-exendin4 scanning protocol to enable reproducible imaging of GLP1R in the pancreas. 68Ga-exendin4 PET may enable quantification of longitudinal changes in pancreatic GLP1R during the development of type 2 diabetes, as well as target engagement studies of novel glucagonlike peptide-1 agonists.
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| 22. |
- Eriksson, Olof, et al.
(författare)
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Imaging of the Glucagon Receptor in Subjects with Type 2 Diabetes
- 2021
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Ingår i: Journal of Nuclear Medicine. - : SOC NUCLEAR MEDICINE INC. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 62:6, s. 833-838
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of the glucagon receptor (GCGR) in disease and in pharmaceutical drug development, there is a lack of specific and sensitive biomarkers of its activation in humans. The PET radioligand Ga-68-DO3A-VS-Tuna-2 (Ga-68-Tuna-2) was developed to yield a noninvasive imaging marker for GCGR target distribution and drug target engagement in humans. Methods: The biodistribution and dosimetry of Ga-68-Tuna-2 was assessed by PET/CT in 13 individuals with type 2 diabetes as part of a clinical study assessing the occupancy of the dual GCGR/glucagon like peptide-1 receptor agonist SAR425899. Binding of Ga-68-Tuna-2 in liver and reference tissues was evaluated and correlated to biometrics (e.g., weight or body mass index) or other biomarkers (e.g., plasma glucagon levels). Results: Ga-68-Tuna-2 binding was seen primarily in the liver, which is in line with the strong expression of GCGR on hepatocytes. The kidneys demonstrated high excretion-related retention, whereas all other tissue demonstrated rapid washout. The SUV55 (min) (SUV during the last 10-min time frame, 50-60 min after administration) uptake endpoint was sensitive to endogenous levels of glucagon. Ga-68-Tuna-2 exhibited a safe dosimetry profile and no adverse events after intravenous administration. Conclusion: Ga-68-Tuna-2 can be used for safe and accurate assessment of the GCGR in human. It may serve as an important tool in understanding the in vivo pharmacology of novel drugs engaging the GCGR.
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| 23. |
- Eriksson, Olof, et al.
(författare)
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Preclinical evaluation of a 68Ga-labeled biotin analogue for applications in islet transplantation
- 2012
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Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 39:3, s. 415-421
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION:Islet transplantation is a promising treatment for type 1 diabetes mellitus, but the fate of the cells after intraportal infusion is unclear. It is therefore imperative to develop novel techniques for noninvasive imaging and quantification of events following islet transplantation.METHODS:Small islet-like microbeads, avidin-covered agarose resins (AARs), were used as a model system for islet transplantation. Capability for specific [(68)Ga]Ga-DOTA-(PEG)(2)-biotin uptake and retention for either AARs or human islets conjugated with avidin by means of a heparin scaffold was studied in vitro. Biodistribution of the novel positron emission tomography (PET) tracer [(68)Ga]Ga-DOTA-(PEG)(2)-biotin was evaluated in mice treated by intraportal transplantation of AARs by μPET/computed tomography and ex vivo organ distribution and compared with control mice.RESULTS:AARs had high capability to bind [(68)Ga]Ga-DOTA-(PEG)(2)-biotin, close to 50% of administrated tracer/μl in vitro (>0.25 MBq/μl). Avidin-tagged human islets could bind on average 2.2% of administered tracer/μl. Specificity (>90%) and retention (>90% after 1 h) were high for both AARs and avidin-tagged islets. Hepatic tracer uptake and retention were increased in mice transplanted with AARs [standardized uptake value (SUV)=2.6] compared to the untreated group (SUV=1.4). In vivo uptake of tracer to AARs was blocked by preadministration of unlabeled biotin.CONCLUSIONS:Avidin-tagged islet-like objects can be tracked in hepatic volume after intraportal transplantation by using [(68)Ga]Ga-DOTA-(PEG)(2)-biotin and PET.
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| 24. |
- Eriksson, Olof, et al.
(författare)
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Radiotracers for Imaging of Fibrosis : Advances during the Last Two Decades and Future Directions
- 2023
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Ingår i: Pharmaceuticals. - : MDPI. - 1424-8247. ; 16:11
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Forskningsöversikt (refereegranskat)abstract
- Fibrosis accompanies various pathologies, and there is thus an unmet medical need for non-invasive, sensitive, and quantitative methods for the assessment of fibrotic processes. Currently, needle biopsy with subsequent histological analysis is routinely used for the diagnosis along with morphological imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US). However, none of these imaging techniques are sufficiently sensitive and accurate to detect minor changes in fibrosis. More importantly, they do not provide information on fibrotic activity on the molecular level, which is critical for fundamental understanding of the underlying biology and disease course. Molecular imaging technology using positron emission tomography (PET) offers the possibility of imaging not only physiological real-time activity, but also high-sensitivity and accurate quantification. This diagnostic tool is well established in oncology and has exhibited exponential development during the last two decades. However, PET diagnostics has only recently been widely applied in the area of fibrosis. This review presents the progress of development of radiopharmaceuticals for non-invasive detection of fibrotic processes, including the fibrotic scar itself, the deposition of new fibrotic components (fibrogenesis), or the degradation of existing fibrosis (fibrolysis).
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| 25. |
- Eriksson, Olof, et al.
(författare)
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Receptor occupancy of dual glucagon-like peptide 1/glucagon receptor agonist SAR425899 in individuals with type 2 diabetes
- 2020
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Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Unimolecular dual agonists for the glucagon-like peptide 1 receptor (GLP1R) and glucagon receptor (GCGR) are emerging as a potential new class of important therapeutics in type 2 diabetes (T2D). Reliable and quantitative assessments of in vivo occupancy on each receptor would improve the understanding of the efficacy of this class of drugs. In this study we investigated the target occupancy of the dual agonist SAR425899 at the GLP1R in pancreas and GCGR in liver by Positron Emission Tomography/Computed Tomography (PET/CT). Patients with T2D were examined by [Ga-68]Ga-DO3A-Tuna-2 and [Ga-68]Ga-DO3A-Exendin4 by PET, to assess the GCGR in liver and GLP1R in pancreas, respectively. Follow up PET examinations were performed after 17 (GCGR) and 20 (GLP-1R) days of treatment with SAR425899, to assess the occupancy at each receptor. Six out of 13 included patients prematurely discontinued the study due to adverse events. SAR425899 at a dose of 0.2 mg daily demonstrated an average GCGR occupancy of 11.2 +/- 14.4% (SD) in N=5 patients and a GLP1R occupancy of 49.9 +/- 13.3%. Fasting Plasma Glucose levels (-3.30 +/- 1.14 mmol/L) and body weight (-3.87 +/- 0.87%) were lowered under treatment with SAR425899. In conclusion, SAR425899 demonstrated strong interactions at the GLP1R, but no clear occupancy at the GCGR. The study demonstrates that quantitative target engagement of dual agonists can be assessed by PET.
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| 26. |
- 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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| 27. |
- Espes, Daniel, et al.
(författare)
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Quantification of Beta-Cell Mass in Intramuscular Islet Grafts using Radiolabeled Exendin-4
- 2016
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Ingår i: Transplantation Direct. - 2373-8731. ; 2:8
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is an increasing interest in alternative implantation sites to the liver for islet transplantation. Intramuscular implantation has even been tested clinically. Possibilities to monitor [beta]-cell mass would be of huge importance not only for the understanding of islet engraftment but also for the decision of changing the immunosuppressive regime. We have therefore evaluated the feasibility of quantifying intramuscular [beta]-cell mass using the radiolabeled glucagon like peptide-1 receptor agonist DO3A-VS-Cys40-Exendin-4.Methods: One hundred to 400 islets were transplanted to the abdominal muscle of nondiabetic mice. After 3 to 4 weeks, 0.2 to 0.5 MBq [177Lu]DO3A-VS-Cys40-Exendin-4 was administered intravenously. Sixty minutes postinjection abdominal organs and graft bearing muscle were retrieved, and the radioactive uptake measured in a well counter within 10 minutes. The specific uptake in native and transplanted islets was assessed by autoradiography. The total insulin-positive area of the islet grafts was determined by immunohistochemistry.Results: Intramuscular islet grafts could easily be visualized by this tracer, and the background uptake was very low. There was a linear correlation between the radioactivity uptake and the number of transplanted islets, both for standardized uptake values and the total radiotracer uptake in each graft (percentage of injected dose). The quantified total insulin area of surviving [beta] cells showed an even stronger correlation to both standardized uptake values (R = 0.96, P = 0.0002) and percentage of injected dose (R = 0.88, P = 0.0095). There was no correlation to estimated [alpha] cell mass.Conclusions: [177Lu]DO3A-VS-Cys40-Exendin-4 could be used to quantify [beta]-cell mass after experimental intramuscular islet transplantation. This technique may well be transferred to the clinical setting by exchanging Lutetium-177 radionuclide to a positron emitting Gallium-68.
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| 28. |
- Fani, Melpomeni, et al.
(författare)
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Current Status of Radiopharmaceuticals for the Theranostics of Neuroendocrine Neoplasms
- 2017
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Ingår i: Pharmaceuticals. - : MDPI AG. - 1424-8247. ; 10:1
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Forskningsöversikt (refereegranskat)abstract
- Nuclear medicine plays a pivotal role in the management of patients affected by neuroendocrine neoplasms (NENs). Radiolabeled somatostatin receptor analogs are by far the most advanced radiopharmaceuticals for diagnosis and therapy (radiotheranostics) of NENs. Their clinical success emerged receptor-targeted radiolabeled peptides as an important class of radiopharmaceuticals and it paved the way for the investigation of other radioligand-receptor systems. Besides the somatostatin receptors (sstr), other receptors have also been linked to NENs and quite a number of potential radiolabeled peptides have been derived from them. The Glucagon-Like Peptide-1 Receptor (GLP-1R) is highly expressed in benign insulinomas, the Cholecystokinin 2 (CCK2)/Gastrin receptor is expressed in different NENs, in particular medullary thyroid cancer, and the Glucose-dependent Insulinotropic Polypeptide (GIP) receptor was found to be expressed in gastrointestinal and bronchial NENs, where interestingly, it is present in most of the sstr-negative and GLP-1R-negative NENs. Also in the field of sstr targeting new discoveries brought into light an alternative approach with the use of radiolabeled somatostatin receptor antagonists, instead of the clinically used agonists. The purpose of this review is to present the current status and the most innovative strategies for the diagnosis and treatment (theranostics) of neuroendocrine neoplasms using a cadre of radiolabeled regulatory peptides targeting their receptors.
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| 29. |
- Hall, Håkan, et al.
(författare)
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In vitro autoradiography of carcinoembryonic antigen in tissue from patients with colorectal cancer using multifunctional antibody TF2 and 67/68Ga-labeled haptens by pretargeting
- 2012
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Ingår i: American Journal of Nuclear Medicine and Molecular Imaging. - 2160-8407. ; 2:2, s. 141-150
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Tidskriftsartikel (refereegranskat)abstract
- The carcinoembryonic antigen (CEA) was visualized in vitro in tissue from patients with colorectal cancer with trivalent bispecific antibody TF2 and two hapten molecules, [(67/68)Ga]Ga-IMP461 and [(67/68)Ga]Ga-IMP485 by means of pretargeting. Colorectal cancer tissue samples obtained from surgery at Uppsala University Hospital, were frozen fresh and cryosectioned. The two hapten molecules comprising 1,4,7-triazacyclononanetriacetic acid chelate moiety (NOTA) were labeled with (67)Ga or (68)Ga. The autoradiography was conducted by incubating the tissue samples with the bispecific antibody TF2, followed by washing and incubation with one of the radiolabeled hapten molecules. After washing, drying and exposure to phosphor imager plates, the autoradiograms were analyzed and compared to standard histochemistry (hematoxylin-eosin). Pronounced binding was found in the tissue from colorectal cancer using the bispecific antibody TF2 and either of the haptens [(67/68)Ga]Ga-IMP461 and [(67/68)Ga]Ga-IMP485. Distinct binding was also detected in the epithelium of most samples of neighboring tissue, taken at a minimum of 10 cm from the site of the tumor. It is concluded that pretargeting CEA with the bispecific antibody TF2 followed by the addition of (67/68)Ga-labeled hapten is extremely sensitive for visualizing this marker for colorectal cancer. This methodology is therefore a very specific complement to other histochemical techniques in the diagnosis of biopsies or in samples taken from surgery. Use of the pretargeting technique in vivo may also be an advance in diagnosing patients with colorectal cancer, either using (67)Ga and SPECT or (68)Ga and PET.
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| 30. |
- Haylock, Anna-Karin, et al.
(författare)
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Generation and evaluation of antibody agents for molecular imaging of CD44v6-expressing cancers
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8:39, s. 65152-65170
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this study was to generate and characterize scFv antibodies directed to human CD44v6, as well as to radiolabel and evaluate top candidates in vitro and in vivo for their potential use in CD44v6-targeted molecular imaging in cancer patients.Materials and methods: Phage display selections were used to isolate CD44v6-specific scFvs. A chain shuffling strategy was employed for affinity maturation based on a set of CD44v6-specific first-generation clones. Two second-generation scFv clones were then chosen for labeling with 111In or 125I and assessed for CD44v6-specific binding on cultured tumor cells. In vivo uptake and distribution was evaluated in tumor-bearing mice using a dual tumor model. Finally, a proof-of-concept small animal PET-CT study was performed on one of the candidates labeled with 124I.Results: Two affinity-matured clones, CD44v6-scFv-A11 and CD44v6-scFv-H12, displayed promising binding kinetics. Seven out of eight radiolabeled conjugates demonstrated CD44v6-specific binding. In vivo studies on selected candidates demonstrated very advantageous tumor-to-organ ratios, in particular for iodinated conjugates, where 125I-labeled scFvs exhibited favorable kinetics and tumor-to-blood ratios above five already at 24 hours p. i.. The small animal PET-CT study using 124I-labeled CD44v6-scFv-H12 was in line with the biodistribution data, clearly visualizing the high CD44v6-expressing tumor.Conclusion: The single chain fragments, CD44v6-scFv-A11 and CD44v6-scFv-H12 specifically bind to CD44v6, and the radiolabeled counterparts provide high tumor-to-blood ratios and fast clearance from organs and blood. We conclude that radioiodinated CD44v6-scFv-A11 and CD44v6-scFv-H12 possess features highly suitable for stringent molecular imaging.
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| 31. |
- Ilan, Ezgi, et al.
(författare)
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Comparison of 68Ga-DOTATATE and 177Lu-DOTATATE kinetics in neuroendocrine tumors
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Tidskriftsartikel (refereegranskat)abstract
- Absorbed dose planning prior peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE would allow maximization of the absorbed dose to tumor tissue whilst minimizing the risk for side-effects in healthy organs. Unfortunately, dosimetry during 177Lu-DOTATATE is only possible post therapy and using 68Ga-DOTATATE to act as surrogate for 177Lu-DOTATATE could potentially enable prediction of absorbed doses prior PRRT with 177Lu-DOTATATE. The aim of this study was to compare uptake and kinetics of 68Ga-DOTATATE and 177Lu-DOTATATE in tumors by performing dynamic or serial scans with both radiopharmaceuticals in the same patients. Methods Six NET patients underwent a 45-min dynamic PET scan after injection of 124 ±38 MBq 68Ga-DOTATATE and serial SPECT scans after a bolus injection of 500 ± 0 MBq 177Lu-DOTATATE assuring similar peptide content in the radiopharmaceuticals. Tumor and whole-blood SUV, tumor-to-blood-ratio (TBR), and net influx rate (Ki) were determined for 68Ga-DOTATATE and 177Lu-DOTATATE. Ki was determined by non-linear regression of an irreversible two-tissue compartment model with a loss parameter and by the Patlak method. Results In majority of tumors, tumor SUV was higher in 68Ga-DOTATATE than in 177Lu-DOTATATE and whole-blood SUV was lower in 68Ga-DOTATATE than in 177Lu-DOTATATE, resulting in a lower TBR for 68Ga-DOTATATE than for 177Lu-DOTATATE. For Ki, Spearman correlation was 0.55 between 68Ga- DOTATATE and 177Lu-DOTATATE with a Demining regression slope of 0.93. For Patlak based Ki (with correction for partial volume effect based on data <100 min p.i. for 177Lu-DOTATATE), the Spearman correlation was 0.90 and with a Deming regression slope close to 1 (0.83). Using a later time interval (with correction for partial volume effect based on data >100 min p.i) for the Patlak analysis also resulted in high correlation (0.87) but the Deming regression slope was 0.18. Conclusion Linear relation with good agreement was found between the SUVs of 68Ga-DOTATATE and 177Lu-DOTATATE. Similar Ki was observed for 68Ga-DOTATATE and 177Lu-DOTATATE during early time interval (<100 min p.i of 177Lu-DOTATATE) however not during late time interval (>100 min p.i.). Hence, late kinetics of 177Lu-DOTATATE cannot be predicted using 68Ga-DOTATATE PET.
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Ilan, Ezgi, et al.
(författare)
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Parametric Net Influx Rate Images of 68Ga-DOTATOC and 68Ga-DOTATATE : Quantitative Accuracy and Improved Image Contrast
- 2017
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 58:5, s. 744-749
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Tidskriftsartikel (refereegranskat)abstract
- (68)Ga-DOTATOC and (68)Ga-DOTATATE are radiolabelled somatostatin analogs used for diagnosis of somatostatin receptor expressing neuroendocrine tumors (NETs) and SUV -measurements are suggested for treatment monitoring. However, changes in net-influx rate (Ki) may better reflect treatment effects than those of the SUV, and accordingly there is a need to compute parametric images showing Ki at the voxel level. The aim of this study was to evaluate parametric methods for computation of parametric Ki images by comparison to volume of interest based methods and to assess image contrast in terms of tumor-to-liver ratio.METHODS: Ten patients with metastatic NETs underwent a 45-min dynamic PET examination followed by whole-body PET/CT at 1 h post injection of (68)Ga-DOTATOC and (68)Ga-DOTATATE on consecutive days. Parametric Ki images were computed using a basis function method (BFM) implementation of the two tissue irreversible compartment model and the Patlak method using a descending aorta image-derived input function, and mean tumor Ki values were determined for 50% isocontour VOIs and compared to Ki values based on non-linear regression (NLR) of the whole-VOI time-activity curve. A subsample of healthy liver was delineated in the whole-body and Ki images and tumor-to-liver ratios were calculated in order to evaluate image contrast. Correlation and agreement between VOI-based and parametric Ki values were assessed using regression and Bland-Altman analysis.RESULTS: Correlation (R2) between NLR-based and parametric image-based (BFM) tumor Ki values was 0.98 (slope 0.81) and 0.97 (slope 0.88) for (68)Ga-DOTATOC and (68)Ga DOTATATE, respectively. For Patlak analysis, correlation between NLR-based and parametric based (Patlak) tumor Ki were 0.95 (slope 0.71) and 0.92 (slope 0.74) for (68)Ga-DOTATOC and (68)Ga-DOTATATE, respectively. There was no bias between NLR and parametric based Ki-values. Tumor-to-liver contrast was 1.6 and 2.0 times higher in the parametric BFM-Ki images, and 2.3 and 3.0 times in the Patlak images, than in the whole-body images for (68)Ga-DOTATOC and (68)Ga-DOTATATE, respectively.CONCLUSION: A high correlation and agreement between NLR- and parametric based Ki values was found, showing that parametric net influx rate images are quantitatively accurate. In addition, tumor-to-liver contrast was superior in the parametric Ki images compared to whole-body images both for (68)Ga-DOTATOC and (68)Ga DOTATATE.
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| 36. |
- Ilan, Ezgi, et al.
(författare)
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Tumor-to-blood ratio for assessment of somatostatin receptor density in neuroendocrine tumors using 68Ga-DOTATOC and 68Ga-DOTATATE.
- 2020
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 61:2, s. 217-221
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Tidskriftsartikel (refereegranskat)abstract
- PET/CT with 68Ga-DOTA-somatostatin analogs has been tested for therapy monitoring in patients with neuroendocrine tumors (NETs). However, standardized uptake values (SUV) in tumors do not correlate with the net influx rate (Ki), as a representation of the somatostatin receptor (SSTR) expression. In this study, tumor-to-blood-ratio (TBR) was evaluated as an alternative tool for semi-quantitative assessment of 68Ga-DOTATOC and 68Ga-DOTATATE tumor uptake and as a therapy monitoring tool for patients with NETs. Methods: Twenty-two NET patients underwent a 45-min dynamic PET/CT scan after injection of 68Ga-DOTATOC and/or 68Ga-DOTATATE. Ki was determined using the Patlak method and TBR was calculated for the 40-45 min time interval. Results: A linear relation was found between Ki and TBR, with a square of Pearson correlation (R2) of 0.98 and 0.93 for 68Ga-DOTATOC and 68Ga-DOTATATE, respectively. Conclusion: High correlation was found between Ki and TBR. Hence, TBR reflects SSTR density more accurately than SUV and is suggested as the preferred metrics for semi-quantitative assessment of 68Ga-DOTATOC and 68Ga-DOTATATE tumor uptake.
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| 37. |
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| 38. |
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| 39. |
- Jahn, Ulrika, et al.
(författare)
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Receptor depletion and recovery in small-intestinal neuroendocrine tumors and normal tissues after administration of a single intravenous dose of octreotide measured by Ga-68-DOTATOC PET/CT
- 2021
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Ingår i: EJNMMI Research. - : Springer Nature. - 2191-219X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Low-grade neuroendocrine tumors (NETs) are characterized by an abundance of somatostatin receptors (SSTR) that can be targeted with somatostatin analogs (SSA). When activated with a single dose of SSA, the receptor-ligand complex is internalized, and the receptor is by default recycled within 24 h. Ongoing medication with long-acting SSAs at Ga-68-DOTA-SSA-PET has been shown to increase the tumor-to-normal organ contrast. This study was performed to investigate the time-dependent extended effect (7 h) of a single intravenous dose of 400 mu g short-acting octreotide on the tumor versus normal tissue uptake of Ga-68-DOTATOC.Methods: Patients with small-intestinal NETs received a single intravenous dose of 400 mu g octreotide and underwent dynamic abdominal Ga-68-DOTATOC-PET/CT at three sessions (0, 3 and 6 h) plus static whole-body (WB) PET/CT (1, 4 and 7 h), starting each PET/CT session by administering 167 +/- 21 MBq, 23.5 +/- 4.2 mu g (mean +/- SD, n = 12) of Ga-68-DOTATOC. A previously acquired clinical whole-body Ga-68-DOTATOC scan was used as baseline. SUV and net uptake rate K-i were calculated in tumors, and SUV in healthy organs.Results: Tumor SUV decreased significantly from baseline to 1 h post-injection but subsequently increased over time and became similar to baseline at 4 h and 7 h. The tumor net uptake rate, K-i, similarly increased significantly over time and showed a linear correlation both with SUV and tumor-to-blood ratio. By contrast, the uptake in liver, spleen and pancreas remained significantly below baseline levels also at 7 h and the receptor turn-over in tumors thus exceeded that in the normal tissue, with restitution of tumor Ga-68-DOTATOC uptake mainly completed at 7 h. These results however differed depending on tumor size, with significant increases in K-i and SUV between the 1st and 2nd PET, in large tumors (>= 4 mL) but not in small (> 1 to < 4 mL) tumors.Conclusion: SSTR recycling is faster in small-intestinal NETs than in liver, spleen and pancreas. This opens the possibility to protect normal tissues during PRRT by administering a single dose of cold peptide hours before peptide receptor radionuclide therapy (PRRT), and most likely additionally improve the availability and uptake of the therapeutic preparation in the tumors.
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| 40. |
- Jansen, Theodorus J. P., et al.
(författare)
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Monitoring beta-Cell Survival After Intrahepatic Islet Transplantation Using Dynamic Exendin PET Imaging : A Proof-of-Concept Study in Individuals With Type 1 Diabetes
- 2023
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 72:7, s. 898-907
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Tidskriftsartikel (refereegranskat)abstract
- Intrahepatic transplantation of islets of Langerhans (ITx) is a treatment option for individuals with complicated type 1 diabetes and profoundly unstable glycemic control, but its therapeutic success is hampered by deterioration of graft function over time. To improve ITx strategies, technologies to noninvasively monitor the fate and survival of transplanted islets over time are of great potential value. We used [Ga-68]Ga-NODAGA-exendin-4 (Ga-68-exendin) positron emission tomography (PET)/computed tomography (CT) imaging to demonstrate the feasibility of quantifying b-cellmass in intrahepatic islet grafts in 13 individuals with type 1 diabetes, nine after ITx with functional islet grafts and four control patients not treated with ITx. beta-Cell function was measured by mixed-meal tolerance test. With dynamic Ga-68-exendin PET/CT images, we determined tracer accumulation in hepatic hotspots, and intrahepatic fat was assessed using MRI and spectroscopy. Quantification of hepatic hotspots showed a significantly higher uptake of Ga-68-exendin in the ITx group compared with the control group (median 0.55 [interquartile range 0.51-0.63] vs. 0.43 [0.42-0.45]). GLP-1 receptor expression was found in transplanted islets by immunohistochemistry. Intrahepatic fat was not detected in a majority of the individuals. Our study provides the first clinical evidence that radiolabeled exendin imaging can be used to monitor viable transplanted islets after intraportal ITx.
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| 41. |
- Jawlakh, Hiba, et al.
(författare)
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Ga-68-DOTATOC-PET/MRI and C-11-5-HTP-PET/MRI are superior to Ga-68-DOTATOC-PET/CT for neuroendocrine tumour imaging
- 2021
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Ingår i: Journal of neuroendocrinology. - : John Wiley & Sons. - 0953-8194 .- 1365-2826. ; 33:6
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Tidskriftsartikel (refereegranskat)abstract
- The present study aimed to assess gadoxetate disodium contrast-enhanced (CE) positron emission tomography (PET)/magnetic resonance imaging (MRI) with Ga-68-DOTATOC and C-11-5-Hydroxy-tryptophan (C-11-5-HTP) in comparison with iodine CE Ga-68-DOTATOC-PET/computed tomography (CT) for neuroendocrine tumour imaging. Detection rate and reader's confidence were evaluated for each separate image volume: CE-CT, CE-MRI including diffusion-weighted imaging, Ga-68-DOTATOC-PET performed at PET/CT, Ga-68-DOTATOC-PET performed at PET/MRI and C-11-5-HTP-PET, and for the three combined hybrid examinations Ga-68-DOTATOC-PET/MRI, C-11-5-HTP-PET/MRI and Ga-68-DOTATOC-PET/CT. In 11 patients, 255 lesions were depicted. Ga-68-DOTATOC-PET performed at PET/MRI depicted 72.5%, Ga-68-DOTATOC-PET performed at PET/CT depicted 62.7%, C-11-5-HTP-PET depicted 68.2% and CE-CT depicted 53% of lesions. Ga-68-DOTATOC-PET performed at PET/MRI (P < 0.001) and PET/CT (P = 0.02), C-11-5-HTP-PET (P < 0.001) and MRI (P < 0.001) were superior to CT. Ga-68-DOTATOC-PET/MRI and C-11-5-HTP-PET/MRI detected 92.5% and 92% of lesions, respectively, and both outperformed Ga-68-DOTATOC-PET/CT (65%) (P < 0.001). For liver metastasis imaging, MRI alone was unsurpassed (P < 0.01) and Ga-68-DOTATOC-PET/MRI and C-11-5-HTP-PET/MRI outperformed Ga-68-DOTATOC-PET/CT (P < 0.001). For lymph node metastasis diagnosis, Ga-68-DOTATOC-PET performed at PET/MRI and PET/CT and C-11-5-HTP-PET detected 94%, 94% and 94% of lesions, respectively, and outperformed MRI and CE-CT alone (P < 0.001). For bone metastasis imaging, Ga-68-DOTATOC-PET performed at PET/MRI and PET/CT and C-11-5-HTP-PET performed equally well (P = 0.05) and better than MRI. Reader's confidence was better for Ga-68-DOTATOC-PET/MRI and C-11-5-HTP-PET/MRI than for Ga-68-DOTATOC-PET/CT. The tumour maximum standardised uptake value and tumour-to-liver ratio were both approximately twice as high as for Ga-68-DOTATOC than for C-11-5-HTP. Ga-68-DOTATOC-PET/MRI and C-11-5-HTP-PET/MRI provided the highest detection rates and reader's confidence and were both superior to Ga-68-DOTATOC-PET/CT, mainly because of the MRI component. The imaging contrast with Ga-68-DOTATOC was superior to that of C-11-5-HTP.
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| 42. |
- Jokar, Narges, et al.
(författare)
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Theranostic Approach in Breast Cancer A Treasured Tailor for Future Oncology
- 2021
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Ingår i: Clinical Nuclear Medicine. - : Lippincott Williams & Wilkins. - 0363-9762 .- 1536-0229. ; 46:8, s. E410-E420
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Tidskriftsartikel (refereegranskat)abstract
- Breast cancer is the most frequent invasive malignancy and the second major cause of cancer death in female subjects mostly due to the considerable diagnostic delay and failure of therapeutic strategies. Thus, early diagnosis and possibility to monitor response to the treatment are of utmost importance. Identification of valid biomarkers, in particular new molecular therapeutic targets, that would allow screening, early patient identification, prediction of disease aggressiveness, and monitoring response to the therapeutic regimen has been in the focus of breast cancer research during recent decades. One of the intensively developing fields is nuclear medicine combining molecular diagnostic imaging and subsequent (radio)therapy in the light of theranostics. This review aimed to survey the current status of preclinical and clinical research using theranostic approach in breast cancer patients with potential to translate into conventional treatment strategies alone or in combination with other common treatments, especially in aggressive and resistant types of breast cancer. In addition, we present 5 patients with breast cancer who were refractory or relapsed after conventional therapy while presumably responded to the molecular radiotherapy with Lu-177-trastuzumab (Herceptin), Lu-177-DOTATATE, and Lu-177-FAPI-46.
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| 43. |
- Khalil, Amina, et al.
(författare)
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Introduction of a fatty acid chain modification to prolong circulatory half-life of a radioligand towards glucose-dependent insulinotropic polypeptide receptor
- 2024
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Ingår i: Nuclear Medicine and Biology. - : Elsevier. - 0969-8051 .- 1872-9614. ; 128
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Tidskriftsartikel (refereegranskat)abstract
- Background: The beneficial role of glucose-dependent insulinotropic polypeptide receptor (GIPR) in weight control and maintaining glucose levels has led to the development of several multi-agonistic peptide drug candidates, targeting GIPR and glucagon like peptide 1 receptor (GLP1R) and/or the glucagon receptor (GCGR). The in vivo quantification of target occupancy by these drugs would accelerate the development of new drug candidates. The aim of this study was to evaluate a novel peptide (GIP1234), based on previously reported ligand DOTA-GIP-C803, modified with a fatty acid moiety to prolong its blood circulation. It would allow higher target tissue exposure and consequently improved peptide uptake as well as in vivo PET imaging and quantification of GIPR occupancy by novel drugs of interest. Method: A 40 amino acid residue peptide (GIP1234) was synthesized based on DOTA-GIP-C803, in turn based on the sequences of endogenous GIP and Exendin-4 with specific amino acid modifications to obtain GIPR selectivity. A palmitoyl fatty acid chain was furthermore added at Lys14 via a glutamic acid linker to prolong its blood circulation time by the interaction with albumin. GIP1234 was conjugated with a DOTA chelator at the C -terminal cysteine residue to achieve 68Ga radiolabeling. The resulting PET probe, [68Ga]Ga-DOTA-GIP1234 was evaluated for receptor binding specificity and selectivity using HEK293 cells transfected with human GIPR, GLP1R, or GCGR. Blocking experiments with tirzepatide (2 mu M) were conducted using huGIPR HEK293 cells to investigate binding specificity. Ex vivo and in vivo organ distribution of [68Ga]Ga-DOTA-GIP1234 was studied in rats and a pig in comparison to [68Ga]Ga-DOTA-C803-GIP. Binding of [68Ga]Ga-DOTA-GIP1234 to albumin was assessed in situ using polyacrylamide gel electrophoresis (PAGE). The stability was tested in formulation buffer and rat blood plasma. Results: [68Ga]Ga-DOTA-GIP1234 was synthesized with non-decay corrected radiochemical yield of 88 +/- 3.7 % and radiochemical purity of 97.8 +/- 0.8 %. The molar activity for the radiotracer was 8.1 +/- 1.1 MBq/nmol. [68Ga]Ga-DOTA-GIP1234 was stable and maintained affinity to huGIPR HEK293 cells (dissociation constant (Kd) = 40 +/- 12.5 nM). The binding of [68Ga]Ga-DOTA-GIP1234 to huGCGR and huGLP1R cells was insignificant. Preincubation of huGIPR HEK293 cell sections with tirzepatide resulted in the decrease of [68Ga]Ga-DOTA-GIP1234 binding by close to 90 %. [68Ga]Ga-DOTA-GIP1234 displayed slow blood clearance in pigs with SUV = 3.5 after 60 min. Blood retention of the tracer in rat was 2-fold higher than that of [68Ga]Ga-DOTA-C803-GIP. [68Ga]Ga- DOTA-GIP1234 also demonstrated strong liver uptake in both pig and rat combined with decreased renal excretion. The concentration dependent binding of [68Ga]Ga-DOTA-GIP1234 to albumin was confirmed in situ by PAGE. Conclusion: [68Ga]Ga-DOTA-GIP1234 demonstrated nanomolar affinity and selectivity for huGIPR in vitro. Addition of a fatty acid moiety prolonged blood circulation time and tissue exposure in both rat and pig in vivo. However, the liver uptake was also increased which may make PET imaging of abdominal tissues such as pancreas challenging. The investigation of the influence of fatty acid moiety on the biological performance of the peptide ligand paved the way for further rational design of GIPR ligand analogues with improved characteristics.
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| 44. |
- Lavén, Martin, et al.
(författare)
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Imaging of peptide adsorption to microfluidic channels in a plastic compact disc using a positron emitting radionuclide
- 2005
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Ingår i: Lab Chip. ; :5, s. 756-763
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Tidskriftsartikel (refereegranskat)abstract
- A method for studying peptide-surface interactions within microfluidic channels by radionuclide imaging is described. With the high surface area-to-volume ratio of channels in miniaturised devices, combined with low amunts of analyte, non-specific peptide adsorption is a critical issue. The objective of the study was therefore to develop a method capable of direct detection of adsorbed peptide within microfluidic channels. A micro-device consisting of channels moulded in a plastic compact disc was chosen for the study, together with two selected peptides of different lengths and isolelectric point (pI) values. A bifunctional chelator, DOTA, was attached to the peptide by conjugation and labelled with the short-lived positron emitting radionuclide 68Ga. Quantitative images of radiotracer distribution within the microfluidic channels were obtained using a PhosphorImager system. The power of the method was demonstrated by the ability to clearly measure changes in adsorption when varying a number of parameters that typically affect peptide adsorption. These included surface modifications, analyte concentration, pH, and ionic strength. Additionally, two quantification methods were developed and compared. Radionuclide imaging also permitted visualisation of adsorption and release processes in microchannel chromatographic columns. The results suggest that radionuclide imaging is a suitable tool not only for the study of peptide adsorption to the microchannels presented in this study but also as a versatile tool to measure peptide-surface interactions in a wide variety of miniaturised structures and devices.
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| 45. |
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| 46. |
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| 47. |
- Lavén, Martin, et al.
(författare)
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Radionuclide Imaging of Miniaturized Chemical Analysis Systems
- 2004
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 76:23, s. 7102-7108
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Tidskriftsartikel (refereegranskat)abstract
- We propose radionuclide imaging as a valuable tool for the study of molecular interactions in miniaturized systems for chemical analysis. Sensitive and quantitative imaging can be performed with compounds labeled with short-lived positron-emitting radionuclides, such as C-11 and Ga-68, within selected parts of the system. Radionuclide imaging is not restricted to transparent materials since the relatively energetic positrons can penetrate high optical density materials. Experimentally, a radiotracer is introduced into the object of study, which is subsequently placed on a phosphor storage plate. After exposure, the plate is scanned with a laser and a digital, quantitative image can be reconstituted. To demonstrate the concept, three types of microstructures suited for integration in chemical analysis systems were imaged with C-11- and Ga-68-labeled tracers. The influence of factors such as geometry of the object and type of radionuclide on resolution and sensitivity was investigated. The resolution ranged from 0.9 to 2.7 mm (fwhm). Measuring low amounts of radioactivity in the three structures, 2-20 Bq could be detected, which corresponded to 2.3-500 amol or 2.4-110 pM tracer. The imaging approach was applied to study analyte concentration and sample dilution effects on the performance of a capillary extraction column integrated in an automated LC-ESI-MS system. The utility of the technique was further illustrated by imaging of microchannels in a zeonor plastic compact disk and in a poly(dimethylsiloxane) material for the study of nonspecific peptide adsorption.
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| 48. |
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| 49. |
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| 50. |
- Lendvai, Gabor, et al.
(författare)
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Biodistribution of Ga-68-labeled LNA-DNA mixmer antisense oligonucleotides for rat Chromogranin-A
- 2008
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Ingår i: Oligonucleotides. - : Mary Ann Liebert Inc. - 1545-4576 .- 1557-8526. ; 18:1, s. 33-49
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Tidskriftsartikel (refereegranskat)abstract
- In vivo monitoring of gene expression may be accomplished using a most advanced imaging technology such as positron emission tomography (PET). However, a range of methodological and biological hurdles needs exploration. In the present study, 20-mer DNA-LNA (locked nucleic acid) mixmer oligonucleotides specific for rat Chromogranin-A (Chg-A) mRNA were labeled with Ga-68 and their biodistribution were investigated in rats; namely, two Antisense (LNA1, LNA2-differing only in the positioning of LNA modification), Mismatched, and Sense sequences. In addition, in vivo and in vitro metabolite analysis of LNA1 and LNA2 was compared, and hybridization in solution was performed to verify the hybridization ability after labeling. Furthermore, semiquantitative polymerase chain reaction was carried out to find organs expressing Chg-A mRNA in the rat. The biodistribution patterns altered according to the sequence and the positioning of LNA modification. The pattern of Mismatched-differing only in two nucleotides from the two Antisenses-was similar to that of Sense, whereas the pattern of LNA1 and LNA2 showed differences. Uptake in the adrenal gland was twofold higher with LNA2 compared to the other three oligonucleotides. Intact LNA2 could be observed in the 60-minute sample in vivo, whereas in vitro, the intact compound of both Antisenses could also be detected after 2 hours. Hybridization in solution revealed that the two Antisenses retained their hybridization abilities after Ga-68-labeling. With decreasing magnitude, Chg-A mRNA was expressed in the adrenal gland, intestine, testis, and pancreas. This study further supported LNA-DNA mixmer to be a favorable modification for antisense targeting approach with respect to hybridization and longer plasma residence; however, the organ uptake was dominated by processes irrelevant to specific hybridization.
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