| 1. |
- Eriksson, Jonas, et al.
(författare)
-
Strategy to develop a MAO-A-resistant 5-hydroxy-L-[beta-C-11]tryptophan isotopologue based on deuterium kinetic isotope effects
- 2014
-
Ingår i: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 4:1
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe serotonin precursor 5-hydroxy-L-[β-11C]tryptophan ([11C]HTP) is in clinical use for localization of neuroendocrine tumors and has been suggested as a proxy marker for pancreatic islet cells. However, degradation by monoamine oxidase-A (MAO-A) reduces retention and the contrast to non-endocrine tissue.MethodsA synthesis method was developed for 5-hydroxy-L-[β-11C2H]tryptophan ([11C]DHTP), an isotopologue of [11C]HTP, labeled with 11C and 2H at the β-position adjacent to the carbon involved in MAO-A decarboxylation. MAO-A-mediated degradation of [11C]DHTP was evaluated and compared to non-deuterated [11C]HTP.Results[11C]DHTP was synthesized with a radiochemical purity of >98%, radioactivity of 620 ± 190 MBq, and deuterium (2H or 2H2) incorporation at the β-position of 22% ±5%. Retention and resistance to MAO-A-mediated degradation of [11C]DHTP were increased in cells but not in non-human primate pancreas.ConclusionsPartial deuteration of the β-position yields improved resistance to MAO-A-mediated degradation in vitro but not in vivo.
|
|
| 2. |
- Eriksson, Olof, et al.
(författare)
-
Detection of Metastatic Insulinoma by Positron Emission Tomography with [(68)Ga]Exendin-4 - : a case report
- 2014
-
Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 99:5, s. 1519-1524
-
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.
|
|
| 3. |
- Eriksson, Olof, et al.
(författare)
-
Quantitative Imaging of Serotonergic Biosynthesis and Degradation in the Endocrine Pancreas
- 2014
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 55:3, s. 460-465
-
Tidskriftsartikel (refereegranskat)abstract
- Serotonergic biosynthesis in the endocrine pancreas, of which the islets of Langerhans is the major constituent, has been implicated in insulin release and β cell proliferation. In this study, we investigated the feasibility of quantitative noninvasive imaging of the serotonergic metabolism in the pancreas using the PET tracer (11)C-5-hydroxy-l-tryptophan ((11)C-5-HTP).METHODS: Uptake of (11)C-5-HTP, and its specificity for key enzymes in the serotonergic metabolic pathway, was assessed in vitro (INS-1 and PANC1 cells and human islet and exocrine preparations) and in vivo (nonhuman primates and healthy and diabetic rats).RESULTS: In vitro tracer uptake in endocrine cells (INS-1 and human islets), but not PANC1 and exocrine cells, was mediated specifically by intracellular conversion into serotonin. Pancreatic uptake of (11)C-5-HTP in nonhuman primates was markedly decreased by inhibition of the enzyme dopa decarboxylase, which converts (11)C-5-HTP to (11)C-serotonin and increased after inhibition of monoamine oxidase-A, the main enzyme responsible for serotonin degradation. Uptake in the rat pancreas was similarly modulated by inhibition of monoamine oxidase-A and was reduced in animals with induced diabetes.CONCLUSION: The PET tracer (11)C-5-HTP can be used for quantitative imaging of the serotonergic system in the endocrine pancreas.
|
|
| 4. |
- Eriksson, Olof, et al.
(författare)
-
The Positron Emission Tomography ligand [11C]5-Hydroxy-Tryptophan can be used as a surrogate marker for the human endocrine pancreas
- 2014
-
Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 63:10, s. 3428-3437
-
Tidskriftsartikel (refereegranskat)abstract
- In humans a well-developed serotonin system is localized to the pancreatic islets while being absent in exocrine pancreas. Assessment of pancreatic serotonin biosynthesis could therefore be used to estimate the human endocrine pancreas. Proof of concept was tested in a prospective clinical trial by comparisons of type 1 diabetic (T1D) patients, with extensive reduction of beta cells, with healthy volunteers (HV).C-peptide negative (i.e. insulin-deficient) T1D subjects (n=10) and HV (n=9) underwent dynamic Positron Emission Tomography with the radiolabeled serotonin precursor [(11)C]5-Hydroxy-Tryptophan ([(11)C]5-HTP).A significant accumulation of [(11)C]5-HTP was obtained in the pancreas of the HV, with large inter-individual variation. A substantial and highly significant reduction (66%) in the pancreatic uptake of [(11)C]5-HTP in T1D subjects was observed, and this was most evident in the corpus and caudal regions of the pancreas where beta-cells normally are the major constituent of the islets.[(11)C]5-HTP retention in the pancreas was reduced in T1D compared to non-diabetic subjects. Accumulation of [(11)C]5-HTP in the pancreas of both HV and subjects with T1D were in agreement with previously reported morphological observations on the beta cell volume implying that [(11)C]5-HTP retention is a useful non-invasive surrogate marker for the human endocrine pancreas.
|
|
| 5. |
- Haylock, Anna-Karin, et al.
(författare)
-
Evaluation of a novel type of imaging probe based on a recombinant bivalent mini-antibody construct for detection of CD44v6-expressing squamous cell carcinoma
- 2016
-
Ingår i: International Journal of Oncology. - : Spandidos Publications. - 1019-6439 .- 1791-2423. ; 48:2, s. 461-470
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed the CD44v6-targeting human bivalent antibody fragment AbD19384, an engineered recombinant human bivalent Fab antibody formed via dimerization of dHLX (synthetic double helix loop helix motif) domains, for potential use in antibody-based molecular imaging of squamous cell carcinoma in the head and neck region. This is a unique construct that has, to the best of our knowledge, never been assessed for molecular imaging in vivo before. The objective of the present study was to evaluate for the first time the in vitro and in vivo binding properties of radio-iodinated AbD19384, and to assess its utility as a targeting agent for molecular imaging of CD44v6-expressing tumors. Antigen specificity and binding properties were assessed in vitro. In vivo specificity and biodistribution of I-125-AbD19384 were next evaluated in tumor-bearing mice using a dual-tumor setup. Finally, AbD19384 was labeled with I-124, and its imaging properties were assessed by small animal PET/CT in tumor bearing mice, and compared with 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG). In vitro studies demonstrated CD44v6-specific binding with slow off-rate for AbD19384. A favorable biodistribution profile was seen in vivo, with tumor-specific uptake. Small animal PET/CT images of I-124-AbD19384 supported the results through clearly visible high CD44v6-expressing tumors and faintly visible low expressing tumors, with superior imaging properties compared to 18F-FDG. Tumor-to-blood ratios increased with time for the conjugate (assessed up to 72 h p.i.), although 48 h p.i. proved best for imaging. Biodistribution and small-animal PET studies demonstrated that the recombinant Fab-dHLX construct AbD19384 is a promising tracer for imaging of CD44v6 antigen expression in vivo, with the future aim to be used for individualized diagnosis and early detection of squamous cell carcinomas in the head and neck region. Furthermore, this proof-of-concept research established the feasibility of using recombinant Fab-dHLX constructs for in vivo imaging of tumor biomarkers.
|
|
| 6. |
- Nalin, Lovisa, et al.
(författare)
-
Positron emission tomography imaging of the glucagon-like peptide-1 receptor in healthy and streptozotocin-induced diabetic pigs
- 2014
-
Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 41:9, s. 1800-1810
-
Tidskriftsartikel (refereegranskat)abstract
- PurposeThe glucagon-like peptide-1 receptor (GLP-1R) has been proposed as a target for molecular imaging of beta cells. The feasibility of non-invasive imaging and quantification of GLP-1R in pancreas using the positron emission tomography (PET) tracer [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 in non-diabetic and streptozotocin (STZ)–induced diabetic pigs treated with insulin was investigated.MethodsNon-diabetic (n = 4) and STZ-induced diabetic pigs (n = 3) from the same litter were examined. Development of diabetes was confirmed by blood glucose values, clinical examinations and insulin staining of pancreatic sections post mortem. Tissue perfusion in the pancreas and kidneys was evaluated by [15O]water PET/computed tomography (CT) scans. The in vivo receptor specificity of [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 was assessed by administration of either tracer alone or by competition with 3–6.5 μg/kg of Exendin-4. Volume of distribution and occupancy in the pancreas were quantified with a single tissue compartment model.Results[15O]water PET/CT examinations showed reduced perfusion in the pancreas and kidneys in diabetic pigs. [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 uptake in the pancreas of both non-diabetic and diabetic pigs was almost completely abolished by co-injection of unlabeled Exendin-4 peptide. [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 uptake did not differ between non-diabetic and diabetic pigs. In all animals, administration of the tracer resulted in an immediate increase in the heart rate (HR).ConclusionPancreatic uptake of [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 was not reduced by destruction of beta cells in STZ-induced diabetic pigs.
|
|
| 7. |
- Samanta, Sumanta, et al.
(författare)
-
Heparin-Derived Theranostic Nanoprobes Overcome the Blood-Brain Barrier and Target Glioma in Murine Model
- 2022
-
Ingår i: Advanced Therapeutics. - : John Wiley & Sons. - 2366-3987. ; 5:6
-
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.
|
|
| 8. |
- Selvaraju, Ram K., et al.
(författare)
-
In Vivo Imaging of the Glucagonlike Peptide 1 Receptor in the Pancreas with Ga-68-Labeled DO3A-Exendin-4
- 2013
-
Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 54:8, s. 1458-1463
-
Tidskriftsartikel (refereegranskat)abstract
- The glucagonlike peptide 1 receptor (GLP-1R) is mainly expressed on beta-cells in the Wets of Langerhans and is therefore an attractive target for imaging of the beta-cell mass. In the present study, Ga-68-labeled exendin-4 was evaluated for PET imaging and quantification of GLP-1R in the pancreas. Methods: Dose escalation studies of Ga-68-labeled 1,4,7-tris(carboxymethylaza)cyclododecane-10-azaacetyl (DO3A)-exendin-4 were performed in rats (organ distribution) and cynomolgus monkeys (PET/CT imaging) to determine the GLP-1R-specific tissue uptake in vivo. Pancreatic uptake (as determined by organ distribution) in healthy rats was compared with that in diabetic rats. GLP-1R occupancy in the cynomolgus pancreas was quantified with a 1-tissue-compartment model. Results: In rodents, uptake in the pancreas was decreased from the baseline by up to 90% (P < 0.0001) by coadministration of DO3A-exendin-4 at 100 mu g/kg. Pancreatic uptake in diabetic animals was decreased by more than 80% (P < 0.001) compared with that in healthy controls, as measured by organ distribution. GLP-1R occupancy in the cynomolgus pancreas after coinjection of DO3A-exendin-4 at 0.15-20 mu g/kg ranged from 49% to 97%, as estimated by compartment modeling. Conclusion: These results strongly support the notion that Ga-68-DO3A-exendin-4 uptake in the pancreas is mediated by specific receptor binding. In addition, pancreatic uptake was decreased by selective destruction of beta-cells. This result suggests that GLP-1R can be quantified in vivo, which has major implications for the prospect of imaging of native beta-cells.
|
|
| 9. |
- Spiegelberg, Diana, et al.
(författare)
-
Molecular imaging of EGFR and CD44v6 for prediction and response monitoring of HSP90 inhibition in an in vivo squamous cell carcinoma model.
- 2016
-
Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 43:5, s. 974-982
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Heat shock protein 90 (HSP90) is essential for the activation and stabilization of numerous oncogenic client proteins. AT13387 is a novel HSP90 inhibitor promoting degradation of oncogenic proteins upon binding, and may also act as a radiosensitizer. For optimal treatment there is, however, the need for identification of biomarkers for patient stratification and therapeutic response monitoring, and to find suitable targets for combination treatments. The aim of this study was to assess the response of surface antigens commonly expressed in squamous cell carcinoma to AT13387 treatment, and to find suitable biomarkers for molecular imaging and radioimmunotherapy in combination with HSP90 inhibition.METHODS: Cancer cell proliferation and radioimmunoassays were used to evaluate the effect of AT13387 on target antigen expression in vitro. Inhibitor effects were then assessed in vivo in mice-xenografts. Animals were treated with AT13387 (5 × 50 mg/kg), and were imaged with PET using either (18)F-FDG or (124)I-labelled tracers for EGFR and CD44v6, and this was followed by ex-vivo biodistribution analysis and immunohistochemical staining.RESULTS: AT13387 exposure resulted in high cytotoxicity and possible radiosensitization with IC50 values below 4 nM. Both in vitro and in vivo AT13387 effectively downregulated HSP90 client proteins. PET imaging with (124)I-cetuximab showed a significant decrease of EGFR in AT13387-treated animals compared with untreated animals. In contrast, the squamous cell carcinoma-associated biomarker CD44v6, visualized with (124)I-AbD19384 as well as (18)F-FDG uptake, were not significantly altered by AT13387 treatment.CONCLUSION: We conclude that AT13387 downregulates HSP90 client proteins, and that molecular imaging of these proteins may be a suitable approach for assessing treatment response. Furthermore, radioimmunotherapy targeting CD44v6 in combination with AT13387 may potentiate the radioimmunotherapy outcome due to radiosensitizing effects of the drug, and could potentially lead to a lower dose to normal tissues.
|
|
| 10. |
|
|
