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The future of nuclear medicine imaging of neuroendocrine tumors: on a clear day one might see forever…. Eur J Nucl Med Mol Imaging 2014; 41:2189-93. [DOI: 10.1007/s00259-014-2836-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Shah CH, Viktorsson K, Kanter L, Sherif A, Asmundsson J, Rosenblatt R, Lewensohn R, Ullén A. Vascular endothelial growth factor receptor 2, but not S100A4 or S100A6, correlates with prolonged survival in advanced urothelial carcinoma. Urol Oncol 2014; 32:1215-24. [PMID: 24880461 DOI: 10.1016/j.urolonc.2014.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/18/2014] [Accepted: 04/18/2014] [Indexed: 12/18/2022]
Abstract
OBJECTIVE A major challenge in muscle-invasive urothelial carcinoma (UC) is to identify biomarkers that can predict disease prognosis and treatment response after cystectomy. Therefore, we analyzed the potential prognostic value of the proteins vascular endothelial growth factor receptor 2 (VEGFR2), S100A4, and S100A6 in UC. METHODS Retrospective outcome data and tumor specimens from 83 cystectomy patients with histologically confirmed invasive UC were included. Expression levels of VEGFR2 (also called flk-1 and KDR), S100A4, and S100A6 were analyzed in primary tumor tissue by immunohistochemistry. RESULTS Immunohistochemical staining and analysis of VEGFR2, S100A4, and S100A6 showed localization mainly in tumor cell cytoplasm. High VEGFR2 expression and low tumor category were independent variables associated with longer overall survival (OS) and disease-free survival, revealed by a bivariate Cox proportional hazards regression model (both P<0.001). In addition, the univariate log-rank test and the Cox model demonstrated that OS beyond 2 years was significantly greater among patients with low S100A6 expression than in those with high S100A6 expression (P = 0.017 and 0.022, respectively). Differences in tumor expression of S100A4 were not significantly associated with outcome. CONCLUSION In this study, VEGFR2 expression was significantly correlated with risk of disease relapse and OS in a defined cohort of patients with UC of the bladder treated by cystectomy.
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Affiliation(s)
- Carl-Henrik Shah
- Department of Oncology, Radiumhemmet, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
| | - Kristina Viktorsson
- Department of Oncology-Pathology, Karolinska Biomics Center, Karolinska Institutet, Stockholm, Sweden
| | - Lena Kanter
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Amir Sherif
- Urology and Andrology, Department of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden
| | - Jurate Asmundsson
- Department of Pathology, Karolinska University Hospital, Stockholm, Sweden
| | | | - Rolf Lewensohn
- Department of Oncology, Radiumhemmet, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Anders Ullén
- Department of Oncology, Radiumhemmet, Karolinska University Hospital, Stockholm, Sweden; Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
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Waser B, Reubi JC. Radiolabelled GLP-1 receptor antagonist binds to GLP-1 receptor-expressing human tissues. Eur J Nucl Med Mol Imaging 2014; 41:1166-71. [PMID: 24519555 DOI: 10.1007/s00259-013-2684-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/20/2013] [Indexed: 01/08/2023]
Abstract
PURPOSE Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. For the somatostatin receptor targeting of tumours, however, it was recently reported that antagonist tracers were superior to agonist tracers. The present study therefore evaluated various forms of the (125)iodinated-Bolton-Hunter (BH)-exendin(9-39) antagonist tracer for the in vitro visualization of GLP-1 receptor-expressing tissues in rats and humans and compared it with the agonist tracer (125)I-GLP-1(7-36)amide. METHODS Receptor autoradiography studies with (125)I-GLP-1(7-36)amide agonist or (125)I-BH-exendin(9-39) antagonist radioligands were performed in human and rat tissues. RESULTS The antagonist (125)I-BH-exendin(9-39) labelled at lysine 19 identifies all human and rat GLP-1 target tissues and GLP-1 receptor-expressing tumours. Binding is of high affinity and is comparable in all tested tissues in its binding properties with the agonist tracer (125)I-GLP-1(7-36)amide. For comparison, (125)I-BH-exendin(9-39) with the BH labelled at lysine 4 did identify the GLP-1 receptor in rat tissues but not in human tissues. CONCLUSION The GLP-1 receptor antagonist exendin(9-39) labelled with (125)I-BH at lysine 19 is an excellent GLP-1 radioligand that identifies human and rat GLP-1 receptors in normal and tumoural tissues. It may therefore be the molecular basis to develop suitable GLP-1 receptor antagonist radioligands for in vivo imaging of GLP-1 receptor-expressing tissues in patients.
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Affiliation(s)
- Beatrice Waser
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, PO Box 62, Murtenstrasse 31, 3010, Berne, Switzerland
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Sabet A, Nagarajah J, Dogan AS, Biersack HJ, Sabet A, Guhlke S, Ezziddin S. Does PRRT with standard activities of 177Lu-octreotate really achieve relevant somatostatin receptor saturation in target tumor lesions?: insights from intra-therapeutic receptor imaging in patients with metastatic gastroenteropancreatic neuroendocrine tumors. EJNMMI Res 2013; 3:82. [PMID: 24369053 PMCID: PMC3877953 DOI: 10.1186/2191-219x-3-82] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/04/2013] [Indexed: 11/12/2022] Open
Abstract
Background Peptide receptor radionuclide therapy (PRRT) with 177Lu-[DOTA0,Tyr3]octreotate (177Lu-octreotate) is generally performed using a fixed activity of 7.4 GBq (200 mCi) per course bound to 180 to 300 μg of the peptide. While this single activity may lead to suboptimal radiation doses in neuroendocrine tumors (NET) with advanced or bulky disease, dose escalation has been withheld due to concerns on potential tumor somatostatin receptor saturation with reduced efficacy of the added activity. In vivo saturation effects during standard-dose PRRT based on quantification of pre- and intra-therapeutic 68Ga-DOTATOC positron emission tomography (PET) imaging might guide potential dose escalation. Methods Five patients with metastatic NET of the pancreas underwent 68Ga-DOTATOC PET/CT before and directly after standard-dose PRRT with 177Lu-octreotate. In each patient, four target tumor lesions, normal liver parenchyma, and the spleen were evaluated and the ratios of SUVmax of the target lesions to liver (SUVT/L) and spleen (SUVT/S) were calculated; paired Student's t test was performed with p < 0.05 for pre-/intra-PRRT comparisons. Results The mean intra-therapeutic tumor SUVmax showed no significant change (per-lesion paired t test) compared to pretreatment values (-9.1%, p = 0.226). In contrast, the SUVmax of the normal liver parenchyma and spleen were significantly lower directly after infusion of 7.4 GBq 177Lu-octreotate. Consequently, SUVT/L and SUVT/S increased significantly from pretreatment to intra-therapeutic examination: SUVT/L (p < 0.001) from 2.8 ± 1.3 (1.3 to 5.8) to 4.7 ± 3.0 (2.1 to 12.7) and SUVT/S (p < 0.001) from 1.2 ± 0.7 (0.4 to 3.0) to 3.5 ± 1.5 (1.6 to 7.9). Conclusions This small retrospective study provides preliminary evidence for the absence of relevant in vivo saturation of somatostatin receptor subtype 2 (sst2) in tumor lesions during PRRT with standard activities of 177Lu-octreotate in contrast to normal tissue (liver, spleen) showing limited receptor capacity. After being confirmed by larger series, this observation will have significant implications for PRRT: (1) Higher activities of 177Lu-octreotate might be considered feasible in patients with high tumor disease burden or clinical need for remission, and (2) striving to reduce the amount of peptide used in standard preparations of 177Lu-octreotate appears futile.
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Affiliation(s)
| | | | | | | | | | | | - Samer Ezziddin
- Department of Nuclear Medicine, University Hospital, Sigmund-Freud-Str, 25, Bonn 53105, Germany.
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Kossatz S, Mansi R, Béhé M, Czerney P, Hilger I. Influence of d-glutamine and d-glutamic acid sequences in optical peptide probes targeted against the cholecystokinin-2/gastrin-receptor on binding affinity, specificity and pharmacokinetic properties. EJNMMI Res 2013; 3:75. [PMID: 24238262 PMCID: PMC4176481 DOI: 10.1186/2191-219x-3-75] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 10/31/2013] [Indexed: 01/23/2023] Open
Abstract
Background Image-based diagnosis of tumours can be advanced and improved by targeted strategies addressing malignant molecular structures. A promising molecular target is the cholecystokinin-2-receptor (CCK2R) which can be targeted by high-affinity peptides called minigastrins. Here we present how the imaging properties of minigastrins tagged with near-infrared fluorescence (NIRF) dyes can be modulated by the introduction of different spacer sequences. We identify interactions of different probe variants with regard to target affinity, specificity and pharmacokinetic properties to optimize early detection of CCK2R-expressing tumours under clinical conditions. Methods Two minigastrin probes with the same near-infrared hemicyanine fluorescence dye (DY-754) for signalling and the same CCK2R-binding peptide A-Y-G-W-M/Nle-N-F-amide but different spacers were designed as follows: ‘QE’ with three alternating d-glutamines and d-glutamic acids and ‘bivQ’ with two minigastrins, each preceded by three d-glutamines. They were tested for affinity and specificity in vitro on CCK2R-expressing and CCK2R-non-expressing cells. In vivo imaging was conducted with subcutaneous tumour-bearing nude mice after i.v. probe injection (54 to 108 nmol/kg) and under competitive conditions with non-fluorescent minigastrin (n = 5/group). We also assessed probe biodistribution as well as NIRF distribution in tumour sections. Results Both probes showed high affinity and specificity to CCK2R-expressing cells in vitro. In vivo tumour-to-background contrasts (tumour/background ratios (TBRs) of around 6) enabled identification of CCK2R-expressing tumours by both probes with low accumulation in CCK2R-negative tumours (TBR of around 2). Specificity of the in vivo accumulation, revealed by competition, was higher for QE. Besides renal retention, probe uptake into organs was very low. Conclusion The properties of optical minigastrin probes can be specifically modified by the introduction of spacer sequences. A spacer of six hydrophilic amino acids increases affinity. A mix of d-glutamic and d-glutamine acids increased target-to-background contrast. Multimerization could not increase affinity but supposedly lowered stability. The probe QE is a promising candidate for clinical evaluation in terms of diagnosis of CCK2R-expressing tumours.
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Affiliation(s)
- Susanne Kossatz
- Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology I, Jena University Hospital-Friedrich Schiller University Jena, Erlanger Allee 101, Jena, 07747, Germany.
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Reubi JC, Schonbrunn A. Illuminating somatostatin analog action at neuroendocrine tumor receptors. Trends Pharmacol Sci 2013; 34:676-88. [PMID: 24183675 DOI: 10.1016/j.tips.2013.10.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/26/2013] [Accepted: 10/03/2013] [Indexed: 02/08/2023]
Abstract
Somatostatin analogs for the diagnosis and therapy of neuroendocrine tumors (NETs) have been used in clinical applications for more than two decades. Five somatostatin receptor subtypes have been identified and molecular mechanisms of somatostatin receptor signaling and regulation have been elucidated. These advances increased understanding of the biological role of each somatostatin receptor subtype, their distribution in NETs, as well as agonist-specific regulation of receptor signaling, internalization, and phosphorylation, particularly for the sst2 receptor subtype, which is the primary target of current somatostatin analog therapy for NETs. Various hypotheses exist to explain differences in patient responsiveness to somatostatin analog inhibition of tumor secretion and growth as well as differences in the development of tumor resistance to therapy. In addition, we now have a better understanding of the action of both first generation (octreotide, lanreotide, Octreoscan) and second generation (pasireotide) FDA-approved somatostatin analogs, including the biased agonistic character of some agonists. The increased understanding of somatostatin receptor pharmacology provides new opportunities to design more sophisticated assays to aid the future development of somatostatin analogs with increased efficacy.
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Affiliation(s)
- Jean Claude Reubi
- Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland.
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Heidari P, Wehrenberg-Klee E, Habibollahi P, Yokell D, Kulke M, Mahmood U. Free somatostatin receptor fraction predicts the antiproliferative effect of octreotide in a neuroendocrine tumor model: implications for dose optimization. Cancer Res 2013; 73:6865-73. [PMID: 24080280 DOI: 10.1158/0008-5472.can-13-1199] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Somatostatin receptors (SSTR) are highly expressed in well-differentiated neuroendocrine tumors (NET). Octreotide, an SSTR agonist, has been used to suppress the production of vasoactive hormones and relieve symptoms of hormone hypersecretion with functional NETs. In a clinical trial, an empiric dose of octreotide treatment prolonged time to tumor progression in patients with small bowel neuroendocrine (carcinoid) tumors, irrespective of symptom status. However, there has yet to be a dose optimization study across the patient population, and methods are currently lacking to optimize dosing of octreotide therapy on an individual basis. Multiple factors such as total tumor burden, receptor expression levels, and nontarget organ metabolism/excretion may contribute to a variation in SSTR octreotide occupancy with a given dose among different patients. In this study, we report the development of an imaging method to measure surface SSTR expression and occupancy level using the PET radiotracer (68)Ga-DOTATOC. In an animal model, SSTR occupancy by octreotide was assessed quantitatively with (68)Ga-DOTATOC PET, with the finding that increased occupancy resulted in decreased tumor proliferation rate. The results suggested that quantitative SSTR imaging during octreotide therapy has the potential to determine the fractional receptor occupancy in NETs, thereby allowing octreotide dosing to be optimized readily in individual patients. Clinical trials validating this approach are warranted.
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Affiliation(s)
- Pedram Heidari
- Authors' Affiliations: Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School and Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
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Starkey JR, Pascucci EM, Drobizhev MA, Elliott A, Rebane AK. Vascular targeting to the SST2 receptor improves the therapeutic response to near-IR two-photon activated PDT for deep-tissue cancer treatment. Biochim Biophys Acta Gen Subj 2013; 1830:4594-603. [PMID: 23747302 DOI: 10.1016/j.bbagen.2013.05.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/11/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Broader clinical acceptance of photodynamic therapy is currently hindered by (a) poor depth efficacy, and (b) predisposition towards establishment of an angiogenic environment during the treatment. Improved depth efficacy is being sought by exploiting the NIR tissue transparency window and by photo-activation using two-photon absorption (2PA). Here, we use two-photon activation of PDT sensitizers, untargeted and targeted to SST2 receptors or EGF receptors, to achieve deep tissue treatment. METHODS Human tumor lines, positive or negative for SST2r expression were used, as well as murine 3LL cells and bovine aortic endothelial cells. Expression of SST2 receptors on cancer cells and tumor vasculature was evaluated in vitro and frozen xenograft sections. PDT effects on tumor blood flow were followed using in vivo scanning after intravenous injection of FITC conjugated dextran 150K. Dependence of the PDT efficacy on the laser pulse duration was evaluated. Effectiveness of targeting to vascular SST2 receptors was compared to that of EGF receptors, or no targeting. RESULTS Tumor vasculature stained for SST2 receptors even in tumors from SST2 receptor negative cell lines, and SST2r targeted PDT led to tumor vascular shutdown. Stretching the pulse from ~120fs to ~3ps led to loss of the PDT efficacy especially at greater depth. PDT targeted to SST2 receptors was much more effective than untargeted PDT or PDT targeted to EGF receptors. GENERAL SIGNIFICANCE The use of octreotate to target SST2 receptors expressed on tumor vessels is an excellent approach to PDT with few recurrences and some long term cures.
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Affiliation(s)
- Jean R Starkey
- Montana State University, Department of Microbiology, Bozeman, MT 59717, USA.
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Bodei L, Mueller-Brand J, Baum RP, Pavel ME, Hörsch D, O'Dorisio MS, O'Dorisio TM, O'Dorisiol TM, Howe JR, Cremonesi M, Kwekkeboom DJ, Zaknun JJ. The joint IAEA, EANM, and SNMMI practical guidance on peptide receptor radionuclide therapy (PRRNT) in neuroendocrine tumours. Eur J Nucl Med Mol Imaging 2013; 40:800-16. [PMID: 23389427 PMCID: PMC3622744 DOI: 10.1007/s00259-012-2330-6] [Citation(s) in RCA: 483] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Peptide receptor radionuclide therapy (PRRNT) is a molecularly targeted radiation therapy involving the systemic administration of a radiolabelled peptide designed to target with high affinity and specificity receptors overexpressed on tumours. PRRNT employing the radiotagged somatostatin receptor agonists (90)Y-DOTATOC ([(90)Y-DOTA(0),Tyr(3)]-octreotide) or (177)Lu-DOTATATE ([(177)Lu-DOTA(0),Tyr(3),Thr(8)]-octreotide or [(177)Lu-DOTA(0),Tyr(3)]-octreotate) have been successfully used for the past 15 years to target metastatic or inoperable neuroendocrine tumours expressing the somatostatin receptor subtype 2. Accumulated evidence from clinical experience indicates that these tumours can be subjected to a high absorbed dose which leads to partial or complete objective responses in up to 30 % of treated patients. Survival analyses indicate that patients presenting with high tumour receptor expression at study entry and receiving (177)Lu-DOTATATE or (90)Y-DOTATOC treatment show significantly higher objective responses, leading to longer survival and improved quality of life. Side effects of PRRNT are typically seen in the kidneys and bone marrow. These, however, are usually mild provided adequate protective measures are undertaken. Despite the large body of evidence regarding efficacy and clinical safety, PRRNT is still considered an investigational treatment and its implementation must comply with national legislation, and ethical guidelines concerning human therapeutic investigations. This guidance was formulated based on recent literature and leading experts' opinions. It covers the rationale, indications and contraindications for PRRNT, assessment of treatment response and patient follow-up. This document is aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRNT and to deliver the treatment in a safe and effective manner. This document is largely based on the book published through a joint international effort under the auspices of the Nuclear Medicine Section of the International Atomic Energy Agency.
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Wang R, Yang F, Wu H, Wang Y, Huang Z, Hu B, Zhang M, Tang C. High-dose versus low-dose octreotide in the treatment of acute pancreatitis: a randomized controlled trial. Peptides 2013; 40:57-64. [PMID: 23275042 DOI: 10.1016/j.peptides.2012.12.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 12/18/2012] [Accepted: 12/18/2012] [Indexed: 02/07/2023]
Abstract
To evaluate the therapeutic efficacy of high-dose octreotide in patients with predicted severe acute pancreatitis (SAP) or SAP, two hundred and thirty-six patients with predicted SAP and 136 patients with SAP were randomized into control, high-dose octreotide (High-O) and low-dose octreotide (Low-O) groups. In addition to the conventional managements administrated in control group, High-O group received an intravenous infusion of octreotide at 50 μg/h × 3d + 25 μg/h × 4d, and Low-O group received octreotide at 25 μg/h × 7d. The major primary outcomes included the numbers of predicted SAP patients which developed SAP after intervention and the number of patients with SAP amelioration. Secondary outcomes included APACHE II, SIRS scores, plasma levels of somatostatin (SST), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). There were no significant differences between the control and Low-O groups in terms of prevention and treatment for SAP. The incidence of SAP in patients with predicted SAP who received High-O was significantly lower than the Low-O group: 37.5% vs. 59.8%, p=0.005. Compared with Low-O group, the number of SAP patients in the SAP arm in the High-O group was reduced by 29.8%. Plasma levels of SST in both predicted SAP and the SAP patients were efficiently recovered (from 132.71±31.40 pg/ml to 180.00±23.50 pg/ml, p<0.05) after high-dose octreotide supplementation, which concomitantly reduced TNF-α and IL-6 levels. High-dose octreotide administration within 48h after AP onset may efficiently reduce the risk of SAP developing and partly attenuate SAP through raising plasma SST to a normal level and decreasing IL-6 and TNF-α.
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Affiliation(s)
- Rui Wang
- Department of Gastroenterology, West China Hospital, Sichuan University, PR China.
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Forssell-Aronsson E, Spetz J, Ahlman H. Radionuclide therapy via SSTR: future aspects from experimental animal studies. Neuroendocrinology 2013; 97:86-98. [PMID: 22572526 DOI: 10.1159/000336086] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 12/11/2011] [Indexed: 12/24/2022]
Abstract
There is need for better therapeutic options for neuroendocrine tumours. The aim of this review was to summarize results of experimental animal studies and raise ideas for future radionuclide therapy based on high expression of somatostatin (SS) receptors by many neuroendocrine tumours. In summary, one of the major options is individualized treatment for each patient, including choice of SS analogues, radionuclides and treatment schedules. Other options are methods to increase the treatment effect on tumour tissue (increasing tumour uptake and retention by upregulation of receptor expression and avoiding saturation of receptor binding), methods to increase the tumour tissue response (by choice of radionuclides, SS analogues or combined therapies), and methods to reduce side effects (diminished uptake and retention in critical organs and reduced normal tissue response). Furthermore, combination therapy with other radiopharmaceuticals, cytotoxic drugs or radiosensitizers can be considered to enhance the effects of radiolabelled SS analogues.
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Affiliation(s)
- Eva Forssell-Aronsson
- Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Cancer Centre, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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Kletting P, Muller B, Erentok B, Schmaljohann J, Behrendt FF, Reske SN, Mottaghy FM, Glatting G. Differences in predicted and actually absorbed doses in peptide receptor radionuclide therapy. Med Phys 2012; 39:5708-17. [PMID: 22957636 DOI: 10.1118/1.4747266] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE An important assumption in dosimetry prior to radionuclide therapy is the equivalence of pretherapeutic and therapeutic biodistribution. In this study the authors investigate if this assumption is justified in sst2-receptor targeting peptide therapy, as unequal amounts of peptide and different peptides for pretherapeutic measurements and therapy are commonly used. METHODS Physiologically based pharmacokinetic models were developed. Gamma camera and serum measurements of ten patients with metastasizing neuroendocrine tumors were conducted using (111)In-DTPAOC. The most suitable model was selected using the corrected Akaike information criterion. Based on that model and the estimated individual parameters, predicted and measured (90)Y-DOTATATE excretions during therapy were compared. The residence times for the pretherapeutic (measured) and therapeutic scenarios (simulated) were calculated. RESULTS Predicted and measured therapeutic excretion differed in three patients by 10%, 31%, and 7%. The measured pretherapeutic and therapeutic excretion differed by 53%, 56%, and 52%. The simulated therapeutic residence times of kidney and tumor were 3.1 ± 0.6 and 2.5 ± 1.2 fold higher than the measured pretherapeutic ones. CONCLUSIONS To avoid the introduction of unnecessary inaccuracy in dosimetry, using the same substance along with the same amount for pretherapeutic measurements and therapy is recommended.
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Affiliation(s)
- Peter Kletting
- Klinik für Nuklearmedizin, Universität Ulm, Ulm, Germany.
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Claringbold PG, Price RA, Turner JH. Phase I-II study of radiopeptide 177Lu-octreotate in combination with capecitabine and temozolomide in advanced low-grade neuroendocrine tumors. Cancer Biother Radiopharm 2012; 27:561-9. [PMID: 23078020 DOI: 10.1089/cbr.2012.1276] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Abstract We conducted a phase I-II clinical trial to assess the safety and efficacy of combining lutetium-177 ((177)Lu)-octreotate with capecitabine and temozolomide in treating advanced low-grade neuroendocrine tumors (NETs). All 35 patients received fixed activities of 7.8 GBq (177)Lu-octreotate each 8 weeks, with 14 days of capecitabine 1500 mg/m(2) for 4 cycles. In phase I, successive cohorts of patients received escalating doses of temozolomide in groupings of 100, 150, and 200 mg/m(2) in the last 5 days of each capecitabine cycle. In phase II, patients were treated with 200 mg/m(2) temozolomide. Treatment was well tolerated in all dosage groups. No dose-limiting grade 2, 3, or 4 toxicities were seen in cohorts 1 (100 mg/m(2)) or 2 (150 mg/m(2)). Twenty-eight patients completed treatment at the 200 mg/m(2) temozolomide level. Adverse events were mild to moderate. The commonest toxicities were transient nausea grade 2 (18%), grade 3 (3%), thrombocytopenia grade 2 (24%), and neutropenia grade 3 (6%). There were no grade 4 events. Thirty-four patients were evaluable for tumor response. Overall, complete response (CR) was achieved in 15% (95% CI 3-27); partial response (PR), in 38% (95% CI 22-55); stable disease (SD), in 38% (95% CI 22-55); and 3 patients failed to respond to treatment. Median progression free survival (PFS) was 31 months (95% CI 21-33), and median overall survival (OS) has not been reached with 90% surviving at 24 months follow-up (range 21-30). Overall objective response rate (ORR) in patients with gastroenteropancreatic NETs showed CR 16% (95% CI 3-28), PR 41% (95% CI 24-58), SD 37% (95% CI 21-54), and PD 6% (95% CI 0-15). Response rates were higher in patients with gastropancreatic NETs than in those with bowel primaries (enteric-NETs); CR 18% versus 13%, PR 64% versus 13%, SD 12% versus 67%. (177)Lu-octreotate, in combination with capecitabine and temozolomide, is well tolerated in patients with advanced low-grade NETs, and shows substantial tumor control rates.
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Affiliation(s)
- Phillip G Claringbold
- Department of Oncology, Fremantle Hospital, The University of Western Australia, Australia
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Sreenivasan VKA, Kim EJ, Goodchild AK, Connor M, Zvyagin AV. Targeting somatostatin receptors using in situ-bioconjugated fluorescent nanoparticles. Nanomedicine (Lond) 2012; 7:1551-60. [DOI: 10.2217/nnm.12.42] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Aim: The author’s group report, for the first time, on the development of a quantum dot (QD)-based fluorescent somatostatin (somatotropin release-inhibiting factor [SRIF]) probe that enables specific targeting of somatostatin receptors. Receptor-mediated endocytosis of SRIF was imaged using this probe. Materials & methods: Biotinylated SRIF-analog (SRIF-B) and streptavidin (Sav)-coated QDs were used for the probe synthesis. A dye-labeled streptavidin complex was used to evaluate the effect of Sav binding on the activity of SRIF-B. Results: A preconjugated probe of the form SRIF-B:Sav-QD, was inactive and unable to undergo receptor-mediated endocytosis. An alternative in situ bioconjugation strategy, where SRIF-B and Sav-QD were added in two consecutive steps, enabled visualization of the receptor-mediated endocytosis. The process of Sav binding appeared to be responsible for the inactivity in the first case. Conclusion: The in situ two-step bioconjugation strategy allowed QDs to be targeted to somatostatin receptors. This strategy should enable flexible fluorescent tagging of SRIF for the investigation of molecular trafficking in cells and targeted delivery in live animals. Original submitted 14 November 2011; Revised submitted 27 February 2012; Published online 20 July 2012
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Affiliation(s)
| | - Eun J Kim
- Department of Science Education – Chemical Education Major, Daegu University, Gyeonbuk, Republic of Korea
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Statham-Ringen KA, Selting KA, Lattimer JC, Henry CJ, Green JA, Bryan JN, Jia F, Lewis MR. Evaluation of a B-cell leukemia-lymphoma 2-specific radiolabeled peptide nucleic acid-peptide conjugate for scintigraphic detection of neoplastic lymphocytes in dogs with B-cell lymphoma. Am J Vet Res 2012; 73:681-8. [PMID: 22533400 DOI: 10.2460/ajvr.73.5.681] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate use of a radiolabeled peptide nucleic acid-peptide conjugate (RaPP) targeting B-cell leukemia-lymphoma 2 (BCL2) mRNA for scintigraphic detection of neoplastic lymphocytes in dogs with B-cell lymphoma and to assess associations among RaPP uptake, time to tumor progression (TTP), and BCL2 mRNA expression. ANIMALS 11 dogs with B-cell lymphoma and 1 clinically normal dog. PROCEDURES Scintigraphic images were acquired 1 hour after IV injection of the RaPP. Regions of interest (ROIs) were drawn around lymph nodes, liver, and spleen; ROI intensity (relative to that of an equally sized region of muscle in the same image) was measured. Each ROI was also subjectively categorized as positive or negative for increased RaPP uptake. Expression of BCL2 mRNA was determined via quantitative reverse transcriptase PCR assay of a lymph node sample from dogs with lymphoma. Associations among imaging results, TTP, and BCL2 mRNA expression were evaluated. RESULTS Increased RaPP uptake was detected in affected tissues of dogs with lymphoma. Dogs with superficial cervical lymph node ROIs categorized as negative (n = 8) for increased RaPP uptake had a significantly longer TTP than did dogs for which this ROI was considered positive (2). Measured intensity of mandibular and superficial cervical lymph node ROIs was negatively associated with TTP. Associations among BCL2 mRNA and ROI intensity or TTP were not significant. CONCLUSIONS AND CLINICAL RELEVANCE Increased RaPP uptake at mandibular or superficial cervical lymph node ROIs may be a negative prognostic indicator in dogs with lymphoma. A larger investigation is needed to determine clinical value of the RaPP for disease detection and prognostication.
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Affiliation(s)
- Kimberly A Statham-Ringen
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
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Waser B, Cescato R, Liu Q, Kao YJ, Körner M, Christ E, Schonbrunn A, Reubi JC. Phosphorylation of sst2 receptors in neuroendocrine tumors after octreotide treatment of patients. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:1942-9. [PMID: 22538189 DOI: 10.1016/j.ajpath.2012.01.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 01/13/2012] [Accepted: 01/26/2012] [Indexed: 12/18/2022]
Abstract
Somatostatin analogues, which are used to treat neuroendocrine tumors, target the high levels of somatostatin receptor subtype 2 (SSTR1; alias sst2) expressed in these cancers. However, some tumors are resistant to somatostatin analogues, and it is unknown whether the defect lies in sst2 activation or downstream signaling events. Because sst2 phosphorylation occurs rapidly after receptor activation, we examined whether sst2 is phosphorylated in neuroendocrine tumors. The sst2 receptor phosphorylation was evaluated by IHC and Western blot analysis with the new Ra-1124 antibody specific for the sst2 receptor phosphorylated at Ser341/343 in receptor-positive neuroendocrine tumors obtained from 10 octreotide-treated and 7 octreotide-naïve patients. The specificity, time course, and subcellular localization of sst2 receptor phosphorylation were examined in human embryo kinase-sst2 cell cultures by immunofluorescence and confocal microscopy. All seven octreotide-naïve tumors displayed exclusively nonphosphorylated cell surface sst2 expression. In contrast, 9 of the 10 octreotide-treated tumors contained phosphorylated sst2 that was predominantly internalized. Western blot analysis confirmed the IHC data. Octreotide treatment of human embryo kinase-sst2 cells in culture demonstrated that phosphorylated sst2 was localized at the plasma membrane after 10 seconds of stimulation and was subsequently internalized into endocytic vesicles. These data show, for the first time to our knowledge, that phosphorylated sst2 is present in most gastrointestinal neuroendocrine tumors from patients treated with octreotide but that a striking variability exists in the subcellular distribution of phosphorylated receptors among such tumors.
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MESH Headings
- Antineoplastic Agents, Hormonal/pharmacology
- Antineoplastic Agents, Hormonal/therapeutic use
- Carcinoma, Neuroendocrine/drug therapy
- Carcinoma, Neuroendocrine/metabolism
- Carcinoma, Neuroendocrine/surgery
- Chemotherapy, Adjuvant
- Humans
- Microscopy, Confocal
- Microscopy, Fluorescence
- Neoplasm Proteins/drug effects
- Neoplasm Proteins/metabolism
- Octreotide/pharmacology
- Octreotide/therapeutic use
- Phosphorylation/drug effects
- Receptors, Somatostatin/drug effects
- Receptors, Somatostatin/metabolism
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Affiliation(s)
- Beatrice Waser
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
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Pfeifer A, Knigge U, Mortensen J, Oturai P, Berthelsen AK, Loft A, Binderup T, Rasmussen P, Elema D, Klausen TL, Holm S, von Benzon E, Højgaard L, Kjaer A. Clinical PET of neuroendocrine tumors using 64Cu-DOTATATE: first-in-humans study. J Nucl Med 2012; 53:1207-15. [PMID: 22782315 DOI: 10.2967/jnumed.111.101469] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED The use of positron emitter-labeled compounds for somatostatin receptor imaging (SRI) has become attractive because of the prospect of improved spatial resolution, accelerated imaging procedures, and the ability to quantify tissue radioactivity concentrations. This paper provides results from first-in-humans use of (64)Cu-DOTATATE, an avidly binding somatostatin receptor ligand linked to a radioisotope with intermediate half-life and favorable positron energy (half-life, 12.7 h; maximum positron energy, 0.653 MeV). METHODS In a prospective setup, 14 patients with a history of neuroendocrine tumors underwent both PET/CT with (64)Cu-DOTATATE and SPECT/CT with our current routine imaging agent (111)In-diethylenetriaminepentaacetic acid-octreotide. After intravenous injection of 193-232 MBq of (64)Cu-DOTATATE, whole-body PET scans were acquired at 1 h (n = 14), 3 h (n = 12), and 24 h (n = 5) after administration. Tissue radioactivity concentrations for normal organs and lesions were quantified, and standardized uptake values were calculated for the early (1 h) and delayed (3 h) scans. Using the data for 5 patients, we assessed the radiation dose with OLINDA/EXM software. Furthermore, the clinical performance of (64)Cu-DOTATATE with respect to lesion detection was compared with conventional SRI. RESULTS SRI with (64)Cu-DOTATATE produced images of excellent quality and high spatial resolution. Images were characterized by high and stable tumor-to-background ratios over an imaging time window of at least 3 h. Compared with conventional scintigraphy, (64)Cu-DOTATATE PET identified additional lesions in 6 of 14 patients (43%). In 5 patients, lesions were localized in organs and organ systems not previously known as metastatic sites, including the early-stage detection of a secondary neuroendocrine tumor in a patient with a known mutation in the multiple endocrine neoplasia type I gene. All major additional findings seen only on PET could be confirmed on the basis of a clinical follow-up interval of 18 mo. Calculated radiation dose estimates yielded an effective dose of 6.3 mSv for an injected activity of 200 MBq of (64)Cu-DOTATATE, with the liver being the organ with the highest absorbed radiation dose (0.16 mGy/MBq). CONCLUSION This first-in-humans study supports the clinical use of (64)Cu-DOTATATE for SRI with excellent imaging quality, reduced radiation burden, and increased lesion detection rate when compared with (111)In-diethylenetriaminepentaacetic acid-octreotide.
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Affiliation(s)
- Andreas Pfeifer
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
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Wildemberg LEA, Vieira Neto L, Costa DF, Nasciutti LE, Takiya CM, Alves LM, Gadelha MR. Validation of immunohistochemistry for somatostatin receptor subtype 2A in human somatotropinomas: comparison between quantitative real time RT-PCR and immunohistochemistry. J Endocrinol Invest 2012; 35:580-4. [PMID: 21897115 DOI: 10.3275/7906] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Somatostatin receptors subtype 2 (SSTR2) expression in somatotropinomas is recognized as a predictor of response to the currently available somatostatin analogs and may be analyzed, mainly, by quantitative RT-PCR or immunohistochemistry (IHC). The former has the advantages of a higher sensitivity and of being quantitative, while the latter, although semi-quantitative, evaluates protein expression and is routinely used in the evaluation of pituitary adenomas. We aimed to evaluate the SSTR2A protein expression in somatotropinomas and to compare it to our previous data regarding mRNA expression, assessed by quantitative real time RTPCR. Thirteen somatotropinomas were analyzed by IHC and the tumors were scored according to percent of immunostained cells: 0 (<25%), 1 (25-50%) and 2 (>50%). SSTR2A immunostaining was present in all but one somatotropinoma, 4 (31%) tumors were classified as score 0, 4 (31%) as score 1, and 5 (38%) as score 2. Median SSTR2 mRNA content was significantly different among the three IHC scores (p=0.036) and was lower in the score 0 than in the score 2 (p=0.016). The finding that there is a positive correlation between RT-PCR and IHC indicates that IHC can be applied in order to assess the SSTR2A content in somatotropinomas.
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Affiliation(s)
- L E A Wildemberg
- Endocrinology Section, Hospital Universitário Clementino Fraga Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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Velikyan I, Xu H, Nair M, Hall H. Robust labeling and comparative preclinical characterization of DOTA-TOC and DOTA-TATE. Nucl Med Biol 2012; 39:628-39. [PMID: 22336375 DOI: 10.1016/j.nucmedbio.2011.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 12/09/2011] [Accepted: 12/14/2011] [Indexed: 01/15/2023]
Abstract
OBJECTIVES Various radionuclide-labeled somatostatin analogues are used currently for diagnosis and therapy of neuroendocrine tumors. In particular, [68Ga]Ga-DOTA-TOC is commonly used for diagnosis, while [177Lu]Lu-DOTA-TATE is used for therapy. With the development of theranostics and personalized medicine where the imaging diagnosis is tailored to the subsequent radiotherapy, it is of paramount importance to investigate the relevance of the ligand exchange. The aim of this study was to compare binding capacity of [67/68Ga]Ga-DOTA-TOC ([67/68Ga]Ga-N-(4,7,10-(tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetyl-D-Phe-c[Cys-D-Tyr-Trp-Lys-Thr-Cys]-Thr(ol)) and [67/68Ga]Ga-DOTA-TATE ([67/68Ga]Ga-N-(4,7,10-(tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetyl-D-Phe-c[Cys-D-Tyr-Trp-Lys-Thr-Cys]-Thr) in vitro in monkey brain cryosections and in vivo in the rat, where, in contrast to transfected cell lines, there is a heterogeneous distribution of somatostatin receptor (SSTR) subtypes. The influence of various production methods of [68Ga]Ga-DOTA-TOC and [68Ga]Ga-DOTA-TATE on the biological performance of the tracers was also studied. MATERIAL AND METHODS [67Ga]Ga-DOTA-TOC, [68Ga]Ga-DOTA-TOC, [67Ga]Ga-DOTA-TATE and [68Ga]Ga-DOTA-TATE were synthesized including preconcentration and purification of the generator eluate. The binding of the radioligands was assessed in vitro using autoradiography on cryosections of Rhesus monkey brains and in vivo/ex vivo using organ distribution studies in rats. RESULTS AND DISCUSSION The tracer production method was improved in terms of higher robustness, simplification and good manufacturing practice (GMP) relevance. The synthesis variation did not influence the biological performance of the tracers. There was no statistically significant difference observed in the binding of [67/68Ga]Ga-DOTA-TOC and [67/68Ga]Ga-DOTA-TATE either in brain cortex in vitro or in rat biodistribution and uptake in SSTR-positive tissues such as pancreas, adrenals and pituitary. The uptake in these organs was precluded by the excess of octreotide (Sandostatin). The 10-fold higher affinity to SSTR2 of DOTA-TATE as compared to DOTA-TOC known from studies in transfected cells was reflected in a slightly more intense binding of [67/68Ga]Ga-DOTA-TATE than of [67/68Ga]Ga-DOTA-TOC in the monkey brain sections in vitro, but not in vivo in the rat. CONCLUSION A robust 68Ga-labeling method was introduced. The difference in the uptake of [67/68Ga]Ga-DOTA-TOC and [67/68Ga]Ga-DOTA-TATE in SSTR2-positive organs was not statistically significant either in vitro in tissue studies or in vivo/ex vivo in rat experiments. The results indicate that the more complex environment in vitro and in vivo diminishes the difference observed in transfected cell line binding.
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Affiliation(s)
- Irina Velikyan
- Department of Radiology, Oncology and Radiation Sciences, Uppsala University, PET Center, Uppsala University Hospital, Uppsala, SE-75185 Uppsala, Sweden.
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Cescato R, Waser B, Fani M, Reubi JC. Evaluation of 177Lu-DOTA-sst2 Antagonist Versus 177Lu-DOTA-sst2 Agonist Binding in Human Cancers In Vitro. J Nucl Med 2011; 52:1886-90. [DOI: 10.2967/jnumed.111.095778] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Haug AR, Rominger A, Mustafa M, Auernhammer C, Göke B, Schmidt GP, Wängler B, Cumming P, Bartenstein P, Hacker M. Treatment with Octreotide Does Not Reduce Tumor Uptake of 68Ga-DOTATATE as Measured by PET/CT in Patients with Neuroendocrine Tumors. J Nucl Med 2011; 52:1679-83. [DOI: 10.2967/jnumed.111.089276] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Fani M, Del Pozzo L, Abiraj K, Mansi R, Tamma ML, Cescato R, Waser B, Weber WA, Reubi JC, Maecke HR. PET of Somatostatin Receptor–Positive Tumors Using 64Cu- and 68Ga-Somatostatin Antagonists: The Chelate Makes the Difference. J Nucl Med 2011; 52:1110-8. [DOI: 10.2967/jnumed.111.087999] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Cakir M, Dworakowska D, Grossman A. Somatostatin receptor biology in neuroendocrine and pituitary tumours: part 1--molecular pathways. J Cell Mol Med 2011; 14:2570-84. [PMID: 20629989 PMCID: PMC4373477 DOI: 10.1111/j.1582-4934.2010.01125.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Neuroendocrine tumours (NETs) may occur at many sites in the body although the majority occur within the gastroenteropancreatic axis. Non-gastroenteropancreatic NETs encompass phaeochromocytomas and paragangliomas, medullary thyroid carcinoma, anterior pituitary tumour, broncho-pulmonary NETs and parathyroid tumours. Like most endocrine tumours, NETs also express somatostatin (SST) receptors (subtypes 1–5) whose ligand SST is known to inhibit endocrine and exocrine secretions and have anti-tumour effects. In the light of this knowledge, the idea of using SST analogues in the treatment of NETs has become increasingly popular and new studies have centred upon the development of new SST analogues. We attempt to review SST receptor (SSTR) biology primarily in neuroendocrine tissues, focusing on pituitary tumours. A full data search was performed through PubMed over the years 2000–2009 with keywords ‘somatostatin, molecular biology, somatostatin receptors, somatostatin signalling, NET, pituitary’ and all relevant publications have been included, together with selected publications prior to that date. SSTR signalling in non-neuroendocrine solid tumours is beyond the scope of this review. SST is a potent anti-proliferative and anti-secretory agent for some NETs. The successful therapeutic use of SST analogues in the treatment of these tumours depends on a thorough understanding of the diverse effects of SSTR subtypes in different tissues and cell types. Further studies will focus on critical points of SSTR biology such as homo- and heterodimerization of SSTRs and the differences between post-receptor signalling pathways of SSTR subtypes.
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Affiliation(s)
- Mehtap Cakir
- Selcuk University, Meram School of Medicine, Division of Endocrinology and Metabolism, Konya, Turkey.
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Giovacchini G, Nicolas G, Freidank H, Mindt TL, Forrer F. Effect of amino acid infusion on potassium serum levels in neuroendocrine tumour patients treated with targeted radiopeptide therapy. Eur J Nucl Med Mol Imaging 2011; 38:1675-82. [PMID: 21553088 DOI: 10.1007/s00259-011-1826-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 04/08/2011] [Indexed: 11/24/2022]
Abstract
PURPOSE Administration of positively charged amino acids has been introduced to reduce the nephrotoxicity of targeted radiopeptide therapy (TRT). However, the amino acid solution may have side effects, including hyperkalaemia. The aim of this study was to evaluate the frequency and the magnitude of hyperkalaemia in neuroendocrine tumour (NET) patients undergoing TRT. METHODS Enrolled in the study were 31 patients with NET eligible for TRT with [(90)Y-DOTA(0),Tyr(3)]octreotide ((90)Y-DOTATOC). Their mean age was 54 ± 14 years. Of these 31 patients, 21 (67%) were referred for the first treatment cycle, while 10 (33%) were referred for a subsequent therapy cycle. Patients were treated with therapeutic doses of (90)Y-DOTATOC ranging from 7,030 to 35,520 MBq. To inhibit tubular reabsorption of (90)Y-DOTATOC, 1 l of physiological saline solution containing 25 g of arginine hydrochloride and 25 g of lysine hydrochloride was given over 4 h starting 1 h before (90)Y-DOTATOC injection. All patients underwent a standard biochemical blood analysis at baseline, and 4 h and 24 h after the beginning of the amino acid infusion. RESULTS ANOVA repeated measures showed a significant overall effect on K(+) levels over time (F = 118.2, df = 2, P < 0.0001). Mean serum levels of K(+) were 4.00 ± 0.33 mmol/l at baseline, 5.47 ± 0.57 mmol/l at 4 h, and 4.38 ± 0.63 mmol/l at 24 h after the beginning of the infusion. Post-hoc analysis showed that K(+) levels at 4 h were significantly (P < 0.05) higher than at baseline. K(+) levels at 24 h were significantly (P < 0.05) lower than at 4 h but they were still significantly (P < 0.05) higher than K(+) levels at baseline. On a subject-by-subject basis, none of the 31 patients had increased K(+) levels at baseline. At 4 h, 24 of the 31 patients (77%) had K(+) levels above the normal range, and 6 patients (19%) experienced severe hyperkalaemia (K(+) ≥ 6 mmol/l). All patients with increased K(+) levels were clinically asymptomatic. At 24 h, only 4 patients (13%) had increased K(+) serum levels. The magnitude of the increase in K(+) levels between baseline and 4 h was relatively homogeneous over the whole group (1.41 ± 0.50 mmol/l) and it was not related (linear regression, P>0.05) to baseline K(+) levels. Intravenous administration of 40 mg furosemide 1 h after the beginning of the amino acid infusion did not have a significant effect on K(+) levels (P>0.05). No clinical characteristic was predictive for the increase in K(+) levels (chi-squared test, P > 0.05). CONCLUSION Hyperkalaemia is a frequent, potentially life-threatening side effect of basic amino acid infusion during TRT. K(+) levels 4 h after the beginning of the infusion should be monitored in patients at risk of complications, such as those with heart disease and those with risk factors for nephrotoxicity.
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Affiliation(s)
- Giampiero Giovacchini
- Department of Radiology and Nuclear Medicine, Division of Endocrine Diagnostics and Radionuclide Therapy, University Hospital Basel, 4031, Basel, Switzerland.
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Nicolas G, Giovacchini G, Müller-Brand J, Forrer F. Targeted radiotherapy with radiolabeled somatostatin analogs. Endocrinol Metab Clin North Am 2011; 40:187-204, ix-x. [PMID: 21349419 DOI: 10.1016/j.ecl.2010.12.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Targeted radiopeptide therapy with (90)Yttrium- or (177)Lutetium-labeled somatostatin analogs has been proven to improve significantly quality of life and survival in patients suffering from metastatic or unresectable neuroendocrine tumors (NETs). Roughly 25% of patients achieve partial remission; progression-free survival is estimated to be 30 to 40 months. A wide range of protocols using different somatostatin analogs, isotopes, injected activity per cycle of administration, and number of cycles are reported. More patient-based therapy protocols are under development, taking into consideration the complexity of NET cell biology, dosimetric issues, and the availability of different radiolabeled analogs. This article reviews the effectiveness and safety of the different protocols and discusses several clinical algorithms used in an attempt to optimize targeted radiopeptide therapy.
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Affiliation(s)
- Guillaume Nicolas
- Department of Radiology and Nuclear Medicine, University Hospital Basel, 4031 Basel, Switzerland
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Zhang H, Moroz MA, Serganova I, Ku T, Huang R, Vider J, Maecke HR, Larson SM, Blasberg R, Smith-Jones PM. Imaging Expression of the Human Somatostatin Receptor Subtype-2 Reporter Gene with 68Ga-DOTATOC. J Nucl Med 2010; 52:123-31. [DOI: 10.2967/jnumed.110.079004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Claringbold PG, Brayshaw PA, Price RA, Turner JH. Phase II study of radiopeptide 177Lu-octreotate and capecitabine therapy of progressive disseminated neuroendocrine tumours. Eur J Nucl Med Mol Imaging 2010; 38:302-11. [PMID: 21052661 DOI: 10.1007/s00259-010-1631-x] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Accepted: 09/13/2010] [Indexed: 12/16/2022]
Abstract
PURPOSE In this phase II study we investigated the safety and efficacy of combination capecitabine and (177)Lu-octreotate for the treatment of disseminated, progressive, unresectable neuroendocrine tumours (NETs). METHODS Enrolled in the study were 33 patients with biopsy-proven NETs, positive (111)In-octreotide scintigraphy and progressive disease measurable by CT/MRI who were to receive four cycles of 7.8 GBq (177)Lu-octreotate 8-weekly, with 14 days of 1,650 mg/m(2) capecitabine per day. RESULTS Of the 33 patients, 25 completed four cycles. Minimal transient myelosuppression at 3-4 weeks caused grade 3 thrombocytopenia in one patient but no neutropenia. Nephrotoxicity was absent. Critical organ radiation dosimetry provided median estimates of the dose per cycle to the kidneys of 2.4 Gy and to the liver of 4.8 Gy, and showed cumulative doses all below toxic thresholds. Objective response rates (ORR) were 24% partial response (PR), 70% stable disease (SD) and 6% progressive disease. Median progression-free survival and median overall survival had not been reached at a median follow-up of 16 months (range 5-33 months). Survival at 1 and 2 years was 91% (95% CI 75-98%) and 88% (95% CI 71-96%), respectively. CONCLUSION The addition of capecitabine radiosensitizing chemotherapy does not increase the minimal toxicity of (177)Lu-octreotate radiopeptide therapy and led to an ORR of 24% PR and 70% minor response or SD in patients with progressive metastatic NETs. Tumour control and stabilization of disease was obtained in 94% of these patients.
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Fani M, Mueller A, Tamma ML, Nicolas G, Rink HR, Cescato R, Reubi JC, Maecke HR. Radiolabeled Bicyclic Somatostatin-Based Analogs: A Novel Class of Potential Radiotracers for SPECT/PET of Neuroendocrine Tumors. J Nucl Med 2010; 51:1771-9. [DOI: 10.2967/jnumed.110.076695] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Waser B, Cescato R, Tamma ML, Maecke HR, Reubi JC. Absence of somatostatin SST2 receptor internalization in vivo after intravenous SOM230 application in the AR42J animal tumor model. Eur J Pharmacol 2010; 644:257-62. [DOI: 10.1016/j.ejphar.2010.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/01/2010] [Accepted: 07/09/2010] [Indexed: 12/19/2022]
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Oberg KE, Reubi JC, Kwekkeboom DJ, Krenning EP. Role of somatostatins in gastroenteropancreatic neuroendocrine tumor development and therapy. Gastroenterology 2010; 139:742-53, 753.e1. [PMID: 20637207 DOI: 10.1053/j.gastro.2010.07.002] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 07/06/2010] [Accepted: 07/08/2010] [Indexed: 12/02/2022]
Abstract
The incidence and prevalence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) have increased in the past 20 years. GEP-NETs are heterogeneous tumors, in terms of clinical and biological features, that originate from the pancreas or the intestinal tract. Some GEP-NETs grow very slowly, some grow rapidly and do not cause symptoms, and others cause hormone hypersecretion and associated symptoms. Most GEP-NETs overexpress receptors for somatostatins. Somatostatins inhibit the release of many hormones and other secretory proteins; their effects are mediated by G protein-coupled receptors that are expressed in a tissue-specific manner. Most GEP-NETs overexpress the somatostatin receptor SSTR2; somatostatin analogues are the best therapeutic option for functional neuroendocrine tumors because they reduce hormone-related symptoms and also have antitumor effects. Long-acting formulations of somatostatin analogues stabilize tumor growth over long periods. The development of radioactive analogues for imaging and peptide receptor radiotherapy has improved the management of GEP-NETs. Peptide receptor radiotherapy has significant antitumor effects, increasing overall survival times of patients with tumors that express a high density of SSTRs, particularly SSTR2 and SSTR5. The multi-receptor somatostatin analogue SOM230 (pasireotide) and chimeric molecules that bind SSTR2 and the dopamine receptor D2 are also being developed to treat patients with GEP-NETs. Combinations of radioactive labeled and unlabeled somatostatin analogues and therapeutics that inhibit other signaling pathways, such as mammalian target of rapamycin (mTOR) and vascular endothelial growth factor, might be the most effective therapeutics for GEP-NETs.
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Affiliation(s)
- Kjell E Oberg
- Department of Endocrine Oncology, University Hospital, Uppsala, Sweden.
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81
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Chen K, Conti PS. Target-specific delivery of peptide-based probes for PET imaging. Adv Drug Deliv Rev 2010; 62:1005-22. [PMID: 20851156 DOI: 10.1016/j.addr.2010.09.004] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/08/2010] [Accepted: 09/08/2010] [Indexed: 12/19/2022]
Abstract
Positron emission tomography (PET) is one of the most rapidly growing areas of medical imaging, with many applications in the clinical management of patients with various diseases. The principal goal of PET imaging is to visualize, characterize, and measure biological processes at the cellular, subcellular, and molecular level in living subjects with non-invasive procedures. PET imaging takes advantage of the traditional diagnostic imaging techniques and introduces positron-emitting probes to determine the expression of indicative molecular targets at different stages of disease. During the last decade, advances in molecular biology have revealed an increasing number of potential molecular targets, including peptide receptors and peptide-related biomolecules. With the help of sophisticated bioconjugation and radiolabeling techniques, numerous peptide-based agents have been developed and evaluated for delivery of PET radionuclides to the specific molecular targets in preclinical and clinical studies. As compared to macromolecules, such as proteins or antibodies, low-molecular-weight peptides have their distinctive advantages and predominantly demonstrate their favorable pharmacokinetics for in vivo PET applications. This review summarizes the criteria of peptide-based PET probes design, the selection of radioisotopes, labeling methods, and provides an overview of the current status and trends in the development of target-specific peptide-based probes with respect to their unique PET imaging applications.
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82
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Development of a potent DOTA-conjugated bombesin antagonist for targeting GRPr-positive tumours. Eur J Nucl Med Mol Imaging 2010; 38:97-107. [DOI: 10.1007/s00259-010-1596-9] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 08/04/2010] [Indexed: 11/25/2022]
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Lee S, Xie J, Chen X. Peptides and peptide hormones for molecular imaging and disease diagnosis. Chem Rev 2010; 110:3087-111. [PMID: 20225899 DOI: 10.1021/cr900361p] [Citation(s) in RCA: 253] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Seulki Lee
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 31 Center Drive, Suite 1C14, Bethesda, Maryland 20892-2281, USA
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84
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Vegt E, de Jong M, Wetzels JF, Masereeuw R, Melis M, Oyen WJ, Gotthardt M, Boerman OC. Renal Toxicity of Radiolabeled Peptides and Antibody Fragments: Mechanisms, Impact on Radionuclide Therapy, and Strategies for Prevention. J Nucl Med 2010; 51:1049-58. [DOI: 10.2967/jnumed.110.075101] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Reubi JC, Waser B, Cescato R, Gloor B, Stettler C, Christ E. Internalized somatostatin receptor subtype 2 in neuroendocrine tumors of octreotide-treated patients. J Clin Endocrinol Metab 2010; 95:2343-50. [PMID: 20228164 PMCID: PMC2869539 DOI: 10.1210/jc.2009-2487] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
CONTEXT Somatostatin receptor subtype 2 (sst(2)) is widely expressed in neuroendocrine tumors and can be visualized immunohistochemically at the cell membrane for diagnostic purposes. Recently, it has been demonstrated in animal sst(2) tumor models in vivo that somatostatin analog treatment was able to induce a complete internalization of the tumor sst(2). PATIENTS AND METHODS In the present study, we evaluated whether sst(2) expressed in neuroendocrine tumors of patients treated with octreotide are also internalized. Tumor samples were assessed in patients that were treated with various octreotide modalities before and during surgery and compared with tumor samples from untreated patients. Sst(2) immunohistochemistry was performed in all samples with three different sst(2) antibodies (R2-88, UMB-1, and SS-800). Sst(2) receptor expression was confirmed by immunoblotting and in vitro receptor autoradiography. RESULTS Patients receiving a high dose of octreotide showed predominantly internalized sst(2), and patients with a low dose of octreotide had a variable ratio of internalized vs. membranous sst(2), whereas untreated patients had exclusively membranous sst(2). The internalized sst(2) receptor corresponded to a single sst(2) band in immunoblots and to sst(2) receptors in in vitro receptor autoradiography. Although generally found in endosome-like structures, internalized sst(2) receptors were also identified to a small extent in lysosomes, as seen in colocalization experiments. CONCLUSION It is the first evidence showing that sst(2) receptors can be internalized in sst(2)-expressing neuroendocrine tumors in patients under octreotide therapy, providing clues about sst(2) receptor biology and trafficking dynamics in patients.
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Affiliation(s)
- Jean Claude Reubi
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, P.O. Box 62, Murtenstrasse 31, CH-3010 Berne, Switzerland.
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Reubi JC, Erchegyi J, Cescato R, Waser B, Rivier JE. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog. Eur J Nucl Med Mol Imaging 2010; 37:1551-8. [PMID: 20396884 DOI: 10.1007/s00259-010-1445-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 03/08/2010] [Indexed: 12/13/2022]
Abstract
PURPOSE Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. METHODS Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst(1)-sst(5)) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst(2) and sst(3) internalization in vitro in HEK293 cells stably expressing the human sst(2) or sst(3) receptor, using an immunofluorescence microscopy-based internalization assay. RESULTS All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst(2) internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst(3) internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. CONCLUSION Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst(3) receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added.
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Affiliation(s)
- Jean Claude Reubi
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, PO Box 62, Murtenstrasse 31, 3010 Berne, Switzerland.
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In vivo binding of [68Ga]-DOTATOC to somatostatin receptors in neuroendocrine tumours — impact of peptide mass. Nucl Med Biol 2010; 37:265-75. [DOI: 10.1016/j.nucmedbio.2009.11.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 10/28/2009] [Accepted: 11/25/2009] [Indexed: 11/20/2022]
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