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Öksüz MÖ, Winter L, Pfannenberg C, Reischl G, Müssig K, Bares R, Dittmann H. Peptide receptor radionuclide therapy of neuroendocrine tumors with (90)Y-DOTATOC: is treatment response predictable by pre-therapeutic uptake of (68)Ga-DOTATOC? Diagn Interv Imaging 2013; 95:289-300. [PMID: 24034971 DOI: 10.1016/j.diii.2013.07.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE PET with (68)Ga-DOTATOC allows for imaging and quantitative assessment of somatostatin receptor expression in neuroendocrine tumors (NET). The aim of this retrospective study was to analyze whether pre-therapeutic (68)Ga-DOTATOC PET/CT is able to predict response to Peptide Receptor Radionuclide Therapy (PRRT). PATIENTS AND METHODS Forty patients with advanced stage NET were treated with a fixed dose of (90)Y-DOTATOC (5550 or 3700MBq). Prior to PRRT, each patient received (68)Ga-DOTATOC PET/CT. Treatment results were evaluated after 3months by CT, tumor marker levels and clinical course and correlated with (68)Ga-DOTATOC uptake (SUVmax) and the assumed uptake of (90)Y-DOTATOC in tumor manifestations (MBq/g). ROC analysis and pairwise comparison of area under the curve (AUC) were performed with pre-treatment uptake of (68)Ga-DOTATOC, assumed uptake of (90)Y-DOTATOC and treatment activity alone and in relation to body weight as continuous variables, and response/no response as classification variable. RESULTS According to conventional criteria (tumor shrinkage, decrease of tumor markers, improved or stable clinical condition), 20 patients were classified as responders, 16 as non-responders and in four patients findings were equivocal. Using a SUV more than 17.9 as cut-off for favorable outcome, PET was able to predict treatment response of all responders and 15 out of 16 non-responders. All four patients with equivocal findings showed SUV less than or equal to 17.9 and soon experienced tumor progression. The assumed uptake of (90)Y-DOTATOC in tumor manifestations using a cut-off more than 1.26MBq/g as predictor of response was able to correctly classify 19 out of 20 responders, and 14 out of 16 non-responders. In all patients with equivocal findings, the assumed uptake of (90)Y-DOTATOC was below 1.26MBq/g. CONCLUSION Pre-therapeutic (68)Ga-DOTATOC tumor uptake as well as assumed uptake of (90)Y-DOTATOC are strongly associated with the results of subsequent PRRT. The defined cut-off values should be confirmed by prospective studies and may then provide the rationale for individual dosing and selecting patients with high likelihood of favorable treatment outcome.
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Affiliation(s)
- M Ö Öksüz
- Département d'Imagerie Médicale, Hôpital neuchâtelois, Maladière 45, 2000 Neuchâtel, Switzerland; Department of Nuclear Medicine, Tübingen University Hospital, Otfried-Müller-Strasse 14, 72076 Tübingen, Germany.
| | - L Winter
- Department of Radiology and Nuclear Medicine, Basel University Hospital, Petersgraben 4, 4031 Basel, Switzerland
| | - C Pfannenberg
- Department of Radiology, Tübingen University Hospital, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany
| | - G Reischl
- Department of Radiopharmacy, Tübingen University Hospital, Röntgenweg 15, 72076 Tübingen, Germany
| | - K Müssig
- Deutsches Diabetes-Zentrum (DDZ), Leibniz-Zentrum für Diabetes-Forschung an der Heinrich-Heine-Universität Düsseldorf, Auf'm Hennekamp 65, 40225 Düsseldorf, Germany
| | - R Bares
- Department of Nuclear Medicine, Tübingen University Hospital, Otfried-Müller-Strasse 14, 72076 Tübingen, Germany
| | - H Dittmann
- Department of Nuclear Medicine, Tübingen University Hospital, Otfried-Müller-Strasse 14, 72076 Tübingen, Germany
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Theodoropoulou M, Stalla GK. Somatostatin receptors: from signaling to clinical practice. Front Neuroendocrinol 2013; 34:228-52. [PMID: 23872332 DOI: 10.1016/j.yfrne.2013.07.005] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/13/2013] [Accepted: 07/12/2013] [Indexed: 02/08/2023]
Abstract
Somatostatin is a peptide with a potent and broad antisecretory action, which makes it an invaluable drug target for the pharmacological management of pituitary adenomas and neuroendocrine tumors. Somatostatin receptors (SSTR1, 2A and B, 3, 4 and 5) belong to the G protein coupled receptor family and have a wide expression pattern in both normal tissues and solid tumors. Investigating the function of each SSTR in several tumor types has provided a wealth of information about the common but also distinct signaling cascades that suppress tumor cell proliferation, survival and angiogenesis. This provided the rationale for developing multireceptor-targeted somatostatin analogs and combination therapies with signaling-targeted agents such as inhibitors of the mammalian (or mechanistic) target of rapamycin (mTOR). The ability of SSTR to internalize and the development of rabiolabeled somatostatin analogs have improved the diagnosis and treatment of neuroendocrine tumors.
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Affiliation(s)
- Marily Theodoropoulou
- Department of Endocrinology, Max Planck Institute of Psychiatry, Kraepelinstrasse 10, 80804 Munich, Germany.
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3
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Dong C, Zhao H, Yang S, Shi J, Huang J, Cui L, Zhong L, Jin X, Li F, Liu Z, Jia B, Wang F. 99mTc-Labeled Dimeric Octreotide Peptide: A Radiotracer with High Tumor Uptake for Single-Photon Emission Computed Tomography Imaging of Somatostatin Receptor Subtype 2-Positive Tumors. Mol Pharm 2013; 10:2925-33. [DOI: 10.1021/mp400040z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Chengyan Dong
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Huiyun Zhao
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Medical and Healthy Analytical
Center, Peking University, Beijing 100191,
China
| | - Sujuan Yang
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Jiyun Shi
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Medical and Healthy Analytical
Center, Peking University, Beijing 100191,
China
| | - Jinming Huang
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Liyang Cui
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Lijun Zhong
- Medical and Healthy Analytical
Center, Peking University, Beijing 100191,
China
| | - Xiaona Jin
- Department of Nuclear
Medicine, Peking Union Medical College Hospital, Beijing 100857,
China
| | - Fang Li
- Department of Nuclear
Medicine, Peking Union Medical College Hospital, Beijing 100857,
China
| | - Zhaofei Liu
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Bing Jia
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
| | - Fan Wang
- Medical Isotopes Research
Center, Peking University, Beijing 100191,
China
- Department of Radiation
Medicine,
School of Basic Medical Sciences, Peking University, Beijing 100191, China
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4
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Klimstra DS. Pathology reporting of neuroendocrine tumors: essential elements for accurate diagnosis, classification, and staging. Semin Oncol 2013; 40:23-36. [PMID: 23391110 DOI: 10.1053/j.seminoncol.2012.11.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Much recent debate has focused on the optimal classification of epithelial neuroendocrine tumors (NETs). Multiple different systems of terminology, grading, and staging have been proposed, and some systems combine elements of grade and stage into a single prognostic classification. Recently, national and international consensus groups have attempted to standardize the classification of NETs, especially for those arising in the gastrointestinal tract and pancreas. Furthermore, the recognition that common classification criteria (such as proliferative rate) span multiple different systems allows the basic data necessary to predict outcome and tailor therapy to be included in pathology reports, even though a single uniform system of terminology may remain elusive. Formal tumor-node-metastasis (TNM)-based staging systems also have been developed recently, and advances in the treatment of some NETs (pancreatic in particular) are pointing towards the need to assess therapeutic biomarkers in routine practice. This review will present the most widely used systems for classifying, grading, and staging NETs and will summarize the recommendations for the data to be included in standard pathology reports of these uncommon tumors.
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Affiliation(s)
- David S Klimstra
- Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
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Abstract
UNLABELLED Biological treatment for GI neuroendocrine tumours (NETs) includes treatment with somatostatin analogues and alpha interferons. Both of these therapies were developed in the early 1980's and initially for treatment of a carcinoid syndrome in patients with small intestinal NETs. Later on tumour biology studies indicated that well differentiated NETs (G1-tumours) benefit from treatment with somatostatin analogues and alpha interferons. Both agents give symptomatic improvement in patients with functioning tumours in 40-60% of the patients, biochemical responses in 50-70% of the patients and significant tumour shrinkage in 5-10% of the patients. Combination therapy with somatostatin analogues and alpha interferon has demonstrated some clinical benefit. IN CONCLUSION Somatostatin analogues and alpha interferons are still playing an important role and considered to be first-line treatment in functioning and in non-functioning well-differentiated NETs, (G1-tumours) and somatostatin analogues might also be applied to control clinical symptoms in G2-tumours with higher proliferation.
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Affiliation(s)
- Kjell Öberg
- Dept. of Endocrine Oncology, University Hospital, Uppsala, Sweden.
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6
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Li Z, Vaziri H. Treatment of chronic diarrhoea. Best Pract Res Clin Gastroenterol 2012; 26:677-87. [PMID: 23384811 DOI: 10.1016/j.bpg.2012.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 10/30/2012] [Accepted: 11/07/2012] [Indexed: 01/31/2023]
Abstract
The treatment of chronic diarrhoea can be challenging. While Oral Rehydration Solution is an important step in treating diarrhoeal illnesses, various medications can be used to alleviate the symptoms while the patient is undergoing diagnostic work up or to target the underlying mechanism responsible for their diarrhoea. Medications are also being prescribed in cases when there is a strong suspicious about a diagnosis or when there is no specific treatment for an underlying aetiology. This chapter discusses the treatment options for diarrhoeal disorders.
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Affiliation(s)
- Zhongzhen Li
- St. Vincent's Medical Center, Department of Medicine, 2800 Main St., Bridgeport, CT 06606, USA.
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7
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Ito T, Igarashi H, Jensen RT. Therapy of metastatic pancreatic neuroendocrine tumors (pNETs): recent insights and advances. J Gastroenterol 2012; 47:941-60. [PMID: 22886480 PMCID: PMC3754804 DOI: 10.1007/s00535-012-0642-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 02/08/2023]
Abstract
Neuroendocrine tumors (NETs) [carcinoids, pancreatic neuroendocrine tumors (pNETs)] are becoming an increasing clinical problem because not only are they increasing in frequency, but they can frequently present with advanced disease that requires diagnostic and treatment approaches different from those used in the neoplasms that most physicians are used to seeing and treating. In the past few years there have been numerous advances in all aspects of NETs including: an understanding of their unique pathogenesis; specific classification systems developed which have prognostic value; novel methods of tumor localization developed; and novel treatment approaches described. In patients with advanced metastatic disease these include the use of newer chemotherapeutic approaches, an increased understanding of the role of surgery and cytoreductive methods, the development of methods for targeted delivery of cytotoxic agents, and the development of targeted medical therapies (everolimus, sunitinib) based on an increased understanding of the disease biology. Although pNETs and gastrointestinal NETs share many features, recent studies show they differ in pathogenesis and in many aspects of diagnosis and treatment, including their responsiveness to different therapies. Because of limited space, this review will be limited to the advances made in the management and treatment of patients with advanced metastatic pNETs over the past 5 years.
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Affiliation(s)
- Tetsuhide Ito
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hisato Igarashi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Robert T. Jensen
- Digestive Diseases Branch, NIDDK, NIH, Building 10, Room 9C-103, Bethesda, MD 20892, USA
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Golor G, Hu K, Ruffin M, Buchelt A, Bouillaud E, Wang Y, Maldonado M. A first-in-man study to evaluate the safety, tolerability, and pharmacokinetics of pasireotide (SOM230), a multireceptor-targeted somatostatin analog, in healthy volunteers. DRUG DESIGN DEVELOPMENT AND THERAPY 2012; 6:71-9. [PMID: 22573933 PMCID: PMC3346155 DOI: 10.2147/dddt.s29125] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pasireotide (SOM230) is a multireceptor-targeted somatostatin analog with high binding affinity for four of the five somatostatin receptor subtypes (sst1,2,3 and sst5), and potential clinical activity in several neuroendocrine and oncologic conditions, including acromegaly, Cushing’s disease, and neuroendocrine tumors (NET). This manuscript reports the first-in-man dose-escalation study of pasireotide, evaluating its safety, tolerability, and pharmacokinetics (PK) in healthy male volunteers. A single dose of pasireotide 1–1200 μg was administered subcutaneously in four to eight subjects per dose level, with two additional subjects per cohort administered placebo. PK and safety evaluations were carried out over 7 days post-dose. Growth hormone (GH) suppression was evaluated using a GH-releasing hormone stimulation test on Day –1 and Day 1 at 3–5 hours post-injection. Seventy-two subjects completed the study. Pasireotide was well tolerated with no serious adverse events observed at any dose. Transient elevations in blood glucose levels were observed 2–6 hours after administration of pasireotide at doses between 200 μg and 1200 μg, but this resolved without intervention by 23 hours post-dosing. The maximum tolerable dose was not established within the tested range. Pasireotide demonstrated a favorable PK profile with fast absorption (tmax: 0.25–0.5 hours), low clearance (CL/F: 8–13 L/hour), long effective elimination half-life (mean t½,β: 7–11 hours), and a proportional dose-exposure relationship. GH suppression of 79%–96% was observed at single pasireotide doses between 200 μg and 1200 μg. In conclusion, pasireotide demonstrated favorable safety, tolerability, and PK profiles, as well as promising activity in suppressing the release of GH. The efficacy and safety of pasireotide is currently being evaluated in patients with acromegaly, Cushing’s disease, NET, and various non-neuroendocrine disorders.
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Affiliation(s)
- Georg Golor
- Parexel International GmbH, Berlin, Germany.
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Prognostic clinicopathologic factors in longitudinally followed patients with metastatic small bowel carcinoid tumors. Pancreas 2011; 40:1253-7. [PMID: 21975435 DOI: 10.1097/mpa.0b013e318225483c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Neuroendocrine tumors demonstrate heterogeneous behavior based on the site of origin and histology. This study aimed to delineate prognostic clinicopathologic features in patients with metastatic midgut carcinoid. METHODS All patients underwent resection of the primary tumor in the setting of metastatic disease. Survival was measured from the date of primary tumor resection and calculated by Kaplan-Meier estimation. Clinical data include age, sex, serum biomarkers, primary tumor size, Ki-67 index, and the performance of hepatic cytoreductive procedure. Serially collected serum biomarkers were considered as mean values within periods relative to primary resection: preoperative, 0 to 1 year postoperative, and years 1 to 5 postoperative. Log-rank comparisons were used to assess the prognostic value of the aforementioned features. RESULTS Forty-nine patients (21 men) with metastatic midgut carcinoid who underwent primary tumor resection were identified. Median survival was 121 months. The overall 5-year survival rate was 83%. Age higher than 65 years (P = 0.01) and late postoperative chromogranin A (CgA; P = 0.02) were associated with decreased survival. CONCLUSIONS This study highlights the favorable prognosis of patients with metastatic small bowel carcinoid in a multidisciplinary treatment program. Among other factors, elevated postoperative CgA is associated with decreased survival. The significance of increased CgA over time underlies the importance of longitudinal follow-up for these patients.
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10
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Schumacher FF, Nobles M, Ryan CP, Smith MEB, Tinker A, Caddick S, Baker JR. In situ maleimide bridging of disulfides and a new approach to protein PEGylation. Bioconjug Chem 2011; 22:132-6. [PMID: 21271715 PMCID: PMC3039925 DOI: 10.1021/bc1004685] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The introduction of non-natural entities into proteins by chemical modification has numerous applications in fundamental biological science and for the development and manipulation of peptide and protein therapeutics. The reduction of native disulfide bonds provides a convenient method to access two nucleophilic cysteine residues that can serve as ideal attachment points for such chemical modification. The optimum bioconjugation strategy utilizing these cysteine residues should include the reconstruction of a bridge to mimic the role of the disulfide bond, maintaining structure and stability of the protein. Furthermore, the bridging chemical modification should be as rapid as possible to prevent problems associated with protein unfolding, aggregation, or disulfide scrambling. This study reports on an in situ disulfide reduction-bridging strategy that ensures rapid sequestration of the free cysteine residues in a bridge, using dithiomaleimides. This approach is then used to PEGylate the peptide hormone somatostatin and retention of biological activity is demonstrated.
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Affiliation(s)
- Felix F Schumacher
- Department of Chemistry, University College London, 20 Gordon Street, London,WC1H OAJ, United Kingdom
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Kukwa W, Andrysiak R, Kukwa A, Hubalewska-Dydejczyk A, Gronkiewicz Z, Wojtowicz P, Krolicki L, Wierzchowski W, Grochowski T, Czarnecka AM. 99mTC-octreotide scintigraphy and somatostatin receptor subtype expression in juvenile nasopharyngeal angiofibromas. Head Neck 2011; 33:1739-46. [DOI: 10.1002/hed.21668] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 09/02/2010] [Accepted: 10/04/2010] [Indexed: 11/08/2022] Open
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Plasma chromogranin A response to octreotide test: prognostic value for clinical outcome in endocrine digestive tumors. Am J Gastroenterol 2010; 105:2072-8. [PMID: 20372113 DOI: 10.1038/ajg.2010.154] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVES Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) expressing somatostatin receptors may be treated with somatostatin analogs (SSAs). Selection criteria are a positive Octreoscan or a >50% hormone level decrease after octreotide subcutaneous (s.c.) injection (octreotide test) (OT). Plasma chromogranin A (CgA) is the best general GEP-NET marker, but data on CgA response to OT are scanty. Thus, we evaluated whether plasma CgA response to OT could predict the clinical response to SSAs. METHODS At diagnosis, 38 GEP-NET patients received octreotide 200 microg s.c., with plasma CgA determination at 0, 3, and 6 h. Long-term SSA treatment was then given by monitoring symptomatic, biochemical, and objective responses, and survival. RESULTS Basal plasma CgA levels were significantly higher in patients with functioning than non-functioning tumors (median (range): 220 (18-2,230) vs. 46 (25-8,610) U/l, P=0.03) and in those with than without metastases (171 (18-8,610) vs. 43 (28-220) U/l, P=0.04). CgA levels significantly correlated with WHO classification, clinical TNM staging, and Ki-67 proliferative index. After OT, CgA levels decreased from 146 (18-8,610) to 61 (10-8,535) U/l (basal and nadir values), P<0.001. In patients responsive to OT, a successful objective response occurred in 21/31 patients (68%). Successful symptomatic response occurred in 13/18 patients (72%), biochemical response in 25/31 (81%), and objective response in 21/31 (68%). In the remaining seven unresponsive cases, with CgA decrement <30%, disease progressed to death in six (86%). Median survival from enrollment was 48 months (6-138) in responsive and 6 (6-30) in unresponsive patients (P=0.0005). CONCLUSIONS In GEP-NETs, plasma CgA is a reliable marker, and a >30% decrease after OT has a relevant prognostic meaning allowing the identification of the subgroup of patients most likely to be responsive to chronic SSAs.
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Smith MEB, Schumacher FF, Ryan CP, Tedaldi LM, Papaioannou D, Waksman G, Caddick S, Baker JR. Protein modification, bioconjugation, and disulfide bridging using bromomaleimides. J Am Chem Soc 2010; 132:1960-5. [PMID: 20092331 PMCID: PMC2842020 DOI: 10.1021/ja908610s] [Citation(s) in RCA: 293] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The maleimide motif is widely used for the selective chemical modification of cysteine residues in proteins. Despite widespread utilization, there are some potential limitations, including the irreversible nature of the reaction and, hence, the modification and the number of attachment positions. We conceived of a new class of maleimide which would address some of these limitations and provide new opportunities for protein modification. We report herein the use of mono- and dibromomaleimides for reversible cysteine modification and illustrate this on the SH2 domain of the Grb2 adaptor protein (L111C). After initial modification of a protein with a bromo- or dibromomaleimide, it is possible to add an equivalent of a second thiol to give further bioconjugation, demonstrating that bromomaleimides offer opportunities for up to three points of attachment. The resultant protein-maleimide products can be cleaved to regenerate the unmodified protein by addition of a phosphine or a large excess of a thiol. Furthermore, dibromomaleimide can insert into a disulfide bond, forming a maleimide bridge, and this is illustrated on the peptide hormone somatostatin. Fluorescein-labeled dibromomaleimide is synthesized and inserted into the disulfide to construct a fluorescent somatostatin analogue. These results highlight the significant potential for this new class of reagents in protein modification.
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Affiliation(s)
- Mark E B Smith
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
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Norton RS. Mu-conotoxins as leads in the development of new analgesics. Molecules 2010; 15:2825-44. [PMID: 20428082 PMCID: PMC6257286 DOI: 10.3390/molecules15042825] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 04/06/2010] [Accepted: 04/12/2010] [Indexed: 02/02/2023] Open
Abstract
Voltage-gated sodium channels (VGSCs) contain a specific binding site for a family of cone shell toxins known as mu-conotoxins. As some VGSCs are involved in pain perception and mu-conotoxins are able to block these channels, mu-conotoxins show considerable potential as analgesics. Recent studies have advanced our understanding of the three-dimensional structures and structure-function relationships of the mu-conotoxins, including their interaction with VGSCs. Truncated peptide analogues of the native toxins have been created in which secondary structure elements are stabilized by non-native linkers such as lactam bridges. Ultimately, it would be desirable to capture the favourable analgesic properties of the native toxins, in particular their potency and channel sub-type selectivity, in non-peptide mimetics. Such mimetics would constitute lead compounds in the development of new therapeutics for the treatment of pain.
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Affiliation(s)
- Raymond S Norton
- Walter and Eliza Hall Institute of Medical Research, Victoria, Australia.
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Pathology reporting of neuroendocrine tumors: application of the Delphic consensus process to the development of a minimum pathology data set. Am J Surg Pathol 2010; 34:300-13. [PMID: 20118772 DOI: 10.1097/pas.0b013e3181ce1447] [Citation(s) in RCA: 274] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epithelial neuroendocrine tumors (NETs) have been the subject of much debate regarding their optimal classification. Although multiple systems of nomenclature, grading, and staging have been proposed, none has achieved universal acceptance. To help define the underlying common features of these classification systems and to identify the minimal pathology data that should be reported to ensure consistent clinical management and reproducibility of data from therapeutic trials, a multidisciplinary team of physicians interested in NETs was assembled. At a group meeting, the participants discussed a series of "yes" or "no" questions related to the pathology of NETs and the minimal data to be included in the reports. After discussion, anonymous votes were taken, using the Delphic principle that 80% agreement on a vote of either yes or no would define a consensus. Questions that failed to achieve a consensus were rephrased once or twice and discussed, and additional votes were taken. Of 108 questions, 91 were answerable either yes or no by more than 80% of the participants. There was agreement about the importance of proliferation rate for tumor grading, the landmarks to use for staging, the prognostic factors assessable by routine histology that should be reported, the potential for tumors to progress biologically with metastasis, and the current status of advanced immunohistochemical and molecular testing for treatment-related biomarkers. The lack of utility of a variety of immunohistochemical stains and pathologic findings was also agreed upon. A consensus could not be reached for the remaining 17 questions, which included both minor points related to extent of disease assessment and some major areas such as terminology, routine immunohistochemical staining for general neuroendocrine markers, use of Ki67 staining to assess proliferation, and the relationship of tumor grade to degree of differentiation. On the basis of the results of the Delphic voting, a minimum pathology data set was developed. Although there remains disagreement among experts about the specific classification system that should be used, there is agreement about the fundamental pathology data that should be reported. Examination of the areas of disagreement reveals significant opportunities for collaborative study to resolve unanswered questions.
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Abstract
Insulinomas are rare neuroendocrine tumors of pancreatic islet cells that retain the ability to produce and secrete insulin. In contrast to normally differentiated β-cells, insulinoma cells continue to secrete insulin and proinsulin at low blood glucose. This deregulated insulin secretion manifests clinically as fasting hypoglycemia. The molecular pathways that characterize normal insulin secretion and β-cell growth are reviewed and contrasted to the biology of insulinomas. The second half of this review summarizes the clinical approach to the disorder. The diagnosis of insulinoma is established by demonstrating inappropriately high insulin levels with coincident hypoglycemia at the time of a supervised fast. Localization of insulinomas is challenging owing to their small size but should be attempted to maximize the chance for successful surgical resection and avoid risks associated with reoperation. In the majority of cases, successful surgical resection leads to lifelong cure.
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Affiliation(s)
- Jean-Marc Guettier
- National Institute of Diabetes and Digestive and Kidney Diseases, Building 10-CRC, Room 6-5952, 10 Center Drive, Bethesda, MD 20892-1612, USA, Tel.: +1 301 496 1913, ,
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Martino MCD, Hofland LJ, Lamberts SW. Somatostatin and Somatostatin Receptors: from Basic Concepts to Clinical Applications. PROGRESS IN BRAIN RESEARCH 2010; 182:255-80. [DOI: 10.1016/s0079-6123(10)82011-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Colao A, Faggiano A, Pivonello R. Somatostatin analogues: treatment of pituitary and neuroendocrine tumors. PROGRESS IN BRAIN RESEARCH 2010; 182:281-94. [PMID: 20541670 DOI: 10.1016/s0079-6123(10)82012-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This chapter summarizes the most recent data on the use of the somatostatin analogues (SSAs), octreotide (OCT) and lanreotide for the treatment of patients with pituitary and neuroendocrine tumors (NETs). These two analogues have a high affinity for somatostatin receptor (SSR) sub-types 2 and 5. The major indications of these compounds are GH- and TSH-secreting pituitary adenomas, secreting NETs and non-functioning NETs in progression. Pasireotide is a new analogue, with a receptor pattern different from previous analogues since it binds with high affinity to SSR types 1, 2, 3 and 5. This analogue will be available to treat patients with ACTH-secreting adenomas in a short time. A recent study has also demonstrated a beneficial effect of OCT long-acting release in patients with non-functioning NETs independently from their progression status. These data open the treatment with SSAs in all NET patients.
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Affiliation(s)
- Annamaria Colao
- Department of Molecular & Clinical Endocrinology and Oncology, Federico II University of Naples, Naples, Italy.
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Chua YJ, Michael M, Zalcberg JR, Hicks RJ, Goldstein D, Liauw W, Price T. Antitumor effect of somatostatin analogs in neuroendocrine tumors. J Clin Oncol 2009; 28:e41-2; author reply e43-4. [PMID: 20008618 DOI: 10.1200/jco.2009.26.0612] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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