1
|
Miao C, Zhao W, Yuan S, Yu J, Zhao S, Ma L, Zhang D, Hu X. A novel molecular agent for glioma angiogenesis imaging. Nucl Med Commun 2017; 38:919-926. [DOI: 10.1097/mnm.0000000000000735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
2
|
Patched targeting peptides for imaging and treatment of hedgehog positive breast tumors. BIOMED RESEARCH INTERNATIONAL 2014; 2014:525680. [PMID: 25276795 PMCID: PMC4172929 DOI: 10.1155/2014/525680] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/11/2014] [Accepted: 07/15/2014] [Indexed: 11/22/2022]
Abstract
High tumor hedgehog expression is correlated with poor prognosis in invasive ductal carcinoma. Peptides which bind the patched receptor have recently been reported to have a growth inhibitory effect in tumors with activated hedgehog signaling. We sought to examine growth inhibition with these peptides in breast cancer cells and use these peptides as molecular imaging probes to follow changes in hedgehog expression after chemotherapy. Significant growth inhibition was observed in breast cancer cell lines treated with PTCH-blocking peptides. Significant in vitro uptake was observed with both FITC- and 99mTc-EC-peptide conjugates. In vivo imaging studies displayed greater accumulation of 99mTc-labeled peptides within tumors as compared to adjacent muscle tissue. Patched receptor expression increased after treatment and this correlated with an increase in tumor radiotracer uptake. These studies suggest that peptides which bind the sonic hedgehog docking site in patched receptor correlate with patched expression and can be used to image patched in vivo. Further, our data suggest that radiolabeled peptides may enable us to examine the activity of the hedgehog signaling pathway and to evaluate response to anti-cancer therapies.
Collapse
|
3
|
Detection of canonical hedgehog signaling in breast cancer by 131-iodine-labeled derivatives of the sonic hedgehog protein. J Biomed Biotechnol 2012; 2012:639562. [PMID: 22811598 PMCID: PMC3395403 DOI: 10.1155/2012/639562] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/23/2012] [Accepted: 05/07/2012] [Indexed: 01/09/2023] Open
Abstract
Activation of hedgehog (HH) pathway signaling is observed in many tumors. Due to a feedback loop, the HH receptor Patched (PTCH-1) is overexpressed in tumors with activated HH signaling. Therefore, we sought to radiolabel the PTCH-1 ligand sonic (SHH) for detection of cancer cells with canonical HH activity. Receptor binding of 131I-SHH was increased in cell lines with high HH pathway activation. Our findings also show that PTCH-1 receptor expression is decreased upon treatment with HH signaling inhibitors, and receptor binding of 131I-SHH is significantly decreased following treatment with cyclopamine. In vivo imaging and biodistribution studies revealed significant accumulation of 131I-SHH within tumor tissue as compared to normal organs. Tumor-to-muscle ratios were approximately 8 : 1 at 5 hours, while tumor to blood and tumor to bone were 2 : 1 and 5 : 1, respectively. Significant uptake was also observed in liver and gastrointestinal tissue. These studies show that 131I-SHH is capable of in vivo detection of breast tumors with high HH signaling. We further demonstrate that the hedgehog receptor PTCH-1 is downregulated upon treatment with hedgehog inhibitors. Our data suggests that radiolabeled SHH derivatives may provide a method to determine response to SHH-targeted therapies.
Collapse
|
4
|
Molecular imaging of mesothelioma with (99m)Tc-ECG and (68)Ga-ECG. J Biomed Biotechnol 2012; 2012:232863. [PMID: 22645409 PMCID: PMC3356907 DOI: 10.1155/2012/232863] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 02/09/2012] [Accepted: 02/16/2012] [Indexed: 01/08/2023] Open
Abstract
We have developed ethylenedicysteine-glucosamine (ECG) as an alternative to (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) for cancer imaging. ECG localizes in the nuclear components of cells via the hexosamine biosynthetic pathway. This study was to evaluate the feasibility of imaging mesothelioma with (99m)Tc-ECG and (68)Ga-ECG. ECG was synthesized from thiazolidine-4-carboxylic acid and 1,3,4,6-tetra-O-acetyl-2-amino-D-glucopyranose, followed by reduction in sodium and liquid ammonia to yield ECG (52%). ECG was chelated with (99m)Tc/tin (II) and (68)Ga/(69)Ga chloride for in vitro and in vivo studies in mesothelioma. The highest tumor uptake of (99m)Tc-ECG is 0.47 at 30 min post injection, and declined to 0.08 at 240 min post injection. Tumor uptake (%ID/g), tumor/lung, tumor/blood, and tumor/muscle count density ratios for (99m)Tc-ECG (30-240 min) were 0.47 ± 0.06 to 0.08 ± 0.01; 0.71 ± 0.07 to 0.85 ± 0.04; 0.47 ± 0.03 to 0.51 ± 0.01, and 3.49 ± 0.24 to 5.06 ± 0.25; for (68)Ga-ECG (15-60 min) were 0.70 ± 0.06 to 0.92 ± 0.08; 0.64 ± 0.05 to 1.15 ± 0.08; 0.42 ± 0.03 to 0.67 ± 0.07, and 3.84 ± 0.52 to 7.00 ± 1.42; for (18)F-FDG (30-180 min) were 1.86 ± 0.22 to 1.38 ± 0.35; 3.18 ± 0.44 to 2.92 ± 0.34, 4.19 ± 0.44 to 19.41 ± 2.05 and 5.75 ± 2.55 to 3.33 ± 0.65, respectively. Tumor could be clearly visualized with (99m)Tc-ECG and (68)Ga-ECG in mesothelioma-bearing rats. (99m)Tc-ECG and (68)Ga-ECG showed increased uptake in mesothelioma, suggesting they may be useful in diagnosing mesothelioma and also monitoring therapeutic response.
Collapse
|
5
|
Guo R, Ma Y, Zhang R, Liang S, Shen H, Xu H, Li B. Rhenium-188 labeled recombinant human plasminogen kringle5 (rhk5) and preliminary biodistribution. Evaluation in mice bearing A549 tumours. Nuklearmedizin 2011; 50:234-9. [PMID: 21808809 DOI: 10.3413/nukmed-0349-10-09] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 02/28/2011] [Indexed: 11/20/2022]
Abstract
AIM Angiogenesis plays a critical role in tumour formation and metastasis. Suitable radiolabeled angiogenesis inhibitor can be used for noninvasive imaging of angiogenesis and radionuclide therapy. Here we prepare rhenium-188 labeled recombinant human plasminogen kringle5 (188Re-rhk5) in a convenient manner than evaluate its properties in A549 lung adenocarcinoma. METHODS 188Re-rhk5 was obtained by conjugating His group at the C end of rhk5 with fac-[188Re(H2O)3(CO)3]+. Chelating efficiency of fac-[188Re(H2O)3(CO)3]+ and radiolabeling efficiency of 188Re-rhk5 were measured by radio thin-layer chromatography (RTLC). In vitro stability of 188Re-rhk5 was determined in human serum at 37°C and analyzed by RTLC. Competition test was also performed to verify the specificity of binding. A biodistribution study was carried out in nude mice bearing A549 lung adenocarcinoma. RESULTS 188Re-rhk5 was obtained with a radiolabel efficiency of 66.1%, the radiochemical purity (RCP) can reach 95.2% after purification. 188Re-rhk5 showed high stability in human serum, the RCP was more than 80% even 12 h after incubation. Competition test showed a high binding specificity. Furthermore, this radio-complex was excreted mainly through kidneys and showed specific tumour uptake in mice bearing A549 tumours. CONCLUSION 188Re-rhk5 was prepared by a simple method. Preliminary biodistribution results showed its potential as an agent for possible tumour imaging, therapy and encouraged further investigation.
Collapse
Affiliation(s)
- R Guo
- Department of Nuclear Medicine, Shanghai Jiaotong University, School of Medicine, Shanghai, People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
6
|
Cholesterol sequestration by nystatin enhances the uptake and activity of endostatin in endothelium via regulating distinct endocytic pathways. Blood 2011; 117:6392-403. [PMID: 21482707 DOI: 10.1182/blood-2010-12-322867] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Specific internalization of endostatin into endothelial cells has been proved to be important for its biologic functions. However, the mechanism of endostatin internalization still remains elusive. In this study, we report for the first time that both caveolae/lipid rafts and clathrin-coated pits are involved in endostatin internalization. Inhibition of either the caveolae pathway or the clathrin pathway with the use of chemical inhibitors, small interfering RNAs, or dominant-negative mutants alters endostatin internalization in vitro. Intriguingly, cholesterol sequestration by nystatin, a polyene antifungal drug, significantly enhances endostatin uptake by endothelial cells through switching endostatin internalization predominantly to the clathrin-mediated pathway. Nystatin-enhanced internalization of endostatin also increases its inhibitory effects on endothelial cell tube formation and migration. More importantly, combined treatment with nystatin and endostatin selectively enhances endostatin uptake and biodistribution in tumor blood vessels and tumor tissues but not in normal tissues of tumor-bearing mice, ultimately resulting in elevated antiangiogenic and antitumor efficacies of endostatin in vivo. Taken together, our data show a novel mechanism of endostatin internalization and support the potential application of enhancing the uptake and therapeutic efficacy of endostatin via regulating distinct endocytic pathways with cholesterol-sequestering agents.
Collapse
|
7
|
Wu JY, Yang DJ, Angelo LS, Kohanim S, Kurzrock R. Molecular imaging of Bcr-Abl phosphokinase in a xenograft model. Mol Cancer Ther 2009; 8:703-10. [PMID: 19258427 DOI: 10.1158/1535-7163.mct-08-0656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The purpose of this study was to determine whether the Bcr-Abl tyrosine kinase can be assessed by gamma-imaging using an 111In-labeled anti-phosphotyrosine (APT) antibody, and if the response to treatment with imatinib could be detected using this imaging technique. APT antibody was labeled with 111In using ethylenedicysteine (EC) as a chelator. To determine if 111In-EC-APT could assess a nonreceptor tyrosine kinase, xenografts of the human chronic myelogenous leukemia cell line K562 were used. gamma-Scintigraphy of the tumor-bearing mice, before and after imatinib treatment, was obtained 1, 24, and 48 h after they were given 111In-EC-APT (100 microCi/mouse i.v.). 111In-EC-APT is preferentially taken up by Bcr-Abl-bearing tumor cells when compared with 111In-EC-BSA or 111In-EC-IgG1 controls and comparable with the level of uptake of 111In-EC-Bcr-Abl. Imatinib treatment resulted in decreased expression of phospho-Bcr-Abl by Western blot analysis, which correlated with early (4 days after starting imatinib) kinase down-regulation as assessed by imaging using 111In-EC-APT. The optimal time to imaging was 24 and 48 h after injection of 111In-EC-APT. Although tumor regression was insignificant on day 4 after starting imatinib treatment, it was marked by day 14. 111In-EC-APT can assess intracellular phosphokinase activity, and down-regulation of phosphokinase activity predates tumor regression. This technique may therefore be useful in the clinic to detect the presence of phosphokinase activity and for early prediction of response.
Collapse
MESH Headings
- Animals
- Antibodies
- Benzamides
- Cysteine/analogs & derivatives
- Cysteine/pharmacokinetics
- Female
- Fusion Proteins, bcr-abl/metabolism
- Humans
- Imatinib Mesylate
- Indium Radioisotopes/pharmacokinetics
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/diagnostic imaging
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Mice
- Mice, Nude
- Phosphotyrosine/immunology
- Phosphotyrosine/pharmacokinetics
- Piperazines/therapeutic use
- Protein-Tyrosine Kinases/metabolism
- Pyrimidines/therapeutic use
- Radioimmunodetection/methods
- Tumor Burden
- Xenograft Model Antitumor Assays
Collapse
Affiliation(s)
- Ji Yuan Wu
- Department of Investigational Cancer Therapeutics (Phase I Program), Division of Cancer Medicine, The University of Texas M. D. Anderson Cancer Center, Unit 455, P.O. Box 301402, Houston, TX 77030, USA
| | | | | | | | | |
Collapse
|
8
|
Abstract
Anatomically based technologies (computed tomography scans, magnetic resonance imaging, and so on) are in routine use in radiotherapy for planning and assessment purposes. Even with improvements in imaging, however, radiotherapy is still limited in efficacy and toxicity in certain applications. Further advances may be provided by technologies that image the molecular activities of tumors and normal tissues. Possible uses for molecular imaging include better localization of tumor regions and early assay for the radiation response of tumors and normal tissues. Critical to the success of this approach is the identification and validation of molecular probes that are suitable in the radiotherapy context. Recent developments in molecular-imaging probes and integration of functional imaging with radiotherapy are promising. This review focuses on recent advances in molecular imaging strategies and probes that may aid in improving the efficacy of radiotherapy.
Collapse
|
9
|
Szabo Z, Xia J, Mathews WB. Radiopharmaceuticals for renal positron emission tomography imaging. Semin Nucl Med 2008; 38:20-31. [PMID: 18096461 DOI: 10.1053/j.semnuclmed.2007.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Radiopharmaceuticals for functional renal imaging, including renal blood flow, renal blood volume, glomerular excretion, and metabolism have been available for some time. This review outlines radiopharmaceuticals for functional renal imaging as well as those that target pertinent molecular constituents of renal injury and repair. The angiotensin and endothelin receptors are particularly appealing molecular targets for renal imaging because of their association with renal physiology and pathology. Other targets such as the vascular endothelial growth factor (VEGF) receptor, integrin, or phosphatidylserine have been investigated at length for cancer imaging, but they are just as important constituents of the renal injury/repair process. Various diseases can involve identical mechanisms, such as angiogenesis and apoptosis, and radiopharmaceuticals developed for these processes in other organs can also be used for renal imaging. The sensitivity and spatial resolution of positron emission tomography makes it an ideal tool for molecular and functional kidney imaging. Radiopharmaceutical development for the kidneys must focus on achieving high target selectivity and binding affinity, stability and slow metabolism in vivo, and minimal nonspecific accumulation and urinary excretion.
Collapse
Affiliation(s)
- Zsolt Szabo
- Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
| | | | | |
Collapse
|
10
|
Abstract
Tumor angiogenesis induces the proliferation of immature blood vessels that are both heterogeneous and leaky. These characteristics can be demonstrated by measuring the perfusion parameters with MRI. Perfusion MRI is usually performed with in T1-weighted dynamic imaging after bolus injection of an exogenous contrast agent such as gadolinium chelate. The perfusion parameters are obtained by semi-quantitative or quantitative analysis of the enhancement curves in the tumor and the arterial input. Perfusion can also be assessed without injecting a contrast agent using arterial spin labeling techniques, diffusion MRI, or BOLD (blood oxygen level dependent) MRI. However, these latter methods are limited by a low signal-to-noise ratio and problems with quantification. The main indication for perfusion MRI is the assessment of antiangiogenic and antivascular treatments. New possibilities for demonstrating angiogenic blood vessels are being opened by molecular imaging.
Collapse
Affiliation(s)
- L Huwart
- Unité de Radiodiagnostic, Université Catholique de Louvain, Cliniques Universitaires St-Luc, Bruxelles, Belgique
| | | | | |
Collapse
|
11
|
Davda S, Bezabeh T. Advances in methods for assessing tumor hypoxia in vivo: implications for treatment planning. Cancer Metastasis Rev 2007; 25:469-80. [PMID: 17029029 DOI: 10.1007/s10555-006-9009-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Tumor hypoxia and its downstream effects have remained of considerable interest for decades due to its negative impact on response to various cancer therapies and promotion of metastasis. Diagnosing hypoxia non-invasively can provide a significant advancement in cancer treatment and is the dire necessity for implementing specific targeted therapies now emerging to treat different aspects of cancer. A variety of techniques are being proposed to do so. However, none of them has yet been established in the clinical arena. This review summarizes the methods currently available to assess tumor hypoxia in vivo and their respective advantages and shortcomings. It also points out the impedances that need to be overcome to establish any particular method in the clinic, along with a broad overview of requirements for further advancement in this sphere of cancer research.
Collapse
Affiliation(s)
- Sonal Davda
- Institute for Biodiagnostics, National Research Council, 435 Ellice Avenue, Winnipeg, Manitoba, Canada, R3B 1Y6
| | | |
Collapse
|
12
|
Cai W, Rao J, Gambhir SS, Chen X. How molecular imaging is speeding up antiangiogenic drug development. Mol Cancer Ther 2006; 5:2624-33. [PMID: 17121909 DOI: 10.1158/1535-7163.mct-06-0395] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Drug development is a long process that generally spans about 10 to 15 years. The shift in recent drug discovery to novel agents against specific molecular targets highlights the need for more robust molecular imaging platforms. Using molecular probes, molecular imaging can aid in many steps of the drug development process, such as providing whole body readout in an intact system, decreasing the workload and speeding up drug development/validation, and facilitating individualized anticancer treatment monitoring and dose optimization. The main focus of this review is the recent advances in tumor angiogenesis imaging, and the targets include vascular endothelial growth factor and vascular endothelial growth factor receptor, integrin alpha(v)beta(3), matrix metalloproteinase, endoglin (CD105), and E-selectin. Through tumor angiogenesis imaging, it is expected that a robust platform for understanding the mechanisms of tumor angiogenesis and evaluating the efficacy of novel antiangiogenic therapies will be developed, which can help antiangiogenic drug development in both the preclinical stage and the clinical settings. Molecular imaging has enormous potential in improving the efficiency of the drug development process, including the specific area of antiangiogenic drugs.
Collapse
Affiliation(s)
- Weibo Cai
- The Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Stanford University School of Medicine, 1201 Welch Road, P095, Stanford, CA 94305-5484, USA
| | | | | | | |
Collapse
|
13
|
Radioiodinated VEGF to image tumor angiogenesis in a LS180 tumor xenograft model. Nucl Med Biol 2006; 33:963-9. [PMID: 17127168 DOI: 10.1016/j.nucmedbio.2006.08.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 08/09/2006] [Accepted: 08/10/2006] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Angiogenesis is essential for tumor growth or metastasis. A method involving noninvasive detection of angiogenic activity in vivo would provide diagnostic information regarding antiangiogenic therapy targeting vascular endothelial cells as well as important insight into the role of vascular endothelial growth factor (VEGF) and its receptor (flt-1 and KDR) system in tumor biology. We evaluated radioiodinated VEGF(121), which displays high binding affinity for KDR, and VEGF(165), which possesses high binding affinity for flt-1 and low affinity for KDR, as angiogenesis imaging agents using the LS180 tumor xenograft model. METHODS VEGF(121) and VEGF(165) were labeled with (125)I by the chloramine-T method. Biodistribution was observed in an LS180 human colon cancer xenograft model. Additionally, autoradiographic imaging and immunohistochemical staining of tumors were performed with (125)I-VEGF(121). RESULTS (125)I-VEGF(121) and (125)I-VEGF(165) exhibited strong, continuous uptake by tumors and the uterus, an organ characterized by angiogenesis. (125)I-VEGF(121) uptake in tumors was twofold higher than that of (125)I-VEGF(165) (9.12+/-98 and 4.79+/-1.08 %ID/g at 2 h, respectively). (125)I-VEGF(121) displayed higher tumor to nontumor (T/N) ratios in most normal organs in comparison with (125)I-VEGF(165). (125)I-VEGF(121) accumulation in tumors decreased with increasing tumor volume. Autoradiographic and immunohistochemical analyses confirmed that the difference in (125)I-VEGF(121) tumor accumulation correlated with degree of tumor vascularity. CONCLUSION Radioiodinated VEGF(121) is a promising tracer for noninvasive delineation of angiogenesis in vivo.
Collapse
|
14
|
Ito M, Yang DJ, Mawlawi O, Mendez R, Oh CS, Azhdarinia A, Greenwell AC, Yu DF, Kim EE. PET and planar imaging of tumor hypoxia with labeled metronidazole. Acad Radiol 2006; 13:598-609. [PMID: 16627201 DOI: 10.1016/j.acra.2006.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2005] [Revised: 01/08/2006] [Accepted: 01/09/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE AND OBJECTIVES This study was aimed to develop 99mTc- and 68Ga-labeled metronidazole (MN) using ethylenedicysteine (EC) as a chelator and evaluate their potential use to assess tumor hypoxia. MATERIALS AND METHODS EC-MN was labeled with 99mTc in the presence of tin (II) chloride. Labeling EC-MN with 68Ga was achieved by adding 68GaCl3 (2 mCi with 3.4 microg cold GaCl3). In vitro cellular uptakes of 99mTc- and 68Ga-EC-MN were obtained in various types of tumor cells at 0.5-4 hours. Tissue distribution and PET imaging of 99mTc and 68Ga-EC-MN were evaluated in breast tumor-bearing rats at 0.5-4 hours. Tumor oxygen tension was measured using an oxygen probe. RESULTS There were similar cellular uptakes (2-10%) between 99mTc- and 68Ga-EC-MN at 0.5-4 hours. In vivo biodistribution of 99mTc- and 68Ga-EC-MN in breast tumor-bearing rats showed increased tumor-to-blood and tumor-to-muscle count density ratios as a function of time. Positron emission tomography images confirmed that the tumors could be visualized clearly with 68Ga-EC-MN. Oxygen tension in tumor tissue was determined to be 6-10 mm Hg compared with 40-50 mm Hg in normal muscle tissue. CONCLUSIONS The results indicated that it is feasible to use 99mTc- and 68Ga-EC-MN for assessment of tumor hypoxia. These agents may be useful in selecting and evaluating cancer therapy.
Collapse
Affiliation(s)
- Megumi Ito
- Division of Diagnostic Imaging, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Abstract
Improvement of scintigraphic tumor imaging is extensively determined by the development of more tumor specific radiopharmaceuticals. Thus, to improve the differential diagnosis, prognosis, planning and monitoring of cancer treatment, several functional pharmaceuticals have been developed. Application of molecular targets for cancer imaging, therapy and prevention using generator-produced isotopes is the major focus of ongoing research projects. Radionuclide imaging modalities (positron emission tomography, PET; single photon emission computed tomography, SPECT) are diagnostic cross-sectional imaging techniques that map the location and concentration of radionuclide-labeled radiotracers. 99mTc- and 68Ga-labeled agents using ethylenedicysteine (EC) as a chelator were synthesized and their potential uses to assess tumor targets were evaluated. 99mTc (t1/2 = 6 hr, 140 keV) is used for SPECT and 68Ga (t1/2 = 68 min, 511 keV) for PET. Molecular targets labeled with Tc-99m and Ga-68 can be utilized for prediction of therapeutic response, monitoring tumor response to treatment and differential diagnosis. Molecular targets for oncological research in (1) cell apoptosis, (2) gene and nucleic acid-based approach, (3) angiogenesis (4) tumor hypoxia, and (5) metabolic imaging are discussed. Numerous imaging ligands in these categories have been developed and evaluated in animals and humans. Molecular targets were imaged and their potential to redirect optimal cancer diagnosis and therapeutics were demonstrated.
Collapse
Affiliation(s)
- David J Yang
- Department of Experimental Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston 77030, USA.
| | | | | |
Collapse
|
16
|
Zeng X, Chen J, Miller YI, Javaherian K, Moulton KS. Endostatin binds biglycan and LDL and interferes with LDL retention to the subendothelial matrix during atherosclerosis. J Lipid Res 2005; 46:1849-59. [PMID: 15995169 DOI: 10.1194/jlr.m500241-jlr200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Retention of lipoproteins to proteoglycans in the subendothelial matrix (SEM) is an early event in atherosclerosis. We recently reported that collagen XVIII and its proteolytically released fragment endostatin (ES) are differentially depleted in blood vessels affected by atherosclerosis. Loss of collagen XVIII/ES in atherosclerosis-prone mice enhanced plaque neovascularization and increased the vascular permeability to lipids by distinct mechanisms. Impaired endothelial barrier function increased the influx of lipoproteins across the endothelium; however, we hypothesized that enhanced retention might be a second mechanism leading to the increased lipid content in atheromas lacking collagen XVIII. We now demonstrate a novel property of ES that binds both the matrix proteoglycan biglycan and LDL and interferes with LDL retention to biglycan and to SEM. A peptide encompassing the alpha coil in the ES crystal structure mediates the major blocking effect of ES on LDL retention. ES inhibits the macrophage uptake of biglycan-associated LDL indirectly by interfering with LDL retention to biglycan, but it has no direct effect on the macrophage uptake of native or modified lipoproteins. Thus, loss of ES in advanced atheromas enhances lipoprotein retention in SEM. Our data reveal a third protective role of this vascular basement membrane component during atherosclerosis.
Collapse
Affiliation(s)
- Xiaokun Zeng
- Vascular Biology Program, Department of Surgery, Children's Hospital, Boston, MA 02115, USA
| | | | | | | | | |
Collapse
|
17
|
Yang DJ, Ozaki K, Oh CS, Azhdarinia A, Yang T, Ito M, Greenwell A, Bryant J, Kohanim S, Wong VK, Kim EE. (99m)Tc-EC-guanine: synthesis, biodistribution, and tumor imaging in animals. Pharm Res 2005; 22:1471-9. [PMID: 16132359 DOI: 10.1007/s11095-005-6157-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Accepted: 05/26/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE DNA markers are useful in assessing cell proliferation. The purpose of this study was to synthesize (99m)Tc-ethylenedicysteine-guanine (EC-Guan) for evaluation of cell proliferation. METHODS Tumor cells were incubated with (99m)Tc-EC-Guan for cell cycle analysis. Prostate tumor cells that were overexpressing the HSV thymidine kinase gene, or various tumor cells were incubated with (99m)Tc-EC-Guan at 0.5-2 h. Thymidine incorporation assays were performed in lung cancer cells incubated with EC-Guan at 0.1-1 mg/well. Tissue distribution, autoradiography, and planar scintigraphy of (99m)Tc-EC-Guan and (99m)Tc-EC (control) were determined in tumor-bearing rodents at 0.5-4 h. RESULTS Cell culture assays indicated that EC-Guan was incorporated in DNA, and there was no significant uptake difference between HSVTK overexpressed and normal groups. Biodistribution and scintigraphic imaging studies of (99m)Tc-EC-Guan showed increased tumor/tissue count density ratios as a function of time. CONCLUSIONS Our results indicate that (99m)Tc-EC-Guan may be useful as a tumor proliferation imaging agent.
Collapse
Affiliation(s)
- David J Yang
- Division of Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Abstract
The technological revolution in imaging during recent decades has transformed the way image-guided radiation therapy is performed. Anatomical imaging (plain radiography, computed tomography, magnetic resonance imaging) greatly improved the accuracy of delineating target structures and has formed the foundation of 3D-based radiation treatment. However, the treatment planning paradigm in radiation oncology is beginning to shift toward a more biological and molecular approach as advances in biochemistry, molecular biology, and technology have made functional imaging (positron emission tomography, nuclear magnetic resonance spectroscopy, optical imaging) of physiological processes in tumors more feasible and practical. This review provides an overview of the role of current imaging strategies in radiation oncology, with a focus on functional imaging modalities, as it relates to staging and molecular profiling (cellular proliferation, apoptosis, angiogenesis, hypoxia, receptor status) of tumors, defining radiation target volumes, and assessing therapeutic response. In addition, obstacles such as imaging-pathological validation, optimal timing of post-therapy scans, spatial and temporal evolution of tumors, and lack of clinical outcome studies are discussed that must be overcome before a new era of functional imaging-guided therapy becomes a clinical reality.
Collapse
Affiliation(s)
- Smith Apisarnthanarax
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | | |
Collapse
|
19
|
Yang DJ, Bryant J, Chang JY, Mendez R, Oh CS, Yu DF, Ito M, Azhdarinia A, Kohanim S, Edmund Kim E, Lin E, Podoloff DA. Assessment of cyclooxygense-2 expression with 99mTc-labeled celebrex. Anticancer Drugs 2004; 15:255-63. [PMID: 15014359 DOI: 10.1097/00001813-200403000-00010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cyclooxygenase-2 (COX-2) plays an important role in angiogenesis and cancer progression. Since many tumor cells exhibit COX-2 expression, functional imaging of COX-2 expression using celebrex (CBX, a COX-2 inhibitor) may provide not only a non-invasive, reproducible, quantifiable alternative to biopsies, but it also greatly complements pharmacokinetic studies by correlating clinical responses with biological effects. Moreover, molecular endpoints of anti-COX-2 therapy could also be assessed effectively. This study aimed at measuring uptake of Tc-EC-CBX in COX-2 expression in tumor-bearing animal models. In vitro Western blot analysis and cellular uptake assays were used to examine the feasibility of using Tc-EC-CBX to measure COX-2 activity. Tissue distribution studies of Tc-EC-CBX were evaluated in tumor-bearing rodents at 0.5-4 h. Dosimetric absorption was then estimated. Planar scintigraphy was performed in mice, rats and rabbits bearing tumors. In vitro cellular uptake indicated that cells with higher COX-2 expression (A549 and 13762) had higher uptake of Tc-EC-CBX than lower COX-2 expression (H226). In vivo biodistribution of Tc-EC-CBX in tumor-bearing rodents showed increased tumor:tissue ratios as a function of time. In vitro and biodistribution studies demonstrated the possibility of using Tc-EC-CBX to assess COX-2 expression. Planar images confirmed that the tumors could be visualized with Tc-EC-CBX from 0.5 to 4 h in tumor-bearing animal models. We conclude that Tc-EC-CBX may be useful to assess tumor COX-2 expression. This may be useful in the future for selecting patients for treatment with anti-COX-2 agents.
Collapse
Affiliation(s)
- David J Yang
- Division of Diagnostic Imaging, University of Texas M D Anderson Cancer Center, Houston, TX 77030, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Molecular imaging aims to visualize the cellular and molecular processes occurring in living tissues, and for the imaging of specific molecules in vivo, the development of reporter probes and dedicated imaging equipment is most important. Reporter genes can be used to monitor the delivery and magnitude of therapeutic gene transfer, and the time variation involved. Imaging technologies such as micro-PET, SPECT, MRI and CT, as well as optical imaging systems, are able to non-invasively detect, measure, and report the simultaneous expression of multiple meaningful genes. It is believed that recent advances in reporter probes, imaging technologies and gene transfer strategies will enhance the effectiveness of gene therapy trials.
Collapse
Affiliation(s)
- E Edmund Kim
- Department of Radiology and Medicine, Center for Metabolic Imaging, Nuclear Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| |
Collapse
|
21
|
Citrin D, Lee AK, Scott T, Sproull M, Ménard C, Tofilon PJ, Camphausen K. In vivo tumor imaging in mice with near-infrared labeled endostatin. Mol Cancer Ther 2004. [DOI: 10.1158/1535-7163.481.3.4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Endostatin is a potent inhibitor of angiogenesis currently in phase I clinical trials. Imaging technologies that use near-infrared fluorescent probes are well suited to the laboratory setting. The goal of this study was to determine whether endostatin labeled with a near-infrared probe (Cy5.5) could be detected in an animal and whether it would selectively localize to a tumor. Endostatin was conjugated to Cy5.5 monofunctional dye and injected into mice bearing Lewis lung carcinoma tumors (350 mm2). Mice were imaged at various time points while under sedation using a lightproof box affixed to a fluorescent microscope mounted with a filter in the near-infrared bandwidth consistent with Cy5.5 fluorescence. After i.p. injection, endostatin-Cy5.5 was absorbed producing a near-infrared fluorescent image within the tumors at 18 h reaching a maximum at 42 h after injection. No signal was emitted from mice injected with unlabeled endostatin or Cy5.5 dye alone or those that received no injection. Further results show that a dose response exists with injection of endostatin-Cy5.5. Mimicking the clinical route of administration, an i.v. injection had a peak signal emission at 3 h but also persisted to 72 h. Finally, to determine the intratumoral binding site for endostatin, we performed immunofluorescence on tumor specimens and demonstrated that endostatin binds to tumor vasculature and colocalizes with platelet/endothelial cell adhesion molecule 1 expression. This study demonstrates that endostatin covalently bound to Cy5.5 will migrate from a distant i.p. injection site to a tumor. These data indicate that endostatin-Cy5.5 is appropriate for selectively imaging tumors in uninjured experimental animals.
Collapse
Affiliation(s)
- Deborah Citrin
- 1Imaging and Molecular Therapeutics Section, Radiation Oncology Branch,
| | - Andrew K. Lee
- 4Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX
| | - Tamalee Scott
- 1Imaging and Molecular Therapeutics Section, Radiation Oncology Branch,
| | - Mary Sproull
- 1Imaging and Molecular Therapeutics Section, Radiation Oncology Branch,
| | - Cynthia Ménard
- 1Imaging and Molecular Therapeutics Section, Radiation Oncology Branch,
| | - Philip J. Tofilon
- 3Molecular Radiation Therapeutics Branch, National Cancer Institute, Bethesda, MD and
| | - Kevin Camphausen
- 1Imaging and Molecular Therapeutics Section, Radiation Oncology Branch,
- 2Vascular Biology Faculty, and
| |
Collapse
|
22
|
Citrin D, Scott T, Sproull M, Menard C, Tofilon PJ, Camphausen K. In vivo tumor imaging using a near-infrared-labeled endostatin molecule. Int J Radiat Oncol Biol Phys 2004; 58:536-41. [PMID: 14751525 DOI: 10.1016/j.ijrobp.2003.09.068] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE Endostatin is a 20-kD C-terminal fragment of collagen XVIII and is a potent inhibitor of angiogenesis. Imaging technologies that use near-infrared (NIR) fluorescent probes are well suited to the laboratory setting. The goal of this study was to determine whether endostatin labeled with a NIR probe (Cy5.5) could be detected in an animal after intraperitoneal injection and whether it would selectively localize in a tumor. METHODS Endostatin was conjugated to Cy5.5 monofunctional dye and purified from free dye by gel filtration. LLC, a murine tumor, was implanted in C57BL/6 mice. The tumors were allowed to grow to 350 mm(2), at which point the mice were injected with 100 microg/100 microL endostatin-Cy5.5 and imaged at various points under sedation. Imaging was performed using a lightproof box affixed to a fluorescent microscope mounted with a filter in the NIR bandwidth (absorbance maximum 675 nm and emission maximum 694 nm). Images were captured by a CCD and desktop computer and stored as 16-bit Tiff files. The mice were also serially imaged for uptake into the tumor and washout from the tumor. RESULTS After intraperitoneal injection, endostatin-Cy5.5 was quickly absorbed, producing a NIR fluorescent image of the tumors at 24 h that persisted through 7 days. However, the signal peaked at 42 h after injection. Control animals included mice containing green fluorescent protein (GFP) under the control of an actin promotor, which expresses GFP in every cell; tumor-free mice injected with endostatin-Cy5.5; mice with tumors that were not injected with endostatin-Cy5.5; and mice with tumors injected with dye alone. In the four sets of control animals, no NIR photon emissions were detected at 24 hours or 5 days. Only the GFP mouse was detected using the GFP filter. Unlike previous analogous studies with 4-N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO)-Cy5.5 in which the tumor image faded with time, the endostatin-Cy5.5 NIR signal was emitted from the tumor up to 7 days after injection, the last time point examined. CONCLUSION The results of this study demonstrated that endostatin covalently bound to Cy5.5 will migrate from a distant intraperitoneal injection site to a tumor. These data indicate that endostatin-Cy5.5 is appropriate for selectively imaging tumors in experimental animals. Furthermore, data suggest that the anti-angiogenic effect of endostatin occurs through a local mechanism of action, within the tumor or tumor vasculature, rather than through a systemic mechanism.
Collapse
Affiliation(s)
- Deborah Citrin
- Imaging and Molecular Therapeutics Section, Radiation Oncology Branch, National Cancer Institute/NIH, Building 10, 10 Center Drive, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
23
|
McDonald DM, Teicher BA, Stetler-Stevenson W, Ng SSW, Figg WD, Folkman J, Hanahan D, Auerbach R, O'Reilly M, Herbst R, Cheresh D, Gordon M, Eggermont A, Libutti SK. Report from the Society for Biological Therapy and Vascular Biology Faculty of the NCI Workshop on Angiogenesis Monitoring. J Immunother 2004; 27:161-75. [PMID: 14770088 DOI: 10.1097/00002371-200403000-00010] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The field of tumor angiogenesis has seen explosive growth over the last 5 years. Preclinical as well as early clinical evaluation of novel compounds is progressing at a rapid pace. To gain a perspective on the field and to take stock of advances in the understanding of molecular mechanisms underlying the process of tumor angiogenesis as well as ways of monitoring the activity of agents, the Society for Biologic Therapy and the National Cancer Institute's Vascular Biology Faculty convened a Workshop on Angiogenesis Monitoring in November 2002. The Workshop was composed of invited speakers and participants from academia, industry, and government. It was divided into 3 sessions, each chaired by leaders in the field. The first focused on advances in the understanding of the cellular and molecular mechanisms of angiogenesis in tumors. The second examined preclinical assay systems that are useful in vascular biology. The third addressed the translation to the clinic and monitoring of antiangiogenic activity of agents in patients and novel trial designs. What follows is a summary of the discussions and findings of each session.
Collapse
|
24
|
Lee KH, Song SH, Paik JY, Byun SS, Lee SY, Choe YS, Kim BT. Specific endothelial binding and tumor uptake of radiolabeled angiostatin. Eur J Nucl Med Mol Imaging 2003; 30:1032-7. [PMID: 12557052 DOI: 10.1007/s00259-002-1094-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Angiostatin (AS) is a potent antiangiogenic agent which inhibits tumor growth through specific action on proliferating endothelial cells. Imaging of radiolabeled AS would enhance our knowledge on the pharmacokinetics of AS and might provide useful information relating to tumor neovasculature. We therefore investigated the potential of radiolabeled AS as a novel tumor imaging agent. Human angiostatin was radioiodine labeled using the lactoperoxidase method. Competition binding studies showed a dose-dependent inhibition of (125)I-AS binding to endothelial cells by excess unlabeled AS, and a displacement curve demonstrated that specific binding was dose dependent and saturable, with a K(d) value of 169 n M. Gel analysis showed that (125)I-AS remained stable in serum for up to 24 h without significant degradation. Intravenously injected (125)I-AS in rats was cleared from the blood in an exponential fashion. Biodistribution data from human colon cancer-bearing Balb/C nude mice showed high uptake in the kidneys, stomach, liver, and lungs. Tumor uptake was 3.2+/-0.7, 2.6+/-0.2, and 1.7+/-0.2%ID/g at 2, 4, and 9 h after injection, respectively. Tumor to muscle count ratio increased from 3.1+/-0.5 at 2 h to 4.4+/-0.5 at 9 h. Serial scintigraphy from 1 to 5 h after (123)I-AS injection demonstrated high uptake in the kidneys and bladder, consistent with renal excretion. There was clear demarcation of tumor by 1 h, with gradual increase in contrast over time (4-h tumor to contralateral thigh ratio =4.7+/-1.1). Thus, radioiodine-labeled angiostatin binds specifically to endothelial cells and has potential as a novel tumor imaging agent.
Collapse
Affiliation(s)
- Kyung-Han Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwondong, Kangnamgu, Seoul, Korea
| | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Advances in imaging are transforming our understanding of angiogenesis and the evaluation of drugs that stimulate or inhibit angiogenesis in preclinical models and human disease. Vascular imaging makes it possible to quantify the number and spacing of blood vessels, measure blood flow and vascular permeability, and analyze cellular and molecular abnormalities in blood vessel walls. Microscopic methods ranging from fluorescence, confocal and multiphoton microscopy to electron microscopic imaging are particularly useful for elucidating structural and functional abnormalities of angiogenic blood vessels. Magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), ultrasonography and optical imaging provide noninvasive, functionally relevant images of angiogenesis in animals and humans. An ongoing dilemma is, however, that microscopic methods provide their highest resolution on preserved tissue specimens, whereas clinical methods give images of living tissues deep within the body but at much lower resolution and specificity and generally cannot resolve vessels of the microcirculation. Future challenges include developing new imaging methods that can bridge this resolution gap and specifically identify angiogenic vessels. Another goal is to determine which microscopic techniques are the best benchmarks for interpreting clinical images. The importance of angiogenesis in cancer, chronic inflammatory diseases, age-related macular degeneration and reversal of ischemic heart and limb disease provides incentive for meeting these challenges.
Collapse
Affiliation(s)
- Donald M McDonald
- Cardiovascular Research Institute, Comprehensive Cancer Center, and Department of Anatomy, University of California, 513 Parnassus Avenue, San Francisco, California 94143-0452, USA.
| | | |
Collapse
|
26
|
Abstract
This review assembles the laboratory and clinical evidence that cytotoxic chemotherapy and antiangiogenic therapy are each dependent on endothelial cell apoptosis. During cytotoxic chemotherapy, apoptosis of endothelial cells in the vascular bed of tumors precedes apoptosis of tumor cells, even when the tumor has been made drug resistant. Administration of an angiogenesis inhibitor which is not directly cytotoxic to tumor cells can increase tumor cell apoptosis and inhibit tumor growth by inhibiting endothelial proliferation and migration and/or by inducing endothelial apoptosis. Furthermore, oncogene expression and loss of tumor suppressor gene activity can at once protect tumor cells against apoptosis and increase their angiogenic output. Both of these survival advantages conferred on the tumor can be overcome by antiangiogenic therapy. They can also be overcome by cytotoxic chemotherapy administered on a low dose 'antiangiogenic schedule' which continuously exposes endothelial cells in the tumor bed to the drug. As a result, endothelial apoptosis can be demonstrated to precede tumor cell apoptosis, and tumors regress or are inhibited, whether or not the tumor cells are resistant to the drug, and with little or no host toxicity. In contrast, cytotoxic chemotherapy administered on a 'conventional schedule' of maximal tolerated dose followed by an off-therapy interval, becomes ineffective after drug resistance is acquired. On the basis of these experimental findings, chemotherapy of cancer may possibly be improved-i.e. decreased drug resistance and decreased toxic side-effects-by changing dose and schedule to maximize apoptosis of endothelial cells in the vascular bed of tumors. Further improvement may be achieved by combining angiogenesis inhibitors with 'antiangiogenic chemotherapy'.
Collapse
Affiliation(s)
- Judah Folkman
- Department of Surgery, Children's Hospital and Harvard Medical School, Hunnewell 103 300 Longwood Avenue, Boston, MA 02115, USA.
| |
Collapse
|
27
|
Schechter NR, Yang DJ, Azhdarinia A, Kohanim S, Wendt R, Oh CS, Hu M, Yu DF, Bryant J, Ang KK, Forster KM, Kim EE, Podoloff DA. Assessment of epidermal growth factor receptor with 99mTc-ethylenedicysteine-C225 monoclonal antibody. Anticancer Drugs 2003; 14:49-56. [PMID: 12544258 DOI: 10.1097/00001813-200301000-00007] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Epidermal growth factor receptor (EGFR) plays an important role in cell division and cancer progression, as well as angiogenesis and metastasis. Since many tumor cells exhibit the EGFR on their surface, functional imaging of EGFR provides not only a non-invasive, reproducible, quantifiable alternative to biopsies, but it also greatly complements pharmacokinetic studies by correlating clinical responses with biological effects. Moreover, molecular endpoints of anti-EGFR therapy could be assessed effectively. C225 is a chimeric monoclonal antibody that targets the human extracellular EGFR and inhibits the growth of EGFR-expressing tumor cells. Also, it has been demonstrated that C225, in combination with chemotherapeutic drugs or radiotherapy, is effective in eradicating well-established tumors in nude mice. We have developed 99mTc-labeled C225 using ethylenedicysteine (EC) as a chelator. This study aimed at measuring uptake of 99mTc-EC-C225 in EGFR+ tumor-bearing animal models and preliminary feasibility of imaging patients with head and neck carcinomas. In vitro Western blot analysis and cytotoxicity assays were used to examine the integrity of EC-C225. Tissue distribution studies of 99mTc-EC-C225 were evaluated in tumor-bearing rodents at 0.5-4 h. In vivo biodistribution of 99mTc-EC-C225 in tumor-bearing rodents showed increased tumor-to-tissue ratios as a function of time. In vitro and biodistribution studies demonstrated the possibility of using 99mTc-EC-C225 to assess EGFR expression. SPECT images confirmed that the tumors could be visualized with 99mTc-EC-C225 from 0.5 to 4 h in tumor bearing rodents. We conclude that 99mTc-EC-C225 may be useful to assess tumor EGFR expression. This may be useful in the future for selecting patients for treatment with C225.
Collapse
Affiliation(s)
- Naomi R Schechter
- Division of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston 77030, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|