1 Department of Nuclear Medicine, 2 Department of Internal Medicine IV, Division of Gastroenterology and Hepatology, and 3 Department of Surgery, University of Vienna, Vienna; 4 Austrian Research Center, Seibersdorf, Austria
Received 1 April 2003; accepted 23 April 2003
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Abstract |
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Recent studies have shown that vascular endothelial growth factor (VEGF) receptor is overexpressed in vascular endothelial cells of various human tumours as well as in human tumour cells. The aim of this study was to evaluate the usefulness of scanning with VEGF165 labeled with 123I for tumor localisation in patients with gastrointestinal tumours.
Patients and methods:
Human recombinant VEGF165 was radiolabelled with 123I by electrophilic radioiodination using the chloramine T method. [123I]VEGF165 was administered intravenously [mean dose 184 ± 18 MBq (130 pmol;
5 µg) per patient] to 18 patients with gastrointestinal tumours. Dynamic acquisition was initiated immediately after administration and carried out until 30 min post-injection. Whole body images were done in anterior and posterior views at various time points. All patients underwent single-photon emission tomography imaging 1.5 h post-injection. Scanning with [123I]VEGF165 was compared with computed tomography and magnetic resonance imaging.
Results:
Intravenous injection of [123I]VEGF165 did not cause any side-effects. Binding of [123I]VEGF165 to primary tumours and metastases was visible shortly after injection. In patients with pancreatic adenocarcinomas, primary tumours were visualised in seven of nine, lymph node metastases in three of four, liver metastases in three of six and lung metastases in one of three. Cholangiocarcinomas were visualised by imaging in one of two patients. Hepatocellular carcinomas were visible by imaging in two of four patients. [123I]VEGF165 scans were weakly positive in one patient with abdominal schwannoma and in one patient with peritoneal carcinosis.
Conclusions:
These results indicate that scanning with [123I]VEGF165 can visualise gastrointestinal tumours and metastases expressing receptors for VEGF165. [123I]VEGF165 receptor scintigraphy may be useful for visualisation of tumour angiogenesis.
Key words: angiogenesis, gastrointestinal, receptors, scintigraphy, tumours, VEGF
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Introduction |
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Recent studies have demonstrated that various tumour cells, including gastrointestinal tumour cells and endothelial cells of proliferating tumours, overexpress receptors for VEGF165 [57]. In our previous studies we have shown that significantly higher amounts of VEGF receptors were found in various human tumour cells and tumour tissues compared with adjacent normal tissues or peripheral blood cells [8]. These observations led us to develop an [123I]VEGF165 receptor scintigraphy to explore a possible role of VEGF receptor scintigraphy in the staging and follow-up of patients with solid tumours. Furthermore, knowledge about the VEGF receptor status in vivo may bring about fascinating aspects for tumour-specific antiangiogenic therapies and strategies [9]. For this purpose we used VEGF receptor scintigraphy in patients with histologically confirmed gastrointestinal tumours to determine the extent of [123I]VEGF165 accumulation in the tumours and/or its metastases. The results of [123I]VEGF165 receptor scintigraphy were also compared with those of computed tomography (CT) scanning and magnetic resonance imaging (MRI).
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Patients and methods |
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Nine patients had a pancreatic adenocarcinoma, four had a hepatocellular carcinoma, two had a cholangiocarcinoma, one had a peritoneal carcinosis of a gastric adenocarcinoma, one had an abdominal schwannoma and one had a benign hepatic focal nodular hyperplasia. In all patients, diagnosis and stage of disease were established according to WHO criteria. The location and size of primary tumours and/or spread of metastases were investigated by conventional CT scan, MRI, endoscopy or surgery.
At time of scintigraphic evaluation, only one patient with pancreatic adenocarcinoma and the patient with abdominal schwannoma had undergone chemotherapy 3 weeks before scintigraphic evaluation. The patient with peritoneal carcinosis of gastric adenocarcinoma had undergone gastroectomy 1 year previously.
Recombinant human VEGF165 (rhVEGF165) (PromoCell GmbH, Heidelberg, Germany) was labelled with 123I by electrophilic radioiodination using chloramine T, essentially as described previously [8]. Briefly, 10 µg (0.26 nmol) of rhVEGF165 were labelled with 30 mCi [123I]Na (Research Center, Karlsruhe, Germany) and chloramine T. After 3 min the reactions were stopped by addition of 4 µl sodium metabisulphite (Na2S2O5, 50 nmol). The reaction mixture was diluted with phosphate-buffered saline containing 0.1% human serum albumin and applied onto a size-exclusion chromatography column (Sephadex G-25 M). The first 123I peak eluting from the column was collected, analysed and filtered using a sterile membrane (Millex GV 0.2 µm).
The study protocol included planar, single-photon emission tomography (SPET) and whole-body gamma camera imaging as well as blood and urine collections over 24 h.
[123I]VEGF165 was administered slowly as a single intravenous bolus injection over 3 min in a dose of 184 ± 18 MBq [130 pmol (
5 µg) VEGF165 per patient]. In order to determine the haemodynamic effects of VEGF, blood pressure and heart rate were monitored during tracer application and scintigraphy. The patients received 400 mg sodium perchlorate three times daily over 3 days for thyroid blockage.
Standard techniques were applied for recording and visualisation. Whole-body acquisitions were performed simultanously in anterior and posterior views with a double-headed and a large feld of view camera (Millenium VG with Hawkeye; GE Medical Systems, Milwaukee, WI, USA) employing medium-energy high-resolution collimators (10 cm/min; matrix 256 x 1024 pixels). Serial whole body images were obtained 1, 2, 18 and 24 h post-injection. A 30 min dynamic image was recorded starting at the time of injection (matrix 128 x 128 pixels). To verify that the activity localisation corresponded to the tumour lesions documented by CT scans, SPET studies in combination with CT scans were obtained 1.5 h post-injection (60 projections over a 360 rotation, 40 s per step and a 64 x 64 pixel matrix). Planar images were acquired 40 min post-injection including anterior and posterior views of abdomen and thorax (matrix 256 x 256 pixels; 800 kcts preset). Additional lateral or oblique views of above regions or other regions were obtained when necessary.
Scintigrams were viewed separately and independently by two experienced observers unaware of tumour findings. [123I]VEGF165 receptor scintigraphy results were compared with the conventional CT and/or MRI. Quantitative analysis of [123I]VEGF165 receptor scintigraphic results with image quality was done in clinically or radiologically known involved sites. Lesion to background uptake ratios were determined on 1.5 h SPET images using regions of interest over the lesion and over the ipsilateral or contralateral side of normal uptake. The mean counts over the lesions and background regions were calculated and ratios were obtained.
For statistical analyses, the 2 test was used to compare sites detection by two techniques. Statistical analysis was using Students t-test and analysis of variance at a confidence level of 95%.
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Results |
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After intravenous injection of [123I]VEGF165, patients showed no clinical adverse reaction, and no side-effects were noted.
The results of a lesion-by-lesion comparison of [123I]VEGF165 receptor scintigraphy with CT and MRI are given in Table 1. Primary pancreatic adenocarcinomas (Figure 1) and liver metastases were visualised by [123I]VEGF165 receptor scanning shortly (30 min) after injection of [123I]VEGF165, and were still visible at 23 h after application. For liver and lung metastases an enhanced tracer uptake was observed in some of the lesions, whereas others showed a heterogenous accumulation of the tracer compared with normal liver or lung tissue. The overall sensitivity of [123I]VEGF165 receptor scintigraphy for detecting pancreatic tumors and their metastases was 64%. [123I]VEGF165 receptor scintigraphy visualised primary pancreatic adenocarcinomas in seven of nine patients (sensitivity 78%). Lymph node metastases were seen in three of four patients (75%), and liver metastases in three of six patients (50%). Lung metastases were detected only in one of three patients (33%). The uptake ratios between pancreatic primary tumour and background ranged from 1.5 to 2.6. A false-negative [123I]VEGF165 receptor scanning for a primary pancreatic cancer lesion was obtained in one patient, who had received the last cycle of chemotherapy (docetaxel and gemcitabine) 3 weeks previously. In one patient with a large primary pancreatic cancer in the pancreatic head, CT scan showed the median diameter to be 6 cm, while [123I]VEGF165 receptor scintigraphy indicated the presence of a ring-shaped tracer accumulation around the lesion; histological examination after surgery revealed the presence of a central necrosis in the primary tumor. For hepatocellular carcinoma (Figure 2) and cholangiocarcinoma, an enhanced tracer uptake was observed in some of the lesions, whereas others showed a heterogenous accumulation of the tracer compared with normal liver tissue. Two of four patients with hepatocellular carcinoma and one of two patients with cholangiocarcinoma could be visualised by [123I]VEGF165 receptor scintigraphy. Interestingly, one patient with a large liver lesion was examined by [123I]VEGF165 receptor scintigraphy because of suspicion of having hepatocellular carcinoma. The [123I]VEGF165 receptor scintigraphy showed a large cold spot in the liver lesion. The histological examination confirmed a diagnosis of benign hepatic focal nodular hyperplasia. In one patient with abdominal schwannoma, the [123I]VEGF165 receptor scintigraphy showed only the liver metastases. In the patient with peritoneal carcinosis who had undergone gastroectomy 1 year previously, the [123I]VEGF165 receptor scan demonstrated the heterogenous accumulation of tracer in the abdomen. The majority of false-negative [123I]VEGF165 receptor scanning results were obtained by tumours and metastases with maximum median diameter of <2 cm. In comparison, almost all primary tumours and metastases were visualised by CT and MRI with the exception of peritoneal carcinosis and lymph node metastases (Table 1).
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Discussion |
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The precondition for the accumulation of VEGF165 in the scintigram is the presence of receptors for VEGF165 on the tumour cells and tumour vascular endothelial cells. Using a direct receptor binding assay, a class of saturable VEGF165 receptors has been identified on various gastrointestinal tumour cell lines and tumour tissues [8]. The cases in which the [123I]VEGF165 receptor scintigraphy was negative may be explained by the low number or absence of VEGF165 receptors or by the blockade of VEGF165 receptors by locally produced ligands or small size of lesions. Tumour cell necrosis or changes in the blood supply of the cancers might also have an effect on cell binding properties. With regard to lung metastases, only about one-third of metastases were found on [123I]VEGF165 receptor scanning, although the largest lung lesions imaged in our studies were only in the range of 2.5 cm in diameter. This might be due to relatively high background activities, indicating a high degree of physiological VEGF165 uptake in the lungs. We observed that there was no substantial VEGF165 uptake by normal gastrointestinal tissue. This characteristic of VEGF165 biodistribution may be an apparent advantage for the detection of gastrointestinal tumours.
In conclusion, our preliminary results demonstrate the safety of imaging with [123I]VEGF165, and that a variety of gastrointestinal tumours and metastases may be visualised by VEGF165 receptor scintigraphy. Although CT/MRI is superior to [123I]VEGF165 receptor scintigraphy for the visualisation of the gastrointestinal tumours and metastases, [123I]VEGF165 scintigraphy might be a useful tool for visualisation of viable tumour angiogenesis.
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Acknowledgements |
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Footnotes |
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References |
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2. Ferrara N, Houck KA, Jakeman LB, Leung DW. Molecular and biological properties of the vascular endothelial growth factor family of proteins. Endocr Rev 1992; 13: 1832.[ISI][Medline]
3. De Vries C, Escobedo JA, Ueno H et al. The fms-like tyrosine kinase, a receptor for vascular endothelial growth factor. Science 1992; 255: 989991.[ISI][Medline]
4. Terman BI, Dougher-Vermazen M, Carrison ME et al. Identification of the KDR tyrosine kinase as a receptor for vascular endothelial cell growth factor. Biochem Biophys Res Commun 1992; 187: 15791586.[ISI][Medline]
5. Harada Y, Ogata Y, Shirouzu K. Expression of vascular endothelial growth factor and its receptor KDR (kinase domain-containing receptor)/Flk-1 (fetal liver kinase-1) as prognostic factors in human colorectal cancer. Int J Clin Oncol 2001; 6: 221228.[Medline]
6. Boocock CA, Charnock-Jones DS, Sharkey AM et al. Expression of vascular growth factor and its receptors flt and KDR in ovarian carcinoma. J Natl Cancer Inst 1995; 87: 506516.[Abstract]
7. Plate KH, Breier G, Weich HA, Risau W. Vascular endothelial growth factor is a potential tumor angiogenesis factor in human gliomas in vivo. Nature 1992; 359: 845848.[CrossRef][ISI][Medline]
8. Li S, Peck-Radosavljevic M, Koller E et al. Characterization of (123)I-vascular endothelial growth factor-binding sites expressed on human tumour cells: possible implication for tumour scintigraphy. Int J Cancer 2001; 91: 789796.[CrossRef][ISI][Medline]
9. Fidler IJ, Ellis LM. The implications of angiogenesis for the biology and therapy of cancer metastasis. Cell 1994; 79: 185188.[ISI][Medline]