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- Saadati, Sofia, 1992, et al.
(author)
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Binding and internalization of 177Lu-octreotate in human tumor cell lines of different origin
- 2017
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In: 63rd Annual Meeting of the Radiation Research Society, Cancun, Mexico.
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Conference paper (other academic/artistic)abstract
- Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-octreotate is used for systemic treatment of patients with somatostatin receptor (SSTR)-expressing neuroendocrine tumors (NETs), mainly for small-intestine NETs and endocrine pancreatic tumors. Further research is needed to evaluate the possibility of using this type of treatment in patients with other SSTR-expressing tumors. Tumor binding and uptake of the radiopharmaceutical is highly dependent on SSTR expression. In order to determine the potential of using 177Lu-octreotate for treatment of other tumor cell lines, in vitro studies of binding and internalization are needed. The aim of this study was to asses binding and internalization of 177Lu-octreotate in various cancer cell lines and compare with our previous results. In vitro studies were performed on neuroblastoma (CLB-BAR, IMR-32), lung adenocarcinoma (h1975, h2228) and invasive breast carcinoma (BT474, MCF-7, MDA-MB-231, MDA-MB-361, T47D, ZR-75-1) cell lines. Cell cultures were incubated with low or high amounts of 177Lu-octreotate. To block SSTR and thereby determine the specific uptake, control groups were incubated with 177Lu-octreotate and excess octreotide. The amount of unbound, membrane-bound, and internalized 177Lu in each sample was determined after 24 h. Several of the studied tumor cell lines showed specific binding of 177Lu-octreotate. The highest binding and internalization after 24 h was seen for the neuroblastoma cell lines IMR-32 (58% internalized, 9.4% membrane-bound) and CLB-BAR (26% internalized, 3.4% membrane-bound). Specific binding was also found in some breast cancer cell lines (e.g. 3.1% internalized, 0.5% membrane-bound in MDA-MB-361). No specific binding was found in lung adenocarcinoma. In comparison with our previous findings in NET and NET-like cell lines, these results indicate that SSTR-based PRRT may be a potential treatment option for patients with neuroblastoma and certain types of breast cancer. Promising results showing specific tumor uptake of 177Lu-octreotate were obtained for SSTR-expressing tumor cell lines in vitro, indicating the possibility of using SSTR-based diagnostic and therapeutic regimes on more tumor types than those in current clinical practice.
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| 3. |
- Sandblom, Viktor, 1987, et al.
(author)
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Combination therapy of medullary thyroid cancer using radiation and vandetanib
- 2017
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In: European Journal of Nuclear Medicine and Molecular Imaging. Annual Congress of the European Association of Nuclear Medicine October 21 – 25, 2017 Vienna, Austria. Vol. 44, Suppl. 2. EP-0792. - : Springer. - 1619-7070 .- 1619-7089.
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Conference paper (peer-reviewed)abstract
- INTRODUCTION Most patients diagnosed with medullary thyroid cancer (MTC) present with metastatic disease. MTC are rare neuroendocrine tumours that occur either sporadically or in a hereditary form. Surgical resection of the thyroid gland followed by external beam radiotherapy (EBRT) or the use of tyrosine kinase inhibitors are current clinical methods for management of MTC. Unfortunately, the 10-year survival for patients with metastatic disease is only about 40%. However, many MTC tumours overexpress somatostatin receptors as molecular targets. Therefore, one option for patients with MTC is systemic treatment with radiolabelled somatostatin analogues (e.g. 177Lu-octreotate) that bind with high affinity and specificity to somatostatin receptors on the tumour cells. In addition, the tyrosine kinase inhibitor vandetanib has recently been approved for single-agent treatment of MTC by the U.S. Food and Drug Administration (FDA). The aim of this study was to investigate the potential synergistic effect of combining irradiation and vandetanib for treatment of MTC. SUBJECTS & METHODS BALB/c nude mice were transplanted with patient-derived MTC cells (GOT2). When developed tumours reached a volume of about 500 mm3, the mice were treated with EBRT, vandetanib or a combination of both. The radiation dose and the amount of vandetanib were chosen to give moderate effect as single treatment to enable detection of any increased effect from the combination. Tumour volume was followed and compared with that in untreated mice. RESULTS We found that the largest treatment effect over time was seen for the animals receiving a combination of both EBRT and vandetanib. Given as single-agent treatment, EBRT and vandetanib resulted in a reduction in tumour size or in tumour growth arrest. For example, at two weeks after start of treatment, the tumour volume was reduced by 64%, 52%, and 73% compared with the untreated control group, for the animals treated with single EBRT, single vandetanib, and the combination, respectively. CONCLUSION The results indicate that an additive or even synergistic effect could be achieved when combining irradiation with vandetanib for treatment of patients with MTC. Further studies are needed to investigate the possibility of using 177Lu-octreotate for treatment of MTC, both as single-agent treatment or in combination with vandetanib.
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| 4. |
- Sandblom, Viktor, 1987, et al.
(author)
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Evaluation of two intraoperative gamma detectors for assessment of 177Lu activity concentration in vivo
- 2017
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In: European Journal of Nuclear Medicine and Molecular Imaging Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 4:1
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Journal article (peer-reviewed)abstract
- Background Patients with somatostatin receptor-expressing neuroendocrine tumours can be treated with intravenously administered 177Lu-octreotate. Few patients are cured with the present protocol due to the current dose limitation of normal organs at risk, such as the kidneys. By locally administering 177Lu-octreotate to the liver for the purpose of treating liver metastases, a substantially reduced absorbed dose to organs at risk could be achieved. The development of such a technique requires the capability of measuring the 177Lu activity concentration in tissues in vivo. The aim of this study was to evaluate different performance parameters of two commercially available intraoperative gamma detectors in order to investigate whether intraoperative gamma detector measurements could be used to determine 177Lu activity concentration in vivo. Results Measurements were made using different sources containing 177Lu. Response linearity, sensitivity, spatial resolution and its depth dependence, organ thickness dependence of the measured count rate and tumour detectability were assessed for two intraoperative gamma detectors. The two detectors (a scintillation and a semiconductor detector) showed differences in technical performance. For example, the sensitivity was higher for the scintillation detector, while the spatial resolution was better for the semiconductor detector. Regarding organ thickness dependence and tumour detectability, similar results were obtained for both detectors, and even relatively small simulated tumours of low tumour-to-background activity concentration ratios could be detected. Conclusions Acceptable results were obtained for both detectors, although the semiconductor detector proved more advantageous for our purpose. The measurements demonstrated factors that must be corrected for, such as organ thickness or dead-time effects. Altogether, intraoperative gamma detector measurements could be used to determine 177Lu activity concentration in vivo.
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