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- Arne, Gabriella, et al.
(författare)
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Gastrointestinal stromal tumors (GISTs) express somatostatin receptors and bind radiolabeled somatostatin analogs.
- 2013
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Ingår i: Acta oncologica (Stockholm, Sweden). - 1651-226X .- 0284-186X. ; 52:4, s. 783-792
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Tidskriftsartikel (refereegranskat)abstract
- Background. Gastrointestinal stromal tumors (GISTs) can be effectively treated with tyrosine kinase inhibitors (TKIs). However, some patients with GIST develop drug resistance, and alternative treatment strategies are therefore needed. The aim of this study was to analyze the expression of somatostatin receptors (SSTR) in GIST as a target for peptide receptor-mediated radiotherapy (PRRT). Material and methods. Expression profiling of SSTR1-5 was performed on biopsies from 34 GISTs (16 gastric tumors, 15 small intestinal tumors, and three rectal tumors). SSTR scintigraphy ((111)In-octreotide) and measurement of (111)In activity in tumor specimens was performed in seven patients. Uptake and internalization of (177)Lu- octreotate was studied in primary cell cultures from two patients. Results. Quantitative PCR analysis showed expression of SSTR1 and SSTR2 in the majority of tumors, while SSTR3-5 were expressed at low levels. Immunohistochemical analysis confirmed the presence of SSTR1 and SSTR2 proteins in all GISTs, and SSTR3-5 in a subset of tumors. Diagnostic imaging by SSTR scintigraphy, using (111)In-octreotide, demonstrated tumor uptake of (111)In in three of six GIST patients. Measurement of (111)In activity in excised tumor specimens from five patients gave tumor-to-blood (T/B) activity ratios of between eight and 96. Tumor cells in primary culture (gastric and small intestinal GIST) specifically bound and internalized (177)Lu when incubated with the therapeutic compound (177)Lu-octreotate for 4-48 hours (p < 0.05). Conclusion. Peptide receptor-mediated radiotherapy via SSTR may provide a novel treatment strategy in carefully selected GIST patients with TKI-resistant tumors.
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- Dalmo, Johanna, et al.
(författare)
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Biodistribution of 177Lu-octreotate and 111In-minigastrin in female nude mice transplanted with human medullary thyroid carcinoma GOT2.
- 2012
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Ingår i: Oncology reports. - : Spandidos Publications. - 1791-2431 .- 1021-335X. ; 27:1, s. 174-181
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Tidskriftsartikel (refereegranskat)abstract
- To be able to evaluate new radiopharmaceuticals and optimize diagnostic and therapeutic procedures, relevant animal models are required. The aim of this study was to evaluate the medullary thyroid carcinoma GOT2 animal model by analyzing the biodistribution of 177Lu-octreotate and 111In-minigastrin (MG0). BALB/c nude mice, subcutaneously transplanted with GOT2, were intravenously injected with either 177Lu-octreotate or 111In-MG0, with or without excess of unlabeled human minigastrin simultaneously with 111In-MG0. Animals were sacrificed 1-7 days after injection in the 177Lu-octreotate study and 1 h after injection of 111In-MG0. The activity concentrations in organs and tissues were determined and mean absorbed doses from 177Lu were calculated. There was a specific tumor uptake of either 177Lu-octreotate or 111In-MG0. 177Lu-octreotate samples showed high activity concentrations in tissues expressing somatostatin receptors (SSTR). For both radiopharmaceuticals the highest activity concentrations were found in the kidneys. Compared to results from similar studies in mice with another MTC cell line (TT) the biodistribution was favorable (higher tumor uptake) for the GOT2 model, while compared to other animal models expressing SSTR, the tumor uptake of 177Lu-octreotate was modest. In conclusion, the GOT2 animal model is a valuable model for evaluation and optimization of diagnostic and therapeutic procedures using radiolabeled somatostatin, CCK2 and gastrin analogues prior to clinical studies.
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- Dalmo, Johanna, et al.
(författare)
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Priming increases the anti-tumor effect and therapeutic window of 177Lu-octreotate in nude mice bearing human small intestine neuroendocrine tumor GOT1.
- 2017
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Ingår i: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: 177Lu-[DOTA0, Tyr3]-octreotate (177Lu-octreotate) is used for treatment of patients with somatostatin receptor (SSTR) expressing neuroendocrine tumors. However, complete tumor remission is rarely seen, and optimization of treatment protocols is needed. In vitro studies have shown that irradiation can up-regulate the expression of SSTR1, 2 and 5, and increase 177Lu-octreotate uptake. The aim of the present study was to examine the anti-tumor effect of a 177Lu-octreotate priming dose followed 24 h later by a second injection of 177Lu-octreotate compared to a single administration of 177Lu-octreotate, performed on the human small intestine neuroendocrine tumor cell line, GOT1, transplanted to nude mice. RESULTS: Priming resulted in a 1.9 times higher mean absorbed dose to the tumor tissue per administered activity, together with a reduced mean absorbed dose for kidneys. Priming gave the best overall anti-tumor effects. Magnetic resonance imaging showed no statistically significant difference in tumor response between treatment with and without priming. Gene expression analysis demonstrated effects on cell cycle regulation. Biological processes associated with apoptotic cell death were highly affected in the biodistribution and dosimetry study, via differential regulation of, e.g., APOE, BAX, CDKN1A, and GADD45A. CONCLUSIONS: Priming had the best overall anti-tumor effects and also resulted in an increased therapeutic window. Results indicate that potential biomarkers for tumor regrowth may be found in the p53 or JNK signaling pathways. Priming administration is an interesting optimization strategy for 177Lu-octreotate therapy of neuroendocrine tumors, and further studies should be performed to determine the mechanisms responsible for the reported effects.
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| 10. |
- Spetz, Johan, et al.
(författare)
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Effects of internal irradiation from 177Lu-octreotate on transcriptional expression in GOT1 midgut carcinoid in nude mice
- 2014
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Ingår i: SweRays Workshop, Malmö, Sweden, Aug 20-22.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Neuroendocrine (NE) tumors expressing somatostatin receptors (SSTR) are often treated with 177Lu-octreotate. The treatment is highly successful in animal models, but low cure rates in clinical studies suggests optimization of treatment protocol is needed. Little is known about which cellular responses play a crucial role in neuroendocrine tumors after irradiation. It is therefore important to identify the effects of 177Lu-octreotate on biological functions for future optimization of treatment parameters and the identification of biomarkers predicting treatment response. The aim of this study was to investigate the transcriptional response of GOT1 midgut carcinoid in nude mice following 177Lu-octreotate treatment. Methods: GOT1 bearing BALB/c nude mice were i.v. injected with 15 MBq 177Lu-octreotate and tumor size was measured twice a week using calipers. Animals were killed after 1, 3, 7 or 41 days and tumor samples excised and snap frozen in liquid nitrogen. Total RNA was extracted from tumor samples and subjected to Illumina microarray expression analysis. Differential transcriptional profiles were identified by comparing treated and untreated tumor samples using Nexus Expression 3.0 software. Associated biological functions and biological pathways (according to Gene Ontology terms) were compared using Nexus Expression 3.0 and Ingenuity IPA. Results: The mean tumor volume was clearly reduced after 177Lu-octreotate treatment. Microarray analysis showed clear difference in regulation pattern between the time points. The analysis of associated biological functions revealed clear effect on cell death and survival, and cell cycle after 1, 3, and 7 days, while cellular movement and cellular development were clearly influenced after 41 days. Cellular growth and proliferation was also affected after 1 day but not at the other time points studied. Conclusions: : Analysis of the transcriptional regulation in GOT1 tumors in nude mice following 177Lu-octreotate treatment revealed responses in different cellular functions that were distinct for each time point. These findings indicate potential venues for increasing clinical effectiveness of midgut carcinoid therapy with 177Lu-octreotate.
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