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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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| 2. |
- Heskamp, Sandra, et al.
(författare)
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Imaging of Human Epidermal Growth Factor Receptor Type 2 Expression with (18)F-Labeled Affibody Molecule Z(HER2:2395) in a Mouse Model for Ovarian Cancer
- 2012
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 53:1, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are small (7 kDa) proteins with subnanomolar targeting affinity. Previous SPECT studies in xenografts have shown that the Affibody molecule (111)In-DOTA-Z(HER2:2395) can discriminate between high and low human epidermal growth factor receptor type 2 (HER2)-expressing tumors, indicating that radiolabeled Affibody molecules have potential for patient selection for HER2-targeted therapy. Compared with SPECT, PET with positron-emitting radionuclides, such as (18)F, may improve imaging of HER2 expression because of higher sensitivity and improved quantification of PET. The aim of the present study was to determine whether the (18)F-labeled NOTA-conjugated Affibody molecule Z(HER2:2395) is a suitable agent for imaging of HER2 expression. The tumor-targeting properties of (18)F-labeled Z(HER2:2395) were compared with (111)In- and (68)Ga-labeled Z(HER2:2395) in mice with HER2-expressing SK-OV-3 xenografts. Methods: Z(HER2:2395) was conjugated with NOTA and radiolabeled with (18)F, (68)Ga, and (111)In. Radiolabeling with (18)F was based on the complexation of Al(18)F by NOTA. The 50% inhibitory concentration values for NOTA-Z(HER2:2395) labeled with (19)F, (69)Ga, and (115)In were determined in a competitive cell-binding assay using SK-OV-3 cells. Mice bearing subcutaneous SK-OV-3 xenografts were injected intravenously with radiolabeled NOTA-Z(HER2:2395). One and 4 h after injection, PET/CT or SPECT/CT images were acquired, and the biodistribution was determined by ex vivo measurement. Results: The 50% inhibitory concentration values for (19)F-, (69)Ga-, and (115)In-NOTA-Z(HER2:2395) were 5.0, 6.3, and 5.3 nM, respectively. One hour after injection, tumor uptake was 4.4 +/- 0.8 percentage injected dose per gram (% ID/g), 5.6 +/- 1.6 % ID/g, and 7.1 +/- 1.4 % ID/g for (18)F-, (68)Ga-, and (111)In-NOTA-Z(HER2:2395), respectively, and the respective tumor-to-blood ratios were 7.4 +/- 1.8, 8.0 +/- 1.3, and 4.8 +/- 1.3. Tumor uptake was specific, because uptake could be blocked efficiently by coinjection of an excess of unlabeled Z(HER2:2395). PET/CT and SPECT/CT images clearly visualized HER2-expressing SK-OV-3 xenografts. Conclusion: This study showed that (18)F-NOTA-Z(HER2:2395) is a promising new imaging agent for HER2 expression in tumors. Affibody molecules were successfully labeled with (18)F within 30 min, based on the complexation of Al(18)F by NOTA. Further research is needed to determine whether this technique can be used for patient selection for HER2-targeted therapy.
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