| 1. |
- Andersson, Ken G., et al.
(författare)
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Feasibility of imaging of epidermal growth factor receptor expression with ZEGFR:2377 affibody molecule labeled with Tc-99m using a peptide-based cysteine-containing chelator
- 2016
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Ingår i: International Journal of Oncology. - : SPANDIDOS. - 1019-6439 .- 1791-2423. ; 49:6, s. 2285-2293
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Tidskriftsartikel (refereegranskat)abstract
- The epidermal growth factor receptor (EGFR) is overexpressed in a number of malignant tumors and is a molecular target for several specific anticancer antibodies and tyrosine kinase inhibitors. The overexpression of EGFR is a predictive biomarker for response to several therapy regimens. Radionuclide molecular imaging might enable detection of EGFR overexpression by a non-invasive procedure and could be used repeatedly. Affibody molecules are engineered scaffold proteins, which could be selected to have a high affinity and selectivity to predetermined targets. The anti-EGFR ZEGFR:2377 affibody molecule is a potential imaging probe for EGFR detection. The use of the generator-produced radionuclide Tc-99m should facilitate clinical translation of an imaging probe due to its low price, availability and favorable dosimetry of the radionuclide. In the present study, we evaluated feasibility of ZEGFR:2377 labeling with Tc-99m using a peptide-based cysteine-containing chelator expressed at the C-terminus of ZEGFR:2377. The label was stable in vitro under cysteine challenge. In addition, Tc-99m-ZEGFR:2377 was capable of specific binding to EGFR-expressing cells with high affinity (274 pM). Studies in BALB/C nu/nu mice bearing A431 xenografts demonstrated that Tc-99m-ZEGFR:2377 accumulates in tumors in an EGFR-specific manner. The tumor uptake values were 3.6 1 and 2.5 0.4% ID/g at 3 and 24 h after injection, respectively. The corresponding tumor-to-blood ratios were 1.8 0.4 and 8 3. The xenografts were clearly visualized at both time-points. This study demonstrated the potential of Tc-99m-labeled ZEGFR:2377 for imaging of EGFR in vivo.
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| 2. |
- Garousi, Javad, et al.
(författare)
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Comparative Evaluation of Affibody Molecules for Radionuclide Imaging of in Vivo Expression of Carbonic Anhydrase IX
- 2016
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 13:11, s. 3676-3687
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Tidskriftsartikel (refereegranskat)abstract
- Overexpression of the enzyme carbonic anhydrase IX (CAIX) is documented for chronically hypoxic malignant tumors as well as for normoxic renal cell carcinoma. Radionuclide molecular imaging of CAIX would be useful for detection of hypoxic areas in malignant tumors, for patients' stratification for CAIX-targeted therapies, and for discrimination of primary malignant and benign renal tumors. Earlier, we have reported feasibility of in vivo radionuclide based imaging of CAIX expressing tumors using Affibody molecules, small affinity proteins based on a non-immunoglobulin scaffold. In this study, we compared imaging properties of several anti-CAIX Affibody molecules having identical scaffold parts and competing for the same epitope on CAIX, but having different binding paratopes. Four variants were labeled using residualizing Tc-99m and nonresidualizing I-125 labels. All radiolabeled variants demonstrated high affinity detection of CAIX-expressing cell line SK-RC-52 in vitro and specific accumulation in SK-RC-52 xenografts in vivo. I-125-labeled conjugates demonstrated much lower radioactivity uptake in kidneys but higher radioactivity concentration in blood compared with Tc-99m-labeled counterparts. Although all variants cleared rapidly from blood and nonspecific compartments, there was noticeable difference in their biodistribution. The best variant for imaging of expression of CAIX in disseminated cancer was Tc-99m-(HE)(3)-ZCAIX:2 providing tumor uptake of 16.3 +/- 0.9% ID/g and tumor-to-blood ratio of 44 +/- 7 at 4 h after injection. For primary renal cell carcinoma, the most promising imaging candidate was I-125-ZCAIX:4 providing tumor-kidney ratio of 2.1 0.5. In conclusion, several clones of scaffold proteins should be evaluated to select the best variant for development of an imaging probe with optimal sensitivity for the intended application.
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| 5. |
- Garousi, Javad, et al.
(författare)
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Influence of the N -Terminal Composition on Targeting Properties of Radiometal-Labeled Anti-HER2 Scaffold Protein ADAPT6
- 2016
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 27:11, s. 2678-2688
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Tidskriftsartikel (refereegranskat)abstract
- Radionuclide-imaging-based stratification of patients to targeted therapies makes cancer treatment more personalized and therefore more efficient. Albumin-binding domain derived affinity proteins (ADAPTs) constitute a novel group of imaging probes based on the scaffold of an albumin binding domain (ABD). To evaluate how different compositions of the N-terminal sequence of ADAPTS influence their biodistribution, a series of human epidermal growth factor receptor type 2 (HER2)-binding ADAPT6 derivatives with different N-terminal sequences were created: GCH(6)DANS (2), GC(HE)(3)DANS (3), GCDEAVDANS (4), and GCVD.ANS(5). These were compared with the parental variant: GCSS(HE)(3)DEAVDANS (1). All variants were site-specifically conjugated with a maleimido-derivative of a DOTA chelator and labeled with In-III. Binding to HER2-expressing cells in vitro, in vivo biodistribution as well as targeting properties of the new variants were compared with properties of the In-III-labeled parental ADAPT variant 1 (In-III-DOTA-1). The composition of the N-terminal sequence had an apparent influence on biodistribution of ADAPT6 in mice. The use of a hexahistidine tag in (InD)-In-III-OTA-2 was associated with elevated hepatic uptake compared to the (HE)(3)-containing counterpart, In-III-DOTA-3. All new variants without a hexahistidine tag demonstrated lower uptake in blood, lung, spleen, and muscle compared to uptake in the parental variant. The best new variants, In-III-DOTA-3 and In-III-DOTA-5, provided tumor uptakes of 14.6 +/- 2.4 and 12.5 +/- 1.3% ID/g at 4 h after injection, respectively. The tumor uptake of In-III-DOTA-3 was significantly higher than the uptake of the parental In-III-DOTA-1 (9.1 +/- 2.0% ID/g). The tumor-to-blood ratios of 395 +/- 75 and 419 +/- 91 at 4 h after injection were obtained for In-III-DOTA-5 and (IIII)n-DOTA-3, respectively. In conclusion, the N-terminal sequence composition affects the biodistribution and targeting properties of ADAPT-based imaging probes, and its optimization may improve imaging contrast.
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| 6. |
- Garousi, Javad, et al.
(författare)
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PET imaging of epidermal growth factor receptor expression in tumours using Zr-89-labelled ZEGFR:2377 affibody molecules
- 2016
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Ingår i: International Journal of Oncology. - : Spandidos. - 1019-6439 .- 1791-2423. ; 48:4, s. 1325-1332
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Tidskriftsartikel (refereegranskat)abstract
- Epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor, which is overexpressed in many types of cancer. The use of EGFR-targeting monoclonal antibodies and tyrosine-kinase inhibitors improves significantly survival of patients with colorectal, non-small cell lung cancer and head and neck squamous cell carcinoma. Detection of EGFR overexpression provides important prognostic and predictive information influencing management of the patients. The use of radionuclide molecular imaging would enable non-invasive repeatable determination of EGFR expression in disseminated cancer. Moreover, positron emission tomography (PET) would provide superior sensitivity and quantitation accuracy in EGFR expression imaging. Affibody molecules are a new type of imaging probes, providing high contrast in molecular imaging. In the present study, an EGFR-binding affibody molecule (ZEGFR:2377) was site-specifically conjugated with a deferoxamine (DFO) chelator and labelled under mild conditions (room temperature and neutral pH) with a radionuclide Zr-89. The Zr-89-DFO-ZEGFR:2377 tracer demonstrated specific high affinity (160 +/- 60 pM) binding to EGFR-expressing A431 epidermoid carcinoma cell line. In mice bearing A431 xenografts, Zr-89-DFO-ZEGFR: 2377 demonstrated specific uptake in tumours and EGFR-expressing tissues. The tracer provided tumour uptake of 2.6 +/- 0.5% ID/g and tumour-to-blood ratio of 3.7 +/- 0.6 at 24 h after injection. Zr-89-DFO-ZEGFR: 2377 provides higher tumour-to-organ ratios than anti-EGFR antibody Zr-89-DFO-cetuximab at 48 h after injection. EGFR-expressing tumours were clearly visualized by microPET using Zr-89-DFO-ZEGFR: 2377 at both 3 and 24 h after injection. In conclusion, Zr-89-DFO-ZEGFR: 2377 is a potential probe for PET imaging of EGFR-expression in vivo.
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| 7. |
- Lindbo, Sarah, et al.
(författare)
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Influence of Histidine-Containing Tags on the Biodistribution of ADAPT Scaffold Proteins.
- 2016
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 27:3, s. 716-726
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Tidskriftsartikel (refereegranskat)abstract
- Engineered scaffold proteins (ESP) are high-affinity binders that can be used as probes for radionuclide imaging. Histidine-containing tags enable both efficient purification of ESP and radiolabeling with (99m)Tc(CO)3. Earlier studies demonstrated that the use of a histidine-glutamate-histidine-glutamate-histidine-glutamate (HE)3-tag instead of the commonly used hexahistidine (H6)-tag reduces hepatic uptake of radiolabeled ESP and short peptides. Here, we investigated the influence of histidine-containing tags on the biodistribution of a novel type of ESP, ADAPTs. A series of anti-HER2 ADAPT probes having H6- or (HE)3-tags in the N-termini were prepared. The constructs, (HE)3-ADAPT6 and H6-ADAPT6, were labeled with two different nuclides, (99m)Tc or (111)In. The labeling with (99m)Tc(CO)3 utilized the histidine-containing tags, while (111)In was attached through a maleimido derivative of DOTA conjugated to the N-terminus. For (111)In-labeled ADAPTs, the use of (HE)3 provided a significantly (p < 0.05) lower hepatic uptake at 1 h after injection, but there was no significant difference in hepatic uptake of (111)In-(HE)3-ADAPT6 and H6-ADAPT6 at later time points. Interestingly, in the case of (99m)Tc, (99m)Tc(CO)3-H6-ADAPT6 provided significantly (p < 0.05) lower uptake in a number of normal tissues and was more suitable as an imaging probe. Thus, the influence of histidine-containing tags on the biodistribution of the novel ADAPT scaffold proteins was different compared to its influence on other ESPs studied so far. Apparently, the effect of a histidine-containing tag on the biodistribution is highly dependent on the scaffold composition of the ESP.
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