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- Tolmachev, Vladimir, et al.
(author)
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Molecular design of radiocopper-labelled Affibody molecules
- 2018
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Journal article (peer-reviewed)abstract
- Cu-CB-TE2A-GEEE-ZHER2:342 was 16 ± 6%ID/g and tumor-to-blood ratio was 181 ± 52. In conclusion, a combination of the cross-bridged CB-TE2A chelator and Gly-Glu-Glu-Glu spacer is preferable for radiocopper labelling of Affibody molecules and, possibly, other scaffold proteins having high renal re-absorption.
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- Garousi, Javad, et al.
(author)
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Comparative evaluation of affibody- and antibody fragments-based CAIX imaging probes in mice bearing renal cell carcinoma xenografts
- 2019
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In: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- Carbonic anhydrase IX (CAIX) is a cancer-associated molecular target for several classes of therapeutics. CAIX is overexpressed in a large fraction of renal cell carcinomas (RCC). Radionuclide molecular imaging of CAIX-expression might offer a non-invasive methodology for stratification of patients with disseminated RCC for CAIX-targeting therapeutics. Radiolabeled monoclonal antibodies and their fragments are actively investigated for imaging of CAIX expression. Promising alternatives are small non-immunoglobulin scaffold proteins, such as affibody molecules. A CAIX-targeting affibody ZCAIX:2 was re-designed with the aim to decrease off-target interactions and increase imaging contrast. The new tracer, DOTA-HE3-ZCAIX:2, was labeled with In-111 and characterized in vitro. Tumor-targeting properties of [In-111]In-DOTA-HE3-ZCAIX:2 were compared head-to-head with properties of the parental variant, [(99)mTc]Tc(CO)(3)-HE3-ZCAIX:2, and the most promising antibody fragment-based tracer, [In-111]In-DTPA-G250(Fab')(2), in the same batch of nude mice bearing CAIX-expressing RCC xenografts. Compared to the (99)mTc-labeled parental variant, [In-111]In-DOTA-HE3-ZCAIX:2 provides significantly higher tumor-to-lung, tumor-to-bone and tumor-to-liver ratios, which is essential for imaging of CAIX expression in the major metastatic sites of RCC. [In-111]In-DOTA-HE3-ZCAIX:2 offers significantly higher tumor-to-organ ratios compared with [In-111]In-G250(Fab']2. In conclusion, [In-111]In-DOTA-HE3-ZCAIX:2 can be considered as a highly promising tracer for imaging of CAIX expression in RCC metastases based on our results and literature data.
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- Huizing, Fokko J., et al.
(author)
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CAIX-targeting radiotracers for hypoxia imaging in head and neck cancer models
- 2019
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- Hypoxia-induced carbonic anhydrase IX (CAIX) expression is a prognostic marker in solid tumors. In recent years many radiotracers have been developed, but a fair comparison of these compounds is not possible because of the diversity in tumor models and other experimental parameters. In this study we performed a direct in vivo comparison of three promising CAIX targeting radiotracers in xenografted head and neck cancer models. The biodistribution of [In-111]In-DOTA-ZCAIX:2 was directly compared with [In-111]In-DTPA-G250-F(ab')(2) and [In-111] In-DTPA-G250 in female BALB/C nu/nu mice bearing two HNSCC xenografts with different levels of CAIX expression. In vivo biodistribution was quantified by means of microSPECT/CT scans and ex vivo biodistribution was determined with the use of gamma-counter. Tumors were snap frozen and sections were stained for CAIX expression, vessels, hypoxia (pimonidazole) and tumor blood perfusion. Tracer uptake was significantly higher in SSCNij153 tumors compared to SCCNij185 tumors for [In-111]In-DOTA-HE3-ZCAIX:2: 0.32 +/- 0.03 versus 0.18 +/- 0.01%ID/g,(p = 0.003) 4 h p.i., for [In-111]In-DTPA-girentuximab-F(ab')(2): 3.0 +/- 0.5%ID/g and 1.2 +/- 0.1%ID/g (p = 0.03), 24 h p.i. and for [In-111]In-DTPA-girentuximab: 30 +/- 2.1%ID/g and 7.0 +/- 1.0%ID/g (p = 0.0002) 72 h p.i. SPECT imaging with both [In-111]In-DTPA-girentuximab-F(ab') 2 and [111In]In-DTPA-girentuximab showed a clear difference in tracer distribution between the two tumor models. The whole IgG, i.e. [In-111]In-DTPA-girentuximab, showed the highest tumor-to-muscle ratio. We showed that different CAIX-targeting radiotracers can discriminate a low CAIX-expressing tumor from a high CAIX-expressing head and neck cancer xenografts model. In these hypoxic head and neck xenograft models [In-111]In-DTPA-girentuximab showed the most promising results.
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- Lindbo, Sarah, et al.
(author)
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Influence of Histidine-Containing Tags on Biodistribution of Radiolabelled ADAPT-Based Imaging Probes
- 2015
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In: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer. - 1619-7070 .- 1619-7089. ; 42, s. S100-S100
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Journal article (peer-reviewed)abstract
- Aim. ADAPTs are a class of small ( ∼ 5 kDa) robust scaffold proteins suitable as probes for radionuclide molecular imaging in vivo. The attachment of a histidine-containing tags to the scaffold proteins allows efficient purification by immobilized metal ion affinity chromatography (IMAC) and permits labelling with 99mTc(CO)3. Earlier, we have demonstrated that replacement of the hexahistidine (H6)-tag with the negatively charged histidine-glutamate-histidine-glutamate-histidine-glutamate (HE3)-tag reduces hepatic uptake of radiolabelled affibody molecules. The same effect has been confirmed for other scaffold proteins, DARPins, and short peptides. The aim of this study was to evaluate effect of histidine-containing tag composition on biodistribution of ADAPTs. Material and methods. A series of anti-HER2 ADAPT6 probes having DEAVDANS lead sequence and H6- or HE3-tags at N-termini has been prepared. In two variants, maleimido derivative of DOTA was conjugated to a unique cysteine was incorporated at N-terminus. DOTA-C-HE3-ADAPT6 and DOTA-C-H6-ADAPT6 were labelled with 111In. HE3-ADAPT6 and H6-ADAPT6 were labelled with 99mTc(CO)3using IsoLink kit. Binding specificity, affinity, and cellular processing of new conjugates was evaluated using HER2-expressing SKOV-3 ovarian carcinoma cells. Biodistribution at 1,4 and 24 h p.i. was evaluated in normal NMRI mice. Tumour-targeting properties of the best 99mTc(CO) 3-labelled variant, 99mTc(CO)3-H6-ADAPT6 were evaluated in BALB/C nu/nu mice bearing SKOV-3 xenografts. Results. All radiolabeled ADAPTs demonstrated specific binding to SKOV-3 cells with affinities in the range of 1.1-2.8 nM. The internalization by SKOV-3 cells was slow. In vivo, all conjugates cleared rapidly from blood via kidneys with subsequent renal re-absorption. The hepatic uptake of 111In-DOTA-C-H6-ADAPT6 was slightly but significantly (p<0.05) higher that the uptake of 111In-DOTA-C-HE3-ADAPT6 at 1 h pi, but biodistribution was very similar at later time points. Surprisingly, the uptake of 99mTc(CO)3-HE3-ADAPT6 was significantly (p<0.05) higher than uptake of 99mTc(CO)3-H6-ADAPT6 in liver, blood, and bone at 1h p.i. At 4 h p.i., hepatic uptakes were equal, but 99mTc(CO)3-H6-ADAPT6 provided lower uptake in blood and bone. 99mTc(CO)3-H6-ADAPT6 demonstrated high (19? 3 %ID/g at 4 h p.i.) and specific tumour uptake. Tumour-to-blood and tumour-to-liver ratios were 102? 29 and 12? 3, respectively. Conclusion. Influence of histidine-containing tag on biodistribution of scaffold proteins depends on composition of a scaffold protein and might differ appreciably. This should be take into account in molecular design of imaging probes based on engineered scaffold proteins
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- Summer, D, et al.
(author)
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PP15 89Zr-Siderophore-Affibody conjugates for imaging EGFR expression
- 2018
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In: EJNMMI Research. - : Springer Science and Business Media LLC. - 2191-219X. ; 8:S1
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Journal article (other academic/artistic)abstract
- Aim: Zirconium-89 has gained great interest for PET, when imaging at late time points is required. Desferrioxamine B (DFO), is mostly used for this radionuclide as bifunctional chelator (BFC) and we recently reported on fusarinine C (FSC) with similar zirconium-89 complexing properties but potentially higher stability related to its cyclic structure. This study reports on the comparison of FSC and DFO as BFCs for 89Zr labelling of the affibody ZEGFR:2377 targeting Epidermal Growth Factor Receptors (EGFR).Methods: FSC-ZEGFR:2377 and DFO-ZEGFR:2377 were evaluated regarding labeling, in vitro stability, specificity, cell uptake, receptor affinity, biodistribution and microPET-CT imaging.Results: Both conjugates showed increased labelling yields at elevated temperature (85°C). Both conjugates revealed remarkable specificity, affinity and slow cell-line dependent internalisation. Labeling at 85°C showed comparable results in A431 tumor xenografted mice with minor differences regarding blood clearance, tumor and liver uptake but clear improvement as compared to 89Zr-DFO-ZEGFR:2377, labeled at room temperature, which was confirmed by MicroPET-CT imaging.Conclusion: We were able to show that FSC is a suitable alternative to DFO for labeling of biomolecules with zirconium-89. Furthermore our findings indicate that 89Zr- labeling of DFO conjugates at higher temperature reduces off-chelate binding leading to significantly improved tumor-to-organ ratios and therefore enhancing image contrast.
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