| 1. |
- Horikoshi, Momoko, et al.
(author)
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New loci associated with birth weight identify genetic links between intrauterine growth and adult height and metabolism.
- 2013
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:1
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Journal article (peer-reviewed)abstract
- Birth weight within the normal range is associated with a variety of adult-onset diseases, but the mechanisms behind these associations are poorly understood. Previous genome-wide association studies of birth weight identified a variant in the ADCY5 gene associated both with birth weight and type 2 diabetes and a second variant, near CCNL1, with no obvious link to adult traits. In an expanded genome-wide association meta-analysis and follow-up study of birth weight (of up to 69,308 individuals of European descent from 43 studies), we have now extended the number of loci associated at genome-wide significance to 7, accounting for a similar proportion of variance as maternal smoking. Five of the loci are known to be associated with other phenotypes: ADCY5 and CDKAL1 with type 2 diabetes, ADRB1 with adult blood pressure and HMGA2 and LCORL with adult height. Our findings highlight genetic links between fetal growth and postnatal growth and metabolism.
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| 2. |
- Bonvicini, Gillian, et al.
(author)
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ImmunoPET imaging of amyloid-beta in a rat model of Alzheimer's disease with a bispecific, brain-penetrating fusion protein
- 2022
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In: Translational Neurodegeneration. - : BioMed Central (BMC). - 2047-9158. ; 11
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Journal article (peer-reviewed)abstract
- Background: Hijacking the transferrin receptor (TfR) is an effective strategy to transport amyloid-beta (A beta) immuno-positron emission tomography (immunoPET) ligands across the blood-brain barrier (BBB). Such ligands are more sensitive and specific than small-molecule ligands at detecting A beta pathology in mouse models of Alzheimer's disease (AD). This study aimed to determine if this strategy would be as sensitive in rats and to assess how TfR affinity affects BBB transport of bispecific immunoPET radioligands.Methods: Two affinity variants of the rat TfR antibody, OX26, were chemically conjugated to a F(ab')(2) fragment of the anti-A beta antibody, bapineuzumab (Bapi), to generate two bispecific fusion proteins: OX26(5)-F(ab')(2)-Bapi and OX26(76)-F(ab')(2)-Bapi. Pharmacokinetic analyses were performed 4 h and 70 h post-injection of radioiodinated fusion proteins in wild-type (WT) rats. [I-124]I-OX26(5)-F(ab')(2)-Bapi was administered to TgF344-AD and WT rats for in vivo PET imaging. Ex vivo distribution of injected [I-124]I-OX26(5)-F(ab')(2)-Bapi and A beta pathology were assessed.Results: More [I-125]I-OX26(5)-F(ab')(2)-Bapi was taken up into the brain 4 h post-administration than [I-124]I-OX26(76)-F(ab')(2)-Bapi. [I-124]I-OX26(5)-F(ab')(2)-Bapi PET visualized A beta pathology with significantly higher signals in the TgF344-AD rats than in the WT littermates without A beta pathology. The PET signals significantly correlated with A beta levels in AD animals.Conclusion: Affinity to TfR affects how efficiently a TfR-targeting bispecific fusion protein will cross the BBB, such that the higher-affinity bispecific fusion protein crossed the BBB more efficiently. Furthermore, bispecific immunoPET imaging of brain A beta pathology using TfR-mediated transport provides good imaging contrast between TgF344-AD and WT rats, suggesting that this immunoPET strategy has the potential to be translated to higher species.
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| 3. |
- Gustavsson, Tobias, et al.
(author)
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Long-term effects of immunotherapy with a brain penetrating Aβ antibody in a mouse model of Alzheimer's disease
- 2023
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In: Alzheimer's Research & Therapy. - : BioMed Central (BMC). - 1758-9193. ; 15:1
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Journal article (peer-reviewed)abstract
- BackgroundBrain-directed immunotherapy is a promising strategy to target amyloid-β (Aβ) deposits in Alzheimer’s disease (AD). In the present study, we compared the therapeutic efficacy of the Aβ protofibril targeting antibody RmAb158 with its bispecific variant RmAb158-scFv8D3, which enters the brain by transferrin receptor-mediated transcytosis.MethodsAppNL−G−F knock-in mice received RmAb158, RmAb158-scFv8D3, or PBS in three treatment regimens. First, to assess the acute therapeutic effect, a single antibody dose was given to 5 months old AppNL−G−F mice, with evaluation after 3 days. Second, to assess the antibodies’ ability to halt the progression of Aβ pathology, 3 months old AppNL−G−F mice received three doses during a week, with evaluation after 2 months. Reduction of RmAb158-scFv8D3 immunogenicity was explored by introducing mutations in the antibody or by depletion of CD4+ T cells. Third, to study the effects of chronic treatment, 7-month-old AppNL−G−F mice were CD4+ T cell depleted and treated with weekly antibody injections for 8 weeks, including a final diagnostic dose of [125I]RmAb158-scFv8D3, to determine its brain uptake ex vivo. Soluble Aβ aggregates and total Aβ42 were quantified with ELISA and immunostaining.ResultsNeither RmAb158-scFv8D3 nor RmAb158 reduced soluble Aβ protofibrils or insoluble Aβ1-42 after a single injection treatment. After three successive injections, Aβ1-42 was reduced in mice treated with RmAb158, with a similar trend in RmAb158-scFv8D3-treated mice. Bispecific antibody immunogenicity was somewhat reduced by directed mutations, but CD4+ T cell depletion was used for long-term therapy. CD4+ T cell-depleted mice, chronically treated with RmAb158-scFv8D3, showed a dose-dependent increase in blood concentration of the diagnostic [125I]RmAb158-scFv8D3, while concentration was low in plasma and brain. Chronic treatment did not affect soluble Aβ aggregates, but a reduction in total Aβ42 was seen in the cortex of mice treated with both antibodies.ConclusionsBoth RmAb158 and its bispecific variant RmAb158-scFv8D3 achieved positive effects of long-term treatment. Despite its ability to efficiently enter the brain, the benefit of using the bispecific antibody in chronic treatment was limited by its reduced plasma exposure, which may be a result of interactions with TfR or the immune system. Future research will focus in new antibody formats to further improve Aβ immunotherapy.
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| 4. |
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| 5. |
- Andersson, Ken G., et al.
(author)
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Autotransporter-mediated display of a naïve Affibody library on the outer membrane of E. coli
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Other publication (other academic/artistic)abstract
- Development of new affinity proteins using combinatorial protein engineering is today established for generation of monoclonal antibodies and also essential for discovery of binders that are based on non-immunoglobulin proteins. Phage display is the most frequently used method, but yeast display is becoming increasingly popular, partly due to the option of utilizing fluorescence-activated cell sorting (FACS) for isolation of new candidates. Escherichia coli have several properties that are valuable for library applications and then in particular the high transformation efficiency. Although the first studies on display of recombinant peptides and proteins on E. coli were reported over 25 years ago, the method is still not fully established for directed evolution of affinity proteins. More recently, the use of various autotransporters and intimins for secretion and anchoring on the outer membrane have shown promising results and in particular for directed evolution of different enzymes. Here, we report on display of a large naïve Affibody library on the outer membrane of E. coli using the autotransporter AIDA-I. The expression cassette was first engineered by removing non-essential sequences, followed by introduction of an Affibody library, comprising more than 109 variants, into the new display vector. Selections by FACS against five different target molecules resulted in a panel of binders with down to nanomolar affinities.
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| 6. |
- Andersson, Ken G., et al.
(author)
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Autotransporter-Mediated Display of a Naive Affibody Library on the Outer Membrane of Escherichia coli
- 2019
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In: Biotechnology Journal. - : WILEY-V C H VERLAG GMBH. - 1860-6768 .- 1860-7314. ; 14:4
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Journal article (peer-reviewed)abstract
- Development of new affinity proteins using combinatorial protein engineering is today established for generation of monoclonal antibodies and also essential for discovery of binders that are based on non-immunoglobulin proteins. Phage display is most frequently used, but yeast display is becoming increasingly popular, partly due to the option of utilizing fluorescence-activated cell sorting (FACS) for isolation of new candidates. Escherichia coli has several valuable properties for library applications and in particular the high transformation efficiency. The use of various autotransporters and intimins for secretion and anchoring on the outer membrane have shown promising results and particularly for directed evolution of different enzymes. Here, the authors report on display of a large naive affibody library on the outer membrane of E. coli using the autotransporter Adhesin Involved in Diffuse Adherence (AIDA-I). The expression cassette is first engineered by removing non-essential sequences, followed by introduction of an affibody library, comprising more than 10(9) variants, into the new display vector. The quality of the library and general performance of the method is assessed by FACS against five different targets, which resulted in a panel of binders with down to nanomolar affinities, suggesting that the method has potential as a complement to phage display for generation of affibody molecules.
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| 7. |
- Andersson, Ken G., 1987-
(author)
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Combinatorial Protein Engineering Of Affibody Molecules Using E. Coli Display And Rational Design Of Affibody-Based Tracers For Medical Imaging
- 2017
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Doctoral thesis (other academic/artistic)abstract
- Directed evolution is today an established strategy for generation of new affinity proteins. This thesis describes the development of a cell-display method using Escherichia coli for directed evolution of Affibody molecules. Further, the thesis describes rational design of Affibody-based tracers, intended for future patient stratification using medical imaging. Fusing recombinant proteins to various autotransporters is a promising approach for efficient surface display on the surface of E. coli, as well as for construction of high-complexity libraries. In paper I, we successfully engineered an expression vector for display of Affibody molecules using the autotransporter AIDA-I. In paper II, a large Affibody library of 2.3x109 variants was constructed and screening using FACS resulted in new specific binders in the nanomolar range. In paper III, we demonstrated Sortase-mediated secretion and conjugation of binders directly from the E. coli surface. The three following studies describe rational design of Affibody-based tracers against two cancer-associated targets for molecular imaging. First, anti-HER3 Affibody molecules were labelled with 111In, and SPECT imaging showed that the conjugates specifically targeted HER3-expressing xenografts. Furthermore, labeling with 68Ga for PET imaging showed that tumor uptake correlated with HER3 expression, suggesting that the tracers have potential for patient stratification. The last study describes the development and investigation of anti-EGFR Affibody-based imaging agents. Labeled with 89Zr, the Affibody tracer demonstrated higher tumor uptake at 3 h post injection than the anti-EGFR antibody cetuximab at 48 h post injection. In conclusion, this thesis describes new tools and knowledge that will hopefully contribute to the development of affinity proteins for biotechnology, therapy and medical imaging in the future.
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| 8. |
- Andersson, Ken G, et al.
(author)
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Comparative evaluation of 111In-labeled NOTA‑conjugated affibody molecules for visualization of HER3 expression in malignant tumors
- 2015
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In: Oncology Reports. - : Spandidos Publications. - 1021-335X .- 1791-2431. ; 34:2, s. 1042-8
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Journal article (peer-reviewed)abstract
- Expression of human epidermal growth factor receptor type 3 (HER3) in malignant tumors has been associated with resistance to a variety of anticancer therapies. Several anti-HER3 monoclonal antibodies are currently under pre-clinical and clinical development aiming to overcome HER3-mediated resistance. Radionuclide molecular imaging of HER3 expression may improve treatment by allowing the selection of suitable patients for HER3-targeted therapy. Affibody molecules are a class of small (7kDa) high-affinity targeting proteins with appreciable potential as molecular imaging probes. In a recent study, we selected affibody molecules with affinity to HER3 at a low picomolar range. The aim of the present study was to develop an anti-HER3 affibody molecule suitable for labeling with radiometals. The HEHEHE-Z08698-NOTA and HEHEHE-Z08699-NOTA HER3-specific affibody molecules were labeled with indium‑111 (111In) and assessed invitro and invivo for imaging properties using single photon emission computed tomography (SPECT). Labeling of HEHEHE-Z08698-NOTA and HEHEHE-Z08699-NOTA with 111In provided stable conjugates. Invitro cell tests demonstrated specific binding of the two conjugates to HER3-expressing BT‑474 breast carcinoma cells. In mice bearing BT‑474 xenografts, the tumor uptake of the two conjugates was receptor‑specific. Direct invivo comparison of 111In-HEHEHE-Z08698-NOTA and 111In-HEHEHE-Z08699‑NOTA demonstrated that the two conjugates provided equal radioactivity uptake in tumors, although the tumor-to-blood ratio was improved for 111In-HEHEHE-Z08698-NOTA [12±3 vs. 8±1, 4h post injection (p.i.)] due to more efficient blood clearance. 111In-HEHEHE-Z08698-NOTA is a promising candidate for imaging of HER3-expression in malignant tumors using SPECT. Results of the present study indicate that this conjugate could be used for patient stratification for anti-HER3 therapy.
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| 9. |
- Andersson, Ken G., et al.
(author)
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Coupled release and site-specific conjugation of Affibody molecules from the surface of E. coli using Sortase A
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Other publication (other academic/artistic)abstract
- Combinatorial protein engineering using libraries displayed on various microorganisms is a powerful method forgeneration of new affinity proteins. Successful efforts often result in broad panels of isolated binders, which are thentypically subcloned, produced, purified and characterized in various assays. Many such assays also require conjugation tofor example reporters or other functional molecules and the downstream production and modification thus tends to be verylaborious and limits the number of candidates that can be screened. Staphylococcal sortase A is a natural transpeptidasethat catalyzes the ligation between a LPXTG motif and N-terminal glycines and is today used in a variety of applicationsfor site-specific conjugation of different molecules to recombinant proteins. We have previously developed a surfacedisplay method for combinatorial protein engineering of Affibody molecules on the outer membrane of E. coli usingautodisplay. Here, we introduced a sortase-A recognition motif into the displayed recombinant proteins and evaluatedsortase-mediated release and specific conjugation of various reporters to Affibody molecules. The approach has potentialto significantly increase the flexibility and throughput of downstream characterization of affinity proteins after directedevolution using cell display and FACS.
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| 10. |
- Andersson, Ken G., et al.
(author)
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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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In: International Journal of Oncology. - : SPANDIDOS. - 1019-6439 .- 1791-2423. ; 49:6, s. 2285-2293
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Journal article (peer-reviewed)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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| 11. |
- Bonvicini, Gillian, et al.
(author)
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Comparing in vitro affinity measurements of antibodies to TfR1 : Surface plasmon resonance versus on-cell affinity
- 2024
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In: Analytical Biochemistry. - : Elsevier. - 0003-2697 .- 1096-0309. ; 686
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Journal article (peer-reviewed)abstract
- Despite years of utilizing the transferrin receptor 1 (TfR1) to transport large biomolecules into the brain, there is no consensus on how to optimally measure affinity to it. The aim of this study was to compare different methods for measuring the affinities of anti-TfR1 antibodies.Antibodies 15G11, OX26 and 8D3 are known to successfully carry large biologics across the blood-brain barrier in humans, rats, and mice, respectively. The affinity to their respective species of TfR1 was measured with different surface plasmon resonance setups in Biacore and an on-cell assay.When the antibody was captured and TfR1 was the analyte, the dissociation in Biacore was very slow. The dissociation was faster when the antibody was the analyte and TfR1 was the ligand. The Biacore setup with capture of N-terminal FLAG-tag TfR1 yielded the most similar apparent affinities as the cell assay.In conclusion, it is important to evaluate assay parameters including assay orientation, surface capture method, and antibody format when comparing binding kinetics for TfR1 antibodies. Although it seems possible to determine relative affinities of TfR1 antibodies using the methods described here, both the FLAG-tag TfR1 capture setup and cell assays likely yield apparent affinities that are most translatable in vivo.
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| 12. |
- Bonvicini, Gillian, et al.
(author)
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Evaluation of valency effects on TfR-mediated brain delivery in vivo
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Other publication (other academic/artistic)abstract
- Monovalent binding to the transferrin receptor (TfR) is assumed to be the most efficient binding mode for avoiding lysosomal degradation of the protein constructs that utilise TfR-mediated transcytosis to cross the blood-brain barrier. However, past studies evaluating the effects of valency to TfR on brain uptake generally had shortcomings in the protein design. This led to protein constructs that differed in valency but also in affinity and/or protein size. Therefore, the aim here was to evaluate the effect of valency on TfR-mediated brain delivery.Affinity variants of antibody 8D3 were produced by introducing alanine point mutations into the complementarity-determining regions. Eleven Fab fragments and 29 IgGs were screened for affinity against murine TfR. Six of each were chosen to be produced with a knob-in-hole design to have monovalent and bivalent TfR binders in full-length antibody format. These 12 antibodies were tested in a cell assay and 2 pairs of monovalent and bivalent antibodies were determined based on the apparent affinity. The stronger apparent affinity pair was radiolabelled with iodine-125 and injected into WT mice at a tracer dose. The biodistribution was measured in brain, blood and peripheral organs at 4 h post-injection.The antibodies from the stronger apparent affinity pair had similar blood pharmacokinetics and peripheral distribution suggesting that the apparent affinities were indeed similar. The monovalent antibody had significantly higher brain uptake than the bivalent antibody; supporting that monovalent binding yields better brain delivery than bivalent binding to TfR. It further suggests that the effect of valency on brain delivery is apparent affinity independent.
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| 13. |
- Bonvicini, Gillian, et al.
(author)
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Stronger affinity to Transferrin receptor enhances detection of amyloid-β pathology with bispecific antibody radioligands at a tracer dose
-
Other publication (other academic/artistic)abstract
- A popular method for delivering biologic therapeutics and diagnostics to the brain is by hijacking transferrin receptor (TfR)-mediated transcytosis. Moderate affinity towards TfR is beneficial for TfR-mediated brain delivery at therapeutic doses while a few studies have indicated that high TfR affinity may be more beneficial at tracer doses. With the development of antibody-based PET radioligands for neurodegenerative diseases, such as Alzheimer’s disease, a better understanding of the pharmacokinetics of TfR-binders at tracer dose is essential. Thus the aim of this study was to evaluate the effect of TfR affinity on brain uptake at a tracer dose in both wild-type (WT) mice and in a mouse model of Aβ pathology.Three different affinity variants of 8D3, produced by alanine point mutations, were selected. Bispecific antibodies were designed with knob-into-hole technology where one arm was the anti-mouse TfR antibody, 8D3, and the other arm was the anti-human Aβ antibody, bapineuzumab (Bapi). Antibody affinities were measured in an in vitro cell assay. In vivo pharmacokinetic analyses of radioiodinated bispecific antibodies and Bapi in brain, blood and peripheral organs were performed over 7 days post-injection in WT and Aβ mice.The affinities of the three bispecific antibodies to TfR were 10 nM, 20 nM and 240 nM. Independent of genotype, stronger TfR-affinity resulted in higher brain uptake. The two bispecific antibodies with stronger affinity behaved similarly and differentiated between WT and Aβ model mice at an earlier time point than the low affinity variant.This study supports the hypothesis that stronger TfR affinity yields better brain uptake at a tracer dose. With the better detection of Aβ pathology, stronger affinity to TfR is a critical feature for the design of future bispecific immunoPET radioligands for intrabrain targets using TfR-mediated transcytosis.
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| 14. |
- Dahlsson Leitao, Charles, et al.
(author)
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Molecular Design of HER3-Targeting Affibody Molecules : Influence of Chelator and Presence of HEHEHE-Tag on Biodistribution of 68Ga-Labeled Tracers
- 2019
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 20:5
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Journal article (peer-reviewed)abstract
- Affibody-based imaging of HER3 is a promising approach for patient stratification. We investigated the influence of a hydrophilic HEHEHE-tag ((HE)3-tag) and two different gallium-68/chelator-complexes on the biodistribution of Z08698 with the aim to improve the tracer for PET imaging. Affibody molecules (HE)3-Z08698-X and Z08698-X (X = NOTA, NODAGA) were produced and labeled with gallium-68. Binding specificity and cellular processing were studied in HER3-expressing human cancer cell lines BxPC-3 and DU145. Biodistribution was studied 3 h p.i. in Balb/c nu/nu mice bearing BxPC-3 xenografts. Mice were imaged 3 h p.i. using microPET/CT. Conjugates were stably labeled with gallium-68 and bound specifically to HER3 in vitro and in vivo. Association to cells was rapid but internalization was slow. Uptake in tissues, including tumors, was lower for (HE)3-Z08698-X than for non-tagged variants. The neutral [68Ga]Ga-NODAGA complex reduced the hepatic uptake of Z08698 compared to positively charged [68Ga]Ga-NOTA-conjugated variants. The influence of the chelator was more pronounced in variants without (HE)3-tag. In conclusion, hydrophilic (HE)3-tag and neutral charge of the [68Ga]Ga-NODAGA complex promoted blood clearance and lowered hepatic uptake of Z08698. [68Ga]Ga-(HE)3-Z08698-NODAGA was considered most promising, providing the lowest blood and hepatic uptake and the best imaging contrast among the tested variants.
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| 15. |
- 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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| 16. |
- Garousi, Javad, et al.
(author)
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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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In: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 13:11, s. 3676-3687
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Journal article (peer-reviewed)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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| 17. |
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| 18. |
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| 19. |
- Garousi, Javad, et al.
(author)
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The use of radiocobalt as a label improves imaging of EGFR using DOTA-conjugated Affibody molecule
- 2017
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Journal article (peer-reviewed)abstract
- Several anti-cancer therapies target the epidermal growth factor receptor (EGFR). Radionuclide imaging of EGFR expression in tumours may aid in selection of optimal cancer therapy. The In-111-labelled DOTA-conjugated Z(EGFR:2377) Affibody molecule was successfully used for imaging of EGFR-expressing xenografts in mice. An optimal combination of radionuclide, chelator and targeting protein may further improve the contrast of radionuclide imaging. The aim of this study was to evaluate the targeting properties of radiocobalt-labelled DOTA-Z(EGFR:2377). DOTA-Z(EGFR:2377) was labelled with Co-57 (T-1/2 = 271.8 d), Co-55 (T-1/2 = 17.5 h), and, for comparison, with the positron-emitting radionuclide Ga-68 (T-1/2 = 67.6 min) with preserved specificity of binding to EGFR-expressing A431 cells. The long-lived cobalt radioisotope Co-57 was used in animal studies. Both Co-57-DOTA-Z(EGFR:2377) and Ga-68-DOTA-Z(EGFR:2377) demonstrated EGFR-specific accumulation in A431 xenografts and EGFR-expressing tissues in mice. Tumour-to-organ ratios for the radiocobalt-labelled DOTA-Z(EGFR:2377) were significantly higher than for the gallium-labelled counterpart already at 3 h after injection. Importantly, Co-57-DOTA-Z(EGFR:2377) demonstrated a tumour-to-liver ratio of 3, which is 7-fold higher than the tumour-to-liver ratio for (68)GaDOTA-Z(EGFR:2377). The results of this study suggest that the positron-emitting cobalt isotope 55Co would be an optimal label for DOTA-Z(EGFR:2377) and further development should concentrate on this radionuclide as a label.
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| 20. |
- Mitran, Bogdan, et al.
(author)
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Affibody-mediated imaging of EGFR expression in prostate cancer using radiocobalt-labeled DOTA-Z(EGFR:2377)
- 2019
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In: Oncology Reports. - : Spandidos Publications. - 1021-335X .- 1791-2431. ; 41:1, s. 534-542
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Journal article (peer-reviewed)abstract
- The epidermal growth factor receptor (EGFR) is often overexpressed during prostate cancer (PCa) progression towards androgen-independence after hormone therapy, but the overexpression is lower than in other types of cancers. Despite the low expression, EGFR has emerged as a promising therapeutic target for patients with castration-resistant PCa. Non-invasive methods for determination of EGFR expression in PCa can serve for patient stratification and therapy response monitoring. Radionuclide imaging probes based on affibody molecules (7 kDa) provide high contrast imaging of cancer-associated molecular targets. We hypothesized that the anti-EGFR affibody molecule DOTA-Z(EGFR:2377) labeled with Co-55 (positron-emitter, T1/2=17.5 h) would enable imaging of EGFR expression in PCa xenografts. The human PCa cell line DU-145 was used for in vitro and in vivo experiments and Co-57 was used as a surrogate for Co-55 in the present study. Binding of Co-57-DOTA-Z(EGFR:2377) to EGFR-expressing xenografts was saturable with anti-EGFR monoclonal antibody cetuximab, which would motivate the use of this tracer for monitoring the receptor occupancy during treatment. A significant dose-dependent difference in radioactivity accumulation in tumors and normal organs was observed when the biodistribution was studied 3 h after the injection of 10 and 35 mu g of Co-57-DOTA-Z(EGFR:2377): At lower doses the tumor uptake was 2-fold higher although tumor-to-organ ratios were not altered. For clinically relevant organs for PCa, tumor-to-organ ratios increased with time, and at 24 h pi were 2.2 +/- 0.5 for colon, 7 +/- 2 for muscle, and 4.0 +/- 0.7 for bones. Small animal SPECT/CT images confirmed the capacity of radiocobalt labeled DOTA-Z(EGFR:2377) to visualize EGFR expression in PCa. In conclusion, the present study demonstrated the feasibility of using the radiocobalt labeled anti-EGFR affibody conjugate Z(EGFR:2377) as an imaging agent for in vivo visualization of low EGFR-expressing tumors, like PCa, and for monitoring of receptor occupancy during cetuximab therapy as well as the importance of optimal dosing in order to achieve higher sensitivity molecular imaging.
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| 21. |
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| 22. |
- Nosrati, Masoumeh, et al.
(author)
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Insights from engineering the Affibody-Fc interaction with a computational-experimental method
- 2017
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In: Protein Engineering Design & Selection. - : Oxford University Press. - 1741-0126 .- 1741-0134. ; 30:9, s. 593-601
-
Journal article (peer-reviewed)abstract
- The interaction between the Staphylococcal Protein A (SpA) domain B (the basis of the Affibody) molecule and the Fc of IgG is key to the use of Affibodies in affinity chromatography and in potential therapies against certain inflammatory diseases. Despite its importance and four-decade history, to our knowledge this interaction has never been affinity matured. We elucidate reasons why single-substitutions in the SpA which improve affinity to Fc may be very rare, and also discover substitutions which potentially serve several engineering purposes. We used a variation of FoldX to predict changes in protein-protein-binding affinity, and produce a list of 41 single-amino acid substitutions on the SpA molecule, of which four are near wild type (wt) and five are at most a factor of four from wt affinity. The nine substitutions include one which removes lysine, and several others which change charge. Subtle modulations in affinity may be useful for modifying column elution conditions. The method is applicable to other protein-protein systems, providing molecular insights with lower workload than existing experimental techniques.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Oroujeni, Maryam, PhD, 1982-, et al.
(author)
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Influence of composition of cysteine-containing peptide-based chelators on biodistribution of Tc-99m-labeled anti-EGFR affibody molecules
- 2018
-
In: Amino Acids. - : Springer. - 0939-4451 .- 1438-2199. ; 50:8, s. 981-994
-
Journal article (peer-reviewed)abstract
- Epidermal growth factor receptor (EGFR) is overexpressed in a number of cancers and is the molecular target for several anti-cancer therapeutics. Radionuclide molecular imaging of EGFR expression should enable personalization of anti-cancer treatment. Affibody molecule is a promising type of high-affinity imaging probes based on a non-immunoglobulin scaffold. A series of derivatives of the anti-EGFR affibody molecule ZEGFR:2377, having peptide-based cysteine-containing chelators for conjugation of Tc-99m, was designed and evaluated. It was found that glutamate-containing chelators Gly-Gly-Glu-Cys (GGEC), Gly-Glu-Glu-Cys (GEEC) and Glu-Glu-Glu-Cys (EEEC) provide the best labeling stability. The glutamate containing conjugates bound to EGFR-expressing cells specifically and with high affinity. Specific targeting of EGFR-expressing xenografts in mice was demonstrated. The number of glutamate residues in the chelator had strong influence on biodistribution of radiolabeled affibody molecules. Increase of glutamate content was associated with lower uptake in normal tissues. The Tc-99m-labeled variant containing the EEEC chelator provided the highest tumor-to-organ ratios. In conclusion, optimizing the composition of peptide-based chelators enhances contrast of imaging of EGFR-expression using affibody molecules.
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| 27. |
- Oroujeni, Maryam, PhD, 1982-, et al.
(author)
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Preclinical Evaluation of [Ga-68]Ga-DFO-ZEGFR:2377 : A Promising Affibody-Based Probe for Noninvasive PET Imaging of EGFR Expression in Tumors
- 2018
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In: Cells. - : MDPI. - 2073-4409. ; 7:9
-
Journal article (peer-reviewed)abstract
- Radionuclide imaging of epidermal growth factor receptor (EGFR) expression in tumors may stratify patients for EGFR-targeting therapies and predict response or resistance to certain treatments. Affibody molecules, which are nonimmunoglobulin scaffold proteins, have a high potential as probes for molecular imaging. In this study, maleimido derivative of desferrioxamine B (DFO) chelator was site-specifically coupled to the C-terminal cysteine of the anti-EGFR affibody molecule ZEGFR:2377, and the DFO-ZEGFR:2377 conjugate was labeled with the generator-produced positron-emitting radionuclide Ga-68. Stability, specificity of binding to EGFR-expressing cells, and processing of [Ga-68]Ga-DFO-ZEGFR:2377 by cancer cells after binding were evaluated in vitro. In vivo studies were performed in nude mice bearing human EGFR-expressing A431 epidermoid cancer xenografts. The biodistribution of [Ga-68]Ga-DFO-ZEGFR:2377 was directly compared with the biodistribution of [Zr-89]Zr-DFO-ZEGFR:2377. DFO-ZEGFR:2377 was efficiently (isolated yield of 73 +/- 3%) and stably labeled with Ga-68. Binding of [Ga-68]Ga-DFO-ZEGFR:2377 to EGFR-expressing cells in vitro was receptor-specific and proportional to the EGFR expression level. In vivo saturation experiment demonstrated EGFR-specific accumulation of [Ga-68]Ga-DFO-ZEGFR:2377 in A431 xenografts. Compared to [Zr-89]Zr-DFO-ZEGFR:2377, [Ga-68]Ga-DFO-ZEGFR:2377 demonstrated significantly (p < 0.05) higher uptake in tumors and lower uptake in spleen and bones. This resulted in significantly higher tumor-to-organ ratios for [Ga-68]Ga-DFO-ZEGFR:2377. In conclusion, [Ga-68]Ga-DFO-ZEGFR:2377 is a promising probe for imaging of EGFR expression.
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| 28. |
- Oroujeni, Maryam, PhD, 1982-, et al.
(author)
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The Use of a Non-Conventional Long-Lived Gallium Radioisotope Ga-66 Improves Imaging Contrast of EGFR Expression in Malignant Tumours Using DFO-ZEGFR:2377 Affibody Molecule
- 2021
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In: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 13:2
-
Journal article (peer-reviewed)abstract
- Epidermal growth factor receptor (EGFR) is overexpressed in many malignancies. EGFR-targeted therapy extends survival of patients with disseminated cancers. Radionuclide molecular imaging of EGFR expression would make EGFR-directed treatment more personalized and therefore more efficient. A previous study demonstrated that affibody molecule [Ga-68]Ga-DFO-ZEGFR:2377 permits specific positron-emission tomography (PET) imaging of EGFR expression in xenografts at 3 h after injection. We anticipated that imaging at 24 h after injection would provide higher contrast, but this is prevented by the short half-life of Ga-68 (67.6 min). Here, we therefore tested the hypothesis that the use of the non-conventional long-lived positron emitter Ga-66 (T-1/2 = 9.49 h, beta(+) = 56.5%) would permit imaging with higher contrast. Ga-66 was produced by the Zn-66(p,n)Ga-66 nuclear reaction and DFO-ZEGFR:2377 was efficiently labelled with Ga-66 with preserved binding specificity in vitro and in vivo. At 24 h after injection, [Ga-66]Ga-DFO-ZEGFR:2377 provided 3.9-fold higher tumor-to-blood ratio and 2.3-fold higher tumor-to-liver ratio than [Ga-68]Ga-DFO-ZEGFR:2377 at 3 h after injection. At the same time point, [Ga-66]Ga-DFO-ZEGFR:2377 provided 1.8-fold higher tumor-to-blood ratio, 3-fold higher tumor-to-liver ratio, 1.9-fold higher tumor-to-muscle ratio and 2.3-fold higher tumor-to-bone ratio than [Zr-89]Zr-DFO-ZEGFR:2377. Biodistribution data were confirmed by whole body PET combined with magnetic resonance imaging (PET/MRI). The use of the positron emitter Ga-66 for labelling of DFO-ZEGFR:2377 permits PET imaging of EGFR expression at 24 h after injection and improves imaging contrast.
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| 29. |
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| 30. |
- Rinne, Sara S., et al.
(author)
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Optimization of HER3 expression imaging using affibody molecules : Influence of chelator for labeling with indium-111
- 2019
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In: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- Radionuclide molecular imaging of human epidermal growth factor receptor 3 (HER3) expression using affibody molecules could be used for patient stratification for HER3-targeted cancer therapeutics. We hypothesized that the properties of HER3-targeting affibody molecules might be improved through modification of the radiometal-chelator complex. Macrocyclic chelators NOTA (1,4,7-triazacyclononane-N,N',N ''-triacetic acid), NODAGA (1-(1,3-carboxypropyl)-4,7-carboxymethyl-1,4,7-triazacyclononane), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaceticacid), and DOTAGA (1,4,7,10-tetraazacyclododececane, 1-(glutaric acid)-4,7,10-triacetic acid) were conjugated to the C-terminus of anti-HER3 affibody molecule Z(08698) and conjugates were labeled with indium-111. All conjugates bound specifically and with picomolar affinity to HER3 in vitro. In mice bearing HER3-expressing xenografts, no significant difference in tumor uptake between the conjugates was observed. Presence of the negatively charged In-111-DOTAGA-complex resulted in the lowest hepatic uptake and the highest tumor-to-liver ratio. In conclusion, the choice of chelator influences the biodistribution of indium-111 labeled anti-HER3 affibody molecules. Hepatic uptake of anti-HER3 affibody molecules could be reduced by the increase of negative charge of the radiometal-chelator complex on the C-terminus without significantly influencing the tumor uptake.
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| 31. |
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| 32. |
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| 33. |
- Rosestedt, Maria, et al.
(author)
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Evaluation of a radiocobalt-labelled affibody molecule for imaging of human epidermal growth factor receptor 3 expression
- 2017
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In: International Journal of Oncology. - : Spandidos Publications. - 1019-6439 .- 1791-2423. ; 51:6, s. 1765-1774
-
Journal article (peer-reviewed)abstract
- The human epidermal growth factor receptor 3 (HER3) is involved in the development of cancer resistance towards tyrosine kinase-Targeted therapies. Several HER3-Targeting therapeutics are currently under clinical evaluation. Non-invasive imaging of HER3 expression could improve patient management. Affibody molecules are small engineered scaffold proteins demonstrating superior properties as targeting probes for molecular imaging compared with monoclonal antibodies. Feasibility of in vivo HER3 imaging using affibody molecules has been previously demonstrated. Preclinical studies have shown that the contrast when imaging using anti-HER3 affibody molecules can be improved over time. We aim to develop an agent for PET imaging of HER3 expression using the long-lived positron-emitting radionuclide cobalt-55 (55Co) (T1/2=17.5 h). A long-lived cobalt isotope 57Co was used as a surrogate for 55Co in this study. The anti-HER3 affibody molecule HEHEHE-ZHER3-NOTA was labelled with radiocobalt with high yield, purity and stability. Biodistribution of 57Co-HEHEHE-ZHER3-NOTA was measured in mice bearing DU145 (prostate carcinoma) and LS174T (colorectal carcinoma) xenografts at 3 and 24 h post injection (p.i.). Tumour-To-blood ratios significantly increased between 3 and 24 h p.i. (p<0.05). At 24 h p.i., tumour-To-blood ratios were 6 for DU145 and 8 for LS174T xenografts, respectively. HER3-expressing xenografts were clearly visualized in a preclinical imaging setting already 3 h p.i., and contrast further improved at 24 h p.i. In conclusion, the radiocobalt-labelled anti-HER3 affibody molecule, HEHEHE-ZHER3-NOTA, is a promising tracer for imaging of HER3 expression in tumours.
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| 34. |
- Rosestedt, Maria, et al.
(author)
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Improved contrast of affibody-mediated imaging of HER3 expression in mouse xenograft model through co-injection of a trivalent affibody for in vivo blocking of hepatic uptake
- 2019
-
In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 9
-
Journal article (peer-reviewed)abstract
- Human epidermal growth factor receptor type 3 (HER3) plays a crucial role in the progression of many cancer types. In vivo radionuclide imaging could be a reliable method for repetitive detection of HER3-expression in tumors. The main challenge of HER3-imaging is the low expression in tumors together with endogenous receptor expression in normal tissues, particularly the liver. A HER3-targeting affibody molecule labeled with radiocobalt via a NOTA chelator [Co-57]Co-NOTA-Z(08699) has demonstrated the most favorable biodistribution profile with the lowest unspecific hepatic uptake and high activity uptake in tumors. We hypothesized that specific uptake of labeled affibody monomer might be selectively blocked in the liver but not in tumors by a co-injection of non-labeled corresponding trivalent affibody (Z(08699))(3). Biodistribution of [Co-57]Co-NOTA-Z(08699) and [In-111]ln-DOTA-(Z(08699))(3) was studied in BxPC-3 xenografted mice. [Co-57]Co-NOTA-Z(08699) was co-injected with unlabeled trivalent affibody DOTA-(Z(08699))(3) at different monomer:trimer molar ratios. HER3-expression in xenografts was imaged using [Co-57]Co-NOTA-Z(08699) and [Co-57]Co-NOTA-Z(08699): DOTA-(Z(08699))(3). Hepatic activity uptake of [Co-57] Co-NOTA-Z(08699): DOTA-(Z(08699))(3) decreased with increasing monomer:trimer molar ratio. The tumor activity uptake and tumor-to-liver ratios were the highest for the 1:3 ratio. SPECT/CT images confirmed the biodistribution data. Imaging of HER3 expression can be improved by co-injection of a radiolabeled monomeric affi body-based imaging probe together with a trivalent affibody.
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| 35. |
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| 36. |
- Schlein, Eva, et al.
(author)
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Aβ targeting ImmunoPET : Brain pharmacokinetics comparison between a brain penetrating and a regular antibody
-
Other publication (other academic/artistic)abstract
- Bispecific antibodies utilizing the transferrin receptor (TfR) for transport into the brain are being developed for both therapeutic and diagnostic applications. Compared with regular monospecific antibodies, the brain uptake of TfR-binding bispecific antibodies is rapid and efficient. However, due to differences in pharmacokinetic properties, it has been challenging to directly compare their brain uptake in vivo. In this study, we have studied the amyloid-β (Aβ) antibody Bapineuzumab (Bapi) and its bispecific variant Bapi-Fab8D3, which contains a fragment of the TfR-binding antibody 8D3. Both antibodies were recombinantly engineered to harbour a mutation that reduces binding to the neonatal Fc receptor (FcRn) and thus contributes to an increased clearance rate from blood.The antibodies were labelled with fluorine-18 (18F) and administered to wildtype (WT) mice, which were PET scanned for 2 h in an alternating manner to cover a period of 9 h, followed by ex vivo analyses. Next, the bispecific antibody [18F]Bapi-Fab8D3 was used for PET imaging if Aβ pathology in the AD mouse model AppNL-G-F compared with WT mice at 12 h after antibody administration. [18F]Bapi and [18F]Bapi-Fab8D3 had identical blood elimination curves in WT mice and PET data quantification demonstrated that [18F]Bapi brain concentration declined from the start and throughout the 9 h time period, while [18F]Bapi-Fab8D3 displayed a higher brain concentration, indicative of its active transport into the brain.[18F]Bapi-Fab PET imaging discriminated AppNL-G-F from WT mice already at 12 h after administration, suggesting that this novel antibody-based ligand could be used for same-day PET imaging.
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| 37. |
- Schlein, Eva, et al.
(author)
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Reduced neonatal Fc receptor binding increases clearance and brain-to-blood ratio of a brain penetrating amyloid-β antibody
-
Other publication (other academic/artistic)abstract
- Recent advances in the development of amyloid-β (Aβ) targeted immunotherapies for Alzheimer’s disease (AD) has highlighted the need for accurate diagnostic methods. Antibody-based positron emission tomography (PET) ligands are well suited for this purpose as they can be directed towards the same target as the therapeutic antibody. Bispecific brain penetrating antibodies are interesting for this purpose, but the slow clearance of antibodies remains a challenge for their use PET radioligands since antibody in the circulation as well as unbound antibody in the brain contribute to a non-specific background signal. Thus, a substantial time between the injection and the time of PET scanning is required to achieve an acceptable specific-to-nonspecific signal in PET. In this study, two antibody pairs were designed based on the Aβ antibody Bapineuzumab (Bapi), one regular IgG (Bapi) and one bispecific antibody with a Fab fragment of the transferrin receptor (TfR) antibody 8D3 fused to one of the heavy chains (Bapi-Fab8D3), for active TfR-mediated transport into the brain. One of the pairs was engineered to harbor a mutation in the Fc domain which reduced its binding to the neonatal Fc receptor (FcRn) and thereby increased the clearance of the antibody. Blood and brain pharmacokinetics of the antibody pairs were studied in WT mice and in the AD mouse model AppNL-G-F. The FcRn mutation substantially reduced blood half-life of both Bapi and Bapi-Fab8D3. With the high brain uptake of Bapi-Fab8D3, the brain-to-blood ratio of its FcRn mutated form was significantly higher in AppNL-G-F than WT mice already 12 h after injection and this difference increased further up to 24 h after antibody injection. Ex vivo autoradiography, used to visualize antibody distribution in the brain, showed specific antibody retention in areas with high amounts of Aβ pathology. Taken together, these results suggest that reducing FcRn binding of a full-sized bispecific antibody could drastically reduce the time from injection to imaging.
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| 38. |
- Schlein, Eva, et al.
(author)
-
Reducing neonatal Fc receptor binding enhances clearance and brain-to-blood ratio of TfR-delivered bispecific amyloid-β antibody
- 2024
-
In: mAbs. - : Taylor & Francis. - 1942-0862 .- 1942-0870. ; 16:1
-
Journal article (peer-reviewed)abstract
- Recent development of amyloid-β (Aβ)-targeted immunotherapies for Alzheimer’s disease (AD) have highlighted the need for accurate diagnostic methods. Antibody-based positron emission tomography (PET) ligands are well suited for this purpose as they can be directed toward the same target as the therapeutic antibody. Bispecific, brain-penetrating antibodies can achieve sufficient brain concentrations, but their slow blood clearance remains a challenge, since it prolongs the time required to achieve a target-specific PET signal. Here, two antibodies were designed based on the Aβ antibody bapineuzumab (Bapi) – one monospecific IgG (Bapi) and one bispecific antibody with an antigen binding fragment (Fab) of the transferrin receptor (TfR) antibody 8D3 fused to one of the heavy chains (Bapi-Fab8D3) for active, TfR-mediated transport into the brain. A variant of each antibody was designed to harbor a mutation to the neonatal Fc receptor (FcRn) binding domain, to increase clearance. Blood and brain pharmacokinetics of radiolabeled antibodies were studied in wildtype (WT) and AD mice (AppNL-G-F). The FcRn mutation substantially reduced blood half-life of both Bapi and Bapi-Fab8D3. Bapi-Fab8D3 showed high brain uptake and the brain-to-blood ratio of its FcRn mutated form was significantly higher in AppNL-G-F mice than in WT mice 12 h after injection and increased further up to 168 h. Ex vivo autoradiography showed specific antibody retention in areas with abundant Aβ pathology. Taken together, these results suggest that reducing FcRn binding of a full-sized bispecific antibody increases the systemic elimination and could thereby drastically reduce the time from injection to in vivo imaging.
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| 39. |
- Summer, D., et al.
(author)
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Cyclic versus Noncyclic Chelating Scaffold for 89Zr-Labeled ZEGFR:2377 Affibody Bioconjugates Targeting Epidermal Growth Factor Receptor Overexpression
- 2018
-
In: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 15:1, s. 175-185
-
Journal article (peer-reviewed)abstract
- Zirconium-89 is an emerging radionuclide for positron emission tomography (PET) especially for biomolecules with slow pharmacokinetics as due to its longer half-life, in comparison to fluorine-18 and gallium-68, imaging at late time points is feasible. Desferrioxamine B (DFO), a linear bifunctional chelator (BFC) is mostly used for this radionuclide so far but shows limitations regarding stability. Our group recently reported on fusarinine C (FSC) with similar zirconium-89 complexing properties but potentially higher stability related to its cyclic structure. This study was designed to compare FSC and DFO head-to-head as bifunctional chelators for 89Zr-radiolabeled EGFR-targeting ZEGFR:2377 affibody bioconjugates. FSC-ZEGFR:2377 and DFO-ZEGFR:2377 were evaluated regarding radiolabeling, in vitro stability, specificity, cell uptake, receptor affinity, biodistribution, and microPET-CT imaging. Both conjugates were efficiently labeled with zirconium-89 at room temperature but radiochemical yields increased substantially at elevated temperature, 85 °C. Both 89Zr-FSC-ZEGFR:2377 and 89Zr-DFO-ZEGFR:2377 revealed remarkable specificity, affinity and slow cell-line dependent internalization. Radiolabeling at 85 °C showed comparable results in A431 tumor xenografted mice with minor differences regarding blood clearance, tumor and liver uptake. In comparison 89Zr-DFO-ZEGFR:2377, radiolabeled at room temperature, showed a significant difference regarding tumor-to-organ ratios. MicroPET-CT imaging studies of 89Zr-FSC-ZEGFR:2377 as well as 89Zr-DFO-ZEGFR:2377 confirmed these findings. In summary we were able to show that FSC is a suitable alternative to DFO for radiolabeling of biomolecules with zirconium-89. Furthermore, our findings indicate that 89Zr-radiolabeling 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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