| 1. |
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| 2. |
- Ahlgren, Sara, et al.
(författare)
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Targeting of HER2-Expressing Tumors Using 111In-ABY-025, a Second-Generation Affibody Molecule with a Fundamentally Reengineered Scaffold
- 2010
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 51:7, s. 1131-1138
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Tidskriftsartikel (refereegranskat)abstract
- Overexpression of HER2 in breast carcinomas predicts response to trastuzumab therapy. Affibody molecules based on a non-immunoglobulin scaffold have demon-strated high potential for in vivo molecular imaging of HER2-expressing tumors. Re-engineering of the molecular scaffold has led to a second generation of optimized Affibody molecules, having a surface distinctly different from the parental protein domain from staphylococcal protein A. The new tracer showed further increased melting point, stability and overall hydrophilicity compared to the parental molecule, and was shown to be more amenable for chemical peptide synthesis. The goal of this study was to assess potential effects of this extensive re-engineering on HER2 targeting, using ABY-025, a DOTA conjugated variant of the novel tracer. Methods: 111In-ABY-025 was compared with previously evaluated parent HER2-binding Affibody tracers in vitro and in vivo. The in vivo behavior was further evaluated in mice bearing SKOV-3 xenografts, in rats and in cynomolgus macaques. Results: 111In-ABY-025 bound specifically to HER2 in vitro and in vivo. Direct comparison with the previous generation of HER2-binding tracers showed that ABY-025 retained excellent targeting properties. Rapid blood clearance was shown in mice, rats and macaques. A highly specific tumor uptake of 16.7 ± 2.5 %IA/g was seen at 4 h after injection. The tumor-to-blood ratio was 6.3 at 0.5 h, 88 at 4 h, and increased up to 3 days after injection. Gamma camera imaging of tumors was already possible 0.5 h after injection. Furthermore, repeated i.v. administration of ABY-025 did not induce antibody formation in rats. Conclusions: The biodistribution of 111In-ABY-025 was in remarkably good agreement with the parent tracers, despite profound re-engineering of the non-binding surface. The molecule displayed rapid blood clearance in all species investigated and excellent targeting capacity in tumor bearing mice, leading to high tumor-to-organ-ratios and high contrast imaging shortly after injection.
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| 3. |
- Ahlgren, Sara, et al.
(författare)
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Targeting of HER2-expressing tumors with a site-specifically 99mTc-labeled recombinant affibody molecule, ZHER2:2395, with C-terminally engineered cysteine
- 2009
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 50:5, s. 781-789
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Tidskriftsartikel (refereegranskat)abstract
- The detection of human epidermal growth factor receptor type 2 (HER2) expression in malignant tumors provides important information influencing patient management. Radionuclide in vivo imaging of HER2 may permit the detection of HER2 in both primary tumors and metastases by a single noninvasive procedure. Small (7 kDa) high-affinity anti-HER2 Affibody molecules may be suitable tracers for SPECT visualization of HER2-expressing tumors. The use of generator-produced (99m)Tc as a label would facilitate the prompt translation of anti-HER2 Affibody molecules into use in clinics. METHODS: A C-terminal cysteine was introduced into the Affibody molecule Z(HER2:342) to enable site-specific labeling with (99m)Tc. Two recombinant variants, His(6)-Z(HER2:342)-Cys (dissociation constant [K(D)], 29 pM) and Z(HER2:2395)-Cys, lacking a His tag (K(D), 27 pM), were labeled with (99m)Tc in yields exceeding 90%. The binding specificity and the cellular processing of Affibody molecules were studied in vitro. Biodistribution and gamma-camera imaging studies were performed in mice bearing HER2-expressing xenografts. RESULTS: (99m)Tc-His(6)-Z(HER2:342)-Cys was capable of targeting HER2-expressing SKOV-3 xenografts in SCID mice, but the liver radioactivity uptake was high. A series of comparative biodistribution experiments indicated that the presence of the His tag caused elevated accumulation in the liver. (99m)Tc-Z(HER2:2395)-Cys, not containing a His tag, showed low uptake in the liver and high and specific uptake in HER2-expressing xenografts. Four hours after injection, the radioactivity uptake values (percentage of injected activity per gram of tissue [%IA/g]) were 6.9 +/- 2.5 (mean +/- SD) %IA/g in LS174T xenografts (moderate level of HER2 expression) and 15 +/- 3 %IA/g in SKOV-3 xenografts (high level of HER2 expression). The corresponding tumor-to-blood ratios were 88 +/- 24 and 121 +/- 24, respectively. Both LS174T and SKOV-3 xenografts were clearly visualized with a clinical gamma-camera 1 h after injection of (99m)Tc-Z(HER2:2395)-Cys. CONCLUSION: The Affibody molecule (99m)Tc-Z(HER2:2395)-Cys is a promising tracer for SPECT visualization of HER2-expressing tumors.
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| 4. |
- Andersen, Jan Terje, et al.
(författare)
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Extending Half-life by Indirect Targeting of the Neonatal Fc Receptor (FcRn) Using a Minimal Albumin Binding Domain
- 2011
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 286:7, s. 5234-5241
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Tidskriftsartikel (refereegranskat)abstract
- The therapeutic and diagnostic efficiency of engineered small proteins, peptides, and chemical drug candidates is hampered by short in vivo serum half-life. Thus, strategies to tailor their biodistribution and serum persistence are highly needed. An attractive approach is to take advantage of the exceptionally long circulation half-life of serum albumin or IgG, which is attributed to a pH-dependent interaction with the neonatal Fc receptor (FcRn) rescuing these proteins from intracellular degradation. Here, we present molecular evidence that a minimal albumin binding domain (ABD) derived from streptococcal protein G can be used for efficient half-life extension by indirect targeting of FcRn. We show that ABD, and ABD recombinantly fused to an Affibody molecule, in complex with albumin does not interfere with the strictly pH-dependent FcRn-albumin binding kinetics. The same result was obtained in the presence of IgG. An in vivo study performed in rat confirmed that the clinically relevant human epidermal growth factor 2 (HER2)-targeting Affibody molecule fused to ABD has a similar half-life and biodistribution profile as serum albumin. The proof-of-concept described may be broadly applicable to extend the in vivo half-life of short lived biological or chemical drugs ultimately resulting in enhanced therapeutic or diagnostic efficiency, a more favorable dosing regimen, and improved patient compliance.
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| 5. |
- Ekblad, Torun, et al.
(författare)
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Development and preclinical characterisation of 99mTc-labelled Affibody molecules with reduced renal uptake
- 2008
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 35:12, s. 2245-2255
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Affibody molecules are low molecular weight proteins (7 kDa), which can be selected to bind to tumour-associated target proteins with subnanomolar affinity. Because of rapid tumour localisation and clearance from nonspecific compartments, Affibody molecules are promising tracers for molecular imaging. Earlier, 99mTc-labelled Affibody molecules demonstrated specific targeting of tumour xenografts. However, the biodistribution was suboptimal either because of hepatobiliary excretion or high renal uptake of the radioactivity. The goal of this study was to optimise the biodistribution of Affibody molecules by chelator engineering. Materials and methods Anti-HER2 ZHER2:342 Affibody molecules, carrying the mercaptoacetyl-glutamyl-seryl-glutamyl (maESE), mercaptoacetyl-glutamyl-glutamyl-seryl (maEES) and mercaptoacetyl-seryl-glutamyl-glutamyl (maSEE) chelators, were prepared by peptide synthesis and labelled with 99mTc. The tumour-targeting capacity of these conjugates was compared with each other and with the best previously available conjugate, 99mTc-maEEE-ZHER2:342, in nude mice bearing SKOV-3 xenografts. The tumour-targeting capacity of the most promising conjugate, 99mTc-maESE-ZHER2:342, was compared with radioiodinated ZHER2:342. Results All novel conjugates demonstrated successful tumour targeting and a low degree of hepatobiliary excretion. The renal uptakes of serine-containing conjugates, 33 ± 5, 68 ± 21 and 71 ± 10%IA/g, for99mTc-maESE-ZHER2:342, 99mTc-maEES-ZHER2:342 and 99mTc-maSEE-ZHER2:342, respectively, were significantly reduced in comparison with 99mTc-maEEE-ZHER2:342 (102 ± 13%IA/g). For 99mTc-maESE-ZHER2:342, a tumour uptake of 9.6 ± 1.8%IA/g and a tumour-to-blood ratio of 58 ± 6 were reached at 4 h p.i. Conclusions A combination of serine and glutamic acid residues in the chelator sequence confers increased renal excretion and relatively low renal uptake of 99mTc-labelled Affibody molecules. In combination with preserved targeting capacity, this improved imaging of targets in abdominal area.
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| 6. |
- Ekblad, Torun, et al.
(författare)
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Synthesis and chemoselective intramolecular cross-linking of a HER2-binding Affibody
- 2009
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 92:2, s. 116-123
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Tidskriftsartikel (refereegranskat)abstract
- The human epidermal growth factor receptor HER2 has emerged as an important target for molecular imaging of breast cancer. This article presents the design and synthesis of a HER2-targeting affibody molecule with improved stability and tumor targeting capacity, and with potential use as an imaging agent. The 58 aa three-helix bundle protein was assembled using solid-phase peptide synthesis, and a chemoselective ligation strategy was used to establish an intramolecular thioether bond between the side chain thiol group of a cysteine residue, positioned in the loop between helices I and II, and a chloroacetyl group on the side chain amino group of the C-terminal lysine residue. The tethered protein offered an increased thermal stability, with a melting temperature of 64 degrees C, compared to 54 degrees C for the linear control. The ligation did not have a major influence on the HER2 binding affinity, which was 320 and 380 pM for the crosslinked and linear molecules, respectively. Biodistribution studies were performed both in normal and tumor-bearing mice to evaluate the impact of the crosslinking on the in vivo behavior and on the tumor targeting performance. The distribution pattern was characterized by a low uptake in all organs except kidney, and rapid clearance from blood and normal tissue. Crosslinking of the protein resulted in a significantly increased tumor accumulation, rendering the tethered HER2-binding affibody molecule a valuable lead in the development of superior HER2 imaging agents.
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| 7. |
- Ekman, Simon, et al.
(författare)
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A novel oral insulin-like growth factor-1 receptor pathway modulator and its implications for patients with non-small cell lung carcinoma : A phase I clinical trial
- 2016
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Ingår i: Acta Oncologica. - 0284-186X .- 1651-226X. ; 55:2, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A phase Ia/b dose-escalation study was performed to characterize the safety, efficacy and pharmacokinetic properties of the oral small molecule insulin-like growth factor-1-receptor pathway modulator AXL1717 in patients with advanced solid tumors.MATERIAL AND METHODS: This was a prospective, single-armed, open label, dose-finding phase Ia/b study with the aim of single day dosing (phase Ia) to define the starting dose for multi-day dosing (phase Ib), and phase Ib to define and confirm recommended phase II dose (RP2D) and if possible maximum tolerated dose (MTD) for repeated dosing.RESULTS AND CONCLUSION: Phase Ia enrolled 16 patients and dose escalations up to 2900 mg BID were successfully performed without any dose limiting toxicity (DLT). A total of 39 patients were treated in phase Ib. AXL1717 was well tolerated with neutropenia as the only dose-related, reversible, DLT. RP2D dose was found to be 390 mg BID for four weeks. Some patients, mainly with NSCLC, demonstrated signs of clinical benefit, including four partial tumor responses (one according to RECIST and three according to PET). The 15 patients with NSCLC with treatment duration longer than two weeks with single agent AXL1717 in third or fourth line of therapy showed a median progression-free survival of 31 weeks and overall survival of 60 weeks. Down-regulation of IGF-1R on granulocytes and increases of free serum levels of IGF-1 were seen in patients treated with AXL1717. AXL1717 had an acceptable safety profile and demonstrated promising efficacy in this heavily pretreated patient cohort, especially in patients with NSCLC. RP2D was concluded to be 390 mg BID for four weeks. Trial number is NCT01062620.
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| 8. |
- Engfeldt, Torun, et al.
(författare)
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99mTc-chelator engineering to improve tumour targeting properties of a HER2-specific Affibody molecule
- 2007
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 34:11, s. 1843-1853
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Monitoring HER2 expression is crucial for selection of breast cancer patients amenable to HER2-targeting therapy. The Affibody molecule Z(HER2:342) binds to HER2 with picomolar affinity and enables specific imaging of HER2 expression. Previously, Z(HER2:342) with the additional N-terminal mercaptoacetyl-glycyl-glycyl-glycyl (maGGG) sequence was labelled with (99m)Tc and demonstrated specific targeting of HER2-expressing xenografts. However, hepatobiliary excretion caused high radioactivity accumulation in the abdomen. We investigated whether the biodistribution of Z(HER2:342) can be improved by substituting glycyl residues in the chelating sequence with more hydrophilic seryl residues. METHODS: The Affibody molecule Z(HER2:342), carrying the chelators mercaptoacetyl-glycyl-seryl-glycyl (maGSG), mercaptoacetyl-glycyl-D: -seryl-glycyl [maG(D-S)G] and mercaptoacetyl-seryl-seryl-seryl (maSSS), were prepared by peptide synthesis and labelled with (99m)Tc. The differences in the excretion pathways were evaluated in normal mice. The tumour targeting capacity of (99m)Tc-maSSS-Z(HER2:342) was studied in nude mice bearing SKOV-3 xenografts and compared with the capacity of radioiodinated Z(HER2:342). RESULTS: A shift towards renal excretion was obtained when glycine was substituted with serine in the chelating sequence. The radioactivity in the gastrointestinal tract was reduced threefold for the maSSS conjugate in comparison with the maGGG conjugate 4 h post injection (p.i.). The tumour uptake of (99m)Tc-maSSS-Z(HER2:342) was 11.5 +/- 0.5% IA/g 4 h p.i., and the tumour-to-blood ratio was 76. The pharmacokinetics and uptake characteristics of technetium-labelled Z(HER2:342) were better than those of radioiodinated Z(HER2:342). CONCLUSION: The introduction of serine residues in the chelator results in better tumour imaging properties of the Affibody molecule Z(HER2:342) compared with glycyl-containing chelators and is favourable for imaging of tumours and metastases in the abdominal area.
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| 9. |
- Feldwisch, Joachim, et al.
(författare)
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Design of an optimized scaffold for affibody molecules.
- 2010
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 398:2, s. 232-247
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are non-immunoglobulin-derived affinity proteins based on a three-helical bundle protein domain. Here, we describe the design process of an optimized Affibody molecule scaffold with improved properties and a surface distinctly different from that of the parental scaffold. The improvement was achieved by applying an iterative process of amino acid substitutions in the context of the human epidermal growth factor receptor 2 (HER2)-specific Affibody molecule Z(HER2:342). Replacements in the N-terminal region, loop 1, helix 2 and helix 3 were guided by extensive structural modeling using the available structures of the parent Z domain and Affibody molecules. The effect of several single substitutions was analyzed followed by combination of up to 11 different substitutions. The two amino acid substitutions N23T and S33K accounted for the most dramatic improvements, including increased thermal stability with elevated melting temperatures of up to +12 degrees C. The optimized scaffold contains 11 amino acid substitutions in the nonbinding surface and is characterized by improved thermal and chemical stability, as well as increased hydrophilicity, and enables generation of identical Affibody molecules both by chemical peptide synthesis and by recombinant bacterial expression. A HER2-specific Affibody tracer, [MMA-DOTA-Cys61]-Z(HER2:2891)-Cys (ABY-025), was produced by conjugating MMA-DOTA (maleimide-monoamide-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) to the peptide produced either chemically or in Escherichia coli. ABY-025 showed high affinity and specificity for HER2 (equilibrium dissociation constant, K(D), of 76 pM) and detected HER2 in tissue sections of SKOV-3 xenograft and human breast tumors. The HER2-binding capacity was fully retained after three cycles of heating to 90 degrees C followed by cooling to room temperature. Furthermore, the binding surfaces of five Affibody molecules targeting other proteins (tumor necrosis factor alpha, insulin, Taq polymerase, epidermal growth factor receptor or platelet-derived growth factor receptor beta) were grafted onto the optimized scaffold, resulting in molecules with improved thermal stability and a more hydrophilic nonbinding surface.
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| 10. |
- Jonsson, Andreas, 1974-, et al.
(författare)
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Engineering of a femtomolar affinity binding protein to human serum albumin
- 2008
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Ingår i: Protein Engineering Design & Selection. - : Oxford University Press (OUP). - 1741-0126 .- 1741-0134. ; 21:8, s. 515-527
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Tidskriftsartikel (refereegranskat)abstract
- We describe the development of a novel serum albumin binding protein showing an extremely high affinity (K(D)) for HSA in the femtomolar range. Using a naturally occurring 46-residue three-helix bundle albumin binding domain (ABD) of nanomolar affinity for HSA as template, 15 residues were targeted for a combinatorial protein engineering strategy to identify variants showing improved HSA affinities. Sequencing of 55 unique phage display-selected clones showed a strong bias for wild-type residues at nine positions, whereas various changes were observed at other positions, including charge shifts. Additionally, a few non-designed substitutions appeared. On the basis of the sequences of 12 variants showing high overall binding affinities and slow dissociation rate kinetics, a set of seven 'second generation' variants were constructed. One variant denoted ABD035 displaying wild-type-like secondary structure content and excellent thermal denaturation/renaturation properties showed an apparent affinity for HSA in the range of 50-500 fM, corresponding to several orders of magnitude improvement compared with the wild-type domain. The ABD035 variant also showed an improved affinity toward serum albumin from a number of other species, and a capture experiment involving human serum indicated that the selectivity for serum albumin had not been compromised from the affinity engineering.
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| 11. |
- Lindgren, Joel, 1982-, et al.
(författare)
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A GLP-1 receptor agonist conjugated to an albumin-binding domain for extended half-life
- 2014
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 102:3, s. 252-259
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Tidskriftsartikel (refereegranskat)abstract
- Glucagon-like peptide 1 (GLP-1) and related peptide agonists have been extensively investigated for glycaemic control in Type 2 diabetes, and may also have therapeutic applications for other diseases. Due to the short half-life (t1/2<2 min) of the endogenous peptide, caused by proteolytic degradation and renal clearance, different strategies for half-life extension and sustained release have been explored. In the present study, conjugates between a GLP-1 analogue and a 5 kDa albumin-binding domain (ABD) derived from streptococcal protein G have been chemically synthesized and evaluated. ABD binds with high affinity to human serum albumin, which is highly abundant in plasma and functions as a drug carrier in the circulation. Three different GLP-1-ABD conjugates, with the two peptides connected by linkers of two, four, and six PEG units, respectively, were synthesized and tested in mouse pancreatic islets at high (11 mM) and low (3 mM) glucose concentration. Insulin release upon stimulation was shown to be glucose-dependent, showing no significant difference between the three different GLP-1-ABD conjugates and unconjugated GLP-1 analogue. The biological activity, in combination with the high affinity binding to albumin, make the GLP-1-ABD conjugates promising GLP-1 receptor agonists expected to show extended in vivo half-life.
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| 12. |
- Lindgren, Joel, et al.
(författare)
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A Native Chemical Ligation Approach for Combinatorial Assembly of Affibody Molecules
- 2012
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Ingår i: ChemBioChem. - : Wiley. - 1439-4227 .- 1439-7633. ; 13:7, s. 1024-1031
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Tidskriftsartikel (refereegranskat)abstract
- Affinity molecules labeled with different reporter groups, such as fluorophores or radionuclides, are valuable research tools used in a variety of applications. One class of engineered affinity proteins is Affibody molecules, which are small (6.5 kDa) proteins that can be produced by solid phase peptide synthesis (SPPS), thereby allowing site-specific incorporation of reporter groups during synthesis. The Affibody molecules are triple-helix proteins composed of a variable part, which gives the protein its binding specificity, and a constant part, which is identical for all Affibody molecules. In the present study, native chemical ligation (NCL) has been applied for combinatorial assembly of Affibody molecules from peptide fragments produced by Fmoc SPPS. The concept is demonstrated for the synthesis of three different Affibody molecules. The cysteine residue introduced at the site of ligation can be used for directed immobilization and does not interfere with the function of the investigated proteins. This strategy combines a high-yield production method with facilitated preparation of proteins with different C-terminal modifications.
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| 13. |
- Lindgren, Joel, et al.
(författare)
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N-terminal engineering of amyloid-beta-binding Affibody molecules yields improved chemical synthesis and higher binding affinity
- 2010
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Ingår i: Protein Science. - : Wiley. - 0961-8368 .- 1469-896X. ; 19:12, s. 2319-2329
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Tidskriftsartikel (refereegranskat)abstract
- The aggregation of amyloid-beta (A beta) peptides is believed to be a major factor in the onset and progression of Alzheimer's disease Molecules binding with high affinity and selectivity to A beta-peptides are important tools for investigating the aggregation process An A beta-binding Affibody molecule, Z(A beta 3), has earlier been selected by phage display and shown to bind A beta(1-40) with nanomolar affinity and to inhibit A beta-peptide aggregation In this study, we create truncated functional versions of the Z(A beta 3) Affibody molecule better suited for chemical synthesis production Engineered Affibody molecules of different length were produced by solid phase peptide synthesis and allowed to form covalently linked homodimers by S-S-bridges The N-terminally truncated Affibody molecules Z(A beta 3)(12-58), Z(A beta 3)(15-58), and Z(A beta 3)(18-58) were produced in considerably higher synthetic yield than the corresponding full-length molecule Z(A beta 3)(1-58) Circular dichroism spectroscopy and surface plasmon resonance-based biosensor analysis showed that the shortest Affibody molecule, Z(A beta 3)(18-58), exhibited complete loss of binding to the A beta(1-40)-peptide, while the Z(A beta 3)(12-58) and Z(A beta 3)(15-58) Affibody molecules both displayed approximately one order of magnitude higher binding affinity to the A beta(1-40)-peptide compared to the full-length Affibody molecule Nuclear magnetic resonance spectroscopy showed that the structure of A beta(1-40) in complex with the truncated Affibody dimers is very similar to the previously published solution structure of the A beta(1-40)-peptide in complex with the full-length Z(A beta 3) Affibody molecule This indicates that the N-terminally truncated Affibody molecules Z(A beta 3)(12-58) and Z(A beta 3)(15-58) are highly promising for further engineering and future use as binding agents to monomeric A beta(1-40)
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| 14. |
- Lindgren, Joel, et al.
(författare)
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N-terminal engineering of amyloid-β-binding Affibody molecules yields improved chemical synthesis and higher binding affinity
- 2010
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Ingår i: Protein Science. - : Wiley. - 0961-8368 .- 1469-896X. ; 19:12, s. 2319-2329
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Tidskriftsartikel (refereegranskat)abstract
- The aggregation of amyloid-beta (A beta) peptides is believed to be a major factor in the onset and progression of Alzheimer's disease Molecules binding with high affinity and selectivity to A beta-peptides are important tools for investigating the aggregation process An A beta-binding Affibody molecule, Z(A beta 3), has earlier been selected by phage display and shown to bind A beta(1-40) with nanomolar affinity and to inhibit A beta-peptide aggregation In this study, we create truncated functional versions of the Z(A beta 3) Affibody molecule better suited for chemical synthesis production Engineered Affibody molecules of different length were produced by solid phase peptide synthesis and allowed to form covalently linked homodimers by S-S-bridges The N-terminally truncated Affibody molecules Z(A beta 3)(12-58), Z(A beta 3)(15-58), and Z(A beta 3)(18-58) were produced in considerably higher synthetic yield than the corresponding full-length molecule Z(A beta 3)(1-58) Circular dichroism spectroscopy and surface plasmon resonance-based biosensor analysis showed that the shortest Affibody molecule, Z(A beta 3)(18-58), exhibited complete loss of binding to the A beta(1-40)-peptide, while the Z(A beta 3)(12-58) and Z(A beta 3)(15-58) Affibody molecules both displayed approximately one order of magnitude higher binding affinity to the A beta(1-40)-peptide compared to the full-length Affibody molecule Nuclear magnetic resonance spectroscopy showed that the structure of A beta(1-40) in complex with the truncated Affibody dimers is very similar to the previously published solution structure of the A beta(1-40)-peptide in complex with the full-length Z(A beta 3) Affibody molecule This indicates that the N-terminally truncated Affibody molecules Z(A beta 3)(12-58) and Z(A beta 3)(15-58) are highly promising for further engineering and future use as binding agents to monomeric A beta(1-40)
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| 15. |
- Orlova, Anna, et al.
(författare)
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Synthetic affibody molecules : a novel class of affinity ligands for molecular imaging of HER2-expressing malignant tumors
- 2007
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 67:5, s. 2178-2186
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Tidskriftsartikel (refereegranskat)abstract
- The Affibody molecule Z(HER2:342-pep2), site-specifically and homogeneously conjugated with a 1,4,7,10-tetra-azacylododecane-N,N',N'',N'''-tetraacetic acid (DOTA) chelator, was produced in a single chemical process by peptide synthesis. DOTA-Z(HER2:342-pep2) folds spontaneously and binds HER2 with 65 pmol/L affinity. Efficient radiolabeling with >95% incorporation of (111)In was achieved within 30 min at low (room temperature) and high temperatures (up to 90 degrees C). Tumor uptake of (111)In-DOTA-Z(HER2:342-pep2) was specific for HER2-positive xenografts. A high tumor uptake of 23% injected activity per gram tissue, a tumor-to-blood ratio of >7.5, and high-contrast gamma camera images were obtained already 1 h after injection. Pretreatment with Herceptin did not interfere with tumor targeting, whereas degradation of HER2 using the heat shock protein 90 inhibitor 17-allylamino-geldanamycin before administration of (111)In-DOTA-Z(HER2:342-pep2) obliterated the tumor image. The present results show that radiolabeled synthetic DOTA-Z(HER2:342-pep2) has the potential to become a clinically useful radiopharmaceutical for in vivo molecular imaging of HER2-expressing carcinomas.
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| 16. |
- Orlova, Anna, et al.
(författare)
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Update : Affibody molecules for molecular imaging and therapy for cancer
- 2007
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - 1084-9785 .- 1557-8852. ; 22:5, s. 573-584
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are scaffold proteins, having a common frame of amino acids determining the overall fold or tertiary structure, but with each member characterized by a unique amino acid composition in an exposed binding surface determining binding specificity and affinity for a certain target. Affibody molecules represent a new class of affinity proteins based on a 58-amino acid residue protein domain, derived from one of the IgG binding domains of staphylococcal protein A. They combine small size ( approximately 6.5 kDa) with high affinity and specificity. Affibody molecules with nanomolar affinities were selected from an initial library (3 x 10(9) members) and, after affinity maturation, picomolar binders were obtained. The small size and simple structure of affibody molecules allow their production by chemical synthesis with homogeneous site-specific incorporation of moieties for further labeling using a wide range of labeling chemistries. The robustness and the refolding properties of affibody molecules make them amenable to labeling conditions that denature most proteins, including incubation at pH 11 at 60 degrees C for up to 60 minutes. Affibody molecules meet the requirements which are key for successful clinical use as imaging agents: high-affinity binding to the chosen target; short plasma half-life time; rapid renal clearance for nonbound drug substance and, high, continuously increasing tumor-to-organ ratios, resulting in high-contrast in vivo images shortly after injection of the diagnostic agent.
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| 17. |
- Seijsing, Johan, et al.
(författare)
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An engineered affibody molecule with pH-dependent binding to FcRn mediates extended circulatory half-life of a fusion protein
- 2014
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 111:48, s. 17110-17115
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Tidskriftsartikel (refereegranskat)abstract
- Proteins endocytosed from serum are degraded in the lysosomes. However, serum albumin (SA) and IgG, through its Fc part, bind to the neonatal Fc receptor (FcRn) at low pH in the endosome after endocytosis, and are transported back to the cellular surface, where they are released into the bloodstream, resulting in an extended serum circulation time. Association with Fc or SA has been used to prolong the in vivo half-life of biopharmaceuticals, using the interaction with FcRn to improve treatment regimens. This has been achieved either directly, by fusion or conjugation to Fc or SA, or indirectly, using SA-binding proteins. The present work takes this principle one step further, presenting small affinity proteins that bind directly to FcRn, mediating extension of the serum half-life of fused biomolecules. Phage display technology was used to select affibody molecules that can bind to FcRn in the pH-dependent manner required for rescue by FcRn. The biophysical and binding properties were characterized in vitro, and the affibody molecules were found to bind to FcRn more strongly at low pH than at neutral pH. Attachment of the affibody molecules to a recombinant protein, already engineered for increased halflife, resulted in a nearly threefold longer half-life in mice. These tags should have general use as fusion partners to biopharmaceuticals to extend their half-lives in vivo.
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| 18. |
- Strand, Joanna, et al.
(författare)
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Gallium-68-Labeled Affibody Molecule for PET Imaging of PDGFRβ Expression in Vivo
- 2014
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 11:11, s. 3957-3964
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor receptor β (PDGFRβ) is a transmembrane tyrosine kinase receptor involved, for example, in angiogenesis. Overexpression and excessive signaling of PDGFRβ has been observed in multiple malignant tumors and fibrotic diseases, making this receptor a pharmaceutical target for monoclonal antibodies and tyrosine kinase inhibitors. Successful targeted therapy requires identification of responding patients. Radionuclide molecular imaging would enable determination of the PDGFRβ status in all lesions using a single noninvasive repeatable procedure. Recently, we have demonstrated that the affibody molecule Z09591 labeled with 111In can specifically target PDGFRβ-expressing tumors in vivo. The use of positron emission tomography (PET) as an imaging technique would provide superior resolution, sensitivity, and quantitation accuracy. In this study, a DOTA-conjugated Z09591 was labeled with the generator-produced positron emitting radionuclide 68Ga (T1/2 = 67.6 min, Eβ + max = 1899 keV, 89% β+). 68Ga-DOTA-Z09591 retained the capacity to specifically bind to PDGFRβ-expressing U-87 MG glioma cells. The half-maximum inhibition concentration (IC50) of 68Ga-DOTA-Z09591 (6.6 ± 1.4 nM) was somewhat higher than that of 111In-DOTA-Z09591 (1.4 ± 1.2 nM). 68Ga-DOTA-Z09591 demonstrated specific (saturable) targeting of U-87 MG xenografts in immunodeficient mice. The tumor uptake at 2 h after injection was 3.7 ± 1.7% IA/g, which provided a tumor-to-blood ratio of 8.0 ± 3.1. The only organ with higher accumulation of radioactivity was the kidney. MicroPET imaging provided high-contrast imaging of U-87 MG xenografts. In conclusion, the 68Ga-labeled affibody molecule Z09591 is a promising candidate for further development as a probe for imaging PDGFRβ expression in vivo using PET.
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| 19. |
- Tolmachev, Vladimir, et al.
(författare)
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Affibody molecules : potential for in vivo imaging of molecular targets for cancer therapy
- 2007
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Ingår i: Expert Opinion on Biological Therapy. - : Informa Healthcare. - 1471-2598 .- 1744-7682. ; 7:4, s. 555-568
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Forskningsöversikt (refereegranskat)abstract
- Targeting radionuclide imaging of tumor-associated antigens may help to select patients who will benefit from a particular biological therapy. Affibody molecules are a novel class of small (approximately 7 kDa) phage display-selected affinity proteins, based on the B-domain scaffold of staphylococcal protein A. A large library (3 x 10(9) variants) has enabled selection of high-affinity (up to 22 pM) binders for a variety of tumor-associated antigens. The small size of Affibody molecules provides rapid tumor localization and fast clearance from nonspecific compartments. Preclinical studies have demonstrated the potential of Affibody molecules for specific and high-contrast radionuclide imaging of HER2 in vivo, and pilot clinical data using indium-111 and gallium-68 labeled anti-HER2 Affibody tracer have confirmed its utility for radionuclide imaging in cancer patients.
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| 20. |
- Tolmachev, Vladimir, et al.
(författare)
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Evaluation of a maleimido derivative of CHX-A'' DTPA for site-specific labeling of affibody molecules
- 2008
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 19:8, s. 1579-1587
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are a new class of small targeting proteins based on a common three-helix bundle structure. Affibody molecules binding a desired target may be selected using phage-display technology. An Affibody molecule Z HER2:342 binding with subnanomolar affinity to the tumor antigen HER2 has recently been developed for radionuclide imaging in vivo. Introduction of a single cysteine into the cysteine-free Affibody scaffold provides a unique thiol group for site-specific labeling of recombinant Affibody molecules. The recently developed maleimido-CHX-A'' DTPA was site-specifically conjugated at the C-terminal cysteine of Z HER2:2395-C, a variant of Z HER2:342, providing a homogeneous conjugate with a dissociation constant of 56 pM. The yield of labeling with (111)In was >99% after 10 min at room temperature. In vitro cell tests demonstrated specific binding of (111)In-CHX-A'' DTPA-Z 2395-C to HER2-expressing cell-line SKOV-3 and good cellular retention of radioactivity. In normal mice, the conjugate demonstrated rapid clearance from all nonspecific organs except kidney. In mice bearing SKOV-3 xenografts, the tumor uptake of (111)In-CHX-A'' DTPA-Z 2395-C was 17.3 +/- 4.8% IA/g and the tumor-to-blood ratio 86 +/- 46 (4 h postinjection). HER2-expressing xenografts were clearly visualized 1 h postinjection. In conclusion, coupling of maleimido-CHX-A'' DTPA to cysteine-containing Affibody molecules provides a well-defined uniform conjugate, which can be rapidly labeled at room temperature and provides high-contrast imaging of molecular targets in vivo.
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| 21. |
- Tolmachev, Vladimir, et al.
(författare)
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HEHEHE-Tagged Affibody Molecule May Be Purified by IMAC, Is Conveniently Labeled with [Tc-99m(CO)(3)](+), and Shows Improved Biodistribution with Reduced Hepatic Radioactivity Accumulation
- 2010
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 21:11, s. 2013-2022
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Tidskriftsartikel (refereegranskat)abstract
- Affibody molecules are a class of small (ca. 7 kDa) robust scaffold proteins suitable for radionuclide molecular imaging of therapeutic targets in vivo. A hexahistidine tag at the N-terminus streamlines development of new imaging probes by enabling facile purification using immobilized metal ion affinity chromatography (IMAC), as well as convenient [Tc-99m(CO)(3)](+)-labeling. However, previous studies in mice have demonstrated that Affibody molecules labeled by this method yield higher liver accumulation of radioactivity, compared to the same tracer lacking the hexahistidine tag and labeled by an alternative method. Two variants of the HER2-binding Affibody molecule Z(HER2:342) were made in an attempt to create a tagged tracer that could be purified by immobilized metal affinity chromatography, yet would not result in anomalous hepatic radioactivity accumulation following labeling with [Tc-99m(CO)(3)](+). In one construct, the hexahistidine tag was moved to the C-terminus. In the other construct, every second histidine residue in the hexahistidine tag was replaced by the more hydrophilic glutamate, resulting in a HEHEHE-tag. Both variants, denoted Z(HER2:342)-H-6 and (HE)(3)-Z(HER2:342), respectively, could be efficiently purified using IMAC and stably labeled with [Tc-99m(CO)(3)](+) and were subsequently compared with the parental H-6-Z(HER2:342) having an N-terminal hexahistidine tag. All three variants were demonstrated to specifically bind to HER2-expressing cells in vitro. The hepatic accumulation of radioactivity in a murine model was 2-fold lower with [Tc-99m(CO)(3)](+)-Z(HER2:342)-H-6 compared to [Tc-99m(CO)(3)](+)-H-6-Z(HER2:342), and more than 10-fold lower with [Tc-99m(CO)(3)](+)-(HE)(3)-Z(HER2:342). These differences translated into appreciably superior tumor-to-liver ratio for [Tc-99m(CO)(3)](+)-(HE)(3)-Z(HER2:342) compared to the alternative conjugates. This information might be useful for development of other scaffold-based molecular imaging probes.
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| 22. |
- Tolmachev, Vladimir, et al.
(författare)
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Imaging of Insulinlike Growth Factor Type 1 Receptor in Prostate Cancer Xenografts Using the Affibody Molecule (111)In-DOTA-Z(IGF1R:4551)
- 2012
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 53:1, s. 90-97
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Tidskriftsartikel (refereegranskat)abstract
- One of the pathways leading to androgen independence in prostate cancer involves upregulation of insulinlike growth factor type 1 receptor (IGF-1R). Radionuclide imaging of IGF-1R in tumors might be used for selection of patients who would most likely benefit from IGF-1R-targeted therapy. The goal of this study was to evaluate the feasibility of in vivo radionuclide imaging of IGF-1R expression in prostate cancer xenografts using a small nonimmunoglobulin-derived binding protein called an Affibody molecule. Methods: The IGF-1R-binding Z(IGF1R:4551) Affibody molecule was site-specifically conjugated with a maleimido derivative of DOTA and labeled with (111)In. The binding of radiolabeled Z(IGF1R:4551) to IGF-1R-expressing cells was evaluated in vitro and in vivo. Results: DOTA-Z(IGF1R:4551) can be stably labeled with (111)In with preserved specific binding to IGF-1R-expressing cells in vitro. In mice, (111)In-DOTAZ(IGF1R):(4551) accumulated in IGF-1R-expressing organs (pancreas, stomach, lung, and salivary gland). Receptor saturation experiments demonstrated that targeting of DU-145 prostate cancer xenografts in NMRI nu/nu mice was IGF-1R-specific. The tumor uptake was 1.1 +/- 0.3 percentage injected dose per gram, and the tumor-to-blood ratio was 3.2 +/- 0.2 at 8 h after injection. Conclusion: This study demonstrates the feasibility of in vivo targeting of IGF-1R-expressing prostate cancer xenografts using an Affibody molecule. Further development of radiolabeled Affibody molecules might provide a useful clinical tool for stratification of patients with prostate cancer for IGF-1R-targeting therapy.
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| 23. |
- Tolmachev, Vladimir, et al.
(författare)
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Imaging of platelet-derived growth factor receptor β expression in glioblastoma xenografts using affibody molecule 111In-DOTA-Z09591
- 2014
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 55:2, s. 294-300
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Tidskriftsartikel (refereegranskat)abstract
- The overexpression and excessive signaling of platelet-derived growth factor receptor β (PDGFRβ) has been detected in cancers, atherosclerosis, and a variety of fibrotic diseases. Radionuclide in vivo visualization of PDGFRβ expression might help to select PDGFRβ targeting treatment for these diseases. The goal of this study was to evaluate the feasibility of in vivo radionuclide imaging of PDGFRβ expression using an Affibody molecule, a small nonimmunoglobulin affinity protein.MethodsThe PDGFRβ-binding Z09591 Affibody molecule was site-specifically conjugated with a maleimido derivative of DOTA and labeled with 111In. Targeting of the PDGFRβ-expressing U-87 MG glioblastoma cell line using 111In-DOTA-Z09591 was evaluated in vitro and in vivo.ResultsDOTA-Z09591 was stably labeled with 111In with preserved specific binding to PDGFRβ-expressing cells in vitro. The dissociation constant for 111In-DOTA-Z09591 binding to U-87 MG cells was determined to be 92 ± 10 pM. In mice bearing U-87 MG xenografts, the tumor uptake of 111In-DOTA-Z09591 was 7.2 ± 2.4 percentage injected dose per gram and the tumor-to-blood ratio was 28 ± 14 at 2 h after injection. In vivo receptor saturation experiments demonstrated that targeting of U-87 MG xenografts in mice was PDGFRβ-specific. U-87 MG xenografts were clearly visualized using small-animal SPECT/CT at 3 h after injection.ConclusionThis study demonstrates the feasibility of in vivo visualization of PDGFRβ-expressing xenografts using an Affibody molecule. Further development of radiolabeled Affibody molecules might provide a useful clinical imaging tool for PDGFRβ expression during various pathologic conditions.
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| 24. |
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| 25. |
- Tolmachev, Vladimir, et al.
(författare)
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Tumor Targeting Using Affibody Molecules : Interplay of Affinity, Target Expression Level, and Binding Site Composition
- 2012
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 53:6, s. 953-960
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Tidskriftsartikel (refereegranskat)abstract
- Radionuclide imaging of cancer-associated molecular alterations may contribute to patient stratification for targeting therapy. Scaffold high-affinity proteins, such as Affibody molecules, are a new, promising class of probes for in vivo imaging. Methods. The effects of human epidermal growth factor receptor 2 (HER2) affinity and binding site composition of HER2-binding Affibody molecules, and of the HER2 density on the tumor targeting, were studied in vivo. The tumor uptake and tumor-to-organ ratios of Affibody molecules with moderate (dissociation constant [K-D)] 10(-9) M) or high (K-D = 10(-10) M) affinity were compared between tumor xenografts with a high (SKOV-3) and low (LS174T) HER2 expression level in BALB/C nu/nu mice. Two Affibody molecules with similar affinity (K-D = 10(-10) M) but having alternative amino acids in the binding site were compared. Results. In SKOV-3 xenografts, uptake was independent of affinity at 4 h after injection, but high-affinity binders provided 2-fold-higher tumor radioactivity retention at 24 h. In LS174T xenografts, uptake of high-affinity probes was already severalfold higher at 4 h after injection, and the difference was increased at 24 h. The clearance rate and tumor-to-organ ratios were influenced by the amino acid composition of the binding surface of the tracer protein. Conclusion. The optimal affinity of HER2-binding Affibody molecules depends on the expression of a molecular target. At a high expression level (>10(6) receptors per cell), an affinity in the low-nanomolar range is sufficient. At moderate expression, subnanomolar affinity is desirable. The binding site composition can influence the imaging contrast. This information may be useful for development of imaging agents based on scaffold affinity proteins.
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| 26. |
- Tordsson, Jesper, et al.
(författare)
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A3 -- a novel colon and pancreatic cancer reactive antibody from a primate phage library selected using intact tumour cells
- 2000
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Ingår i: International Journal of Cancer. - 0020-7136. ; 87:4, s. 559-568
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Tidskriftsartikel (refereegranskat)abstract
- The identification of novel tumour-associated antigens (TAAs) is pivotal for progression in the fields of tumour immunotherapy and diagnosis. In the present study, we have developed, based on flow cytometric evaluation and use of a mini-library composed of specific antibody clones linked to different antibiotic resistance markers, methods for positive and subtractive selection of phage antibodies employing intact cells as the antigen source. An scFv phage library (2.7 x 10(7)) was constructed from a primate (Macaca fascicularis) immunised with pooled human colon carcinomas. This library was selected for 3 rounds by binding to Colo 205 colon adenocarcinoma cells and proteolytic elution followed by phage amplification. Several antibodies reactive with colon carcinomas and with restricted reactivity to a few epithelial normal tissues were identified by immunohistochemistry. One clone, A3 scFv, recognised an epitope that was homogeneously expressed in 11/11 of colon and 4/4 pancreatic carcinomas studied and in normal tissue restricted to subtypes of epithelia in the gastrointestinal tract. The A3 scFv had an apparent overall affinity approximately 100-fold higher than an A3 Fab, suggesting binding of scFv homodimers. The cell surface density of the A3 epitope, calculated on the basis of Fab binding, was exceptionally high, approaching 3 million per cell. We also demonstrate efficient T-cell-mediated killing of colon cancer cells coated with A3 scFv fused to the low MHC class II binding superantigen mutant SEA(D227A). The identified A3 molecule thus represents a TAA with properties that suggest its use for immunotherapy of colon and pancreatic cancer.
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| 27. |
- Tran, Thuy, et al.
(författare)
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99mTc-maEEE-ZHER2:342, an Affibody Molecule-Based Tracer for the Detection of HER2 Expression in Malignant Tumors
- 2007
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 18:6, s. 1956-1964
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Tidskriftsartikel (refereegranskat)abstract
- Detection of HER2-overexpression in tumors and metastases is important for the selection of patients who will benefit from trastuzumab treatment. Earlier investigations showed successful imaging of HER2-positive tumors in patients using indium- or gallium-labeled Affibody molecules. The goal of this study was to evaluate the use of 99mTc-labeled Affibody molecules for the detection of HER2 expression. The Affibody molecule ZHER2:342 with the chelator sequences mercaptoacetyl-Gly-Glu-Gly (maGEG) and mercaptoacetyl-Glu-Glu-Glu (maEEE) was synthesized by peptide synthesis and labeled with technetium-99m. Binding specificity, cellular retention, and in vitro stability were investigated. The biodistribution of 99mTc-maGEG-ZHER2:342 and 99mTc-maEEE-ZHER2:342 was compared with 99mTc-maGGG-ZHER2:342 in normal mice, and the tumor targeting properties of 99mTc-maEEE-ZHER2:342 were determined in SKOV-3 xenografted nude mice. The results showed that the Affibody molecules were efficiently labeled with technetium-99m. The labeled conjugates were highly stable in vitro with preserved HER2-binding capacity. The use of glutamic acid in the chelator sequences for 99mTc-labeling of ZHER2:342 reduced the hepatobiliary excretion 3-fold with a single Gly-to-Glu substitution and 10-fold with three Gly-to-Glu substitutions. 99mTc-maEEE-ZHER2:342 showed a receptor-specific tumor uptake of 7.9 ± 1.0 %IA/g and a tumor-to-blood ratio of 38 at 4 h pi. Gamma-camera imaging with 99mTc-maEEE-ZHER2:342 could detect HER2-expressing tumors in xenografts already at 1 h pi. It was concluded that peptide synthesis for the coupling of chelator sequences to Affibody molecules for 99mTc labeling is an efficient way to modify the in vivo kinetics. Increased hydrophilicity, combined with improved stability of the mercaptoacetyl-triglutamyl chelator, resulted in favorable biodistribution, making 99mTc-maEEE-ZHER2:342 a promising tracer for clinical imaging of HER2 overexpression in tumors.
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| 28. |
- Tran, Thuy A., 1980-, et al.
(författare)
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Design, synthesis and biological evaluation of a multifunctional HER2-specific Affibody molecule for molecular imaging
- 2009
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 36:11, s. 1864-1873
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this study was to design and evaluate a novel platform for labelling of Affibody molecules, enabling for both recombinant and synthetic production and for site-specific labelling with 99mTc or trivalent radiometals. Methods: The HER2-specific Affibody molecule PEP05352 was made by peptide synthesis. The chelator sequence SECG (serine-glutamic acid-cysteine-glycine) was anchored on the C-terminal to allow 99mTc-labelling. The cysteine can alternatively serve as a conjugation site of the chelator DOTA for indium-labelling. The resulting 99mTc- and 111In-labelled Affibody molecules were evaluated both in vitro and in vivo. Results: Both conjugates retained their capacity to bind to HER2 receptors in vitro and in vivo. The tumour-to-blood ratio in LS174T xenografts was 30 at 4 h p.i. for both conjugates. Biodistribution data showed that 99mTc-labelled Affibody molecule had 4-fold lower kidney accumulation compared with 111In-labelled Affibody molecule while the accumulation in other organs was similar. Gamma-camera imaging of the conjugates could clearly visualise the tumours 4 h after injection. Conclusions: Incorporation of C-terminal SECG sequence in Affibody molecules provides a general multifunctional platform for site-specific labelling with different nuclides (technetium, indium, gallium, cobalt, or yttrium) and for a flexible production (chemical synthesis or recombinant).
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| 29. |
- Tran, Thuy, et al.
(författare)
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Effects of Lysine-Containing Mercaptoacetyl-Based Chelators on the Biodistribution of Tc-99m-Labeled Anti-HER2 Affibody Molecules
- 2008
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Ingår i: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 19:12, s. 2568-2576
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Tidskriftsartikel (refereegranskat)abstract
- The effects of polar (mercaptoacetyl-triseryl) and negatively charged (mercaptoacetyl-triglumatyl) chelators on the biodistribution of Tc-99m-labeled anti-HER2 Affibody molecules were previously investigated. With glycine, serine, and glutamate, we demonstrated that substitution with a single amino acid in the chelator can significantly influence the biodistribution properties and the excretion pathways. Here, we have taken this investigation further, by analyzing the effects of introduction of a positive amino acid residue on the in vivo properties of the Tc-99m-labeled Affibody molecule. The Affibody molecules with mercaptoacetyl-seryl-lysyl-seryl (maSKS) and mercaptoacetyl-trilysyl (maKKK) extensions were produced by peptide synthesis and labeled with Tc-99m in alkaline conditions. A comparative biodistribution was performed in normal mice to evaluate the excretion pathway. A shift toward renal excretion was obtained when serine was substituted with lysine in the chelatin sequence. The radioactivity in the gastrointestinal tract was reduced 3-fold for the Tc-99m-maSKS-Z(HER2:342) and Tc-99m-maKKK-Z(HER2:342) in comparison with the Tc-99m-maSSS-Z(HER2:342) conjugate 4 h post injection (p.i.). The radioactivity in the liver was elevated when a triple substitution of positively charged lysine was used. The tumor targeting properties of Tc-99m-maSKS-Z(HER2:342) were further investigated in SKOV-3 xenografts. The tumor uptake of Tc-99m-maSKS-Z(HER2:342) was 17 +/- 7% IA/g 4 h p.i. Tumor xenografts were well-visualized by gamma scintigraphy. In conclusion, the substitution with one single lysine in the chelator results in better tumor imaging properties of the Affibody molecule Z(HER2:342) and is favorable for imaging of tumors and metastases in the abdominal area. Multiple lysine residues in the chelator are, however, undesirable due to elevated uptake both in the liver and kidneys.
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| 30. |
- Wang, Ellen, et al.
(författare)
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Automated functional characterization of radiolabeled antibodies : a time-resolved approach
- 2014
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 35:7, s. 767-776
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Tidskriftsartikel (refereegranskat)abstract
- Background The number of radiolabeled monoclonal antibodies (mAbs) used for medical imaging and cancer therapy is increasing. The required chemical modification for attaching a radioactive label and all associated treatment may lead to a damaged mAb subpopulation. This paper describes a novel method, concentration through kinetics (CTK), for rapid assessment of the concentration of immunoreactive mAb and the specific radioactivity, based on monitoring binding kinetics. Methods The interaction of radiolabeled mAb with either the antigen or a general mAb binder such as Protein A was monitored in real time using the instrument LigandTracer. As the curvature of the binding trace has a distinct shape based on the interaction kinetics and concentration of the functional mAb, the immunoreactive mAb concentration could be calculated through reverse kinetic fitting of the binding curves, using software developed for this project. The specific activity, describing the degree of radioactive labeling, was determined through the use of calibrated signal intensities. Results The performance of the CTK assay was evaluated on the basis of various mAb-based interaction systems and assay formats, and it was shown that the assay can provide accurate and repeatable results for immunoreactive concentration and specific activity, with both accuracy and relative SD values below 15%. Conclusion By applying reverse kinetics on real-time binding traces it is possible to estimate the functional concentration and specific activity of radiolabeled mAb. The CTK assay may in the future be included as a complement to current quality assessment methods of radiolabeled mAbs.
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