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Affibody mediated tumor targeting of HER-2 expressing xenografts in mice
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2006 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 33, no 6, 631-638 p.Article in journal (Refereed) Published
Abstract [en]


Targeted delivery of radionuclides for diagnostic and therapeutic applications has until recently largely been limited to receptor ligands, antibodies and antibody-derived molecules. Here, we present a new type of molecule, a 15-kDa bivalent affibody called (Z(HER2:4))(2), with potential for such applications. The (Z(HER2:4))(2) affibody showed high apparent affinity (K (D)=3 nM) towards the oncogene product HER-2 (also called p185/neu or c-erbB-2), which is often overexpressed in breast and ovarian cancers. The purpose of this study was to investigate the in vivo properties of the new targeting agent.


The biodistribution and tumour uptake of the radioiodinated (Z(HER2:4))(2) affibody was studied in nude mice carrying tumours from xenografted HER-2 overexpressing SKOV-3 cells.


The radioiodinated (Z(HER2:4))(2) affibody was primarily excreted through the kidneys, and significant amounts of radioactivity were specifically targeted to the tumours. The blood-borne radioactivity was, at all times, mainly in the macromolecular fraction. A tumour-to-blood ratio of about 10:1 was obtained 8 h post injection, and the tumours could be easily visualised with a gamma camera at this time point.


The results indicate that the (Z(HER2:4))(2) affibody is an interesting candidate for applications in nuclear medicine, such as radionuclide-based tumour imaging and therapy.

Place, publisher, year, edition, pages
2006. Vol. 33, no 6, 631-638 p.
Keyword [en]
affibody, HER-2, imaging, SKOV-3, tumour, breast-cancer, in-vitro, cellular retention, human tissues, antibody, proteins, binding, overexpression, localization, penetration
National Category
Medical Engineering
URN: urn:nbn:se:kth:diva-5179DOI: 10.1007/s00259-005-0012-3ISI: 000238023000002ScopusID: 2-s2.0-33646259546OAI: diva2:7987
Updated from submitted to published. QC 20111007Available from: 2005-05-30 Created: 2005-05-30 Last updated: 2012-02-22Bibliographically approved
In thesis
1. Rational and combinatorial protein engineering for vaccine delivery and drug targeting
Open this publication in new window or tab >>Rational and combinatorial protein engineering for vaccine delivery and drug targeting
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis describes recombinant proteins that have been generated by rational and combinatorial protein engineering strategies for use in subunit vaccine delivery and tumor targeting.

In a first series of studies, recombinant methods for incorporating immunogens into an adjuvant formulation, e.g. immunostimulating complexes (iscoms), were evaluated. Protein immunogens, which are not typically immunogenic in themselves, are normally administered with an adjuvant to improve their immunogenicity. To accomplish iscom incorporation of a Toxoplasma gondii surface antigen through hydrophobic interaction, lipids were added either in vivo via E. coli expression, or in vitro via interaction of an introduced hexahistidyl (His6) peptide and a chelating lipid. The possibility of exploiting the strong interaction between biotin and streptavidin was also explored, in order to couple a Neospora caninum surface antigen to iscom matrix, i.e. iscom particles without any antigen. Subsequent analyses confirmed that the immunogens were successfully incorporated into iscoms by the investigated strategies. In addition, immunization of mice with the recombinant Neospora antigen NcSRS2, associated with iscoms through the biotin-streptavidin interaction, induced specific antibodies to native NcSRS2 and reduced clinical symptoms following challenge infection. The systems described in this thesis might offer convenient and efficient methods for incorporating recombinant immunogens into adjuvant formulations that might be considered for the generation of future recombinant subunit vaccines.

In a second series of studies, Affibody® (affibody) ligands directed to the extracellular domain of human epidermal growth factor receptor 2 (HER2/neu), which is known to be overexpressed in ∼ 20-30% of breast cancers, were isolated by phage display in vitro selection from a combinatorial protein library based on the 58 amino acid residue staphylococcal protein A-derived Z domain. Biosensor analyses demonstrated that one of the variants from the phage selection, denoted His6-ZHER2/neu:4, selectively bound with nanomolar affinity (KD ≈ 50 nM) to the extracellular domain of HER2/neu (HER2-ECD) at a different site than the monoclonal antibody trastuzumab. In order to exploit avidity effects, a bivalent affibody ligand was constructed by head-to-tail dimerization, resulting in a 15.6 kDa affibody ligand, termed His6-(ZHER2/neu:4)2, that was shown to have an improved apparent affinity to HER2-ECD (KD ≈ 3 nM) compared to the monovalent affibody. Moreover, radiolabeled monovalent and bivalent affibody ligands showed specific binding in vitro to native HER2/neu molecules expressed in human cancer cells. Biodistribution studies in mice carrying SKOV-3 xenografted tumors revealed that significant amounts of radioactivity were specifically targeted to the tumors in vivo, and the tumors could easily be visualized with a gamma camera. These results suggest that affibody ligands would be interesting candidates for specific tumor targeting in clinical applications, such as in vivo imaging and radiotherapy.

Biomedicine, affibody, affinity chromatography, biotin, combinatorial, delivery, phage display, Biomedicin
National Category
Microbiology in the medical area
urn:nbn:se:kth:diva-231 (URN)91-7178-003-3 (ISBN)
Public defence
2005-06-03, Sal FD5, AlbaNova, Roslagstullsbacken 21, Stockholm, 13:00
Available from: 2005-05-30 Created: 2005-05-30 Last updated: 2012-03-22

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