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Targeting of HER2-Expressing Tumors Using 111In-ABY-025, a Second-Generation Affibody Molecule with a Fundamentally Reengineered Scaffold
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science. (BMS)ORCID iD: 0000-0001-6120-2683
Affibody AB, Stockholm, Sweden.
Affibody AB, Stockholm, Sweden.
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2010 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 51, no 7, 1131-1138 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2010. Vol. 51, no 7, 1131-1138 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-122176DOI: 10.2967/jnumed.109.073346ISI: 000279430900021PubMedID: 20554729OAI: oai:DiVA.org:uu-122176DiVA: diva2:309248
Available from: 2010-04-07 Created: 2010-04-07 Last updated: 2015-03-24Bibliographically approved
In thesis
1. Molecular Radionuclide Imaging Using Site-specifically Labelled Recombinant Affibody Molecules: Preparation and Preclinical Evaluation
Open this publication in new window or tab >>Molecular Radionuclide Imaging Using Site-specifically Labelled Recombinant Affibody Molecules: Preparation and Preclinical Evaluation
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radionuclide molecular imaging is an emerging multidisciplinary technique that is used in modern medicine to visualise diseases at cellular and molecular levels. This thesis is based on five papers (I-V) and focuses on the development of site-specific radiolabelled recombinant anti-HER2 Affibody molecules and preclinical evaluations in vitro and in vivo of the labelled conjugates. This work is part of a preclinical development of an Affibody molecule-based tracer for molecular imaging of HER2 expressing tumours.

Papers I and II report the evaluation of the Affibody molecule ZHER2:2395-C, site-specifically labelled with the radiometals 111In (for SPECT) and 57Co (as a surrogate for 55Co, suitable for PET applications) using a thiol reactive DOTA derivative as a chelator. Both conjugates demonstrated very suitable biodistribution properties, enabling high contrast imaging just a few hours after injection.

Papers III and IV report the development and optimization of a technique for site-specific labelling of ZHER2:2395-C with 99mTc using an N3S chelating peptide sequence. 99mTc-ZHER2:2395-C demonstrated high and specific tumour uptake and rapid clearance of non-bound tracer from the blood, resulting in high tumour-to-non-tumour ratios shortly after injection, enabling high contrast imaging. In addition, in the study described in paper IV, freeze-dried kits previously developed for 99mTc-labelling were optimised, resulting in the development of a kit in which all the reagents and protein needed for labelling of ZHER2:2395-C with 99mTc were contained in a single vial.

Paper V reports the evaluation of an anti-HER2 Affibody molecule, ABY-025, with a fundamentally re-engineered scaffold. Despite the profound re-engineering, the biodistribution pattern of 111In-ABY-025 was very similar to that of two variants of the parental molecule.

It seems reasonable to believe that these results will also be applicable to Affibody molecules towards other targets. Hopefully, this work will also be helpful in the development of other small proteinaceous tracers.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 70 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 553
molecular radionuclide imaging, Affibody molecules, HER2, cancer detection, radiolabelling, technetium, indium, cobalt, SPECT, PET
National Category
Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging Radiology, Nuclear Medicine and Medical Imaging
Research subject
Biomedical Radiation Science; Medical Science
urn:nbn:se:uu:diva-122177 (URN)978-91-554-7787-5 (ISBN)
Public defence
2010-05-22, Rudbecksalen, Rudbecklaboratoriet, Dag Hammarskjölds väg 20, Uppsala, 09:15 (English)
Available from: 2010-04-29 Created: 2010-04-07 Last updated: 2010-04-29Bibliographically approved

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