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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
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 Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences. (BMS)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences. (BMS)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Section of Medical Physics.
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2009 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 50, no 5, 781-789 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2009. Vol. 50, no 5, 781-789 p.
Keyword [en]
Affibody molecule, technetium, imaging, HER2, C-terminal cysteine
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-122172DOI: 10.2967/jnumed.108.056929ISI: 000272487900017PubMedID: 19372467OAI: oai:DiVA.org:uu-122172DiVA: diva2:309246
Available from: 2010-04-07 Created: 2010-04-07 Last updated: 2017-12-12Bibliographically 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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 553
Keyword
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
Identifiers
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)
Opponent
Supervisors
Available from: 2010-04-29 Created: 2010-04-07 Last updated: 2010-04-29Bibliographically approved

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Orlova, AnnaTolmachev, Vladimir

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