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Gallium-68-Labeled Affibody Molecule for PET Imaging of PDGFRβ Expression in Vivo
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences. (Tolmachev)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Preclinical PET Platform. (Orlova)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Preclinical PET Platform.
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2014 (English)In: Molecular Pharmaceutics, ISSN 1543-8384, Vol. 11, no 11, 3957-3964 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2014. Vol. 11, no 11, 3957-3964 p.
National Category
Medical Biotechnology
URN: urn:nbn:se:uu:diva-235390DOI: 10.1021/mp500284tPubMedID: 24972112OAI: oai:DiVA.org:uu-235390DiVA: diva2:759958
Available from: 2014-11-01 Created: 2014-11-01 Last updated: 2015-10-01Bibliographically approved
In thesis
1. Affibody Molecules for PET Imaging
Open this publication in new window or tab >>Affibody Molecules for PET Imaging
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Optimization of Affibody molecules would allow for high contrast imaging of cancer associated surface receptors using molecular imaging. The primary aim of the thesis was to develop Affibody-based PET imaging agents to provide the highest possible sensitivity of RTK detection in vivo. The thesis evaluates the effect of radiolabelling chemistry on biodistribution and targeting properties of Affibody molecules directed against HER2 and PDGFRβ. The thesis is based on five published papers (I-V).

Paper I. The targeting properties of maleimido derivatives of DOTA and NODAGA for site-specific labelling of a recombinant HER2-binding Affibody molecule radiolabelled with 68Ga were compared in vivo. Favourable in vivo properties were seen for the Affibody molecule with the combination of 68Ga with NODAGA.

Paper II. The aim was to compare the biodistribution of 68Ga- and 111In-labelled HER2-targeting Affibody molecules containing DOTA, NOTA and NODAGA at the N-terminus. This paper also demonstrated favourable in vivo properties for Affibody molecules in combination with 68Ga and NODAGA placed on the N-terminus.

Paper III.  The influence of chelator positioning on the synthetic anti-HER2 affibody molecule labelled with 68Ga was investigated. The chelator DOTA was conjugated either at the N-terminus, the middle of helix-3 or at the C-terminus of the Affibody molecules. The N-terminus placement provided the highest tumour uptake and tumour-to-organ ratios.

Paper IV. The aim of this study was to evaluate if the 68Ga labelled PDGFRβ-targeting Affibody would provide an imaging agent suitable for PDGFRβ visualization using PET. The 68Ga labelled conjugate provided high-contrast imaging of PDGFRβ-expressing tumours in vivo using microPET as early as 2h after injection.

Paper V. This paper investigated if the replacement of IHPEM with IPEM as a linker molecule for radioiodination of Affibody molecules would reduce renal retention of radioactivity. Results showed that the use of the more lipophilic linker IPEM reduced the renal radioactivity retention for radioiodinated Affibody molecules.

In conclusion, this thesis clearly demonstrates that the labelling strategy is of great importance with a substantial influence on the targeting properties of Affibody molecules and should be taken under serious considerations when developing new imaging agents.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 70 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1125
Affibody molecules, Molecular imaging, PET, Radiolabelling, HER2, PDGFRβ
National Category
Medical and Health Sciences
Research subject
Biomedical Radiation Science
urn:nbn:se:uu:diva-259410 (URN)978-91-554-9299-1 (ISBN)
Public defence
2015-10-03, Fåhraeussalen, Rudbecklaboratoriet, Dag Hammarskjölds väg 20, 751 85, Uppsala, 09:00 (English)
Available from: 2015-09-03 Created: 2015-08-03 Last updated: 2015-10-01

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Strand, JoannaVarasteh, ZohrehEriksson, OlofOrlova, AnnaTolmachev, Vladimir
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