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Comparative evaluation of synthetic anti-HER2 Affibody molecules site-specifically labelled with 111In using N-terminal DOTA, NOTA and NODAGA chelators in mice bearing prostate cancer xenografts.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Preclinical PET Platform. (Anna Orlova)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Preclinical PET Platform. (Anna Orlova)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences. (Vladimir Tolmachev)
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2012 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 39, no 3, 481-492 p.Article in journal (Refereed) Published
Abstract [en]

PURPOSE: In disseminated prostate cancer, expression of human epidermal growth factor receptor type 2 (HER2) is one of the pathways to androgen independence. Radionuclide molecular imaging of HER2 expression in disseminated prostate cancer might identify patients for HER2-targeted therapy. Affibody molecules are small (7 kDa) targeting proteins with high potential as tracers for radionuclide imaging. The goal of this study was to develop an optimal Affibody-based tracer for visualization of HER2 expression in prostate cancer.

METHODS: A synthetic variant of the anti-HER2 Z(HER2:342) Affibody molecule, Z(HER2:S1), was N-terminally conjugated with the chelators DOTA, NOTA and NODAGA. The conjugated proteins were biophysically characterized by electrospray ionization mass spectroscopy (ESI-MS), circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR)-based biosensor analysis. After labelling with (111)In, the biodistribution was assessed in normal mice and the two most promising conjugates were further evaluated for tumour targeting in mice bearing DU-145 prostate cancer xenografts.

RESULTS: The HER2-binding equilibrium dissociation constants were 130, 140 and 90 pM for DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1), respectively. A comparative study of (111)In-labelled DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1) in normal mice demonstrated a substantial influence of the chelators on the biodistribution properties of the conjugates. (111)In-NODAGA-Z(HER2:S1) had the most rapid clearance from blood and healthy tissues. (111)In-NOTA-Z(HER2:S1) showed high hepatic uptake and was excluded from further evaluation. (111)In-DOTA-Z(HER2:S1) and (111)In-NODAGA-Z(HER2:S1) demonstrated specific uptake in DU-145 prostate cancer xenografts in nude mice. The tumour uptake of (111)In-NODAGA-Z(HER2:S1), 5.6 ± 0.4%ID/g, was significantly lower than the uptake of (111)In-DOTA-Z(HER2:S1), 7.4 ± 0.5%ID/g, presumably because of lower bioavailability due to more rapid clearance. (111)In-NODAGA-Z(HER2:S1) provided higher tumour-to-blood ratio, but somewhat lower tumour-to-liver, tumour-to-spleen and tumour-to-bone ratios.

CONCLUSION: Since distant prostate cancer metastases are situated in bone or bone marrow, the higher tumour-to-bone ratio is the most important. This renders (111)In-DOTA-Z(HER2:S1) a preferable agent for imaging of HER2 expression in disseminated prostate cancer.

Place, publisher, year, edition, pages
2012. Vol. 39, no 3, 481-492 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-173741DOI: 10.1007/s00259-011-1992-9ISI: 000302287200015PubMedID: 22322933OAI: oai:DiVA.org:uu-173741DiVA: diva2:525024
Available from: 2012-05-04 Created: 2012-05-04 Last updated: 2015-03-24Bibliographically approved
In thesis
1. Preclinical Development of Imaging Agents for HER2 Expression in Prostate Cancer Using Radiolabeled Affibody Molecules
Open this publication in new window or tab >>Preclinical Development of Imaging Agents for HER2 Expression in Prostate Cancer Using Radiolabeled Affibody Molecules
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is focused on pre-clinical evaluation of in vivo detection of HER2-expression in prostate cancer (PCa) patients and on the possibility of using targeted molecular imaging to personalize treatment of disseminated PCa. The work is divided into three distinct parts: (1) the establishment of a preclinical model for further studies, (2) imaging of HER2 in a murine model of PCa and (3) exploration of new treatment regimes against PCa. The characterized cell line panel reflect the heterogeneity of PCa in a way that one cell line never could, and is crucial for a better understanding of different developmental stages during the progression toward androgen independence. The possibility of molecular detection of HER2 in PCa was determined in vitro using 111In-labeled CHX-A’’DTPA-trastuzumab and anti-HER2 ABY-025 affibody molecules. A novel real-time assay for radiolabeled tracer kinetics on living cells was evaluated, in an attempt to bring early developmental work a step closer to the target environment (imaging in living systems). The second part demonstrated the possibility of imaging PCa xenografts, despite the low expression levels, and that  ABY-025 is better adapted for this than the therapeutic anti-HER2 antibody trastuzumab. The study also demonstrated that a residualizing radiometal-label further improves imaging contrast. A comparative study of a HER2-binding affibody molecule N-terminally conjugated to DOTA, NOTA or NODAGA highlighted the influence of the chelator on biodistribution and emphasized the importance of taking into account potential metastatic sited during tracer development. The final study used the previously established in vitro model to explore the hypothesis of using molecular imaging of HER2 to identify PCa patients that may benefit from complemental treatment.

One conclusion from this thesis is that for imaging of PCa, molecular biological context and expression of the molecular target are equally important to consider. Another, that evaluation of response to treatment also need to consider the effect on the overall phenotypic profile, and consequently what this could mean for the efficacy of the treatment. The results of this thesis are in a larger perspective related to how the heterogeneity of tumors may affect the models used for diagnostics and monitoring of cancer in general.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 66 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 179
National Category
Pharmaceutical Sciences
Research subject
Pharmaceutical Science; Biomedical Radiation Science
urn:nbn:se:uu:diva-207256 (URN)978-91-554-8764-5 (ISBN)
Public defence
2013-11-08, Rudbecksalen, Dag Hammarskjölds väg 20, Uppsala, 09:15 (English)
Available from: 2013-10-17 Created: 2013-09-11 Last updated: 2014-01-23

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Malmberg, JennieVarasteh, ZohrehAltai, MohamedGarske, UlrikeTolmachev, VladimirOrlova, Anna
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