Research Article Comparative Evaluation of Anti-HER2 Affibody Molecules Labeled with 64 Cu Using NOTA and NODAGA Vladimir Tolmachev, 1 Cheng-Bin Yim, 2,3 Johan Rajander, 3 Anna Perols, 4 Amelie Eriksson Karlström, 4 Merja Haaparanta-Solin, 2,5 Tove J. Grönroos, 2,5,6 Olof Solin, 2,3,7 and Anna Orlova 8 1 Department of Immunology, Genetics and Pathology, Uppsala University, 75185 Uppsala, Sweden 2 Turku PET Centre, University of Turku, P.O. Box 52, 20521 Turku, Finland 3 Turku PET Centre, ˚ Abo Akademi University, P.O. Box 52, 20521 Turku, Finland 4 Division of Protein Technology, School of Biotechnology, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden 5 MediCity Research Laboratory, University of Turku, 20520 Turku, Finland 6 Department of Oncology and Radiotherapy, Turku University Hospital, 20520 Turku, Finland 7 Department of Chemistry, University of Turku, 20014 Turku, Finland 8 Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, 751 05 Uppsala, Sweden Correspondence should be addressed to Vladimir Tolmachev; vladimir.tolmachev@igp.uu.se Received 4 January 2017; Accepted 8 February 2017; Published 28 February 2017 Academic Editor: Ralf Schirrmacher Copyright © 2017 Vladimir Tolmachev et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Imaging using affibody molecules enables discrimination between breast cancer metastases with high and low expression of HER2, making appropriate therapy selection possible. is study aimed to evaluate if the longer half-life of 64 Cu ( 1/2 = 12.7 h) would make 64 Cu a superior nuclide compared to 68 Ga for PET imaging of HER2 expression using affibody molecules. e synthetic ZHER2:S1 affibody molecule was conjugated with the chelators NOTA or NODAGA and labeled with 64 Cu. e tumor-targeting properties of 64 Cu-NOTA-ZHER2:S1 and 64 Cu-NODAGA-ZHER2:S1 were evaluated and compared with the targeting properties of 68 Ga-NODAGA-ZHER2:S1 in mice. Both 64 Cu-NOTA-ZHER2:S1 and 64 Cu-NODAGA-ZHER2:S1 demonstrated specific targeting of HER2-expressing xenograſts. At 2 h aſter injection of 64 Cu-NOTA-ZHER2:S1, 64 Cu-NODAGA-ZHER2:S1, and 68 Ga-NODAGA- ZHER2:S1, tumor uptakes did not differ significantly. Renal uptake of 64 Cu-labeled conjugates was dramatically reduced at 6 and 24 h aſter injection. Notably, radioactivity uptake concomitantly increased in blood, lung, liver, spleen, and intestines, which resulted in decreased tumor-to-organ ratios compared to 2 h postinjection. Organ uptake was lower for 64 Cu-NODAGA-ZHER2:S1. e most probable explanation for this biodistribution pattern was the release and redistribution of renal radiometabolites. In conclusion, monoamide derivatives of NOTA and NODAGA may be suboptimal chelators for radiocopper labeling of anti-HER2 affibody molecules and, possibly, other scaffold proteins with high renal uptake. 1. Introduction Treatment of disseminated breast cancer, which overex- presses human epidermal growth factor receptor type 2 (HER2), with the monoclonal antibody trastuzumab, the antibody-drug conjugate trastuzumab DM-1, or the tyrosine kinase inhibitor lapatinib improves the survival of patients [1]. HER2 overexpression is a predictive biomarker for HER2-targeting therapies [2]. e use of sensitive radionu- clide molecular imaging may permit repetitive noninvasive assessment of HER2 expression in breast cancer metastases, addressing the issue of spatial and temporal heterogeneity of HER2 expression. e use of radiolabeled HER2-specific antibodies [3, 4] and their fragments [5] for clinical imaging of HER2 expression has been reported. Mathematic modeling suggests that for a proteinaceous imaging probe the combination of small size with high affin- ity provides the highest contrast and consequently the highest sensitivity of radionuclide molecular imaging [6]. Indeed, Hindawi Contrast Media & Molecular Imaging Volume 2017, Article ID 8565802, 12 pages https://doi.org/10.1155/2017/8565802