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In vivo characterization of the novel CD44v6-targeting Fab fragment AbD15179 for molecular imaging of squamous cell carcinoma: a dual-isotope study
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Biomedical Radiation Sciences.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
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2014 (English)In: EJNMMI Research, ISSN 2191-219X, Vol. 4, no 1, 11- p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Patients with squamous cell carcinoma in the head and neck region (HNSCC) offer a diagnostic challenge due to difficulties to detect small tumours and metastases. Imaging methods available are not sufficient, and radio-immunodiagnostics could increase specificity and sensitivity of diagnostics. The objective of this study was to evaluate, for the first time, the in vivo properties of the radiolabelled CD44v6-targeting fragment AbD15179 and to assess its utility as a targeting agent for radio-immunodiagnostics of CD44v6-expressing tumours.

METHODS: The fully human CD44v6-targeting Fab fragment AbD15179 was labelled with 111In or 125I, as models for radionuclides suitable for imaging with SPECT or PET. Species specificity, antigen specificity and internalization properties were first assessed in vitro. In vivo specificity and biodistribution were then evaluated in tumour-bearing mice using a dual-tumour and dual-isotope setup.

RESULTS: Both species-specific and antigen-specific binding of the conjugates were demonstrated in vitro, with no detectable internalization. The in vivo studies demonstrated specific tumour binding and favourable tumour targeting properties for both conjugates, albeit with higher tumour uptake, slower tumour dissociation, higher tumour-to-blood ratio and higher CD44v6 sensitivity for the 111In-labelled fragment. In contrast, the 125I-Fab demonstrated more favourable tumour-to-organ ratios for liver, spleen and kidneys.

CONCLUSIONS: We conclude that AbD15179 efficiently targets CD44v6-expressing squamous cell carcinoma xenografts, and particularly, the 111In-Fab displayed high and specific tumour uptake. CD44v6 emerges as a suitable target for radio-immunodiagnostics, and a fully human antibody fragment such as AbD15179 can enable further clinical imaging studies.

Place, publisher, year, edition, pages
2014. Vol. 4, no 1, 11- p.
National Category
Radiology, Nuclear Medicine and Medical Imaging
URN: urn:nbn:se:uu:diva-221094DOI: 10.1186/2191-219X-4-11PubMedID: 24598405OAI: oai:DiVA.org:uu-221094DiVA: diva2:707653
Available from: 2014-03-25 Created: 2014-03-25 Last updated: 2015-07-07Bibliographically approved
In thesis
1. Towards Personalized Cancer Therapy: New Diagnostic Biomarkers and Radiosensitization Strategies
Open this publication in new window or tab >>Towards Personalized Cancer Therapy: New Diagnostic Biomarkers and Radiosensitization Strategies
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on the evaluation of biomarkers for radio-immunodiagnostics and radio-immunotherapy and on radiosensitization strategies after HSP90 inhibition, as a step towards more personalized cancer medicine. There is a need to develop new tracers that target cancer-specific biomarkers to improve diagnostic imaging, as well as to combine treatment strategies to potentiate synergistic effects. Special focus has been on the cell surface molecule CD44 and its oncogenic variants, which were found to exhibit unique expression patterns in head and neck squamous cell carcinoma (HNSCC). The variant CD44v6 seems to be a promising target, because it is overexpressed in this cancer type and is associated with radioresistance. Two new radioconjugates that target CD44v6, namely, the Fab fragment AbD15179 and the bivalent fragment AbD19384, were investigated with regard to specificity, biodistribution and imaging performance. Both conjugates were able to efficiently target CD44v6-positive tumors in vitro and in vivo. PET imaging of CD44v6 with 124I-AbD19384 revealed many advantages compared with the clinical standard 18F-FDG. Furthermore, the efficacy of the novel HSP90 inhibitor AT13387 and its potential use in combination with radiation treatment were evaluated. AT13387 proved to be a potent new cancer drug with favorable pharmacokinetics. Synergistic combination effects at clinically relevant drug and radiation doses are promising for both radiation dose reduction and minimization of side effects, or for an improved therapeutic response. The AT13387 investigation indicated that CD44v6 is not dependent on the molecular chaperone HSP90, and therefore, radio-immunotargeting of CD44v6 in combination with the HSP90 inhibitor AT13387 might potentiate treatment outcomes. However, EGFR expression levels did correlate with HSP90 inhibition, and therefore, molecular imaging of EGFR-positive tumors may be used to assess the treatment response to HSP90 inhibitors.

In conclusion, these results demonstrate how tumor targeting with radiolabeled vectors and chemotherapeutic compounds can provide more specific and sensitive diagnostic tools and treatment options, which can lead to customized treatment decisions and a functional diagnosis that provides more precise and safer drug prescribing, as well as a more effective treatment for each patient.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 62 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1085
tumor targeting, radionuclide targeting, HSP90 inhibition, AT13387, radiosensitization, molecular imaging, combination treatment, EGFR, CD44v6
National Category
Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging Cell and Molecular Biology
Research subject
Biomedical Radiation Science
urn:nbn:se:uu:diva-247539 (URN)978-91-554-9207-6 (ISBN)
Public defence
2015-05-13, Fåhraeussalen, Rudbecklaboratoriet, Dag Hammarskjölds väg 20, 751 85 Uppsala, 09:15 (English)
Available from: 2015-04-21 Created: 2015-03-20 Last updated: 2015-07-07

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