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Preparation and evaluation of (68)Ga-DOTA-hEGF for visualisation of EGFR expression in malignant tumours
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences.
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2005 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 46, no 11, 1881-1888 p.Article in journal (Refereed) Published
Abstract [en]

Detection of epidermal growth factor receptor (EGFR) overexpression in many carcinomas provides important diagnostic information, which can influence patient management. The use of PET may enable such detection in vivo by a noninvasive procedure with high sensitivity. The aim of this study was to develop a method for preparation of a positron-emitting tracer based on a natural ligand to EGFR, the recombinant human epidermal growth factor (hEGF), and to perform a preclinical evaluation of the tracer.

METHODS: DOTA-hEGF (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) was prepared by coupling of a N-sulfosuccinimide ester of DOTA to hEGF. The conjugate was labeled with a generator-produced positron-emitting nuclide, (68)Ga (half-life = 68 min), using microwave heating. Binding specificity, affinity, internalization, and retention of (68)Ga-DOTA-hEGF was studied in 2 EGFR-expressing cell lines, U343 glioma cells and A431 cervical carcinoma cells. Biodistribution and microPET visualization studies were performed in BALB/c nu/nu mice bearing A431 carcinoma xenografts.

RESULTS: A 1-min-long microwave-assisted labeling provided radioactivity incorporation of 77% +/- 4%. Both cell lines demonstrated receptor-specific uptake of the conjugate, rapid internalization of the tracer, and good retention of radioactivity. Binding to both cell lines occurred with high affinity, approximately 2 nmol/L. The biodistribution study demonstrated accumulation of radioactivity in xenografts and in EGFR-expressing organs. The microPET imaging study enabled visualization of tumors and demonstrated quick--within 5 min--localization of radioactivity in tumors.

CONCLUSION: (68)Ga-DOTA-hEGF has potential for imaging EGFR overexpression in tumors.

Place, publisher, year, edition, pages
2005. Vol. 46, no 11, 1881-1888 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-93263PubMedID: 16269603OAI: oai:DiVA.org:uu-93263DiVA: diva2:166693
Available from: 2005-09-02 Created: 2005-09-02 Last updated: 2013-05-29Bibliographically approved
In thesis
1. Synthesis, Characterisation and Application of 68Ga-labelled Macromolecules
Open this publication in new window or tab >>Synthesis, Characterisation and Application of 68Ga-labelled Macromolecules
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The positron emitting radionuclide 68Ga (T1/2 = 68 min) might become of practical interest for clinical positron emission tomography (PET). The metallic cation, 68Ga(III), is suitable for complexation with chelators, either naked or conjugated with biological macromolecules. Such labelling procedures require pure and concentrated preparations of 68Ga(III), which cannot be sufficiently fulfilled by the presently available 68Ge/68Ga generator eluate. This thesis presents methods to increase the concentration and purity of 68Ga obtained from a commercial 68Ge/68Ga generator. The use of the preconcentrated and purified 68Ga eluate along with microwave heating allowed quantitative 68Ga-labelling of peptide conjugates within 15 min. The specific radioactivity of the radiolabelled peptides was improved considerably compared to previously applied techniques using non-treated generator eluate and conventional heating. A commercial 68Ge/68Ga generator in combination with the method for preconcentration/purification and microwave heated labelling might result in an automated device for 68Ga-based radiopharmaceutical kit production with quantitative incorporation of 68Ga(III).

Macromolecules were labelled with 68Ga(III) either directly or via a chelator. The bifunctional chelator, DOTA, was conjugated in solution to peptides, an antibody and oligonucleotides. The peptides had varied pI values, constitution, and length ranging from 8 to 53 amino acid residues. The oligonucleotides were of various sequences and length with modifications in backbone, sugar moiety and both 3' and 5' ends with a molecular weight up to 9.8 kDa. The bioconjugates were labeled with 68Ga(III), and the resulting tracers were characterised chemically and biologically. The identity of the 68Ga-labelled bioconjugates was verified. The tracers were found to be stable and their biological activity maintained. Specific radioactivity was shown to be an important parameter influencing the feasibility of accurate imaging data quantification.

Furthermore, 68Ga-labelled peptide imaging was shown to be a useful tool to study peptide adsorption to microstructures in a chemical analysis device.

Place, publisher, year, edition, pages
Uppsala: Kemiska institutionen, 2005. 68 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 73
Chemistry, 68Ga, 68Ge/68Ga generator, radiolabelling, microwave heating, specific radioactivity, peptide, protein, antibody, oligonucleotide, positron emission tomography, tumour, Kemi
National Category
Chemical Sciences
urn:nbn:se:uu:diva-5876 (URN)91-554-6295-2 (ISBN)
Public defence
2005-09-23, Room B21, BMC, Husarg. 3, Uppsala, 13:15
Available from: 2005-09-02 Created: 2005-09-02Bibliographically approved

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