Imaging of EGFR expression in murine xenografts using site-specifically labelled anti-EGFR In-111-DOTA-Z(EGFR:2377) Affibody molecule: aspect of the injected tracer amount
2010 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 37, no 3, 613-622 p.Article in journal (Refereed) Published
Overexpression of epidermal growth factor receptor (EGFR) is a prognostic and predictive biomarker in a number of malignant tumours. Radionuclide molecular imaging of EGFR expression in cancer could influence patient management. However, EGFR expression in normal tissues might complicate in vivo imaging. The aim of this study was to evaluate if optimization of the injected protein dose might improve imaging of EGFR expression in tumours using a novel EGFR-targeting protein, the DOTA-Z(EGFR:2377) Affibody molecule. An anti-EGFR Affibody molecule, Z(EGFR:2377), was labelled with In-111 via the DOTA chelator site-specifically conjugated to a C-terminal cysteine. The affinity of DOTA-Z(EGFR:2377) for murine and human EGFR was measured by surface plasmon resonance. The cellular processing of In-111-DOTA-Z(EGFR:2377) was evaluated in vitro. The biodistribution of radiolabelled Affibody molecules injected in a broad range of injected Affibody protein doses was evaluated in mice bearing EGFR-expressing A431 xenografts. Site-specific coupling of DOTA provided a uniform conjugate possessing equal affinity for human and murine EGFR. The internalization of In-111-DOTA-Z(EGFR:2377) by A431 cells was slow. In vivo, the conjugate accumulated specifically in xenografts and in EGFR-expressing tissues. The curve representing the dependence of tumour uptake on the injected Affibody protein dose was bell-shaped. The highest specific radioactivity (lowest injected protein dose) provided a suboptimal tumour-to-blood ratio. The results of the biodistribution study were confirmed by gamma-camera imaging. The In-111-DOTA-Z(EGFR:2377) Affibody molecule is a promising tracer for radionuclide molecular imaging of EGFR expression in malignant tumours. Careful optimization of protein dose is required for high-contrast imaging of EGFR expression in vivo.
Place, publisher, year, edition, pages
2010. Vol. 37, no 3, 613-622 p.
Affibody molecules, EGFR, Indium-111, Gamma-camera imaging
Atom and Molecular Physics and Optics Radiology, Nuclear Medicine and Medical Imaging
IdentifiersURN: urn:nbn:se:kth:diva-28816DOI: 10.1007/s00259-009-1283-xISI: 000274544600020ScopusID: 2-s2.0-77949273331OAI: oai:DiVA.org:kth-28816DiVA: diva2:396837
FunderSwedish Research Council
QC 201102112011-02-112011-01-212011-02-11Bibliographically approved