TY - JOUR
T1 - Imaging of EGFR expression in murine xenografts using site-specifically labelled anti-EGFR 111In-DOTA-ZEGFR:2377 Affibody molecule
T2 - Aspect of the injected tracer amount
AU - Tolmachev, Vladimir
AU - Rosik, Daniel
AU - Wållberg, Helena
AU - Sjöberg, Anna
AU - Sandström, Mattias
AU - Hansson, Monika
AU - Wennborg, Anders
AU - Orlova, Anna
N1 - Funding Information:
Acknowledgments This study was supported by grants from the Swedish Cancer Society (Cancerfonden) and the Swedish Research Council (Vetenskapsrådet). We thank Veronika Eriksson and the staff of the animal facility at Rudbeck Laboratory for technical assistance.
Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2010/3
Y1 - 2010/3
N2 - Introduction: 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-ZEGFR:2377 Affibody molecule. Methods: An anti-EGFR Affibody molecule, ZEGFR:2377, was labelled with 111In via the DOTA chelator site-specifically conjugated to a C-terminal cysteine. The affinity of DOTA-ZEGFR:2377 for murine and human EGFR was measured by surface plasmon resonance. The cellular processing of 111In-DOTA-ZEGFR: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. Results: Site-specific coupling of DOTA provided a uniform conjugate possessing equal affinity for human and murine EGFR. The internalization of 111In-DOTA-ZEGFR: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 γ-camera imaging. Conclusion: The 111In-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.
AB - Introduction: 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-ZEGFR:2377 Affibody molecule. Methods: An anti-EGFR Affibody molecule, ZEGFR:2377, was labelled with 111In via the DOTA chelator site-specifically conjugated to a C-terminal cysteine. The affinity of DOTA-ZEGFR:2377 for murine and human EGFR was measured by surface plasmon resonance. The cellular processing of 111In-DOTA-ZEGFR: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. Results: Site-specific coupling of DOTA provided a uniform conjugate possessing equal affinity for human and murine EGFR. The internalization of 111In-DOTA-ZEGFR: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 γ-camera imaging. Conclusion: The 111In-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.
KW - Affibody molecules
KW - EGFR
KW - Gamma-camera imaging
KW - Indium-111
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U2 - 10.1007/s00259-009-1283-x
DO - 10.1007/s00259-009-1283-x
M3 - Article
C2 - 19838701
AN - SCOPUS:77949273331
VL - 37
SP - 613
EP - 622
JO - European Journal of Nuclear Medicine and Molecular Imaging
JF - European Journal of Nuclear Medicine and Molecular Imaging
SN - 1619-7070
IS - 3
ER -