title: Feasibility of imaging of epidermal growth factor receptor expression with ZEGFR:2377 affibody molecule labeled with 99mTc using a peptide-based cysteine-containing chelator.
abstract: The epidermal growth factor receptor (EGFR) is overexpressed in a number of malignant tumors and is a molecular target for several specific anticancer antibodies and tyrosine kinase inhibitors. The overexpression of EGFR is a predictive biomarker for response to several therapy regimens. Radionuclide molecular imaging might enable detection of EGFR overexpression by a non-invasive procedure and could be used repeatedly. Affibody molecules are engineered scaffold proteins, which could be selected to have a high affinity and selectivity to predetermined targets. The anti-EGFR ZEGFR:2377 affibody molecule is a potential imaging probe for EGFR detection. The use of the generator-produced radionuclide 99mTc should facilitate clinical translation of an imaging probe due to its low price, availability and favorable dosimetry of the radionuclide. In the present study, we evaluated feasibility of ZEGFR:2377 labeling with 99mTc using a peptide-based cysteine-containing chelator expressed at the C-terminus of ZEGFR:2377. The label was stable in vitro under cysteine challenge. In addition, 99mTc-ZEGFR:2377 was capable of specific binding to EGFR-expressing cells with high affinity (274 pM). Studies in BALB/C nu/nu mice bearing A431 xenografts demonstrated that 99mTc-ZEGFR:2377 accumulates in tumors in an EGFR-specific manner. The tumor uptake values were 3.6±1 and 2.5±0.4% ID/g at 3 and 24 h after injection, respectively. The corresponding tumor-to-blood ratios were 1.8±0.4 and 8±3. The xenografts were clearly visualized at both time-points. This study demonstrated the potential of 99mTc-labeled ZEGFR:2377 for imaging of EGFR in vivo.
authors.affiliation: Division of Protein Technology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors.forename: Ken G
authors.initials: KG
authors.lastname: Andersson
authors.affiliation: Institute of Immunology, Genetic and Pathology, Uppsala University, SE-75185 Uppsala, Sweden.
authors.forename: Maryam
authors.initials: M
authors.lastname: Oroujeni
authors.affiliation: Institute of Immunology, Genetic and Pathology, Uppsala University, SE-75185 Uppsala, Sweden.
authors.forename: Javad
authors.initials: J
authors.lastname: Garousi
authors.affiliation: Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, SE-75183 Uppsala, Sweden.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Mitran
authors.affiliation: Division of Protein Technology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors.forename: Stefan
authors.initials: S
authors.lastname: Ståhl
authors.affiliation: Division of Molecular Imaging, Department of Medicinal Chemistry, Uppsala University, SE-75183 Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Orlova
authors.affiliation: Division of Protein Technology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors.forename: John
authors.initials: J
authors.lastname: Löfblom
authors.affiliation: Institute of Immunology, Genetic and Pathology, Uppsala University, SE-75185 Uppsala, Sweden.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Tolmachev
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D009368:Neoplasm Transplantation; D011868:Radioisotopes / Q000378:metabolism*; D011877:Radionuclide Imaging / Q000379:methods*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D013667:Technetium / Q000378:metabolism*; D014183:Transplantation, Heterologous
chemical_list: D011868:Radioisotopes; D011993:Recombinant Fusion Proteins; D013667:Technetium; C512478:EGFR protein, human; D066246:ErbB Receptors