PET of EGFR Expression with an 18F-Labeled Affibody Molecule

• DOI: 10.2967/jnumed.111.100842
• Publication Date: 2012-06-12T05:39:58Z
• Authors: Zheng Miao; Gang Ren; Hongguang Liu; Shibo Qi; Song Wu; Zhen Cheng
• Keywords: Biodistribution; Clearance; A431 cells

Epidermal growth factor receptor (EGFR) is often overexpressed in a variety of human cancers, and its expression associated with poor prognosis for many cancer types. However, an accurate technique to noninvasively image EGFR vivo not available the clinical setting. In this research, Affibody analog, anti-EGFR Ac-Cys-Z_EGFR:1907, was successfully site-specifically ¹⁸F-labeled PET expression. <b>Methods:</b> The prosthetic group <i>N</i>-[2-(4-¹⁸F-fluorobenzamido) ethyl] maleimide (¹⁸F-FBEM) conjugated Ac-Cys-Z_EGFR:1907 under mild conditions (pH 7) produce probe ¹⁸F-FBEM-Cys-Z_EGFR:1907. binding affinity specificity tests ¹⁸F-FBEM-Cys-Z_EGFR:1907 were conducted using A431 cells. Small-animal biodistribution studies on various mice tumor xenograft models overexpression (6 types) after injection approximately 2.0 MBq or without coinjection unlabeled up 3 h injection. A correlation study between small- animal quantification ex Western blot analysis those 6 types models. <b>Results:</b>¹⁸F-FBEM-Cys-Z_EGFR:1907 binds low nanomolar (37 nM) rapidly accumulated cleared from most normal organs except liver kidneys at injection, allowing excellent tumor–to–normal tissue contrast be obtained. model, 45 μg able improve uptake (3.9 vs. 8.1 percentage injected radioactive dose per gram tissue, injection) imaging contrast, whereas 500 blocked significantly (8.1 1.0 88% inhibition, <i>P</i> &lt; 0.05). Moderate found tracer quantified by levels measured assay (<i>P</i> = 0.007, <i>R</i> 0.59). <b>Conclusion:</b>¹⁸F-FBEM-Cys-Z_EGFR:1907 novel protein scaffold–based tumors, ability differentiate tumors high holds promise future translation.