Data from Imaging Epidermal Growth Factor Receptor Expression <i>In vivo</i>: Pharmacokinetic and Biodistribution Characterization of a Bioconjugated Quantum Dot Nanoprobe

Abstract

&lt;div&gt;Abstract&lt;p&gt;&lt;b&gt;Purpose:&lt;/b&gt; To develop and validate an optical imaging nanoprobe for the discrimination of epidermal growth factor (EGF) receptor (EGFR)–overexpressing tumors from surrounding normal tissues that also expresses EGFR.&lt;/p&gt;&lt;p&gt;&lt;b&gt;Experimental Design:&lt;/b&gt; Near-infrared (NIR) quantum dots (QD) were coupled to EGF using thiol-maleimide conjugation to create EGF-QD nanoprobes. &lt;i&gt;In vitro&lt;/i&gt; binding affinity of these nanoprobes and unconjugated QDs was evaluated in a panel of cell lines, with and without anti-EGFR antibody pretreatment. Serial optical imaging of HCT116 xenograft tumors was done after systemic injection of QD and EGF-QD.&lt;/p&gt;&lt;p&gt;&lt;b&gt;Results:&lt;/b&gt; EGF-QD showed EGFR-specific binding &lt;i&gt;in vitro. In vivo&lt;/i&gt; imaging showed three distinct phases, tumor influx (∼3 min), clearance (∼60 min), and accumulation (1-6 h), of EGF-QD nanoprobes. Both QD and EGF-QD showed comparable nonspecific rapid tumor influx and clearance followed by attainment of an apparent dynamic equilibrium at ∼60 min. Subsequently (1-6 h), whereas QD concentration gradually decreased in tumors, EGF-QDs progressively accumulated in tumors. On delayed imaging at 24 h, tumor fluorescence decreased to near-baseline levels for both QD and EGF-QD. &lt;i&gt;Ex vivo&lt;/i&gt; whole-organ fluorescence, tissue homogenate fluorescence, and confocal microscopic analyses confirmed tumor-specific accumulation of EGF-QD at 4 h. Immunofluorescence images showed diffuse colocalization of EGF-QD fluorescence within EGFR-expressing tumor parenchyma compared with patchy perivascular sequestration of QD.&lt;/p&gt;&lt;p&gt;&lt;b&gt;Conclusion:&lt;/b&gt; These results represent the first pharmacokinetic characterization of a robust EGFR imaging nanoprobe. The measurable contrast enhancement of tumors 4 h after systemic administration of EGF-QD and its subsequent normalization at 24 h imply that this nanoprobe may permit quantifiable and repetitive imaging of EGFR expression.&lt;/p&gt;&lt;/div&gt;