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Abstract #0485

MR Imaging of U87δEGFR Human Glioma Tumor Xenografts Using Targeted Signal-Amplifying Enzymatic System

Mohammed Salman Shazeeb1, Suresh Gupta1, Alexei Bogdanov1, 2

1Department of Radiology, University of Massachusetts Medical School, Worcester, MA, United States; 2Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA, United States

Molecular MR imaging of tumors expressing the EGF receptor variant III (EGFRvIII) was carried out in rats implanted with U87EGFR human glioma xenografts in brain. Following systemic administration, anti-EGFRvIII monoclonal antibody conjugates of deglycosylated horseradish peroxidase (HRP) and glucose oxidase (GOX), facilitated local binding and prolonged retention of a paramagnetic molecular substrate, diTyr-DTPA(Gd), to sites of EGFRvIII overexpression. Retention of contrast agent following conjugate administration resulted in signal enhancement that was similar to that observed in our earlier studies of Gli36EGFR tumors. This further demonstrates the utility of a self-complementing enzymatic signal amplification system for EGFRvIII targeted imaging.