Quantitative evaluation of individual fluorophore and paired agent imaging performance for glioma visualization

The current standard of care for glioma treatment remains limited and contributes to a dismal medial overall survival of 16.7 months. It involves maximal surgical resection followed by radiation and/or chemotherapy. However, the success of surgical resection strongly relies on the surgeon’s ability to accurately visualize the tumor intraoperatively1. To improve visualization, Fluorescence guided surgery (FGS) has been increasingly used, with fluorescein, indocyanine green (IGC), and 5- aminolaevulinic acid (5-ALA) being the most commonly employed fluorescent agents for imaging brain tumors. However, all of these agents are non-targeting or susceptible to non-specific signal. Molecular targeted fluorescence agents like ABY-029, which targets epidermal growth factor receptor (EGFR), offers improved tumor specificity when the target receptor is expressed in the tumor. In this study, we evaluate the performance of ABY-029, IRDye 680LT, 5-ALA, and binding potential (BP) compared to ground truth formalin fixed paraffin embedded hematoxylin and eosin (H&E) stained tissue in a non-EGFR expressing orthotopic rat glioma models (F98). IRDye 680LT the highest agreement with H&E staining (AUC = 0.876, positive contrast), followed by BP (AUC = 0.866, negative contrast), PpIX (AUC = 0.833, positive contrast), and ABY-029 (AUC = 0.774, positive contrast). These results suggest that IRDye 680LT and BP imaging outperform the commonly used 5-ALA. While the high performance of IRDye 680LT was unexpected, it may be credited enhanced permeability caused by a disrupted blood brain barrier. BP was also high performing and demonstrated robust tumor delineation and highlights the potential utility of paired-agent imaging approaches in brain tumor surgery of non– EGFR-expressing gliomas.