Preclinical evaluation of near‐infrared (NIR) fluorescently labeled cetuximab as a potential tool for fluorescence‐guided surgery

The high rate of recurrence in patients with pancreatic ductal adenocarcinoma (PDAC) could be reduced by supporting the surgeons in discriminating healthy from diseased tissues with intraoperative fluorescence‐guidance. Here, we studied the suitability of Cetuximab, a therapeutic monoclonal antibody targeting the human epidermal growth factor receptor (EGFR), near‐infrared (NIR) fluorescently labeled as a new tool for fluorescence‐guided surgery. Distribution and binding of systemically injected Cetuximab Alexa Fluor 647 conjugate (Cetux‐Alexa‐647) and the co‐injected control human IgG Alexa Fluor 750 conjugate (hIgG‐Alexa‐750) was studied over 48 h by NIR fluorescence imaging in mice bearing human orthotopic AsPC‐1 and MIA PaCa‐2 PDAC tumors. Cetux‐Alexa‐647, but not the control hIgG‐Alexa‐750 fluorescence, was specifically detected in vivo in both primary pancreatic tumors with maximum fluorescence intensities at 24 h, and in metastases of AsPC‐1 tumors as small as 1 mm. Lifetime analysis and NIR fluorescence microscopy of tumor sections confirmed the binding specificity of Cetux‐Alexa‐647 to PDAC cells. Comparable results were obtained with Cetuximab conjugated to Alexa Fluor 750 dye (Cetux‐Alexa‐750). Fluorescence‐guided dissection, performed 24 h after injection of Cetuximab conjugated to IRDye 800CW (Cetux‐800CW), enabled a real‐time delineation of AsPC‐1 tumor margins, and small metastases. Odyssey scans revealed that only the vital part of the tumor, but not the necrotic part was stained with Cetux‐800CW. NIR fluorescently labeled Cetuximab may be a promising tool that can be applied for fluorescence‐guided surgery to visualize tumor margins and metastatic sites in order to allow a precise surgical resection.