Intraoperative near-infrared (NIR) fluorescence imaging is a technology with high potential to provide the surgeon with real-time visualization of tumors during surgery. Our study explores the feasibility for clinical translation of an epidermal growth factor receptor (EGFR)-targeting nanobody for intraoperative imaging and resection of orthotopic tongue tumors and cervical lymph node metastases. The anti-EGFR nanobody 7D12 and the negative control nanobody R2 were conjugated to the NIR fluorophore IRDye800CW (7D12-800CW and R2-800CW). Orthotopic tongue tumors were induced in nude mice using the OSC-19-luc2-cGFP cell line. Tumor-bearing mice were injected with 25 μg 7D12-800CW, R2–800CW or 11 μg 800CW. Subsequently, other mice were injected with 50 or 75 μg of 7D12-800CW. The FLARE imaging system and the IVIS spectrum were used to identify, delineate and resect the primary tumor and cervical lymph node metastases. All tumors could be clearly identified using 7D12-800CW. A significantly higher tumor-to-background ratio (TBR) was observed in mice injected with 7D12–800CW compared to mice injected with R2-800CW and 800CW. The highest average TBR (2.00 ± 0.34 and 2.72 ± 0.17 for FLARE and IVIS spectrum, respectively) was observed 24 hr after administration of the EGFR-specific nanobody. After injection of 75 μg 7D12-800CW cervical lymph node metastases could be clearly detected. Orthotopic tongue tumors and cervical lymph node metastases in a mouse model were clearly identified intraoperatively using a recently developed fluorescent EGFR-targeting nanobody. Translation of this approach to the clinic would potentially improve the rate of radical surgical resections.What's new?
In surgical oncology, adequate tumor-free margins must be established to benefit patient prognosis and outcome. Surgeons typically discriminate healthy tissue from cancerous tissue by visual inspection and palpation during surgery, though studies have suggested that fluorescence-guided surgery could greatly aid this process. Here, a novel epidermal growth factor receptor-(EGFR-)targeting nanobody for intraoperative fluorescence imaging was explored for potential clinical translation in the resection of tongue cancer and related lymph node metastases. The EGFR nanobody enabled clear identification of tumors and cervical lymph node metastases in mice, indicating that its use in fluorescence-guided surgery could benefit human patients.