BACKGROUND: Presence of lymph node (LN) metastasis is considered the most important prognostic factor in patients with head and neck cancer, yet intraoperative identification of metastatic LNs is considered challenging. We propose the near-infrared fluorescently labeled epidermal growth factor receptor (EGFR) antibody panitumumab-IRDye800 for intraoperative metastatic LN identification.
METHODS: Patients were injected 2-5 days before surgery with panitumumab-IRDye800 (0.5 or 1.0 mg/kg). On the day of surgery, (excised) LN samples were evaluated on high sensitivity fluorescence imaging systems (SurgVision (SurgOptix), PINPOINT (Novadaq), and Pearl imager and Odyssey CLx (LI-COR Biosciences). Location and intensity of the fluorescence signal was correlated to the location of tumor as defined on the hematoxylin and eosin staining by the pathologist, and the EGFR expression pattern. We calculated the sensitivity, specificity, positive and negative predictive values of panitumumab-IRdye800 for metastatic LN identification.
RESULTS: We thus far included 9/27 patients in our ongoing phase I trial. 244 LNs were removed intraoperatively of which 8 were tumor-positive. Fluorescence imaging of panitumumab-IRdye800 revealed 236 true-negative nodes (not fluorescent, not tumor-positive), 8 true-positive nodes (fluorescent, tumor-positive), 0 false-positive nodes (fluorescent, not tumor-positive) and 0 false-negative nodes (not fluorescent, tumor-positive) resulting in a sensitivity of 100%, a specificity of 100%, and a positive and negative predictive value of 100% and 100%, respectively.
CONCLUSION: Preliminary results from our ongoing study suggest panitumumab-IRDye800 can identify metastatic LNs. Upon trial progression, if findings remain constant, it can open a whole new era for intraoperative metastatic LN identification.