Translation of c-Met Targeted Image-Guided Surgery Solutions in Oral Cavity Cancer—Initial Proof of Concept Data

SIMPLE SUMMARY: Translation of tumor-specific fluorescent tracers is crucial in the realization intraoperative of tumor identification during fluorescence-guided surgery. Ex vivo assessment of surgical specimens after topical tracer application has the potential to reveal the suitability of a potential surgical target prior to in vivo use in patients. In this study, the c-Met receptor was identified as a possible candidate for fluorescence-guided surgery in oral cavity cancer. Freshly excised tumor specimens obtained from ten patients with squamous cell carcinoma of the tongue were incubated with EMI-137 and imaged with a clinical-grade Cy5 prototype fluorescence camera. In total, 9/10 tumors were fluorescently illuminated, while non-visualization could be linked to non-superficial tumor localization. Immunohistochemistry revealed c-Met expression in all ten specimens. Tumor assessment was improved via video representation of the tumor-to-background ratio. ABSTRACT: Intraoperative tumor identification (extension/margins/metastases) via receptor-specific targeting is one of the ultimate promises of fluorescence-guided surgery. The translation of fluorescent tracers that enable tumor visualization forms a critical component in the realization of this approach. Ex vivo assessment of surgical specimens after topical tracer application could help provide an intermediate step between preclinical evaluation and first-in-human trials. Here, the suitability of the c-Met receptor as a potential surgical target in oral cavity cancer was explored via topical ex vivo application of the fluorescent tracer EMI-137. Freshly excised tumor specimens obtained from ten patients with squamous cell carcinoma of the tongue were incubated with EMI-137 and imaged with a clinical-grade Cy5 prototype fluorescence camera. In-house developed image processing software allowed video-rate assessment of the tumor-to-background ratio (TBR). Fluorescence imaging results were related to standard pathological evaluation and c-MET immunohistochemistry. After incubation with EMI-137, 9/10 tumors were fluorescently illuminated. Immunohistochemistry revealed c-Met expression in all ten specimens. Non-visualization could be linked to a more deeply situated lesion. Tumor assessment was improved via video representation of the TBR (median TBR: 2.5 (range 1.8–3.1)). Ex vivo evaluation of tumor specimens suggests that c-Met is a possible candidate for fluorescence-guided surgery in oral cavity cancer.