RA07.02: IDENTIFYING TUMOR MARKERS IN ESOPHAGEAL ADENOCARCINOMA AND LYMPH NODE METASTASES FOR TARGETED FLUORESCENCE IMAGING

Abstract

Abstract Background Neoadjuvant chemoradiotherapy (nCRT) followed by resection of the tumor with two field lymphadenectomy is a standard treatment for esophageal cancer. After nCRT, however, in more than 70% of patients no lymph node metastases are found, suggesting extensive overtreatment. Tumor-targeted fluorescence imaging is a promising technique to detect lymph node metastases intra-operatively and guide personalized resection. The aim of this study is to identify potential viable tumor markers for fluorescence imaging of lymph node metastases in patients with esophageal adenocarcinoma (EAC). Methods Immunohistochemistry (IHC) was performed on tissue microarrays from EAC’s patients that underwent surgical resection between 2007 and 2016. Patients were subdivided in five groups, non-pretreated patients with and without metastatic lymph nodes, complete responders, partial responders and non-responders after nCRT. Five membranous markers, c-MET, CAIX, EGFR, EpCAM, HER2, and two cytoplasmic markers, VEGF-A and VEGF-A receptor were included. Tumor marker expression was scored on intensity (none (0), slight (1), moderate (2), strong (3)) and the percentage of positive cells (estimation). Threshold for positive detection rate was defined as an intensity of ≥ 2 in more than 10% the cells. Results EpCAM showed the highest expression in metastastic lymph nodes, with a median intensity of 3 (range 2–3) in > 70% of the tumor cells. Expression was found in 37 out of 39 EAC’s (95%). VEGF-A and CAIX expression was observed in 28 of 33 (85%) and 10 of 33 (30%) of metastatic lymph nodes and 34 of 39 (87%) and 17 of 39 (44%) in the primary EAC’s, respectively. For the other tumor biomarkers the detection rate ranged between 0 and 11% for metastatic lymph nodes and primary EAC’s. Only EpCAM and VEGF-A showed weak, non-specific staining in the fibrotic tissue. Conclusion High expression rates in primary EAC and metastatic lymph nodes were observed using immunohistochemical antibodies for EpCAM, VEGF-A and CA-IX, making these clinically relevant viable EAC tumor markers. A phase 1 dose finding study targeting VEGF-A by Bevacizumab-800-CW in patient with EAC is in preparation. Disclosure All authors have declared no conflicts of interest.