Molecular Fluorescence Endoscopy Targeting Vascular Endothelial Growth Factor A for Improved Colorectal Polyp Detection

Abstract

Small and flat adenomas are known to carry a high miss-rate during standard white-light endoscopy. Increased detection rate may be achieved by molecular fluorescence endoscopy with targeted nearinfrared (NIR) fluorescent tracers. The aim of this study was to validate vascular endothelial growth factor A (VEGF-A) and epidermal growth factor receptor (EGFR)-targeted fluorescent tracers during ex vivo colonoscopy with an NIR endoscopy platform. Methods: VEGF-A and EGFR expression was determined by immunohistochemistry on a large subset of human colorectal tissue samples-48 sessile serrated adenomas/polyps, 70 sporadic high-grade dysplastic adenomas, and 19 hyperplastic polyps-and tissue derived from patients with Lynch syndrome-78 low-grade dysplastic adenomas, 57 high-grade dysplastic adenomas, and 31 colon cancer samples. To perform an ex vivo colonoscopy procedure, 14 mice with small intraperitoneal EGFR-positive HCT116 luc tumors received intravenous bevacizumab-800CW (anti-VEGF-A), cetuximab-800CW (anti-EGFR), control tracer IgG-800CW, or sodium chloride. Three days later, 8 resected HCT116 luc tumors (2-5 mm) were stitched into 1 freshly resected human colon specimen and followed by an ex vivo molecular fluorescence colonoscopy procedure. Results: Immunohistochemistry showed high VEGF-A expression in 79%-96% and high EGFR expression in 51%-69% of the colorectal lesions. Both targets were significantly overexpressed in the colorectal lesions, compared with the adjacent normal colon crypts. During ex vivo molecular fluorescence endoscopy, all tumors could clearly be delineated for both bevacizumab-800CW and cetuximab-800CW tracers. Specific tumor uptake was confirmed with fluorescent microscopy showing, respectively, stromal and cell membrane fluorescence. Conclusion: VEGF-A is a promising target for molecular fluorescence endoscopy because it showed a high protein expression, especially in sessile serrated adenomas/polyps and Lynch syndrome. We demonstrated the feasibility to visualize small tumors in real time during colonoscopy using a NIR fluorescence endoscopy platform, providing the endoscopist a wide-field redflag technique for adenoma detection. Clinical studies are currently being performed in order to provide in-human evaluation of our approach.

The level of epidermal growth factor receptors expression is correlated with the advancement of colorectal adenoma: validation of a surface biomarker

“…Indeed, samples issued from biopsies are known to be exposed to heterogeneous bias, as well as EGFR expression is known to show a heterogeneous staining pattern, also in adenomas. Moreover, adenomas are also heterogeneous lesions [13]. Despite CRC are also lesions with heterogeneity, there is at least adenoma with HGD, which are lesions with EGFR overexpression in 77.8% in our study.…”

“…It is interesting to note that (mild) inflammation related to IBD did not increase the EGFR expression of the macroscopically normal mucosa in this patient (Goldstein grade: 1 in both side of the colon; intensity of staining and composite score ranked from 1(left side) to 2 (right side colon)). In a recent study [13], there was no difference between Lynch adenomas and sporadic adenomas in terms of EGFR expression. It would be interesting to assess these lesions with the clone 113 that we used for immunohistochemistry, despite there is probably no major difference regarding EGFR expression.…”

“…This nanotechnology could be useful in the case of multiple polypoid lesions, such as pseudopolyp in inflammatory bowel disease, to identify this or those that are truly adenomatous and so that should be removed. Few preliminary studies had demonstrated the feasibility of such nanotechnology during colonoscopy [13]. …”

“…However, data remain scares about the level of EGFR expression on colorectal adenomas [12, 13], in contrast with CRC [10–12, 14–18]. The level of EGFR expression varies significantly in CRC, due to the use of variable immunohistochemistry methods across studies.…”

Harnessing Integrative Omics to Facilitate Molecular Imaging of the Human Epidermal Growth Factor Receptor Family for Precision Medicine

“…In a preclinical intraoperative study, 800CW-7D12 could visualize orthotopic primary tongue tumor xenografts and resulting cervical lymph node metastases which were otherwise not detectable with the naked eye 81. Also, 800CW-cetuximab was successfully used to detect EGFR-positive lesions in a preclinical simulated colonoscopy of a resected human colon with human EGFR-expressing colon cancer HCT116 luc xenografts stitched into the colon wall 82. 800CW-cetuximab was likewise tested in HNSCC patients during surgery using wide-field NIR imaging.…”