Detection of human gastric cancer in resected specimens using a novel infrared fluorescent anti-human carcinoembryonic antigen antibody with an infrared fluorescence endoscope in vitro

Background and Study Aims: An indocyanine green derivative (ICG-sulfo-OSu) that can be used as an infrared fluorescent labeling substance suitable for detecting microlesions with an infrared fluorescence endoscope has been de veloped. The aims of the present study were to develop an infrared fluoresc ence endoscope and to demonstrate its usefulness in detecting cancerous tis sue using an antibody coupled with ICG-sulfo-OSu. Materials and Methods: ICG-sulfo-OSu-labeled mouse anti-human carcinoembryo nic antigen (CEA) antibody and an infrared fluorescence endoscope were used in this study. Biopsy specimens of gastric cancer were stained with anti-C EA antibody using the avidin-biotinylated peroxidase complex method. The po sitive specimens used for the infrared imaging analysis were freshly resect ed stomachs from three patients. Results: Treatment of freshly resected stomach specimens with ICG-sulfo-OSu -labeled-anti-CEA antibody complex resulted in positive staining of the tum or sites on infrared fluorescence endoscopy, and the infrared fluorescent i mages correlated well with the tumor sites. Conclusions: An anti-CEA antibody with affinity for cancerous lesions and l abeled with ICG-sulfo-OSu can therefore be imaged using this infrared fluor escence endoscope. Specific antibodies tagged with ICG-sulfo-OSu can label cancer cells and can generate a strong enough fluorescent signal to detect small cancers when examined with an infrared fluorescence endoscope.