Molecular Imaging in Endoscopic Oncology

The goal of our study is to develop a molecular imaging in gastrointestinal tract using infrared fluorescence endoscope (IRFE) and labeled antibodies with indocyanine green (ICG)-derivative in detecting cancerous tissue. IRFE consisted of an infrared endoscope equipped with excitation (710-790 nm) and barrier (810-920 nm) filters. We have developed ICG-N-hydroxy sulfo succinimide ester (ICG-sulfo-OSu) and 3-ICG-acyl-1,3-thiazolidine-2-thione (ICG-ATT) as an infrared fluorescent-labeling reagent. ICG-derivative-labeled anti-human carcinoembryonic antigen (CEA) antibody and MUC1 antibody were prepared. Freshly resected specimens with gastric cancer were observed by IRFE after reaction with ICG-derivative labeled antibodies. It resulted in positive fluorescence at the tumor location by IRFE, and the immnofluorescent images correlated well with the tumor sites. The immunohistochemical studies suggested the intensity of IR fluorescence of ICGATT-MUC1 stronger than ICG-sulfo-OSu. We conclude that an anti-CEA or MUC1 antibody with affinity for cancerous lesions and labeled with ICG-derivative can be imaged with this IRFE. Specific antibodies labeled with ICG-derivative with the reinforcing agent and electronic device can visualize cancer proteins generating a strong enough fluorescent signal.