Feasibility of Anti-CEA Dye Conjugate for Cancer-Specific Imaging in Gastric Cancer Cell Lines and Mouse Xenograft Models.

Purpose: Near-infrared fluorescence-guided surgery (FGS) using cancer-specific tracers is promising for tailored gastric cancer (GC) surgery. Carcinoembryonic antigen (CEA) is a potential target due to its high expression in various digestive cancers, including GC. Materials and Methods: SGM-101, a chimeric anti-CEA monoclonal antibody conjugated with the near-infrared dye BM-104, was evaluated in GC. CEA expression was identified in GC cell lines at the mRNA and protein levels. Xenograft models (MKN-45, SNU-16, SNU-668, 85As2mLuc) were established in mice and injected with SGM-101 or PBS. Biodistribution was monitored using in vivo fluorescence imaging. Tumors were further analyzed by immunofluorescence. In a peritoneal carcinomatosis model, 85As2mLuc cells were injected intraperitoneally, and tumors were evaluated by bioluminescence and fluorescence and histology. Results: MKN-45, SNU-16, and 85As2mLuc were CEA-positive, while SNU-668 was CEA-negative. Flow cytometry confirmed CEA expression: MKN-45 (98%), SNU-16 (85.6%), SNU-668 (6.42%) and 85As2mLuc (78.4%). SGM-101 selectively targeted CEA-expressing tumors, with fluorescence peaking at 48 h, and immunofluorescence verified localization in tumor cells. In the peritoneal models, SGM-101 enabled precise detection of CEA-positive tumors. Conclusions: This study provides the first evidence for the feasibility of SGM-101 in gastric cancer, demonstrating its novelty and translational potential as a cancer-specific imaging agent for fluorescence-guided surgery.