Indocyanine Green-Labeled Antibodies Cotargeting CDCP1 and Mesothelin for Fluorescence-Guided Imaging of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest cancers due to late-stage diagnosis, aggressive progression, inadequate modalities for detection and monitoring, and treatment options, including surgery, that generally do not achieve durable responses. CUB domain containing protein 1 (CDCP1) and mesothelin (MSLN) are cell surface proteins, commonly expressed at elevated levels in PDAC, that are potential targets for detection and treatment of these tumors. In this study, we generated anti-CDCP1 antibody ch10D7 and anti-MSLN antibody amatuximab conjugated with the near-infrared fluorophore indocyanine green (ICG). With the goal of characterizing ch10D7 ICG and anti-MSLN ICG for detection of PDAC, we noted that ICG labeling did not impact the affinity or specificity of either antibody. Both ICG-labeled antibodies selectively accumulated in subcutaneous and orthotopic PDAC models in mice, as visualized by in vivo fluorescence imaging. Postmortem fluorescence endoscopy imaging clearly delineated tumors, with optimal signal observed at 120 h post agent administration. Demonstrating specificity in vivo, depletion of CDCP1 and MSLN abolished tumor localization in xenografts of, respectively, ch10D7 ICG and amatuximab ICG . Quantitative ex vivo fluorescence analysis of excised xenografts demonstrated that combining ch10D7 ICG and amatuximab ICG enhances tumor-associated fluorescence by 2.8- to 12.5-fold compared with either agent alone. The results support the potential of dual-targeted, antibody-based fluorescence imaging for enhanced intraoperative visualization and excision of PDAC, including for tumors with heterogeneous expression of either or both of the targeted receptors CDCP1 and MSLN.