800CW Dye and ⁸⁹Zr Dual-labeled Antibody for the PET/NIRF/Cerenkov Multi-modality Imaging of ICAM-1 (CD54) in Pancreatic Cancer

Purpose: Pancreatic cancer (PcCa) is one of the primary causes of death from cancer in the developed countries and always exhibits poor prognosis. Early detection and intervention are of great demand clinically in PcCa. Non-invasive targeting imaging is a promising strategy for the diagnosis and monitoring of PcCa. In this study, we applied near-infrared dye and [⁸⁹Zr]zirconium dual-labeled intercellular adhesion molecule 1 (ICAM-1, CD54) monoclonal antibody (mAb) to the imaging of positron emission tomography (PET), near-infrared fluorescence (NIRF) and Cerenkov optics, aiming to provide a proof-of-concept for the in vivo multi-modality visualization of PcCa foci targeting the ICAM-1 in tumor tissue.

Methods: The difference between the expressions of ICAM-1 in BXPC-3 and ASPC-1 PcCa cell lines were tested by flow cytometry and immuno-fluorescent confocal imaging. Then we synthesized the 800CW/⁸⁹Zr-ICAM-1 mAb tracer by bio-conjugation chemistry. The efficacy and specificity of 800CW/⁸⁹Zr-ICAM-1 mAb were confirmed by the comparative in vivo PET/NIRF/Cerenkov imaging in the nude mice bearing subcutaneous (s.c.) BXPC-3 and ASPC-1 tumors, plus the imaging in the same modalities using the 800CW/⁸⁹Zr-labeled non-specific IgG protein, followed by bio-distribution studies. Apart from that, the imaging function of 800CW/⁸⁹Zr-ICAM-1 mAb was also validated in the orthotopic BXPC-3 tumor model by in vivo PET and ex vivo NIRF/Cerenkov optical imaging. Finally, the histo-pathological assay was conducted to characterize the ICAM-1 distribution in PcCa tumor tissues.

Results: The expression contrast of ICAM-1 in the BXPC-3 (positive) and ASPC-1 (negative) cell lines is evident. The data of multi-modality imaging and bio-distribution indicated that the uptake in s.c. BCPX-3 is more prominent than that in the s.c. ASPC-1 tumors, and the uptake of 800CW/⁸⁹Zr-IgG in s.c. BXPC-3 tumors are similar to the uptake of 800CW/⁸⁹Zr-ICAM-1 mAb in s.c. ASPC-1 tumors. These results demonstrated the fine avidity and specificity of the 800CW/⁸⁹Zr-ICAM-1 mAb tracer. In the images of orthotopic BXPC-3 tumor model, the tumor foci can be delineated clearly in PET tomographs and the outlines of tumors are co-inside with each other in the ex vivo NIRF/Cerenkov images. In the confocal images, the profile of ICAM-1 expression in BXPC-3 tumor tissue is confirmed to be higher than in the ASPC-1 tumor tissue.

Conclusions: Taken together, we reported the first example of PET/NIRF/Cerenkov imaging based on the NIRF dye and PET nuclide dual-labeled ICAM-1 mAb, which sets a paradigm for the multi-modality visualization of ICAM-1 expressed in PcCa and implies the potential of its further clinical translation.

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