A Claudin-1 Near-Infrared Fluorescent Antibody Conjugate for In Vivo Primary and Metastatic Colorectal Cancer...

Despite advancements in colorectal cancer (CRC) therapy, surgery remains the only curative option. Incomplete resection resulting in tumor cell positive surgical margins occurs in ~ 7% of CRC surgeries and is associated with recurrence and poor prognosis. Fluorescence-guided surgery (FGS) enhances tumor detection and enables real-time identification of tumor margins. Claudins, a large family of tight junction proteins, are being explored as cancer biomarkers and therapeutic targets due to their presence on the cell surface, tissue-specific expression, and selective upregulation in carcinomas. Claudin-1 (CLDN1) is overexpressed in CRC and associated with therapy resistance and metastasis, making it a promising target for fluorescence-based tumor detection.

CLDN1 expression in CRC was analyzed using the Cancer Genome Atlas Colorectal Adenocarcinoma (TCGA-COAD) dataset. To enable in vivo tumor detection, a CLDN1 monoclonal antibody was conjugated to a near-infrared fluorescent dye (CLDN1-IR800). Sensitivity, specificity, and tumor-to-background ratio were tested in vitro and in vivo using CRC cell lines, patient-derived organoids, and an orthotopic, syngeneic model of CRC metastasis.

This study demonstrates that CLDN1 is upregulated in 100% of CRC tumors compared to patient-matched normal adjacent colon in the TCGA-COAD dataset, with an average 40-fold increase in expression. CLDN1-IR800 showed specific binding and strong fluorescence in CLDN1-expressing CRC cells, with minimal signal in non-expressing cells or IgG-IR800 controls. In vivo, CLDN1-IR800 produced a significantly higher tumor-to-background ratio in CLDN1-expressing CRC cell line and patient-derived organoid xenografts compared to CLDN1-negative tumors or IgG-IR800-injected mice. Necropsy revealed significantly higher fluorescence in tumors than in other organs. In an orthotopic syngeneic mouse model, both primary and metastatic lesions were detectable. Ex vivo imaging confirmed signal in a panel of patient-derived organoids.

These findings demonstrate CLDN1's potential as a target for tumor detection and FGS in CRC.