Treatment of cholangiocarcinoma using humanized monoclonal antibodies targeting Claudin-1(CCA organoids)

Cholangiocarcinoma (CCA) is an adenocarcinoma of the hepatobiliary system showing an alarming rise in incidence and mortality with unsatisfactory treatment options. Claudin-1 (CLDN1) is a transmembrane protein expressed in tight junctions and exposed on the cell surface in liver fibrosis and cancer. Using single cell RNA-sequencing (scRNA-Seq) and spatial transcriptomics of CCA patient tissues, we show that CLDN1 expression is highly upregulated in cancer cells and is associated with stemness and cell fate. Gain-of-function studies in CCA orthotopic in vivo mouse models showed decreased survival and enhanced tumor growth, unraveling a functional role of CLDN1 as an oncogenic driver. Targeting exposed CLDN1 using highly specific CLDN1 monoclonal antibodies (mAbs) robustly inhibited tumor growth across CCA CDX and PDX mouse models and patient-derived CCA organoids including tumors with medium or low CLDN1 expression. Moreover, antibody treatment markedly inhibited tumor cell migration, invasion, and extrahepatic metastasis. Mechanistically, targeting exposed CLDN1 on CCA tumors inhibited Notch1, FAK/SRC, and Hippo-YAP signaling, resulting in decreased cancer cell stemness, EMT and extracellular matrix remodeling. In conclusion, these results uncover CLDN1 as a previously undiscovered CCA driver and therapeutic target, paving the way for the clinical development of CLDN1 mAbs to improve the dismal outcome of patients with advanced CCA.