Abstract P153: Claudin-1 is a therapeutic target for hepatocellular carcinoma

Introduction: Hepatocellular carcinoma (HCC) is the fastest rising and fourth leading cause of cancer death worldwide. While new therapeutic modalities have been recently approved, treatment response and survival in patients remain poor. Claudin-1 (CLDN1) is a cell membrane protein mediating cell-cell adhesion, fate and differentiation. While the function of CLDN1 within tight junctions is well characterized, the role of non-junctional CLDN1 in HCC remains unexplored. Aim and methods: Using humanized monoclonal antibodies (mAbs) targeting specifically the extracellular loop of human non-junctional CLDN1 and a large series of patient-derived cell-based and animal model systems we aimed to investigate the role of CLDN1 as therapeutic target for treatment of HCC. Results: Targeting non-junctional CLDN1 robustly suppressed tumor growth in a large series of patient-derived model systems, including multicellular tumorspheres and patient-derived xenograft (PDX) mouse models. In vivo and ex vivo studies further suggested synergistic efficacy in combination with sorafenib. Mechanistic studies revealed that CLDN1 mAbs suppressed tumor cell proliferation, invasion and stemness by interfering with Src, Wnt-β-catenin and STAT3 signaling. Treatment with humanized anti-CLDN1 mAbs is considered to be safe, as administration in non-human primates and mouse models did not reveal any major toxicity even when high doses largely exceeding the therapeutic need were repeatedly applied. Conclusion: Our results provide robust pre-clinical proof-of-concept for humanized CLDN1-specific mAbs for treatment of HCC. The unique and differentiated mechanism of action has the potential to break the plateau of limited response and survival offered by currently approved therapies. Citation Format: Natascha Roehlen, Marion Muller, Sara Cherradi, Frank Juehling, Francois H.T. Duong, Nuno Almeida, Fabio Del Zompo, Mirian Fernandez, Tobias Riedl, Hussein El Saghire, Antonio Saviano, Sarah Durand, Clara Ponsolles, Marine Oudot, Emanuele Felli, Patrick Pessaux, Irwin Davidson, Emilie Crouchet, Patrick Laquerriere, Mathias Heikenwälder, Roberto Iacone, Markus Meyer, Greg Elson, Tamas Schweighoffer, Catherine Schuster, Laurent Mailly, Joachim Lupberger, Thomas F Baumert. Claudin-1 is a therapeutic target for hepatocellular carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P153.