Cholangiocarcinoma (CCA) is an adenocarcinoma of the hepatobiliary system that has recently risen 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 tissues of patients with CCA, we show that CLDN1 expression is up-regulated in cancer cells and is associated with stemness and cell fate. Genetic 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 nonjunctional CLDN1 using highly specific CLDN1 monoclonal antibodies (mAbs) 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 inhibited tumor cell migration, invasion, and extrahepatic metastasis. Mechanistically, targeting exposed cell surface CLDN1 on CCA tumors using mAbs inhibited Notch1 and TROP2/STAT3 signaling pathways, resulting in decreased cancer cell stemness and epithelial-to-mesenchymal transition. Loss-of-function studies using CRISPR-Cas9 and RNAi combined with rescue and confocal imaging studies confirmed the functional and mechanistic role of these pathways. 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.

Abstract Introduction: Cholangiocarcinoma (CCA) is a highly aggressive 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, but exposed at the cell surface on cancer epithelial cells. Using highly specific monoclonal antibodies (mAbs) targeting the extracellular loop 1 of exposed CLDN1 with an excellent safety profile (Roehlen, Saviano et al. Science Transl Med 2022), we aimed to investigate the role of CLDN1 as therapeutic target for CCA. Methods: Integrative CCA patient CLDN1 expression analyses, spatial transcriptomics and mouse models were used to evaluate the role of CLDN1 as an oncogenic driver for CCA. Proof-of-concept studies were performed in cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse as well as patient CCA organoid models using humanized CLDN1 mAbs. Results: Integrative expression analyses of CLDN1 in CCA patient tissues revealed robust CLDN1 upregulation across several cohorts and patients with well-characterized driver mutations. scRNASeq and spatial transcriptomics of patient CCA showed that CLDN1 expression in cancer cells is associated with stemness, oncogenic signaling and EMT. Gain-of-function studies using an orthotopic HDTVi and syngeneic mouse model revealed a decrease in survival and an enhanced tumor growth, unraveling a functional role of CLDN1 as an oncogenic driver in CCA. Targeting exposed CLDN1 using highly CLDN1-specific mAb demonstrated a robust anti-tumoral effect across intra- and extra-hepatic CCA mouse models, with a significant inhibition of metastatic disease including models with medium or low CLDN1 expression. Functional studies in patient-derived CCA organoids demonstrated that CLDN1 mAb decreased cellular viability and altered cancer cell plasticity and fate. Mechanistically, CLDN1 mAb treatment suppressed gene expression of pathways mediating proliferation, stemness and EMT by inhibition of Notch1, SRC-FAK, and Hippo-YAP signaling. Conclusion: These results demonstrate that CLDN1 is a CCA driver and therapeutic target. The proof-of-concept studies in patient-derived models pave the way for the clinical development of CLDN1 mAbs to improve the outcomes of patients with advanced CCA. Citation Format: Zeina Nehme, Marion Muller, Emilie Crouchet, Frank Juehling, Julien Moehlin, Romain Désert, Jade Brochon, Fabio Del Zompo, Natascha Roehlen, Christine Thumann, Patrick Pessaux, Emanuele Felli, Aïna Venkatasamy, Patrice Marchand, Mihaela Alina Onea, Roberto Iacone, Markus Meyer, Alberto Toso, Nabeel Bardeesy, Lipika Goyal, Vikas Prakash Ranvir, Mirian Fernández-Vaquero, Mathias Heikenwälder, Tessa Ostyn, Tania Roskams, Patrice Laquerriere, Catherine Schuster, Laurent Mailly, Thomas F. Baumert. Treatment of cholangiocarcinoma using humanized monoclonal antibodies targeting claudin-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5981.

Background & Aims: Despite recent approvals, the response to treatment and prognosis of patients with advanced hepato-cellular carcinoma (HCC) remain poor. Claudin-1 (CLDN1) is a membrane protein that is expressed at tight junctions, but it can also be exposed non-junctionally, such as on the basolateral membrane of the human hepatocyte. While CLDN1 within tight junctions is well characterized, the role of non-junctional CLDN1 and its role as a therapeutic target in HCC remains unexplored.Methods: Using humanized monoclonal antibodies (mAbs) specifically targeting 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 a therapeutic target for HCC.Results: Targeting non-junctional CLDN1 markedly suppressed tumor growth and invasion in cell line-based models of HCC and patient-derived 3D ex vivo models. Moreover, the robust effect on tumor growth was confirmed in vivo in a large series of cell line -derived xenograft and patient-derived xenograft mouse models. Mechanistic studies, including single-cell RNA sequencing of multicellular patient HCC tumorspheres, suggested that CLDN1 regulates tumor stemness, metabolism, oncogenic signaling and perturbs the tumor immune microenvironment.Conclusions: Our results provide the rationale for targeting CLDN1 in HCC and pave the way for the clinical development of CLDN1-specific mAbs for the treatment of advanced HCC.(c) 2022 The Authors. Published by Elsevier B.V. on behalf of European Association for the Study of the Liver. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Tissue fibrosis is a key driver of end-stage organ failure and cancer, overall accounting for up to 45% of deaths in developed countries. There is a large unmet medical need for antifibrotic therapies. Claudin-1 (CLDN1) is a member of the tight junction protein family. Although the role of CLDN1 incorporated in tight junctions is well established, the function of nonjunctional CLDN1 (njCLDN1) is largely unknown. Using highly specific monoclonal antibodies targeting a conformation-dependent epitope of exposed njCLDN1, we show in patient-derived liver three-dimensional fibrosis and human liver chimeric mouse models that CLDN1 is a mediator and target for liver fibrosis. Targeting CLDN1 reverted inflammation-induced hepatocyte profibrogenic signaling and cell fate and suppressed the myofibroblast differentiation of hepatic stellate cells. Safety studies of a fully humanized antibody in nonhuman primates did not reveal any serious adverse events even at high steady-state concentrations. Our results provide preclinical proof of concept for CLDN1-specific monoclonal antibodies for the treatment of advanced liver fibrosis and cancer prevention. Antifibrotic effects in lung and kidney fibrosis models further indicate a role of CLDN1 as a therapeutic target for tissue fibrosis across organs. In conclusion, our data pave the way for further therapeutic exploration of CLDN1-targeting therapies for fibrotic diseases in patients.

accelerated liver regeneration and improved survival were recently obtained in 85% hepatectomy pig model upon treatment with the MKK4 inhibitor HRX-0215 (5 mg/kg i.v.) (Klotz et al., Hepatology, 2021).Here, we now report data from a FIH clinical trial for HRX-0215 related to safety, tolerability and pharmacokinetics.Method: A FIH Clinical trial for HRX-0215 was conducted in 48 healthy volunteers to assess safety, tolerability and pharmacokinetics in a single-center, double-blind, randomized, placebo-controlled manner.In the Single Ascending Dose part volunteers were dosed from 5 to 500 mg, the Multiple Ascending dose part used daily doses between 100 and 500 mg.HRX-0215 was well tolerated at all doses, no relevant changes of any clinical or laboratory parameters were observed.Within a given dosing strength, PK analysis revealed a dose-proportional increase of exposure with very low interindividual variability.Concentration vs. time profiles of HRX-0215 supports a once-daily dose regimen during further clinical development.Results: In the 4 wk GLP toxicity study in rats and dogs, a NOAEL of 300 mg/kg p.o. and 250 mg/kg p.o. was obtained, respectively.No organ toxicity was observed, which is in line with results from 12 mths ubiquitously, genetically suppressed MKK4 expression in mice.Most importantly, risk mitigation for liver tumor burden was achieved in a diet-induced obese mouse model with biopsyconfirmed NASH (non-alcoholic steatohepatitis) and advanced fibrosis, where HRX-0215 administered at a dose level of 30/kg once daily for 12 weeks attenuated progression in tumor numbers and growth.Conclusion: Our FIH clinical trial demonstrates a favorable safety profile of HRX-0215 and confirms that pharmacological MKK 4 inhibition is well tolerated.PK characteristics indicate that therapeutic efficacy is achieved with a once-daily dose regimen This profile enables further clinical development and Phase 2 trials of HRX-0215 in patients with acute and chronic liver diseases.

Objective Hepatocellular carcinoma (HCC) is the fastest-growing cause of cancer-related mortality with chronic viral hepatitis and non-alcoholic steatohepatitis (NASH) as major aetiologies. Treatment options for HCC are unsatisfactory and chemopreventive approaches are absent. Chronic hepatitis C (CHC) results in epigenetic alterations driving HCC risk and persisting following cure. Here, we aimed to investigate epigenetic modifications as targets for liver cancer chemoprevention. Design Liver tissues from patients with NASH and CHC were analysed by ChIP-Seq (H3K27ac) and RNA-Seq. The liver disease-specific epigenetic and transcriptional reprogramming in patients was modelled in a liver cell culture system. Perturbation studies combined with a targeted small molecule screen followed by in vivo and ex vivo validation were used to identify chromatin modifiers and readers for HCC chemoprevention. Results In patients, CHC and NASH share similar epigenetic and transcriptomic modifications driving cancer risk. Using a cell-based system modelling epigenetic modifications in patients, we identified chromatin readers as targets to revert liver gene transcription driving clinical HCC risk. Proof-of-concept studies in a NASH-HCC mouse model showed that the pharmacological inhibition of chromatin reader bromodomain 4 inhibited liver disease progression and hepatocarcinogenesis by restoring transcriptional reprogramming of the genes that were epigenetically altered in patients. Conclusion Our results unravel the functional relevance of metabolic and virus-induced epigenetic alterations for pathogenesis of HCC development and identify chromatin readers as targets for chemoprevention in patients with chronic liver diseases.

Chronic liver disease and hepatocellular carcinoma (HCC) are life-threatening diseases with limited treatment options. The lack of clinically relevant/tractable experimental models hampers therapeutic discovery. Here, we develop a simple and robust human liver cell-based system modeling a clinical prognostic liver signature (PLS) predicting long-term liver disease progression toward HCC. Using the PLS as a readout, followed by validation in nonalcoholic steatohepatitis/fibrosis/HCC animal models and patient-derived liver spheroids, we identify nizatidine, a histamine receptor H2 (HRH2) blocker, for treatment of advanced liver disease and HCC chemoprevention. Moreover, perturbation studies combined with single cell RNA-Seq analyses of patient liver tissues uncover hepatocytes and HRH2 + , CLEC5A high , MARCO low liver macrophages as potential nizatidine targets. The PLS model combined with single cell RNA-Seq of patient tissues enables discovery of urgently needed targets and therapeutics for treatment of advanced liver disease and cancer prevention.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection is an important risk factor for hepatocellular carcinoma (HCC). Despite effective antiviral therapies, the risk for HCC is decreased but not eliminated after a sustained virologic response (SVR) to direct-acting antiviral (DAA) agents, and the risk is higher in patients with advanced fibrosis. We investigated HCV-induced epigenetic alterations that might affect risk for HCC after DAA treatment in patients and mice with humanized livers. METHODS: We performed genome-wide ChIPmentation-based ChIP-Seq and RNA-seq analyses of liver tissues from 6 patients without HCV infection (controls), 18 patients with chronic HCV infection, 8 patients with chronic HCV infection cured by DAA treatment, 13 patients with chronic HCV infection cured by interferon therapy, 4 patients with chronic hepatitis B virus infection, and 7 patients with nonalcoholic steatohepatitis in Europe and Japan. HCV-induced epigenetic modifications were mapped by comparative analyses with modifications associated with other liver disease etiologies. uPA/SCID mice were engrafted with human hepatocytes to create mice with humanized livers and given injections of HCV-infected serum samples from patients; mice were given DAAs to eradicate the virus. Pathways associated with HCC risk were identified by integrative pathway analyses and validated in analyses of paired HCC tissues from 8 patients with an SVR to DAA treatment of HCV infection. RESULTS: We found chronic HCV infection to induce specific genome-wide changes in H3K27ac, which correlated with changes in expression of mRNAs and proteins. These changes persisted after an SVR to DAAs or interferon-based therapies. Integrative pathway analyses of liver tissues from patients and mice with humanized livers demonstrated that HCV-induced epigenetic alterations were associated with liver cancer risk. Computational analyses associated increased expression of SPHK1 with HCC risk. We validated these findings in an independent cohort of patients with HCV-related cirrhosis (n = 216), a subset of which (n = 21) achieved viral clearance. CONCLUSIONS: In an analysis of liver tissues from patients with and without an SVR to DAA therapy, we identified epigenetic and gene expression alterations associated with risk for HCC. These alterations might be targeted to prevent liver cancer in patients treated for HCV infection.

Objective HCV infection is a leading cause of chronic liver disease and a major indication for liver transplantation. Although direct-acting antivirals (DAAs) have much improved the treatment of chronic HCV infection, alternative strategies are needed for patients with treatment failure. As an essential HCV entry factor, the tight junction protein claudin-1 (CLDN1) is a promising antiviral target. However, genotype-dependent escape via CLDN6 and CLDN9 has been described in some cell lines as a possible limitation facing CLDN1-targeted therapies. Here, we evaluated the clinical potential of therapeutic strategies targeting CLDN1. Design We generated a humanised anti-CLDN1 monoclonal antibody (mAb) (H3L3) suitable for clinical development and characterised its anti-HCV activity using cell culture models, a large panel of primary human hepatocytes (PHH) from 12 different donors, and human liver chimeric mice. Results H3L3 pan-genotypically inhibited HCV pseudoparticle entry into PHH, irrespective of donor. Escape was likely precluded by low surface expression of CLDN6 and CLDN9 on PHH. Co-treatment of a panel of PHH with a CLDN6-specific mAb did not enhance the antiviral effect of H3L3, confirming that CLDN6 does not function as an entry factor in PHH from multiple donors. H3L3 also inhibited DAA-resistant strains of HCV and synergised with current DAAs. Finally, H3L3 cured persistent HCV infection in human-liver chimeric uPA-SCID mice in monotherapy. Conclusions Overall, these findings underscore the clinical potential of CLDN1-targeted therapies and describe the functional characterisation of a humanised anti-CLDN1 antibody suitable for further clinical development to complement existing therapeutic strategies for HCV.

Chronic hepatitis B, C, and D virus (HBV, HCV, and HDV) infections are the leading causes of liver disease and cancer worldwide. Recently, the solute carrier and sodium taurocholate co-transporter NTCP has been identified as a receptor for HBV and HDV. Here, we uncover NTCP as a host factor regulating HCV infection. Using gain- and loss-of-function studies, we show that NTCP mediates HCV infection of hepatocytes and is relevant for cell-to-cell transmission. NTCP regulates HCV infection by augmenting the bile-acid-mediated repression of interferon-stimulated genes (ISGs), including IFITM3. In conclusion, our results uncover NTCP as a mediator of innate antiviral immune responses in the liver, and they establish a role for NTCP in the infection process of multiple viruses via distinct mechanisms. Collectively, our findings suggest a role for solute carriers in the regulation of innate antiviral responses, and they have potential implications for virus-host interactions and antiviral therapies.