D19-02 Pharmacological Evaluation of the TG2-targeting Antibody Zampilimab in Diseased Human Lung Fibroblasts and Ex Vivo Lung Tissue Models

Abstract Introduction During Idiopathic pulmonary fibrosis (IPF), extracellular matrix (ECM) crosslinking and stabilization is promoted by Transglutaminase 2 (TG2) activity. Accordingly, we hypothesize that Zampilimab, a highly selective and potent TG2 inhibitor with demonstrated anti-fibrotic efficacy in renal fibrosis models, will inhibit lung fibrosis 1. Materials and Methods IPF-derived fibroblasts and IPF/ILD-donor derived human precision cut lung slices (hPCLS) were cultured in the presence of clinically relevant concentrations of Zampilimab. Secreted and intracellular pro-fibrotic markers, tissue stiffness and Ashcroft scoring were quantified as key endpoints to assess Zampilimab’s anti-fibrotic effects. TG2-mediated crosslinking activity was measured to confirm target engagement. Reference compounds were included for comparative analysis 2. Results 1) Characterization of IPF-derived fibroblasts revealed a significant upregulation of TG2 expression and TG2-mediated crosslinking activity, underscoring the pivotal role of this enzyme in fibrotic cell function. 2) Treating IPF fibroblasts with Zampilimab significantly reduced extracellular matrix (ECM) deposition, consistent with confirmed TG2 target engagement. 3) In the IPF/ILD hPCLS, elevated pro-fibrotic marker expression—including ECM components (Collagen I, FN) and inflammatory mediators (ICAM-1, CXCL13, CXCL18)—was observed alongside increased extracellular TG2 levels. Notably, labeling with Zampilimab confirmed selective binding to the open, active conformation of TG2 within fibrotic regions. Competitive binding assays further validated Zampilimab’s high specificity for TG2. 4) Treating IPF/ILD hPCLS with Zampilimab markedly decreased TG2-mediated crosslinking, collagen accumulation, and tissue stiffness across all tested samples, supporting its proposed mechanism of action in attenuating ECM accumulation and fibrotic remodelling. Conclusions The findings highlight Zampilimab’s potential as a targeted anti-fibrotic therapeutic through selective inhibition of TG2 activity, offering a promising strategy for the treatment of pulmonary fibrosis. This abstract is funded by: None