Metelimumab is a fully human monoclonal antibody that specifically targets transforming growth factor-beta 1 (TGF-β1), a key profibrotic cytokine. By binding to TGF-β1, it neutralizes the cytokine and prevents it from interacting with its receptors, thereby blocking downstream Smad-dependent signaling pathways that drive fibroblast activation, collagen production, and tissue fibrosis. It was developed as a potential anti-fibrotic therapy and was clinically evaluated for the treatment of diffuse cutaneous systemic sclerosis (scleroderma), a disease characterized by excessive collagen deposition and progressive skin thickening. However, its development was discontinued due to lack of efficacy in Phase II trials.