Fresolimumab (development code GC-1008) is an investigational, fully human monoclonal IgG4 antibody developed for the treatment of fibrotic diseases and advanced cancers, most notably malignant melanoma and idiopathic pulmonary fibrosis (IPF). It functions as a pan-neutralizing agent against transforming growth factor-beta (TGF-β) isoforms. By binding with high affinity to all three mammalian isoforms of TGF-β (TGF-β1, TGF-β2, and TGF-β3), fresolimumab prevents them from interacting with their cell surface receptors. This blockade inhibits the activation of downstream Smad-dependent and Smad-independent signaling pathways, thereby aiming to suppress the pleiotropic biological effects of TGF-β that drive fibrosis, immunosuppression, and tumor progression.