Cirevetmab, a novel canine anti–TGFβ monoclonal antibody, exerts antifibrotic effects on renal cells in vitro

Introduction Transforming Growth Factor-β (TGF-β) has been implicated for its role in fibrosis and progression of chronic kidney disease (CKD) in both humans and rodents. Additionally, CKD is a common and progressive condition in canines, with striking pathological similarities to human disease. However, targeted therapies addressing fibrogenic mediators in dogs remain underexplored. Methods We investigated the role of all three TGF-β isoforms (TGF-β1, TGF-β2, and TGF-β3) in CKD and renal fibrosis with in vitro model systems using human and canine primary renal proximal tubular epithelial cells. The studies assessed the induction of the canonical TGF-β pathway and the ability of a novel canine anti-TGF-β monoclonal antibody, cirevetmab, to neutralize these effects. All three TGF-β isoforms induced phosphorylation of SMAD3 (homologs of Drosophila mothers against decapentaplegic and C. elegans SMA proteins), nuclear translocation, and alpha-smooth muscle actin (αSMA). Results Treatment with cirevetmab led to robust neutralization of TGF-β1-induced SMAD phosphorylation and fibrotic marker changes. Notably, although cirevetmab exerted modest neutralization of TGF-β3-induced SMAD phosphorylation, this was not associated with a significant change in TGF-β3-induced fibrotic markers. Conversely, no neutralization of TGF-β2-induced activity was observed with cirevetmab. Discussion Our results demonstrate that cirevetmab selectively neutralizes TGF-β1 and, to a lesser extent, TGF-β3-induced SMAD phosphorylation in vitro , while only significantly neutralizing TGF-β1-induced fibrotic markers in renal proximal tubule cells.