SAT-035 Small Molecule Allosteric Agonist of Relaxin Receptor Ml290 Demonstrates Antifibrotic Properties in Liver Fibrosis

Fibrosis is an underlying cause of cirrhosis and hepatic failure resulting in end stage liver disease with limited pharmacological therapeutic options. The beneficial effects of relaxin peptide treatment have been demonstrated previously in clinically relevant animal models of liver disease. However, the low stability of the recombinant relaxin peptide in vivo requires continuous intravenous delivery for chronic therapeutic application. We have recently identified a first series of small molecule allosteric biased agonists of the human relaxin receptor RXFP1 which showed efficacy similar to relaxin in several functional assays in vitro. Here we investigated the therapeutic effects of small molecule RXFP1 agonist on activated hepatic stellate cells, the main source of excessive collagen production in liver fibrosis. We have demonstrated that RXFP1 expression is increased in fibrotic mouse liver, specifically in activated hepatic stellate cells. The lead compound, ML290, was selected based on its effects on the expression of the genes involved in fibrosis in primary human stellate cells. RNA-Seq analysis of TGFβ1-activated LX-2 hepatic stellate cells showed that about 500 genes were misregulated by ML290. Gene Ontology analysis demonstrated that ML290 treatment primarily affects extracellular matrix remodeling and cytokine signaling, with expression profiles indicating an antifibrotic effect of ML290. ML290 treatment of human liver organoids with lipopolysaccharide-induced fibrotic phenotype resulted in dramatic reduction of type I collagen. The pharmacokinetics of ML290 in mice after multiple injections demonstrated its high stability in vivo, as evidenced by the sustained concentrations of compound in the liver. The ML290 treatment of mice expressing human RXFP1 gene with carbon tetrachloride-induced liver fibrosis resulted in significantly reduced collagen content, alpha-smooth muscle actin expression and cell proliferation around portal ducts, and the decrease of pro-fibrotic genes’ expression. In summary, ML290, the small molecule agonist of relaxin receptor, has anti-fibrotic effects in liver fibrosis. Funding source: NIH/NIDDK