NR1H4 and primary biliary cholangitis: Chemically, BAR502 is a non bile acid steroidal ligand for FXR, that is similarly to obeticholic acid (OCA), a FXR ligand clinically approved for the treatment of primary biliary cholangitis (PBC), is generated from the addition of an ethyl group in the position 6 to a steroid core, CDCA in the case of OCA24,32.