NR1H4 and primary biliary cholangitis: Under an FDA-pre-authorized development program, FXR was trialed in PBC patients who were non-responders to UDCA for its efficacy in reducing alkaline phosphatase (ALP), a surrogate marker of disease progression [68], and although its use resulted in various side effects, the most common of which was pruritus (Table 2), OCA was granted clinical approval in the treatment of adult PBC patients who were resistant or intolerant to UDCA in 2016.