Obeticholic Acid and Other Farnesoid-X-Receptor (FXR) Agonists in the Treatment of Liver Disorders

The Farnesoid-X-receptor (FXR) is a bile sensor involved in the regulation of bile acid homeostasis, fibrosis, inflammation, and metabolism. Obeticholic acid (OCA), a semisynthetic derivative of chenodeoxycholic acid (CDCA), initially named 6-ethyl-CDCA or INT-747, is the first in a class of FXR ligands that have been approved for clinical use for the treatment of patients with primary biliary cholangitis (PBC) who are unresponsive or intolerant to ursodeoxycholic acid. In this narrative review, we will examine the current status and future perspective of clinical use of OCA. Based on results from phase 2 and 3 clinical trials, OCA received a conditional market approval for its use as a second-line treatment for the management of PBC in 2016. However, concerns over drug (OCA)-induced liver injury (DILI), including hepatic decompensation in cirrhotic and non-cirrhotic PBC patients, have led to discontinuation of OCA commercialization in the EU, but not in North America and the UK, in 2024. Based on positive results from preclinical models, OCA has been investigated also for the treatment of metabolic dysfunction-associated steatohepatitis (MASH). Results from phase 2 and 3 trials, however, have shown that while OCA reduces liver fibrosis, the beneficial effects on steatosis are marginal, thus preventing its clinical approval under the current regulatory guidelines. Here, we review potential applications of OCA in PBC patients in the context of a highly competitive therapeutic landscape, generated by the approval for clinical use of safer and effective second-line therapies, including PPARs agonists such as elafibranor and seladelapar and increased off-label use of fibrates. The current status of development of second-generation FXR agonists such as cilofexor, tropifexor, and vonafexor and their potential in the treatment of liver fibrosis in MASH will be discussed and compared to recently approved therapies, resmetirom, and semaglutide, a GLP-1 agonist. Finally, since some of the novel candidates for treating MASH, have shown limited efficacy on liver fibrosis, we suggest that development of combinatorial therapies based on FXR ligands and agents acting on different molecular targets might offer the opportunity for the repositioning of drug candidates whose development has been abandoned for insufficient efficacy, minimizing/recovering costs linked to drug development.