Development of systemic FXR agonists to treat the metabolic
liver disease has been proven challenging because the side effects associated with these agents including increased levels of
cholesterol and
LDL-c and reduced HDL-c raising concerns over their long-term cardiovascular safety. Additionally,
pruritus has emerged as a common, although poorly explained, dose-related side effect with all FXR
ligands, but is especially common with OCA. FXR agonists that are currently undergoing phase 2/3 trials are
cilofexor,
tropifexor, nidufexor and MET409. Some of these agents are currently being developed as combination
therapies with other agents including
cenicriviroc, a CCR2/CCR5 inhibitor, or
firsocostat an
acetyl CoA carboxylase inhibitor. Additional investigations are needed to evaluate the beneficial effects of combination of these agents with
statins. It is expected that in the coming years, FXR agonists will be developed as a combination
therapy to minimize side effects and increase likelihood of success by targeting different metabolic pathways.