Peroxisome Proliferator-Activated Receptor Agonists in Primary Biliary Cholangitis and Other Liver Diseases: Mechanisms, Clinical Evidence, and Future Directions

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated nuclear transcription factors comprising three isoforms—PPARα, PPARγ, and PPARβ/δ—that regulate hepatic lipid metabolism, glucose homeostasis, inflammation, bile acid synthesis, and fibrogenesis. Because liver diseases involve overlapping metabolic, inflammatory, cholestatic, and fibrotic pathways, PPAR agonists have emerged as a versatile therapeutic class across a spectrum of hepatic conditions. PPARα agonists (e.g., fenofibrate) promote fatty acid β-oxidation and suppress de novo lipogenesis; PPARγ agonists (e.g., pioglitazone) improve insulin sensitivity and exert anti-inflammatory and antifibrotic effects; and PPARδ agonists (e.g., seladelpar) regulate bile acid and cholesterol metabolism. Dual agonists (elafibranor [PPARα/δ] and saroglitazar [PPARα/γ]) and pan-PPAR agonists (lanifibranor [PPARα/γ/δ] and bezafibrate) aim to simultaneously address multiple pathogenic mechanisms. In primary biliary cholangitis (PBC), elafibranor and seladelpar received accelerated FDA approval in 2024 based on phase 3 trials (ELATIVE and RESPONSE, respectively), demonstrating significant biochemical response rates of 51% and 62% versus 4% and 20% with the placebo. Long-term open-label extension data from the ELATIVE trial have demonstrated sustained improvements in cholestatic biomarkers and stabilization of fibrosis markers over three years, with durable benefits on fatigue and pruritus. The ASSURE open-label study has confirmed the durability of seladelpar’s effects on biochemical response and pruritus through up to two years of treatment. Saroglitazar, a dual PPARα/γ agonist, has shown positive topline phase 3 results in the EPICS-III trial and received an FDA priority review designation. Bezafibrate has shown a survival benefit in large retrospective analyses and is used as a second-line therapy in Europe and Japan; notably, bezafibrate functions as a dual PPAR/pregnane X receptor (PXR) agonist, inducing CYP3A4 and efflux transporters that contribute to bile acid detoxification. In metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH), pioglitazone remains the most extensively studied PPAR agonist, with meta-analytic evidence supporting MASH resolution and fibrosis reduction regardless of diabetes status. Lanifibranor demonstrated histological improvement in the phase 2b NATIVE trial and is currently in phase 3 development (NATiV3). PPAR agonists have also demonstrated therapeutic effects on liver fibrosis inhibition through direct modulation of hepatic stellate cell activation and suppression of fibrogenic signaling. This narrative review synthesizes the molecular pharmacology of PPAR isoforms; the available clinical and preclinical evidence for mono-, dual-, and pan-PPAR agonists; and their therapeutic applications across MASLD/MASH, alcohol-associated liver disease (ALD), PBC, primary sclerosing cholangitis (PSC), intestinal failure-associated liver disease (IFALD), and advanced chronic liver disease (ACLD). The evolution from single-isoform to multi-isoform PPAR agonism reflects the recognition that overlapping pathogenic mechanisms in liver diseases may require broader receptor coverage for optimal therapeutic efficacy.