Obeticholic acid (OCA) is not approved for metabolic dysfunction-associated steatohepatitis (MASH), and the United States development pathway for its use in precirrhotic NASH ended after regulatory non-approval. The compound is still useful scientifically, because no other farnesoid X receptor (FXR) agonist has produced a comparable human dataset in steatohepatitis. A frequent interpretive problem is that histological benefit, low-density lipoprotein cholesterol (LDL-C) elevation, pruritus and possible liver-intrinsic injury are compressed into one FXR activation continuum. This hypothesis-driven narrative article argues for a narrower reading. OCA is treated here as an index scaffold that separates clinical response, systemic lipid risk, tolerability and candidate liver-intrinsic sterol-stress biology into distinct evidence layers. We first place OCA in the current MASLD/MASH therapeutic setting, then outline hepatic and intestinal FXR pharmacology relevant to the model. Human OCA data, cross-scaffold observations from non-bile acid FXR agonists, and mechanistic work on FATP5/SLC27A5, cholesterol stress and ACOX1 are then reassessed. Within the proposed model, FATP5 is a putative OCA-linked substrate-entry node supported mainly by preclinical and humanized-transporter work. Cholesterol retention, free-cholesterol burden, cholesterol crystals, macrophage crown-like structures, IL-1beta signaling and hepatic stellate-cell activation are better handled as a candidate sterol-stress liability branch. ACOX1 is interpreted as a context-dependent modifier, not as a validated therapeutic target. The model is not a class-wide claim for all FXR agonists. It should be tested, and if necessary rejected, using matched FXR target engagement, paired human tissue and human multicellular systems.
Obeticholic acid as an index farnesoid X receptor scaffold in metabolic dysfunction-associated steatohepatitis: a testable model for efficacy-liability separation and biomarker interpretation
Xiaojuan Wu

