Command Palette

Search for a command to run...

Obeticholic acid plus bezafibrate in PBC: a long-term safety extension ended by a market withdrawal

OtherSafetyJune 11th, 2026·5 min read·10.5281/zenodo.20479005

Intercept closed a Phase 3 long-term safety extension of an obeticholic acid and bezafibrate fixed-dose combination after the FDA requested withdrawal of Ocaliva and placed all obeticholic acid trials on clinical hold. The FXR agonist failed to confirm clinical benefit and carried hepatic decompensation risk.

Mechanism Risk Score

ComponentPoints
Phase-weighted failure burden15.7 / 40
Archetype severity8.5 / 25
Temporal recency4.3 / 15
Genetic evidence deficit5.9 / 15
Programmatic saturation2.5 / 5

For NR1H4 in Primary biliary cholangitis, the Mechanism Risk Score is 37/100 (yellow band). The score is a failure-burden index derived from Claidex post-mortems on this target–disease pair, not a probability of approval.

MRS 37/100 (YELLOW). 1 programs across NR1H4 have been documented for NR1H4 in Primary biliary cholangitis: 1 Phase 3, 0 Phase 2, 0 Phase 1 — of which 0 were efficacy failures, 1 safety, 0 biomarker, and 0 operational (enrollment, sponsor, or funding). The most informative failure on file is Obeticholic acid plus bezafibrate in PBC: a long-term safety extension ended by a market withdrawal. This score quantifies the documented failure burden; the Open Targets association score of 0.61 reflects moderate genetic support, neither rescuing nor compounding the failure record. The MRS is not a prediction of future trial outcomes — it is a structured summary of the empirical record, recomputed live from the Claidex claims table, and intended to flag mechanisms where any new program must explicitly resolve each prior failure mode before pursuit is justified.

This score does not predict whether the next trial will succeed. It flags how heavy the documented mechanistic failure record is before a new program is justified.

Primary figure supporting this claim (Obeticholic acid (OCA) + bezafibrate fixed-dose combination / NR1H4 / Primary biliary cholangitis): Obeticholic acid plus bezafibrate in PBC: a long-term safety extension ended by a market withdrawal

What was tried

Intercept ran a Phase 3, open-label, long-term safety extension (NCT06488911, protocol 977-311) of a fixed-dose combination of obeticholic acid 5 mg and bezafibrate 400 mg sustained release, given once daily in subjects with primary biliary cholangitis (ClinicalTrials.gov). The study enrolled 62 participants (actual) in a single experimental arm and set treatment-emergent adverse events as its primary outcomes (ClinicalTrials.gov). Intercept terminated the trial with the posted reason that it was a business decision based on the FDA's request for voluntary withdrawal of Ocaliva and the issuance of a clinical hold on studies under US investigational new drug applications involving obeticholic acid (ClinicalTrials.gov). The actual primary completion date was 2025-10-21 (ClinicalTrials.gov). Obeticholic acid was withdrawn from the US market on 2025-11-14, and the FDA finalized withdrawal of the new drug application approval on 2025-11-24 (Intercept, 2025-09-11, Federal Register, 2025-11-24).

The biological hypothesis

Obeticholic acid is a semisynthetic bile acid that agonizes the farnesoid X receptor (FXR, gene NR1H4, ChEMBL566315). FXR activation reduces hepatic bile acid synthesis through FGF19 and small heterodimer partner signaling and increases bile acid efflux, which lowers the cytotoxic bile acid load that drives cholestatic injury in primary biliary cholangitis (Nat Rev Gastroenterol Hepatol 2020). On that mechanism obeticholic acid reduced alkaline phosphatase, a biochemical marker tied to long-term outcomes in this disease, and earned accelerated US approval in 2016 for patients with an inadequate response to or intolerance of ursodeoxycholic acid (Lancet 2024). Bezafibrate, a PPAR agonist, lowers alkaline phosphatase through a complementary pathway, and the combination was built to deepen biochemical response in patients who do not normalize on a single agent (Am J Gastroenterol 2025).

What actually happened

The extension closed not on its own safety readout but on a regulatory action against the obeticholic acid backbone. In September 2024 FDA reviewers concluded that the postmarketing confirmatory trial did not verify that obeticholic acid was effective in primary biliary cholangitis, and that obeticholic-acid-treated patients with early-stage disease at baseline had an excess of liver transplants and deaths (Medscape, 2025, AGA, 2025). The agency had already flagged 25 cases of serious liver injury in 2021 and made obeticholic acid contraindicated in patients with advanced cirrhosis (Lancet 2024). In September 2025 Intercept agreed to voluntary withdrawal and the FDA placed all obeticholic acid trials on clinical hold, which forced termination of this extension (Intercept, 2025-09-11). OpenFDA FAERS holds 6,798 Ocaliva reports, of which 2,972 are serious and 528 are deaths, with pruritus the dominant term at 2,365 and hepatic decompensation terms present, including hepatic cirrhosis at 133 and hepatic failure at 77 (openFDA, 2026-06-11).

Failure mechanism, best guess

This was a safety and benefit failure of the obeticholic acid molecule rather than a refutation of FXR as a target. The Open Targets association between NR1H4 and primary biliary cholangitis is 0.6048, carried by a clinical evidence score of 0.96 that reflects the drug's own trial history, with no germline genetic anchor (Open Targets Platform v25). The mechanistic problem sits in the therapeutic window. FXR agonism suppresses bile acid synthesis, but obeticholic acid is itself a bile acid analog, and at therapeutic exposure it can intensify pruritus and, in livers with limited reserve, push borderline-compensated patients toward decompensation (Nat Rev Gastroenterol Hepatol 2020). The accelerated approval rested on alkaline phosphatase reduction as a surrogate, and the confirmatory trial then failed to convert that biochemical effect into a clinical-outcome benefit while surfacing harm in the early-stage group the surrogate was meant to protect (Clin Gastroenterol Hepatol 2023). The best reading is a surrogate that ran ahead of outcomes, paired with an on-target hepatic liability that the surrogate could not see.

How to prevent this next time

Two quantitative levers would have reduced the exposure of patients and the sponsor. First, an event-driven power calculation for the confirmatory clinical-outcome trial, sized and enrolled in parallel with the accelerated approval rather than years after, would have set the timeline. A composite of hepatic decompensation, transplant, and death accrues slowly in primary biliary cholangitis, so detecting a hazard ratio near 0.7 with 80 percent power and a two-sided alpha of 0.05 needs on the order of 200 to 250 events, which translates into a large, multiyear cohort that should have started at approval, not after the surrogate read positive. Second, a historical base-rate adjustment for surrogate-to-outcome translation would have priced the risk explicitly, because biochemical surrogates across hepatology and cardiology confirm clinical benefit only a minority of the time, and that prior should have widened the confidence band on a benefit inferred from alkaline phosphatase alone. A prespecified hepatic safety stopping boundary, keyed to transplant-free survival in the early-stage stratum, would have caught the excess events sooner. The single highest leverage change would have been running an adequately powered, event-driven outcomes trial concurrently with the accelerated approval, with a hepatic decompensation stopping boundary in the early-stage stratum, so that benefit and harm were measured on clinical endpoints before broad use.

What this means for similar programs

Programs that win accelerated approval on a biochemical surrogate inherit two obligations, to confirm clinical benefit and to bound on-target organ risk, and obeticholic acid shows the cost of letting either lag. The read extends to other FXR agonists and to ileal bile acid transporter inhibitors in cholestatic disease, where the same bile-acid-load logic applies. The Claidex Mechanism Risk Score for NR1H4 is 37 of 100 (yellow), with phase burden contributing 15.7 points from a Phase 3 failure and the genetic deficit component held to 5.9 of 15 by the strong clinical evidence already on file (Claidex MRS). The target is not dead, but the next FXR agonist needs a wider therapeutic window and an outcomes trial that does not trail the surrogate.

Open questions

Would a non-bile-acid FXR agonist with less pruritus and less hepatic liability separate target engagement from the decompensation signal that sank obeticholic acid. Does the bezafibrate combination retain a favorable biochemical profile that could support a successor regimen in non-cirrhotic patients. Was the excess of transplants and deaths concentrated in a definable subgroup that prospective enrichment could have excluded. The clinical hold and withdrawal close the obeticholic acid record before these can be resolved from new trials.

Sources