Tag Archives: IBAT inhibitor

New Era in Cholestatic Liver Diseases

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H Sutton, RJ Sokol, BM Kamath. Hepatology 2025; 82: 985-995. Open Access! IBAT inhibitors in pediatric cholestatic liver diseases: Transformation on the horizon?

This review article is one of many in the same issue (#4) of Hepatology.

Key points:

  • “In the last few years, a novel class of agents, intestinal bile acid transporter (Ileal bile acid transporter (IBAT); also known as apical sodium-dependent bile acid transporter [ASBT]) inhibitors, has emerged and gained approval from the FDA… the pivotal studies on which these approvals were granted were all performed in rare pediatric cholestatic diseases, namely Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC).3 Additional expansion of these approvals will possibly follow as there are ongoing trials of IBAT inhibitors in primary biliary cirrhosis, primary sclerosing cholangitis, and biliary atresia.”
  • “The role of bile acids in promoting hepatic injury in cholestasis is perhaps best illustrated in human infants with ABCB11 (bile salt export pump; BSEP) disease or PFIC type 2…The response to IBAT inhibition in this disease further supports the notion that retained bile acids are a key factor leading to progressive liver injury and cholestatic symptoms including pruritus, fat-soluble vitamin deficiencies, and growth failure.4“
  • These medications may improve liver histology and not just reduce pruritic symptoms: “Using the MDR2−/− mouse cholangiopathy model, Miethke et al22 demonstrated that ASBT inhibition led to a reduction in both serum and intrahepatic bile acid concentrations by 98% and 65%, respectively. These reductions in bile acid concentrations were associated with improved liver biochemistry and a reduction in peri-portal inflammation and fibrosis on histology. The histopathologic improvements seen in these treated MDR2−/− are important to highlight, as they support the rationale of this therapeutic approach: that lowering serum bile acid (sBA) with IBAT inhibition leads to a reduction in intrahepatic bile acid accumulation and toxicity, improvements in liver inflammation and fibrosis, and ultimately improved liver disease biology.”
  • Numerous clinical trials are listed in Table 1 (completed trials) and Table 2 (ongoing).
  • Physiology: “Bile acids are key regulators of their own enterohepatic circulation, predominately through activation of the farnesoid X receptor (FXR)…the fecal elimination of bile acids in IBAT inhibitor–treated patients appears to far exceed the rate of synthesis of new bile acids in the liver; thus, IBAT inhibitors reduce the total bile acid pool size and the bile acid load presented to the liver.22,34,39“
  • Alagille syndrome (ALGS): Key trials are summarized including the ICONIC trial with maralixibat and the ASSERT trial with odevixibat.
  • PFIC (Type 1 and 2) Trials: Key trials are summarized including the MARCH-PFIC trial with maralixibat and the PEDFIC1 & PEDFIC 2 trialswith odevixibat.
  • Safety: These medications are well-tolerated with self-limiting diarrhea and abdominal pain especially at the initiation of these medications. Liver blood test abnormalities have been noted in up to 20%. “This is an interesting finding, and the underlying etiology is unknown. Maralixibat is largely luminally restricted and so, without systemic absorption, a direct hepatotoxic effect is unlikely. It may reflect an alteration in the speciation of the bile acid pool with increasing bile acid synthesis or alterations in the gut-liver axis signaling. More importantly, it is not known if there are any clinical consequences to the increase in ALT.”
  • Cost: The authors note that ursodeoxycholic acid and antihistamines are frequently used for management of pruritus. They also not that “from a cost standpoint, it seems appropriate to offer rifampin before IBAT inhibitors in the treatment of cholestatic pruritus.”
  • Conclusions: “The clinical trial data are encouraging. As more physicians gain experience prescribing IBAT inhibitors, we will continue to learn how to best apply them to our patient populations. Like any new drug, there are still several unknowns. One of these unknowns is the potential for loss of efficacy…The short-term to medium-term clinical effects of IBAT inhibitors are clear, but we have not yet begun to see the long-term benefits. Whether durable reductions in oncogenic and fibrogenic bile acids reduce rates of HCC or slow the progression of (or reverse) portal hypertension remains to be seen.”

Related article: M Trauner, SJ Karpen, PA Dawson. Hepatology 2025; 82: 855-876. Open Access! Benefits and challenges to therapeutic targeting of bile acid circulation in cholestatic liver disease

“Recent advances in understanding bile acid (BA) transport in the liver… This has led to new treatments targeting BA transport and signaling. These include inhibitors of BA transport systems in the intestine and kidney (IBAT/ASBT inhibitors) and liver (NTCP inhibitors), as well as receptor agonists that modify BA synthesis and transport genes. BA analogs like norucholic acid also show promise. This review discusses the molecular and clinical basis for these therapies, particularly for cholestatic liver disorders.

Principal therapeutic targets within the entero-nephro-hepatic circulation of BAs in cholestasis.

My take (borrowed from Trauner et al): “We have arrived at a new era in the treatment of cholestatic disorders. This has been made possible by incorporating findings from discoveries into the molecular pathogenesis of cholestasis and adaptive processes that direct rational therapeutics to improve patients’ lives.”

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Advancements in Pediatric Cholestatic Liver Disease Management

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KR Mysore et al. J Pediatr Gastroenterol Nutr. 2025;80:549–558. Recent advances in the management of pediatric cholestatic liver diseases

This is a useful review summarizing advances in the management of cholestatic diseases.

Treatment with IBAT inhibitors:

“Improvement in both pruritus and serum BAs/bilirubin levels has been associated with improved event‐free survival and 6‐year transplant‐free survival in ALGS patients treated with maralixibat. Additionally, this class of medication improved overall growth of the patient by improving mean height and weight Z scores that may be related to reduced impact of high serum bile acid levels on the growth axis although further studies are needed to better define the mechanism responsible for this out-come. This finding suggests these parameters could be used as surrogate end‐points for disease severity in diseases like ALGS or PFIC, where the time course to develop the need for LT commonly occurs over many years.”

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Six Year Data for IBAT Inhibitor Treatment for Alagille Syndrome

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RJ Sokol et al. Hepatology 2023; 78: 1698-1710. Open Access! Predictors of 6-year event-free survival in Alagille syndrome patients treated with maralixibat, an ileal bile acid transporter inhibitor

In this study, the authors examined 43 potential predictors of outcomes in pediatric patients (n=76) treated with maralixibat (MRX). The median duration of MRX treatment was 4.7 years. Key findings:

  • There were 10 liver transplantations, 3 decompensations, 2 deaths, and 1 surgical biliary diversion; thus, 16/76 (21%) had liver-related events.
  • The 6-year event-free survival improved with a clinically meaningful >1-point ItchRO(Obs) reduction from baseline to W48 (88% vs. 57%; p = 0.005), W48 bilirubin < 6.5 mg/dL (90% vs. 43%; p < 0.0001), and W48 serum bile acid < 200 µmol/L (85% vs. 49%; p = 0.001). These parameters were also predictive of 6-year transplant-free survival.
  • In this cohort, younger children (<36 months) fared worse, though this was likely related to selection bias as they had more severe cholestasis. In the discussion, the authors note that in their cohort, “there is a survivor bias such that older children are inherently healthier or they would have already undergone transplantation.”
  • Improved event-free survival could be largely related to symptomatic improvement. Many kids with Alagille require transplantation due to refractory pruritus. Since this study did not include histology or noninvasive techniques to assess hepatic fibrosis, it is unclear if there was also improvement in underlying liver function/fibrosis subsequent to reduction in toxic bile acid retention.
  • 46/76 (61%) had improvement in pruritus, 52/76 (68%) had improvement in bilirubin, and 56/76 (74%) had improvement in serum bile acids.

In their discussion, the authors note that in the GALA study, “which included natural history data from >1400 patients, 358 patients required a liver transplant, with 69% being transplanted for intractable pruritus.4“

My take: In patients with moderate to severe pruritus, patients who respond to IBAT inhibitors are likely to have improvement in important clinical outcomes.

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