Potential of ileal bile acid transporter inhibition as a therapeutic target in Alagille syndrome and progressive familial intrahepatic cholestasis

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic biliary inflammation associated with periductular fibrosis of the intrahepatic and extrahepatic bile ducts leading to strictures, bacterial cholangitis, decompensated liver disease and need for liver transplantation. This rare focal liver disease affects all races and ages, with a predominance of young males. There is an up to 88% association with inflammatory bowel disease. Although the aetiology is unknown and the pathophysiology is poorly understood, PSC is regarded as an autoimmune liver disease based on a strong immunogenetic background. Further, the associated risk for various malignancies, particularly cholangiocellular carcinoma, is also poorly understood. No medical therapy has been approved so far nor has been shown to improve transplant-free survival. However, ursodeoxycholic acid is widely used since it improves the biochemical parameters of cholestasis and is safe at low doses. MRI of the biliary tract is the primary imaging technology for diagnosis. Endoscopic interventions of the bile ducts should be limited to clinically relevant strictures for balloon dilatation, biopsy and brush cytology. End-stage liver disease with decompensation is an indication for liver transplantation with recurrent PSC in up to 38% of patients. Several novel therapeutic strategies are in various stages of development, including apical sodium-dependent bile acid transporter and ileal bile acid transporter inhibitors, integrin inhibitors, peroxisome proliferator-activated receptor agonists, CCL24 blockers, recombinant FGF19, CCR2/CCR5 inhibitors, farnesoid X receptor bile acid receptor agonists, and nor-ursodeoxycholic acid. Manipulation of the gut microbiome includes faecal microbiota transplantation. This article summarizes present knowledge and defines unmet medical needs to improve quality of life and survival.

Pruritus in Chronic Cholestatic Liver Diseases, Especially in Primary Biliary Cholangitis: A Narrative Review

Patients with chronic cholestatic liver diseases often experience itch and struggle with this symptom. We discuss the mechanism of itch in patients with chronic cholestatic liver diseases, such as primary biliary cholangitis (PBC) and others, and their therapies, including ileal bile acid transporter (IBAT) inhibitors. In patients with PBC, there are high serum/plasma concentrations of multiple factors, including bile salts, bilirubin, endogenous opioids, lysophosphatidic acid (LPA), autotaxin, and histamine. Bile salts, bilirubin, LPA, and autotaxin affect itch mediators in the skin and sensory nerves, while the endogenous opioid balance affects mediators in the spinal cord. Itch is sensitized by both the peripheral and central nervous systems. Both mechanisms are involved in itch in patients with chronic cholestatic liver disease. Although IBAT inhibitors have been approved for use in pediatric cholestatic conditions, such as progressive familial intrahepatic cholestasis and Alagille syndrome, IBAT inhibition seems to be a promising treatment for chronic refractory itch in patients with PBC. A traditional non-systematic review results in this narrative review. Multidisciplinary cooperation, involving hepatologists, dermatologists, and pharmacists, could provide better treatment for PBC patients suffering from refractory itch. In conclusion, we summarized the existing knowledge on itch caused by chronic cholestatic liver diseases, especially in PBC with a focus on the mechanisms and therapies. This narrative review provides the mechanisms and therapeutic options for itch in patients with chronic cholestatic liver diseases.

Genotypes and different clinical variants between children and adults in progressive familial intrahepatic cholestasis: a state-of-the-art review

INTRODUCTION

Progressive Familial intrahepatic cholestasis (PFIC) are rare disorders of bile acid (BAs) secretion and transport with a genetic background. PFIC are paediatric manifestations, but the same variants causing PFIC can also cause cholestasis with a later paediatric onset or adult-onset cholestatic disease (AOCD). Pruritus is a symptom of cholestasis that can be so devastating that it requires a liver transplant (LT) in children; some PFIC types have been described as at risk of liver cancer development. Commonly prescribed medications for PFIC symptoms can partially relieve pruritus without changing the natural history of the disease. Recently, a therapy reducing the intestinal resorption of BAs has been approved; it is effective on both pruritus and cholestasis in PFIC, potentially being a disease-modifying intervention.

AREAS COVERED

The clinical and genetic characteristics of different PFIC and AOCD are summarized to provide a common background for geneticists and paediatric and adult hepatologists in diagnosis and management.

EXPERT OPINION

Collaboration between paediatric and adult hepatologists and geneticists will become crucial for cholestatic disease research and patient treatment. Therefore, adult hepatologists will need to learn more about FIC. This might enable the implementation of individualized surveillance in FIC patients and the evaluation of patient family histories.

The burden of Alagille syndrome: uncovering the potential of emerging therapeutics - a comprehensive systematic literature review

Aim: Alagille syndrome (ALGS) is a rare, cholestatic multiorgan disease associated with bile duct paucity, leading to cholestasis. Clinical symptoms of cholestasis include debilitating pruritus, xanthomas, fat-soluble vitamin deficiencies, growth failure, renal disease and impaired health-related quality of life (HRQoL). The main objective was to review the current literature on the epidemiological, clinical, psychosocial and economic burden of ALGS in view of the development of ileal bile acid transporter (IBAT) inhibitors. Methods: Electronic literature databases were searched in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Results: 330 publications were screened, 119 were relevant: 11 randomized controlled trials (RCTs), 21 non-RCTs, 10 HRQoL studies, two studies assessing cost/resource use and 77 epidemiological studies across several databases through 31 July 2024. Studies confirm that patients with ALGS experience cardiac anomalies, impaired growth, renal disease, poor HRQoL, fat-soluble vitamin deficiencies and debilitating pruritus; until the approval of IBAT inhibitors for the treatment of cholestatic pruritus in patients with ALGS, supportive management was the standard of care. Conclusion: This review confirms the substantial clinical, economic and HRQoL burden associated with ALGS and consolidates current treatment evidence. Data from recent trials in ALGS demonstrate the potential impact of IBAT inhibitors to transform lives by improving cholestatic pruritus symptoms, HRQoL and native liver survival.

Odevixibat treatment in a child with hypoplastic left heart syndrome and severe cholestatic pruritus: a case report

Liver-related abnormalities are commonly observed in patients with congenital heart disease, and these may lead to secondary manifestations such as pruritus. Odevixibat is an ileal bile acid transporter inhibitor under investigation for the treatment of cholestatic liver diseases. Here, we describe the effects of odevixibat treatment in a pediatric patient with congenital heart disease and severe cholestatic pruritus. A 2-year-old male with Kleefstra syndrome, hypoplastic left heart syndrome, and a history of Giessen procedure and biventricular correction surgery presented to the pediatric cardiology and hepatology outpatient clinics at University Children's Hospital Bonn. Portal hypertension was evident on imaging, and the patient was experiencing severe itching attacks that did not respond to treatment with naltrexone, ursodeoxycholic acid, dimetindene, or rifampicin. Sleep and quality of life were poor. Treatment with odevixibat was initiated off label due to refractory pruritus and elevated serum bile acids. Improvements in pruritus and sleep occurred rapidly with odevixibat and were sustained for the duration of treatment. The patient's serum bile acids decreased from 111 μmol/L before treatment with odevixibat to 24 μmol/L within 1 month of initiating therapy. Relief from pruritus had positive effects on psychomotor development and quality of life. Mild diarrhea lasting 2 days was reported by the patient's mother. In this case report, odevixibat was effective and well tolerated. Together with those of previous studies in patients with progressive familial intrahepatic cholestasis and Alagille syndrome, these results suggest that odevixibat warrants further study as a potential treatment option for patients with cholestatic pruritus of diverse etiologies.

Practical Considerations for Odevixibat Treatment in Patients with Progressive Familial Intrahepatic Cholestasis: A Single-Center Case Series

Background: Patients with progressive familial intrahepatic cholestasis (PFIC) experience cholestasis-associated symptoms, including severe pruritus. Odevixibat is an ileal bile acid transporter inhibitor indicated for treatment of PFIC in the European Union and for the treatment of pruritus in PFIC in the United States. The aim of the current study was to characterize the real-world effectiveness and safety of odevixibat in patients with PFIC. Methods: This retrospective study included 9 patients with PFIC treated with odevixibat in a single center in Tübingen, Germany. Data were recorded using case report forms. Results: Of the 9 patients (PFIC1, n = 2; PFIC2, n = 7), 5 had improved serum bile acid levels, pruritus, liver function tests, and sleep with odevixibat treatment. Two siblings with periodic relapses of PFIC symptoms also had improved pruritus and sleep within 4 months of treatment. Two siblings with complete loss of bile salt export pump (BSEP) protein did not respond to treatment; both underwent liver transplantation (indications: hepatocellular carcinoma [HCC] manifestation [n = 1] and severe failure to thrive and refractory pruritus [n = 1]). Four patients reported abdominal complaints that were transient or responded to dose reduction; no other safety issues were reported. Conclusions: In this case series, clinical benefits were observed in most patients with PFIC1 and PFIC2 treated with odevixibat. In patients with periodic relapse of PFIC symptoms, ≥3 months of treatment with odevixibat may be required for symptom control. Patients with complete loss of BSEP did not have consistent symptom relief and require careful monitoring. Effectiveness and feasibility results from our cohort demonstrate potential for long-term benefits with odevixibat in real-world treatment of patients with PFIC.

Stereoselective Synthesis of Maralixibat via VO(acac)2/Schiff Base-Catalyzed Asymmetric Oxidation of Its Sulfide Intermediate

The stereoselective synthesis of maralixibat was achieved by harnessing the chiral transferring effect of the stereogenic R-sulfoxide functionality, which was obtained via the VO(acac)2/Schiff base-catalyzed asymmetric oxidation of a phenylthiophenol prochiral intermediate. The R-sulfoxide intermediate underwent a ring closure reaction to form the seven-membered ring core structure with the desired stereochemistry, ultimately ensuring the drug's exceptional isomeric purity and synthetic efficiency.

What's new in pediatric genetic cholestatic liver disease: advances in etiology, diagnostics and therapeutic approaches

PURPOSE OF REVIEW

To highlight recent advances in pediatric cholestatic liver disease, including promising novel prognostic markers and new therapies.

FINDINGS

Additional genetic variants associated with the progressive familial intrahepatic cholestasis (PFIC) phenotype and new genetic cholangiopathies, with an emerging role of ciliopathy genes, are increasingly being identified. Genotype severity predicts outcomes in bile salt export pump (BSEP) deficiency, and post-biliary diversion serum bile acid levels significantly affect native liver survival in BSEP and progressive familial intrahepatic cholestasis type 1 (FIC1 deficiency) patients. Heterozygous variants in the MDR3 gene have been associated with various cholestatic liver disease phenotypes in adults. Ileal bile acid transporter (IBAT) inhibitors, approved for pruritus in PFIC and Alagille Syndrome (ALGS), have been associated with improved long-term quality of life and event-free survival.

SUMMARY

Next-generation sequencing (NGS) technologies have revolutionized diagnostic approaches, while discovery of new intracellular signaling pathways show promise in identifying therapeutic targets and personalized strategies. Bile acids may play a significant role in hepatic damage progression, suggesting their monitoring could guide cholestatic liver disease management. IBAT inhibitors should be incorporated early into routine management algorithms for pruritus. Data are emerging as to whether IBAT inhibitors are impacting disease biology and modifying the natural history of the cholestasis.

Emerging drugs for the treatment of progressive familial intrahepatic cholestasis: a focus on phase II and III trials

INTRODUCTION

Progressive familial intrahepatic cholestasis (PFIC) is a group of disorders characterized by inappropriate bile formation, causing hepatic accumulation of bile acids and, subsequently, liver injury. Until recently, no approved treatments were available for these patients.

AREAS COVERED

Recent clinical trials for PFIC treatment have focused on intestine-restricted ileal bile acid transporter (IBAT) inhibitors. These compounds aim to reduce the pool size of bile acids by interrupting their enterohepatic circulation. Other emerging treatments in the pipeline include systemic IBAT inhibitors, synthetic bile acid derivatives, compounds targeting bile acid synthesis via the FXR/FGF axis, and chaperones/potentiators that aim to enhance the residual activity of the mutated transporters.

EXPERT OPINION

Substantial progress has been made in drug development for PFIC patients during the last couple of years. Although data concerning long-term efficacy are as yet only scarcely available, new therapies have demonstrated robust efficacy in a considerable fraction of patients at least on the shorter term. However, a substantial fraction of PFIC patients do not respond to these novel therapies and thus still requires surgical treatment, including liver transplantation before adulthood. Hence, there is still an unmet medical need for long-term effective medical, preferably non-surgical, treatment for all PFIC patients.

Clinical, pathological and genetic characteristics of 17 unrelated children with Alagille Syndrome

BACKGROUND

Alagille syndrome (ALGS) is a multisystem genetic disorder frequently characterized by hepatic manifestations. This study analyzed the clinical, pathological, and molecular genetic features of ALGS to improve the efficiency of clinical diagnosis.

METHODS

We retrospectively analyzed the clinical manifestations, pathological examination findings, and genetic testing results of 17 children diagnosed with ALGS based on the revised criteria and hospitalized at our center from January 2012 to January 2022.

RESULTS

The clinical manifestations are as follows: Cholestasis (16/17, 94%), characteristic facies (15/17, 88%), heart disease (12/16, 75%), butterfly vertebrae (12/17, 71%) and posterior embryotoxon (7/12, 58%). Among the 15 patients who underwent liver pathology examination, 13 (87%) were found to have varying degrees of bile duct paucity. Genetic testing was performed on 15 children, and pathogenic variants of the jagged canonical Notch ligand 1 (JAG1) gene were identified in 13 individuals, including 4 novel variants. No pathogenic variant in the notch homolog 2 (NOTCH2) gene were identified, and 2 children exhibited none of the aforementioned gene pathogenic variants. The median follow-up duration was 7 years. Of the remaining 15 patients (excluding 2 lost to follow-up), 11 remained stable, 4 deteriorated, and no patient died during the follow-up period.

CONCLUSIONS

Among children diagnosed with ALGS, cholestasis stands as the most common feature. To minimize the risk of misdiagnosis, genetic testing should be performed on children exhibiting cholestasis, followed by the application of the revised diagnostic criteria for ALGS. While pharmacological therapy has shown effectiveness for ALGS patients, liver transplantation may be considered in instances of severe pruritus.

Differences in bile acid profiles between cholestatic diseases - Development of a high throughput assay for dried bloodspots

BACKGROUND

Cholestasis causes accumulation of bile acids (BAs) and changes the circulating bile acid profile. Quantification of circulating BAs in dried bloodspots (DBS) may demonstrate obstruction of bile flow and altered bile acid metabolism in the liver. High sample throughput enables rapid screening of cholestatic diseases.

MATERIALS AND METHODS

Ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was used for optimizing separation and detection of the primary unconjugated BAs cholic acid (CA) and chenodeoxycholic acid (CDCA); the secondary unconjugated BAs ursodeoxycholic acid (UDCA), hyodeoxycholic acid (HDCA) and deoxycholic acid (DCA), as well as the glycine- and taurine-conjugated variants of CA, CDCA, DCA and UDCA. Donor blood was obtained to prepare DBS calibrators and quality controls for method development and validation.

RESULTS

We developed a quantitative bile acid assay with a run-time of two minutes, and one-step sample preparation of 3.2 mm DBS discs. Validation results demonstrated overall good performance and was considered fit for purpose. Children with Alagille syndrome, Aagenaes syndrome and alpha-1 antitrypsin deficiency had increased BAs in DBS from newborn screening samples compared with age matched controls, and had different bile acids profiles.

CONCLUSION

We propose that our high throughput assay allows bile acid profiling in DBS that can be a valuable assessment tool for early screening of cholestasis in children. Assaying BAs in dried bloodspots is key for early detection of cholestasis, and provides transferability to a newborn screening setting.

Maralixibat in progressive familial intrahepatic cholestasis (MARCH-PFIC): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) is a group of autosomal recessive disorders, the most prevalent being BSEP deficiency, resulting in disrupted bile formation, cholestasis, and pruritus. Building on a previous phase 2 study, we aimed to evaluate the efficacy and safety of maralixibat-an ileal bile acid transporter inhibitor-in participants with all types of PFIC.

METHODS

MARCH-PFIC was a multicentre, randomised, double-blind, placebo-controlled, phase 3 study conducted in 29 community and hospital centres across 16 countries in Europe, the Americas, and Asia. We recruited participants aged 1-17 years with PFIC with persistent pruritus (>6 months; average of ≥1·5 on morning Itch-Reported Outcome [Observer; ItchRO(Obs)] during the last 4 weeks of screening) and biochemical abnormalities or pathological evidence of progressive liver disease, or both. We defined three analysis cohorts. The BSEP (or primary) cohort included only those with biallelic, non-truncated BSEP deficiency without low or fluctuating serum bile acids or previous biliary surgery. The all-PFIC cohort combined the BSEP cohort with participants with biallelic FIC1, MDR3, TJP2, or MYO5B deficiencies without previous surgery but regardless of bile acids. The full cohort had no exclusions. Participants were randomly assigned (1:1) to receive oral maralixibat (starting dose 142·5 μg/kg, then escalated to 570 μg/kg) or placebo twice daily for 26 weeks. The primary endpoint was the mean change in average morning ItchRO(Obs) severity score between baseline and weeks 15-26 in the BSEP cohort. The key secondary efficacy endpoint was the mean change in total serum bile acids between baseline and the average of weeks 18, 22, and 26 in the BSEP cohort. Efficacy analyses were done in the intention-to-treat population (all those randomly assigned) and safety analyses were done in all participants who received at least one dose of study drug. This completed trial is registered with ClinicalTrials.gov, NCT03905330, and EudraCT, 2019-001211-22.

FINDINGS

Between July 9, 2019, and March 4, 2022, 125 patients were screened, of whom 93 were randomly assigned to maralixibat (n=47; 14 in the BSEP cohort and 33 in the all-PFIC cohort) or placebo (n=46; 17 in the BSEP cohort and 31 in the all-PFIC cohort), received at least one dose of study drug, and were included in the intention-to-treat and safety populations. The median age was 3·0 years (IQR 2·0-7·0) and 51 (55%) of 93 participants were female and 42 (45%) were male. In the BSEP cohort, least-squares mean change from baseline in morning ItchRO(Obs) was -1·7 (95% CI -2·3 to -1·2) with maralixibat versus -0·6 (-1·1 to -0·1) with placebo, with a significant between-group difference of -1·1 (95% CI -1·8 to -0·3; p=0·0063). Least-squares mean change from baseline in total serum bile acids was -176 μmol/L (95% CI -257 to -94) for maralixibat versus 11 μmol/L (-58 to 80) for placebo, also representing a significant difference of -187 μmol/L (95% CI -293 to -80; p=0·0013). The most common adverse event was diarrhoea (27 [57%] of 47 patients on maralixibat vs nine [20%] of 46 patients on placebo; all mild or moderate and mostly transient). There were five (11%) participants with serious treatment-emergent adverse events in the maralixibat group versus three (7%) in the placebo group. No treatment-related deaths occurred.

INTERPRETATION

Maralixibat improved pruritus and predictors of native liver survival in PFIC (eg, serum bile acids). Maralixibat represents a non-surgical, pharmacological option to interrupt the enterohepatic circulation and improve the standard of care in patients with PFIC.

FUNDING

Mirum Pharmaceuticals.

Efficacy and safety of odevixibat in patients with Alagille syndrome (ASSERT): a phase 3, double-blind, randomised, placebo-controlled trial

BACKGROUND

In patients with Alagille syndrome, cholestasis-associated clinical features can include high serum bile acids and severe pruritus that can necessitate liver transplantation. We aimed to evaluate the efficacy and safety of the ileal bile acid transporter inhibitor odevixibat versus placebo in patients with Alagille syndrome.

METHODS

The ASSERT study was a phase 3, double-blind, randomised, placebo-controlled trial that enrolled patients at 21 medical centres or hospitals in ten countries (Belgium, France, Germany, Italy, Malaysia, the Netherlands, Poland, Türkiye, the UK, and the USA). Eligible patients had a genetically confirmed diagnosis of Alagille syndrome, a history of significant pruritus, and elevated serum bile acids. Patients were randomly assigned (2:1) to receive oral odevixibat 120 μg/kg per day or placebo for 24 weeks (in a block size of six and stratified by age: <10 years and ≥10 years to <18 years) via a web-based system. Patients, clinicians, study staff, and people analysing the data were masked to treatment allocation. The primary efficacy endpoint was change in caregiver-reported scratching score (on the PRUCISION instrument; range 0-4) from baseline to weeks 21-24. The prespecified key secondary efficacy endpoint was change in serum bile acid concentration from baseline to the average of weeks 20 and 24. Outcomes were analysed in patients who received at least one dose of study drug (the full analysis set for efficacy outcomes and the safety analysis set for safety outcomes). This trial is registered on ClinicalTrials.gov (NCT04674761) and EudraCT (2020-004011-28), and is completed.

FINDINGS

Between Feb 26, 2021, and Sept 9, 2022, 52 patients were randomly assigned to receive odevixibat (n=35) or placebo (n=17), all of whom were included in the analysis sets. The median age was 5·5 years (IQR 3·2 to 8·9). 27 (52%) of 52 patients were male and 25 (48%) were female. The mean scratching score was elevated at baseline in both groups (2·8 [SD 0·5] for odevixibat vs 3·0 [0·6] for placebo). Mean scratching scores at weeks 21-24 were 1·1 (0·9) for odevixibat and 2·2 (1·0) for placebo, representing a least-squares (LS) mean change of -1·7 (95% CI -2·0 to -1·3) for odevixibat and -0·8 (-1·3 to -0·3) for placebo, which was significantly greater for odevixibat than for placebo (difference in LS mean change from baseline -0·9 [95% CI -1·4 to -0·3]; p=0·0024). Odevixibat also resulted in significantly greater reductions in mean serum bile acids from baseline versus placebo (237 μmol/L [SD 115] with odevixibat vs 246 μmol/L [121] with placebo) to the average of weeks 20 and 24 (149 μmol/L [102] vs 271 μmol/L [167]; LS mean change -90 μmol/L [95% CI -133 to -48] with odevixibat vs 22 μmol/L [-35 to 80] with placebo; difference in LS mean change -113 μmol/L [95% CI -179 to -47]; p=0·0012). The most common treatment-emergent adverse events were diarrhoea (ten [29%] of 35 patients in the odevixibat group vs one [6%] of 17 in the placebo group) and pyrexia (eight [23%] vs four [24%]). Seven patients had serious treatment-emergent adverse events during the treatment period: five (14%) in the odevixibat group and two (12%) in the placebo group. No patients discontinued treatment and there were no deaths.

INTERPRETATION

Odevixibat could be an efficacious non-surgical intervention to improve pruritus, reduce serum bile acids, and enhance the standard of care in patients with Alagille syndrome. Longer-term safety and efficacy data of odevixibat in this population are awaited from the ongoing, open-label ASSERT-EXT study.

FUNDING

Albireo Pharma, an Ipsen company.

Transporter Proteins as Therapeutic Drug Targets-With a Focus on SGLT2 Inhibitors

Membrane transporters interact not only with endogenous substrates but are also engaged in the transport of xenobiotics, including drugs. While the coordinated function of uptake (solute carrier family-SLC and SLCO) and efflux (ATP-binding cassette family-ABC, multidrug and toxic compound extrusion family-MATE) transporter system allows vectorial drug transport, efflux carriers alone achieve barrier functions. The modulation of transport functions was proved to be effective in the treatment strategies of various pathological states. Sodium-glucose cotransporter-2 (SGLT2) inhibitors are the drugs most widely applied in clinical practice, especially in the treatment of diabetes mellitus and heart failure. Sodium taurocholate co-transporting polypeptide (NTCP) serves as virus particles (HBV/HDV) carrier, and inhibition of its function is applied in the treatment of hepatitis B and hepatitis D by myrcludex B. Inherited cholestatic diseases, such as Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC) can be treated by odevixibat and maralixibat, which inhibit activity of apical sodium-dependent bile salt transporter (ASBT). Probenecid can be considered to increase uric acid excretion in the urine mainly via the inhibition of urate transporter 1 (URAT1), and due to pharmacokinetic interactions involving organic anion transporters 1 and 3 (OAT1 and OAT3), it modifies renal excretion of penicillins or ciprofloxacin as well as nephrotoxicity of cidofovir. This review discusses clinically approved drugs that affect membrane/drug transporter function.

Event-free survival of maralixibat-treated patients with Alagille syndrome compared to a real-world cohort from GALA

BACKGROUND AND AIMS

Alagille syndrome (ALGS) is characterized by chronic cholestasis with associated pruritus and extrahepatic anomalies. Maralixibat, an ileal bile acid transporter inhibitor, is an approved pharmacologic therapy for cholestatic pruritus in ALGS. Since long-term placebo-controlled studies are not feasible or ethical in children with rare diseases, a novel approach was taken comparing 6-year outcomes from maralixibat trials with an aligned and harmonized natural history cohort from the G lobal AL agille A lliance (GALA) study.

APPROACH AND RESULTS

Maralixibat trials comprise 84 patients with ALGS with up to 6 years of treatment. GALA contains retrospective data from 1438 participants. GALA was filtered to align with key maralixibat eligibility criteria, yielding 469 participants. Serum bile acids could not be included in the GALA filtering criteria as these are not routinely performed in clinical practice. Index time was determined through maximum likelihood estimation in an effort to align the disease severity between the two cohorts with the initiation of maralixibat. Event-free survival, defined as the time to first event of manifestations of portal hypertension (variceal bleeding, ascites requiring therapy), surgical biliary diversion, liver transplant, or death, was analyzed by Cox proportional hazards methods. Sensitivity analyses and adjustments for covariates were applied. Age, total bilirubin, gamma-glutamyl transferase, and alanine aminotransferase were balanced between groups with no statistical differences. Event-free survival in the maralixibat cohort was significantly better than the GALA cohort (HR, 0.305; 95% CI, 0.189-0.491; p <0.0001). Multiple sensitivity and subgroup analyses (including serum bile acid availability) showed similar findings.

CONCLUSIONS

This study demonstrates a novel application of a robust statistical method to evaluate outcomes in long-term intervention studies where placebo comparisons are not feasible, providing wide application for rare diseases. This comparison with real-world natural history data suggests that maralixibat improves event-free survival in patients with ALGS.

Benign Recurrent Intrahepatic Cholestasis: Where Are We Now?

Benign recurrent intrahepatic cholestasis (BRIC) stands as a rare genetic contributor to cholestasis, aligning itself within the spectrum of inherited intrahepatic cholestasis syndromes, such as progressive familial intrahepatic cholestasis (PFIC) and intrahepatic cholestasis of pregnancy. Manifesting in infancy or early adulthood, BRIC is marked by recurrent episodes of jaundice accompanied by intense pruritus, enduring from weeks to years across the lifespan. Normal gamma-glutamyl transferase (GGT) levels are a characteristic laboratory finding. Initially considered unlikely to progress to chronic liver disease or cirrhosis, some reports suggest BRIC may evolve into a continuous and progressive form of cholestasis. Moreover, these recurrent cholestatic episodes significantly impact quality of life, and certain mutations elevate the risk of hepatobiliary malignancy. Between episodes, histological findings of centrilobular cholestasis and abnormal laboratory parameters revert to normal, potentially obviating the need for liver biopsy. This review focuses on the genetic aspects of BRIC, its pathophysiology, clinical presentation, and prognosis. Additionally, it outlines triggering factors and available treatment options.

Outcomes of pediatric liver transplantation for progressive familial intrahepatic cholestasis

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) is a heterogenous group of inherited hepatocellular disorders and the clinical aspects, role of liver transplantation (LT), and its outcomes remain largely unelucidated. We present our data of LT for each type of PFIC and compare their early, and long-term outcomes, highlighting their individual differences and management strategies.

METHODS

Prospectively collected data over a decade (2011-2022) of children with PFIC who underwent LT was analyzed. The groups (PFIC 1-4) were compared with regard to early and long-term outcomes including attainment of catch-up growth.

RESULTS

Of 60 children with PFIC who underwent LT, 13, 11, 31 & 5 were of PFIC 1, 2, 3 & 4, respectively. There were no significant differences in gender, PELD scores, BMI, type of grafts, cold and warm ischemia times, intraoperative blood loss, and morbidity among the groups. Post-LT chronic diarrhea was observed in 6 (46.1%) children with PFIC-I, and of them, 3 (23%) developed graft steatohepatitis. Three of these children underwent total internal biliary diversion (TIBD) and on 1-year follow-up, their graft steatosis resolved and they attained catch-up growth. Catch-up growth was significantly poorer in the PFIC1 group (44.4% vs. 88%, 90%, 100% p < .001). Overall 1- and 5-year patient survival of the four PFIC groups (1-4) were 69.2%, 81.8%, 96.8%, 100% & 69.2%, 81.8%, 96.8%, 100%, respectively.

CONCLUSION

Ours is the largest to-date series of LT for PFIC illustrating their short- and long-term outcomes. While the results for the whole cohort were excellent, those after LT for PFIC1 was relatively poorer as reflected by catch-up growth, graft steatosis, and post-LT diarrhea, which can be optimized by the addition of TIBD during LT.

Predictors of 6-year event-free survival in Alagille syndrome patients treated with maralixibat, an ileal bile acid transporter inhibitor

BACKGROUND AND AIMS

Refractory pruritus and other complications of cholestasis are indications for liver transplantation (LT) in patients with Alagille syndrome (ALGS). We evaluated predictors of event-free survival and transplant-free survival in patients with ALGS treated with maralixibat (MRX), an ileal bile acid transporter inhibitor.

APPROACH AND RESULTS

We assessed patients with ALGS from 3 clinical trials of MRX with up to 6 years of follow-up. Event-free survival was defined as the absence of LT, surgical biliary diversion, hepatic decompensation, or death; transplant-free survival was the absence of LT or death. Forty-three potential predictors were evaluated, including age, pruritus (ItchRO[Obs] 0-4 scale), biochemistries, platelets, and serum bile acids. Harrell's concordance statistic assessed goodness-of-fit, and then, Cox proportional hazard models confirmed the statistical significance of the predictors identified. A further analysis was performed to identify cutoffs using a grid search. Seventy-six individuals met the criteria of receiving MRX for ≥48 weeks with laboratory values available at week 48 (W48). The median duration of MRX was 4.7 years (IQR: 1.6-5.8); 16 had events (10 LT, 3 decompensation, 2 death, and 1 surgical biliary diversion). 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.

CONCLUSIONS

Improvement in pruritus by 48 weeks, and lower W48 bilirubin and serum bile acid levels were associated with fewer events. These data may help identify potential markers of disease progression for ALGS patients treated with MRX.

Management of adults with Alagille syndrome

Alagille syndrome (ALGS) is a complex rare genetic disorder that involves multiple organ systems and is historically regarded as a disease of childhood. Since it is inherited in an autosomal dominant manner in 40% of patients, it carries many implications for genetic counselling of patients and screening of family members. In addition, the considerable variable expression and absence of a clear genotype-phenotype correlation, results in a diverse range of clinical manifestations, even in affected individuals within the same family. With recent therapeutic advancements in cholestasis treatment and the improved survival rates with liver transplantation (LT), many patients with ALGS survive into adulthood. Although LT is curative for liver disease secondary to ALGS, complications secondary to extrahepatic involvement remain problematic lifelong. This review is aimed at providing a comprehensive review of ALGS to adult clinicians who will take over the medical care of these patients following transition, with particular focus on certain aspects of the condition that require lifelong surveillance. We also provide a diagnostic framework for adult patients with suspected ALGS and highlight key aspects to consider when determining eligibility for LT in patients with this syndrome.

Outcomes of 38 patients with PFIC3: Impact of genotype and of response to ursodeoxycholic acid therapy

Background & Aims

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare liver disease caused by biallelic variations in ABCB4. Data reporting on the impact of genotype and of response to ursodeoxycholic acid (UDCA) therapy on long-term outcomes are scarce.

Methods

We retrospectively describe a cohort of 38 patients with PFIC3 with a median age at last follow-up of 19.5 years (range 3.8-53.8).

Results

Twenty patients presented with symptoms before 1 year of age. Thirty-one patients received ursodeoxycholic acid (UDCA) therapy resulting in serum liver test improvement in 20. Twenty-seven patients had cirrhosis at a median age of 8.1 years of whom 18 received a liver transplant at a median age of 8.5 years. Patients carrying at least one missense variation were more likely to present with positive (normal or decreased) canalicular MDR3 expression in the native liver and had prolonged native liver survival (NLS; median 12.4 years [range 3.8-53.8]). In contrast, in patients with severe genotypes (no missense variation), there was no detectable canalicular MDR3 expression, symptom onset and cirrhosis occurred earlier, and all underwent liver transplantation (at a median age of 6.7 years [range 2.3-10.3]). The latter group was refractory to UDCA treatment, whereas 87% of patients with at least one missense variation displayed an improvement in liver biochemistry in response to UDCA. Biliary phospholipid levels over 6.9% of total biliary lipid levels predicted response to UDCA. Response to UDCA predicted NLS.

Conclusions

Patients carrying at least one missense variation, with positive canalicular expression of MDR3 and a biliary phospholipid level over 6.9% of total biliary lipid levels were more likely to respond to UDCA and to exhibit prolonged NLS.

Impact and implications

In this study, data show that genotype and response to ursodeoxycholic acid therapy predicted native liver survival in patients with PFIC3 (progressive familial intrahepatic cholestasis type 3). Patients carrying at least one missense variation, with positive (decreased or normal) immuno-staining for canalicular MDR3, and a biliary phospholipid level over 6.9% of total biliary lipids were more likely to respond to ursodeoxycholic acid therapy and to exhibit prolonged native liver survival.

Interim results from an ongoing, open-label, single-arm trial of odevixibat in progressive familial intrahepatic cholestasis

BACKGROUND & AIMS

PEDFIC 2, an ongoing, open-label, 72-week study, evaluates odevixibat, an ileal bile acid transporter inhibitor, in patients with progressive familial intrahepatic cholestasis.

METHODS

PEDFIC 2 enrolled and dosed 69 patients across two cohorts; all received odevixibat 120 μg/kg per day. Cohort 1 comprised children from PEDFIC 1, and cohort 2 comprised new patients (any age). We report data through 15 July 2020, with Week 24 of PEDFIC 2 the main time point analysed. This represents up to 48 weeks of cumulative exposure for patients treated with odevixibat from the 24-week PEDFIC 1 study (cohort 1A) and up to 24 weeks of treatment for those who initiated odevixibat in PEDFIC 2 (patients who received placebo in PEDFIC 1 [cohort 1B] or cohort 2 patients). Primary endpoints for this prespecified interim analysis were change from baseline to Weeks 22-24 in serum bile acids (sBAs) and proportion of positive pruritus assessments (≥1-point drop from PEDFIC 2 baseline in pruritus on a 0-4 scale or score ≤1) over the 24-week period. Safety monitoring included evaluating treatment-emergent adverse events (TEAEs).

RESULTS

In cohort 1A, mean change from PEDFIC 1 baseline to Weeks 22-24 of PEDFIC 2 in sBAs was -201 μmol/L (p <0.0001). For cohort 1B and cohort 2, mean changes from odevixibat initiation to weeks 22-24 in sBAs were -144 and -104 μmol/L, respectively. The proportion of positive pruritus assessments in the first 24-week period of PEDFIC 2 was 33%, 56%, and 62% in cohorts 1A, 1B, and 2, respectively. Most TEAEs were mild or moderate. No drug-related serious TEAEs occurred.

CONCLUSIONS

Odevixibat in patients with progressive familial intrahepatic cholestasis was generally well tolerated and associated with sustained reductions in sBAs and pruritus.

CLINICAL TRIALS REGISTRATION

This study is registered at ClinicalTrials.gov (NCT03659916).

IMPACT AND IMPLICATIONS

Disrupted bile flow is a hallmark feature of patients with progressive familial intrahepatic cholestasis and can result in build-up of bile constituents in the liver with spill over into the bloodstream; other effects that patients can experience include extremely itchy skin, and because not enough bile reaches the gut, patients can have problems digesting food, which may lead to poor growth. Odevixibat is an orally administered medication that shunts bile acids away from the liver. The current study, called PEDFIC 2, suggested that odevixibat can improve the problematic signs and symptoms of progressive familial intrahepatic cholestasis and was generally safe for patients.

Cholestatic Pruritus in Children: Conventional Therapies and Beyond

Pruritus in the setting of cholestatic liver disease is difficult to treat and occurs in patients ranging in age from infancy to adulthood. Likely multifactorial in etiology, this symptom often involves multimodal therapy targeting several pathways and mechanisms proposed in the underlying etiology of cholestatic pruritus. Many patients in both the pediatric and adult populations continue to experience unrelenting pruritus despite maximal conventional therapy. Options are further limited in treating pediatric patients due to sparse data regarding medication safety and efficacy in younger patients. Conventional therapies for the treatment of cholestatic pruritus in children include ursodeoxycholic acid, cholestyramine, hydroxyzine, and rifampin. Certain therapies are more routinely used in the adult populations but with limited data available for use in child and adolescent patients, including opioid antagonists and selective serotonin reuptake inhibitors. Recently, ileal bile acid transport inhibitors have been shown to alleviate pruritus in many children with Alagille syndrome and progressive familial intrahepatic cholestasis and is an additional therapy available for consideration for these patients. Ultimately, surgical options such as biliary diversion or liver transplantation are considered in specific circumstances when medical therapies have been exhausted and pruritus remains debilitating. While further investigation regarding underlying etiologies and effective therapies are needed to better understand itch pathogenesis and treatment in pediatric cholestasis, current considerations beyond conventional management include the use of opioid antagonists, selective serotonin reuptake inhibitors, ileal bile acid transport inhibitors, and surgical intervention.

Formulary Drug Review: Odevixibat

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are available online to subscribers. Monographs can be customized to meet the needs of a facility. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, contact Wolters Kluwer customer service at 866-397-3433.

Odevixibat: A Review of a Bioactive Compound for the Treatment of Pruritus Approved by the FDA

Odevixibat is synthesized through chemical modification of Benzothiazepine's structure. It is a tiny chemical that inhibits the ileal bile acid transporter and is used to treat a variety of cholestatic illnesses, including progressive familial intrahepatic cholestasis (PFIC). For cholestatic pruritus and liver disease development, bile acid transporter inhibition is a unique treatment strategy. Odevixibat reduces enteric bile acid reuptake. Oral odevixibat was also studied in children with cholestatic liver disease. Odevixibat received its first approval in the European Union (EU) in July 2021 for the treatment of PFIC in patients aged 6 months, followed by approval in the USA in August 2021 for the treatment of pruritus in PFIC patients aged 3 months. Bile acids in the distal ileum can be reabsorbed by the ileal sodium/bile acid cotransporter, a transport glycoprotein. Odevixibat is a sodium/bile acid co-transporter reversible inhibitor. An average 3 mg once-daily dose of odevixibat for a week resulted in a 56% reduction in the area under the curve of bile acid. A daily dose of 1.5 mg resulted in a 43% decrease in the area under the curve for bile acid. Odevixibat is also being evaluated in many countries for the treatment of other cholestatic illnesses, including Alagille syndrome and biliary atresia. This article reviews the updated information on odevixibat with respect to its clinical pharmacology, mechanism of action, pharmacokinetics, pharmacodynamics, metabolism, drug-drug interactions, pre-clinical studies, and clinical trials.

Primary biliary cholangitis as a roadmap for the development of novel treatments for cholestatic liver diseases†

The discovery of nuclear receptors and transporters has contributed to the development of new drugs for the treatment of cholestatic liver diseases. Particular progress has been made in the development of second-line therapies for PBC. These new drugs can be separated into compounds primarily targeting cholestasis, molecules targeting fibrogenesis and molecules with immune-mediated action. Finally, drugs aimed at symptom relief (pruritus and fatigue) are also under investigation. Obeticholic acid is currently the only approved second-line therapy for PBC. Drugs in the late phase of clinical development include peroxisome proliferator-activated receptor agonists, norursodeoxycholic acid and NADPH oxidase 1/4 inhibitors.

Health Care Resource Utilization by Patients with Alagille Syndrome

OBJECTIVE

To assess and characterize health care resource utilization (HRU) in children with the rare, genetic, multisystem disorder, Alagille syndrome.

STUDY DESIGN

This retrospective analysis reviewed commercially insured and Medicaid-insured claims from October 1, 2015 to December 31, 2019 to assess HRU in patients with Alagille syndrome. As there is no specific International Classification ofDiseases-10 code for Alagille syndrome, patients were identified using the following algorithm: ≥1 claim with diagnosis code Q44.7 (other congenital malformations of the liver); <18 years of age, with no history of biliary atresia (International Classification ofDiseases-10 code: Q44.2); and ≥6 months of insurance eligibility prior to diagnosis. HRU was summarized per patient per year over all available claims postdiagnosis.

RESULTS

A total of 171 commercially insured and 215 Medicaid-insured patients with Alagille syndrome were available for analysis. Annually, commercially insured and Medicaid-insured patients averaged 31 medical visits (range, 1.5-237) and 48 medical visits (range, 0.7-690), respectively. The most common visits were outpatient with the majority encompassing lab/imaging and primary care visits (commercially insured: 21 [range, 0.0-183]; Medicaid-insured: 26 [range, 0.0-609]). Inpatient visits were the highest driver of costs in both the commercial and Medicaid populations.

CONCLUSIONS

Patients with Alagille syndrome have a substantial HRU burden driven largely by numerous outpatient visits and costly inpatient stays. Given the complexity and variability of Alagille syndrome presentation, patients may benefit from multidisciplinary and subspecialized care.

The Landscape of HNF1B Deficiency: A Syndrome Not Yet Fully Explored

The hepatocyte nuclear factor 1β (HNF1B) gene is involved in the development of specialized epithelia of several organs during the early and late phases of embryogenesis, performing its function mainly by regulating the cell cycle and apoptosis pathways. The first pathogenic variant of HNF1B (namely, R177X) was reported in 1997 and is associated with the maturity-onset diabetes of the young. Since then, more than 230 different HNF1B variants have been reported, revealing a multifaceted syndrome with complex and heterogenous genetic, pathologic, and clinical profiles, mainly affecting the pediatric population. The pancreas and kidneys are the most frequently affected organs, resulting in diabetes, renal cysts, and a decrease in renal function, leading, in 2001, to the definition of HNF1B deficiency syndrome, including renal cysts and diabetes. However, several other organs and systems have since emerged as being affected by HNF1B defect, while diabetes and renal cysts are not always present. Especially, liver involvement has generally been overlooked but recently emerged as particularly relevant (mostly showing chronically elevated liver enzymes) and with a putative relation with tumor development, thus requiring a more granular analysis. Nowadays, HNF1B-associated disease has been recognized as a clinical entity with a broader and more variable multisystem phenotype, but the reasons for the phenotypic heterogeneity are still poorly understood. In this review, we aimed to describe the multifaceted nature of HNF1B deficiency in the pediatric and adult populations: we analyzed the genetic, phenotypic, and clinical features of this complex and misdiagnosed syndrome, covering the most frequent, unusual, and recently identified traits.

Mechanisms of pruritus in cholestasis: understanding and treating the itch

Pruritus in cholestatic liver diseases can be a major burden and dramatically impair the quality of life of those affected. Here, we provide an update on the latest insights into the molecular pathogenesis of and novel therapeutic approaches for cholestasis-associated itch. Endogenous and exogenous small-molecule pruritogen candidates bind to their receptors on unmyelinated itch C-fibres in the skin. Candidate pruritogens in cholestasis include certain lysophospholipids and sulfated progesterone metabolites, among others, whereas total bile acid or bilirubin conjugates seem unlikely to have a dominant role in the pathogenesis of cholestasis-associated pruritus. Transmission of itch signals via primary, secondary and tertiary itch neurons to the postcentral gyrus and activation of scratch responses offer various targets for therapeutic intervention. At present, evidence-based treatment options for pruritus in fibrosing cholangiopathies, such as primary biliary cholangitis and primary sclerosing cholangitis, are the peroxisome proliferator-associated receptor (PPAR) agonist bezafibrate and the pregnane X receptor (PXR) agonist rifampicin. In pruritus of intrahepatic cholestasis of pregnancy, ursodeoxycholic acid is recommended and might be supported in the third trimester by rifampicin if needed. Alternatively, non-absorbable anion exchange resins, such as cholestyramine, can be administered, albeit with poor trial evidence. Liver transplantation for intolerable refractory pruritus has become an extremely rare therapeutic strategy.

Maralixibat Treatment Response in Alagille Syndrome is Associated with Improved Health-Related Quality of Life

OBJECTIVE

The objective of this study was to assess the impact of treatment response to the ileal bile acid transporter inhibitor maralixibat on health-related quality of life (HRQoL) in children with Alagille syndrome.

STUDY DESIGN

This analysis used data from the ICONIC trial, a phase 2 study with a 4-week double-blind, placebo-controlled, randomized drug withdrawal period in children with Alagille syndrome with moderate-to-severe pruritus. Clinically meaningful treatment response to maralixibat was defined a priori as a ≥1-point reduction in the Itch-Reported Outcome (Observer) score, from baseline to week 48. HRQoL was assessed using the Pediatric Quality of Life Inventory Generic Core, Family Impact, and Multidimensional Fatigue scale scores, which were collected via the caregiver. The minimal clinically important difference for HRQoL ranged from 4 to 5 points, depending on the scale.

RESULTS

Twenty of the 27 patients (74%) included in this analysis achieved an Itch-Reported Outcome (Observer) treatment response at week 48. The mean (SD) change in Multidimensional Fatigue score was +25.8 (23.0) for responders vs -3.1 (19.8) for nonresponders (P = .03). Smaller and non-statistically significant mean changes were observed for the Pediatric Quality of Life Inventory Generic Core and Family Impact scores. Controlling for baseline Family Impact score, responders' Family Impact scores increased an average of 16.9 points over 48 weeks compared with non-responders (P = .05). Smaller and non-statistically significant point estimates were observed for the Pediatric Quality of Life Inventory Generic Core and Multidimensional Fatigue scores.

CONCLUSION

The significant improvements in pruritus seen with maralixibat at week 48 of the ICONIC study are clinically meaningful and are associated with improved HRQoL.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02160782.

Odevixibat: a promising new treatment for progressive familial intrahepatic cholestasis

INTRODUCTION

Progressive familial intrahepatic cholestasis (PFIC) refers to a group of heterogeneous, mostly autosomal recessive disorders resulting from the inability to properly form and excrete bile from hepatocytes. The resulting shared phenotype is one of hepatocellular cholestasis. Clinical management targeting refractory itch and surgical interventions to interrupt the enterohepatic circulation are often pursued with variable efficacy. Recent development of the family of IBAT inhibitor therapeutics has introduced a novel tool in the armamentarium for the treatment of PFIC.

AREAS COVERED

Data from Phase 3 and 3 clinical trials were reviewed. The primary endpoints in most studies included effect on pruritus, serum bile acid levels, and quality of life metrics, with the duration of the study ranging between 24 and 72 weeks. Most common adverse events included diarrhea, vomiting, and elevation in transaminases.

EXPERT OPINION

IBAT inhibition with therapeutics such as odevibixat have shown that it is well-tolerated and efficacious in mitigating itch and reducing serum bile acid levels. While the few early published trials with odevixibat have shown good efficacy, what remains to be seen is long-term, sustainable improvement and if or how these medications will supplement or replace the current medical and surgical therapies available for managing PFIC disorders.

Validation of the PRUCISION Instruments in Pediatric Patients with Progressive Familial Intrahepatic Cholestasis

INTRODUCTION

Patients with cholestatic liver disease, including progressive familial intrahepatic cholestasis (PFIC) and Alagille syndrome, may have debilitating pruritus, and reducing pruritus is a key therapeutic goal. However, few instruments are available that adequately measure pruritus in pediatric patients with cholestatic liver disease. The objectives of the current study were to establish the measurement properties of the novel PRUCISION patient-reported outcome (PRO) and observer-reported outcome (ObsRO) instruments and to estimate a threshold for clinically meaningful change in pruritus score.

METHODS

The PRO/ObsRO instruments are completed twice daily via electronic diary and include 5-point pictorial responses to assess pruritus. Sleep disturbance and tiredness were quantified using 5-point pictorial responses, yes/no responses, and numerical ratings. Data from PEDFIC 1 (NCT03566238), a phase 3 study evaluating odevixibat efficacy and safety in children with PFIC, were used to assess the psychometric properties of these instruments. Quantitative assessments included evaluation of test-retest reliability, determination of construct validity via convergent and known-group validity analyses, and characterization of sensitivity to change. A threshold for within-patient meaningful change from baseline to week 24 was determined using blinded data from PEDFIC 1 and distribution- and anchor-based analyses.

RESULTS

Because the majority of patients in PEDFIC 1 were aged < 8 years (n = 52/62) and thus too young to complete the PRO instrument, which was intended for patients aged ≥ 8 years, the small sample size of patients who completed the PRO precluded a full psychometric analysis of the PRO instrument. The ObsRO was completed by a caregiver of every patient in PEDFIC 1. The ObsRO instrument had acceptable test-retest reliability based on intraclass correlation values (most > 0.75). Convergent validity analyses revealed moderate-to-strong correlations (r ≥ 0.3) between baseline ObsRO pruritus scores and baseline Global Impression of Symptoms (GIS) items. In known-groups validity analyses, there were significant differences between baseline groups defined by the GIS for ObsRO pruritus scores and for some sleep disturbance scores. Week 24 ObsRO scores were in the expected direction in groups defined by the Global Impression of Change scale (i.e., improved or not improved); many mean differences between these groups were significant. Sensitivity to change for the ObsRO PRUCISION instrument was also demonstrated by moderate-to-strong Pearson correlations between change from baseline to weeks 21-24 in ObsRO scores and GIS items (r ≥ 0.3). Based on these analyses, a within-patient change of -1.00 from baseline in ObsRO pruritus score was determined to be clinically meaningful.

CONCLUSION

The PRUCISION ObsRO instrument is reliable, valid, and sensitive to change, supporting its use as a tool to measure pruritus and sleep disturbance in patients with PFIC and other pediatric cholestatic liver diseases.

Odevixibat treatment in progressive familial intrahepatic cholestasis: a randomised, placebo-controlled, phase 3 trial

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) is a group of inherited paediatric liver diseases resulting from mutations in genes that impact bile secretion. We aimed to evaluate the effects of odevixibat, an ileal bile acid transporter inhibitor, versus placebo in children with PFIC.

METHODS

Patients eligible for this 24-week, randomised, double-blind, completed, phase 3 study were paediatric outpatients diagnosed with PFIC1 or PFIC2 who had pruritus and elevated serum bile acids at screening. Patients were randomly assigned (1:1:1) using an interactive web-based system to once a day oral placebo, odevixibat 40 μg/kg, or odevixibat 120 μg/kg. Randomisation was done in a block size of six and stratified by PFIC type and patient age; patients, clinicians, and study staff were blinded to treatment allocation. Patients were enrolled at one of 33 global sites. Two primary endpoints were evaluated: proportion of positive pruritus assessments (PPAs; ie, scratching score of ≤1 or ≥1-point decrease as assessed by caregivers using the Albireo observer-reported outcome [ObsRO] PRUCISION instrument) over 24 weeks, and proportion of patients with serum bile acid response (ie, serum bile acids reduced by ≥70% from baseline or concentrations of ≤70 μmol/L) at week 24. Efficacy and safety were analysed in randomly allocated patients who received one or more doses of study drug. This study is registered with ClinicalTrials.gov, NCT03566238.

FINDINGS

Between June 21, 2018, and Feb 10, 2020, 62 patients (median age 3·2 [range 0·5-15·9] years) were randomly allocated to placebo (n=20), odevixibat 40 μg/kg per day (n=23), or odevixibat 120 μg/kg per day (n=19). Model-adjusted (least squares) mean proportion of PPAs was significantly higher with odevixibat versus placebo (55% [SE 8] in the combined odevixibat group [58% in the 40 μg/kg per day group and 52% in the 120 μg/kg per day group] vs 30% [SE 9] in the placebo group; model-adjusted mean difference 25·0% [95% CI 8·5-41·5]; p=0·0038). The percentage of patients with serum bile acid response was also significantly higher with odevixibat versus placebo (14 [33%] of 42 patients in the combined odevixibat group [10 in the 40 μg/kg per day group and four in the 120 μg/kg per day group] vs none of 20 in the placebo group; adjusting for stratification factor [PFIC type], the proportion difference was 30·7% [95% CI 12·6-48·8; p=0·0030]). The most common treatment-emergent adverse events (TEAEs) were diarrhoea or frequent bowel movements (13 [31%] of 42 for odevixibat vs two [10%] of 20 for placebo) and fever (12 [29%] of 42 vs five [25%] of 20); serious TEAEs occurred in three (7%) of 42 odevixibat-treated patients and in five (25%) of 20 placebo-treated patients.

INTERPRETATION

In children with PFIC, odevixibat effectively reduced pruritus and serum bile acids versus placebo and was generally well tolerated. Odevixibat, administered as once a day oral capsules, is a non-surgical, pharmacological option to interrupt the enterohepatic circulation in patients with PFIC.

FUNDING

Albireo Pharma.

Use of funded multicenter prospective longitudinal databases to inform clinical trials in rare diseases-Examination of cholestatic liver disease in Alagille syndrome

The conduct of long-term conventional randomized clinical trials in rare diseases is very difficult, making evidenced-based drug development problematic. As a result, real-world data/evidence are being used more frequently to assess new therapeutic approaches in orphan diseases. In this investigation, inclusion and exclusion criteria from a published trial of maralixibat in Alagille syndrome (ALGS, ITCH NCT02057692) were applied to a prospective longitudinal cohort of children with cholestasis (LOGIC NCT00571272) to derive contextual comparator data for evolving clinical trials of intestinal bile acid transport inhibitors in ALGS. A natural history/clinical care cohort of 59 participants who met adapted inclusion and exclusion criteria of ITCH was identified from 252 LOGIC participants with ALGS with their native liver. Frequency weighting was used to match the age distribution of ITCH and yielded a cohort (Alagille Syndrome Natural History [ALGS NH]) that was very similar to the baseline status of ITCH participants. During a 2-year prospective follow-up there was a significant reduction in pruritus in the weighted ALGS NH cohort as assessed by the clinician scratch score (-1.43 [0.28] -1.99, -0.87; mean [SEM] 95% confidence interval). During the same time period, the total bilirubin, albumin, and alanine aminotransferase levels were unchanged, whereas platelet count dropped significantly (-65.2 [16.2] -98.3, -32.1). Weighted survival with native liver was 91% at 2 years in the ALGS NH. These investigations provide valuable real-world data that can serve as contextual comparators to current clinical trials, especially those without control populations, and highlight the value and importance of funded multicenter, prospective, natural history studies.

Impact of long-term administration of maralixibat on children with cholestasis secondary to Alagille syndrome

There is growing interest in, but limited data about, intestinal bile acid transport inhibitors as treatment for cholestatic liver disease. The current analyses combine two similar randomized placebo-controlled trials with subsequent extension phases investigating the impact of maralixibat in children with severe cholestasis secondary to Alagille Syndrome (n = 57). The primary outcomes were measures of pruritus (ItchRO[Obs]) and clinician scratch scale (CSS), both increasing in severity from 0 to 4) and quality of life (QoL) (Parent PedsQL and Multidimensional Fatigue Scale module [MFS] scaled 0-100 with increased QoL) at week 48 of the extension phase relative to the baseline of the placebo-controlled trials (week 13). Secondary assessments included other clinical and biochemical parameters assessed in participants at week 72 or end of treatment (after week 48). At week 48, statistically and clinically significant least square mean (95% CI) improvements in pruritus and QoL were observed (ItchRO[Obs] -1.59 [-1.81, -1.36], CSS -1.36 [-1.67, -1.05], PedsQL +10.17 [4.48, 15.86], and multidimension fatigue [MFS] +13.97 [7.85, 20.08]). At week 48, serum bile acids, platelet count, and cholesterol decreased, whereas alanine aminotransferase (ALT) increased and total bilirubin (TB) and albumin were stable. Changes were durable at week 72 and end of treatment. There were no deaths; 2 participants underwent liver transplantation. Study drug was discontinued in 9 participants after treatment-emergent adverse events, 6 of which were events of increased ALT or TB. Conclusion: Maralixibat administration was associated with marked improvement in pruritus and QoL. Interpretation of these findings is complicated by the complex natural history of severe cholestasis in Alagille syndrome.

Case Report: A Rare Heterozygous ATP8B1 Mutation in a BRIC1 Patient: Haploinsufficiency?

Benign recurrent intrahepatic cholestasis (BRIC) is an autosomal recessive disorder characterized by recurrent cholestasis. ATPase class I, type 8B, member 1 (ATP8B1) encodes familial intrahepatic cholestasis 1 (FIC1), which acts as a phosphatidylserine reversing enzyme in the tubule membrane of hepatocytes to mediate the inward translocation of phosphatidylserine (PS). At present, dozens of ATP8B1 pathogenic mutations have been identified that mainly cause BRIC1 and progressive familial intrahepatic cholestasis 1 (PFIC1). The diagnosis of BRIC1 is based on symptoms, laboratory tests, imaging, liver histology, and genetic testing. BRIC1 treatment seeks to prevent recurrence and reduce disease severity. At present, the main treatment methods include ursodeoxycholic acid (UDCA), rifampin, cholestyramine and haemofiltration, and endoscopic nasobiliary drainage (ENBD). Here, we report a 17-year-old patient with cholestasis who has a rare heterozygous ATP8B1 gene mutation (p.T888K). The patient was treated with UDCA, glucocorticoids and haemofiltration, after which bilirubin levels gradually returned to normal. This case was thought to be caused by an ATP8B1 heterozygous mutation, which may be related to haploinsufficiency (HI).

Cholestatic liver diseases of genetic etiology: Advances and controversies

With the application of modern investigative technologies, cholestatic liver diseases of genetic etiology are increasingly identified as the root cause of previously designated "idiopathic" adult and pediatric liver diseases. Here, we review advances in the field enhanced by a deeper understanding of the phenotypes associated with specific gene defects that lead to cholestatic liver diseases. There are evolving areas for clinicians in the current era specifically regarding the role for biopsy and opportunities for a "sequencing first" approach. Risk stratification based on the severity of the genetic defect holds promise to guide the decision to pursue primary liver transplantation versus medical therapy or nontransplant surgery, as well as early screening for HCC. In the present era, the expanding toolbox of recently approved therapies for hepatologists has real potential to help many of our patients with genetic causes of cholestasis. In addition, there are promising agents under study in the pipeline. Relevant to the current era, there are still gaps in knowledge of causation and pathogenesis and lack of fully accepted biomarkers of disease progression and pruritus. We discuss strategies to overcome the challenges of genotype-phenotype correlation and draw attention to the extrahepatic manifestations of these diseases. Finally, with attention to identifying causes and treatments of genetic cholestatic disorders, we anticipate a vibrant future of this dynamic field which builds upon current and future therapies, real-world evaluations of individual and combined therapeutics, and the potential incorporation of effective gene editing and gene additive technologies.

Gene Therapy for Acquired and Genetic Cholestasis

Cholestatic diseases can be caused by the dysfunction of transporters involved in hepatobiliary circulation. Although pharmacological treatments constitute the current standard of care for these diseases, none are curative, with liver transplantation being the only long-term solution for severe cholestasis, albeit with many disadvantages. Liver-directed gene therapy has shown promising results in clinical trials for genetic diseases, and it could constitute a potential new therapeutic approach for cholestatic diseases. Many preclinical gene therapy studies have shown positive results in animal models of both acquired and genetic cholestasis. The delivery of genes that reduce apoptosis or fibrosis or improve bile flow has shown therapeutic effects in rodents in which cholestasis was induced by drugs or bile duct ligation. Most studies targeting inherited cholestasis, such as progressive familial intrahepatic cholestasis (PFIC), have focused on supplementing a correct version of a mutated gene to the liver using viral or non-viral vectors in order to achieve expression of the therapeutic protein. These strategies have generated promising results in treating PFIC3 in mouse models of the disease. However, important challenges remain in translating this therapy to the clinic, as well as in developing gene therapy strategies for other types of acquired and genetic cholestasis.

Ileal Bile Acid Transporter Inhibition Reduces Post-Transplant Diarrhea and Growth Failure in FIC1 Disease—A Case Report

Familial intrahepatic cholestasis 1 (FIC1) disease is a genetic disorder characterized by hepatic and gastrointestinal disease due to ATP8B1 deficiency, often requiring liver transplantation (LT). Extrahepatic symptoms, such as diarrhea, malabsorption, and failure to thrive, do not improve and instead may be aggravated after LT. We describe a patient with FIC1 disease who underwent LT at 2 years, 8 months of age. After LT, the child developed severe refractory diarrhea and failed to thrive. The response to bile acid resins was unsatisfactory, and the parents declined our recommendation for partial external biliary diversion (PEBD). Quality of life was extremely impaired, especially due to severe diarrhea, making school attendance impossible. Attempting to reduce the total bile acids, we initiated off-label use of the ileal bile acid transporter (IBAT) inhibitor Elobixibat (Goofice^™), later converted to Odevixibat (Bylvay^™). After six months of treatment, the patient showed less stool output, increased weight and height, and improved physical energy levels. The child could now pursue higher undergraduate education. In our patient with FIC1 disease, the use of IBAT inhibitors was effective in treating chronic diarrhea and failure to thrive. This approach is novel; further investigations are needed to clarify the exact mode of action in this condition.

The neonatal liver: Normal development and response to injury and disease

The liver emerges from the ventral foregut endoderm around 3 weeks in human and 1 week in mice after fertilization. The fetal liver works as a hematopoietic organ and then develops functions required for performing various metabolic reactions in late fetal and neonatal periods. In parallel with functional differentiation, the liver establishes three dimensional tissue structures. In particular, establishment of the bile excretion system consisting of bile canaliculi of hepatocytes and bile ducts of cholangiocytes is critical to maintain healthy tissue status. This is because hepatocytes produce bile as they functionally mature, and if allowed to remain within the liver tissue can lead to cytotoxicity. In this review, we focus on epithelial tissue morphogenesis in the perinatal period and cholestatic liver diseases caused by abnormal development of the biliary system.

Recent updates on progressive familial intrahepatic cholestasis types 1, 2 and 3: Outcome and therapeutic strategies

Recent evidence points towards the role of genotype to understand the phenotype, predict the natural course and long term outcome of patients with progressive familial intrahepatic cholestasis (PFIC). Expanded role of the heterozygous transporter defects presenting late needs to be suspected and identified. Treatment of pruritus, nutritional rehabilitation, prevention of fibrosis progression and liver transplantation (LT) in those with end stage liver disease form the crux of the treatment. LT in PFIC has its own unique issues like high rates of intractable diarrhoea, growth failure; steatohepatitis and graft failure in PFIC1 and antibody-mediated bile salt export pump deficiency in PFIC2. Drugs inhibiting apical sodium-dependent bile transporter and adenovirus-associated vector mediated gene therapy hold promise for future.

Long-term liver transplant outcomes for progressive familial intrahepatic cholestasis type 1: The Pittsburgh experience

BACKGROUND

Progressive familial intrahepatic cholestasis type 1 (PFIC1) arises from biallelic variants in the ATP8B1 gene that annul FIC1 activity, resulting in progressive liver disease. Liver transplant (LT) is indicated in refractory disease; however, post-LT complications including worsening diarrhea and steatohepatitis progressing to fibrosis with graft loss have been reported. We aim to describe long-term outcomes of PFIC1 LT recipients at our center, focusing on the histological changes of the allografts.

METHODS

We assessed 7 PFIC1 patients post-LT at the Children's Hospital of Pittsburgh (CHP). All pre-transplant, explant, and sequential post-transplant pathology samples were reviewed. Continuous data are presented as the mean ± SD. We compared the pre- and post-transplant height and weight z-scores using Wilcoxon signed-rank test.

RESULTS

Seven (29% male) patients with PFIC1 received a LT (n = 6) or had post-LT care (n = 1) at CHP. Six had confirmed or suspected identical genetic. At a mean follow-up of 10.9 years, both patient survival and graft survival were 100%. Diarrhea persisted (n = 3) or newly developed (n = 4) in all patients after LT contributing to ongoing growth failure, with mean z-scores -2.63 (weight) and -2.98 (height) at follow-up. Histologically, allograft steatosis was common but was not accompanied by significant inflammation, ballooning, or fibrosis.

CONCLUSION

We show that extrahepatic disease persists and near-universal allograft steatosis occurs. However, at a mean follow-up period of over 10 years, no patients developed steatohepatitis or significant fibrosis, and both patient survival and graft survival are excellent.

Efficacy and safety of maralixibat treatment in patients with Alagille syndrome and cholestatic pruritus (ICONIC): a randomised phase 2 study

BACKGROUND

Alagille syndrome is a rare genetic disease that often presents with severe cholestasis and pruritus. There are no approved drugs for management. Maralixibat, an apical, sodium-dependent, bile acid transport inhibitor, prevents enterohepatic bile acid recirculation. We evaluated the safety and efficacy of maralixibat for children with cholestasis in Alagille syndrome.

METHODS

ICONIC was a placebo-controlled, randomised withdrawal period (RWD), phase 2b study with open-label extension in children (aged 1-18 years) with Alagille syndrome (NCT02160782). Eligible participants had more than three times the normal serum bile acid (sBA) levels and intractable pruritus. After 18 weeks of maralixibat 380 μg/kg once per day, participants were randomly assigned (1:1) to continue maralixibat or receive placebo for 4 weeks. Subsequently, all participants received open-label maralixibat until week 48. During the long-term extension (204 weeks reported), doses were increased up to 380 μg/kg twice per day. The primary endpoint was the mean sBA change during the RWD in participants with at least 50% sBA reduction by week 18. Cholestastic pruritus was assessed using observer-rated, patient-rated, and clinician-rated 0-4 scales. The safety population was defined as all participants who had received at least one dose of maralixibat. This trial was registered with ClinicalTrials.gov, NCT02160782, and is closed to recruitment.

FINDINGS

Between Oct 28, 2014, and Aug 14, 2015, 31 participants (mean age 5·4 years [SD 4·25]) were enrolled and 28 analysed at week 48. Of the 29 participants who entered the randomised drug withdrawal period, ten (34%) were female and 19 (66%) were male. In the RWD, participants switched to placebo had significant increases in sBA (94 μmol/L, 95% CI 23 to 164) and pruritus (1·7 points, 95% CI 1·2 to 2·2), whereas participants who continued maralixibat maintained treatment effect. This study met the primary endpoint (least square mean difference -117 μmol/L, 95% CI -232 to -2). From baseline to week 48, sBA (-96 μmol/L, -162 to -31) and pruritus (-1·6 pts, -2·1 to -1·1) improved. In participants who continued to week 204 (n=15) all improvements were maintained. Maralixibat was generally safe and well tolerated throughout. The most frequent adverse events were gastrointestinal related. Most adverse events were self-limiting in nature and mild-to-moderate in severity.

INTERPRETATION

In children with Alagille syndrome, maralixibat is, to our knowledge, the first agent to show durable and clinically meaningful improvements in cholestasis. Maralixibat might represent a new treatment paradigm for chronic cholestasis in Alagille syndrome.

FUNDING

Mirum Pharmaceuticals.

The spectrum of Progressive Familial Intrahepatic Cholestasis diseases: Update on pathophysiology and emerging treatments

The Progressive Familial Intrahepatic Cholestasis (PFIC) disease spectrum encompasses a variety of genetic diseases that affect the bile production and the secretion of bile acids. Typically, the first presentation of these diseases is in early childhood, frequently followed by a severe course necessitating liver transplantation before adulthood. Except for transplantation, treatment modalities have been rather limited and frequently only aim at the symptoms of cholestasis, such as cholestatic pruritus. In recent years, progress has been made in understanding the pathophysiology of these diseases and new treatment modalities have been emerging. Herewith we summarize the latest developments in the field and formulate the current key questions and opportunities for further progress.

Structure of mouse cytosolic sulfotransferase SULT2A8 provides insight into sulfonation of 7α-hydroxyl bile acids

Cytosolic sulfotransferases (SULTs) catalyze the transfer of a sulfonate group from the cofactor 3'-phosphoadenosine 5'-phosphosulfate to a hydroxyl (OH) containing substrate and play a critical role in the homeostasis of endogenous compounds, including hormones, neurotransmitters, and bile acids. In human, SULT2A1 sulfonates the 3-OH of bile acids; however, bile acid metabolism in mouse is dependent on a 7α-OH sulfonating SULT2A8 via unknown molecular mechanisms. In this study, the crystal structure of SULT2A8 in complex with adenosine 3',5'-diphosphate and cholic acid was resolved at a resolution of 2.5 Å. Structural comparison with human SULT2A1 reveals different conformations of substrate binding loops. In addition, SULT2A8 possesses a unique substrate binding mode that positions the target 7α-OH of the bile acid close to the catalytic site. Furthermore, mapping of the critical residues by mutagenesis and enzyme activity assays further highlighted the importance of Lys44 and His48 for enzyme catalysis and Glu237 in loop 3 on substrate binding and stabilization. In addition, limited proteolysis and thermal shift assays suggested that the cofactor and substrates have protective roles in stabilizing SULT2A8 protein. Together, the findings unveil the structural basis of bile acid sulfonation targeting 7α-OH and shed light on the functional diversity of bile acid metabolism across species.

Metabolic consequences of ileal interruption of the enterohepatic circulation of bile acids

The enterohepatic circulation of bile acids comprises a tightly regulated process of hepatic bile acid secretion, intestinal reabsorption and transport back to the liver. Disruption of this process has significant consequences for gastrointestinal, liver and whole body homeostasis and therefore offers opportunities for therapeutic intervention. In this review we discuss the effects of (pharmacological) interruption of the enterohepatic circulation at different levels. Recently, several studies have been published on ileal interruption of the enterohepatic circulation of bile acids, targeting the apical-sodium dependent bile acid transporter (ASBT, SLC10A2), as therapy for various diseases. However, ambiguous results have been reported and in-depth mechanistic insights are lacking. Here we discuss these novel studies and review the current knowledge on the consequences of ASBT inhibition and its potential effects on physiology and metabolism.