Partial external biliary diversion in children with progressive familial intrahepatic cholestasis and Alagille disease

EASL Clinical Practice Guidelines on genetic cholestatic liver diseases

Genetic cholestatic liver diseases are caused by (often rare) mutations in a multitude of different genes. While these diseases differ in pathobiology, clinical presentation and prognosis, they do have several commonalities due to their cholestatic nature. These Clinical Practice Guidelines (CPGs) offer a general approach to genetic testing and management of cholestatic pruritus, while exploring diagnostic and treatment approaches for a subset of genetic cholestatic liver diseases in depth. An expert panel appointed by the European Association for the Study of the Liver has created recommendations regarding diagnosis and treatment, based on the best evidence currently available in the fields of paediatric and adult hepatology, as well as genetics. The management of these diseases generally takes place in a tertiary referral centre, in order to provide up-to-date approaches and expertise. These CPGs are intended to support hepatologists (for paediatric and adult patients), residents and other healthcare professionals involved in the management of these patients with concrete recommendations based on currently available evidence or, if not available, on expert opinion.

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.

Treatment of Cholestasis in Infants and Young Children

PURPOSE OF REVIEW

Cholestasis is characterized by a conjugated hyperbilirubinemia secondary to impaired bile synthesis, transport, or excretion from the liver. It is always pathologic and can be indicative of an underlying hepatobiliary, genetic, or metabolic disorder, several of which require timely diagnosis to ensure proper management and optimal outcomes. This review provides an overview of the evaluation of cholestasis with a focus on current and emerging treatment strategies.

RECENT FINDINGS

Increased accessibility of next generation sequencing (NGS) allows for utilization of genetic testing early in the diagnostic process. This may alter the clinical algorithm for diagnosis of cholestatic disorders. An enhanced understanding of the underlying pathophysiology may help guide future development of targeted therapies, such as ileal bile acid transporter (IBAT) inhibitors. These were recently approved for treatment of cholestatic pruritus in patients with Alagille syndrome and Progressive Familial Intrahepatic Cholestasis. Current management of cholestasis is aimed at the biochemical consequences of impaired bile flow, including malnutrition, pruritus, and progressive fibrosis. NGS has led to an enhanced understanding of biliary pathology and may guide development of future treatment modalities based on specific gene mutations. Rapid discernment of the underlying etiology is essential as new treatment modalities emerge.

Bile acids and their receptors: modulators and therapeutic targets in liver inflammation

Bile acids participate in the intestinal emulsion, digestion, and absorption of lipids and fat-soluble vitamins. When present in high concentrations, as in cholestatic liver diseases, bile acids can damage cells and cause inflammation. After the discovery of bile acids receptors about two decades ago, bile acids are considered signaling molecules. Besides regulating bile acid, xenobiotic, and nutrient metabolism, bile acids and their receptors have shown immunomodulatory properties and have been proposed as therapeutic targets for inflammatory diseases of the liver. This review focuses on bile acid-related signaling pathways that affect inflammation in the liver and provides an overview of the preclinical and clinical applications of modulators of these pathways for the treatment of cholestatic and autoimmune liver diseases.

Long-Term Outcomes of Patients With Progressive Familial Intrahepatic Cholestasis After Biliary Diversion

OBJECTIVES

Progressive familial intrahepatic cholestasis is a heterogeneous group of genetic disorders characterized by disrupted bile homeostasis. Patients with this disease typically present with cholestasis and pruritus early in life and often progress to end-stage liver disease. The clinical symptoms that patients with progressive familial intrahepatic cholestasis encounter are usually refractory to medical treatment. Although the effects of biliary diversion surgery on native liver survival are not exactly known, this procedure may provide a positive impact on pruritus and laboratory parameters in these patients.

MATERIALS AND METHODS

We retrospectively evaluated the clinical and laboratory characteristics of patients with progressive familial intrahepatic cholestasis who underwent partial external biliary diversion between 2002 and 2020 at our center. Diagnosis of progressive familial intrahepatic cholestasis was made by clinical, biochemical, and histopathological characteristics as well as genetic testing.

RESULTS

Nine patients were included in the study. Five patients required liver transplant during follow-up, with 4 having liver transplant as a result of endstage liver disease (median interval of 5 years). In 1 patient, partial external biliary diversion was performed 1.5 years after liver transplant for severe diarrhea, metabolic acidosis, and hepatic steatosis. Four patients did not require liver transplant during follow-up (median follow-up time of 7.6 years). Pruritus responded well to partial external biliary diversion in all patients. Among laboratory values evaluated 6 months after biliary diversion, only albumin showed significant improvement.

CONCLUSIONS

Partial external biliary diversion had favorable results on long-term follow-up. This procedure can provide the relief of pruritus and delay the requirement for liver transplant in patients with progressive familial intrahepatic cholestasis. In our view, partial external biliary diversion should be considered the first-line surgical management for patients with this disease.

Biliary diversion in progressive familial intrahepatic cholestasis: a systematic review and meta-analysis

BACKGROUND

Biliary diversion (BD) is indicated in progressive familial intrahepatic cholestasis (PFIC) with refractory pruritus. Three types-partial external biliary drainage (PEBD), partial internal biliary drainage (PIBD), and ileal exclusion (IE) are described, with no consensus about the relative efficacy of these procedures.

METHODS

PubMed, Scopus, and Google Scholar were searched for publications on PFIC and BD. Improvement in pruritus, serum bile acid (BA), and need for liver transplantation (LT) were compared between the various BD procedures.

RESULTS

25 studies [424 children (PEBD-301, PIBD-93, IE-30)] were included. Pruritus resolved in 59.5% [PIBD:72% (95%CI 43-96%), PEBD:57% (95%CI 43-71%) and IE:48% (95%CI 14-82%)] cases. Significant overlap in confidence intervals indicated no significant differences. Absolute decrease in BA (AUROC-0.72) and bilirubin (AUROC-0.69) discriminated responders and non-responders. Eventually, 27% required LT: PIBD 10.7%, PEBD32%, IE 27%. The post-operative BA (AUROC-0.9) and bilirubin (AUROC-0.85) determined need for LT. Complications were commoner in PEBD than PIBD (38% vs 21.8%: p=0.02).

CONCLUSION

59.5% children have pruritus relief after BD and 27% need LT. PIBD has lower complications and LT requirement than PEBD. However, this requires cautious interpretation as the 2 groups differed in PFIC type and follow-up duration.

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.

Systemic causes of non-dermatologic chronic pruritus in the pediatric population and their management: An unexplored area

Chronic pruritus associated with systemic diseases in the pediatric population has been infrequently addressed in the literature. This review focuses on chronic pruritus presenting without cutaneous manifestations. Common systemic etiologies include diseases with hepatic, renal, and hematologic origins. This encompasses several congenital liver disorders, end-stage renal disease (ESRD), and lymphoproliferative disorders such as Hodgkin's lymphoma. In this paper, an expert panel describes the clinical characteristics, pathophysiology, and therapeutic treatment ladders for chronic pruritus associated with the aforementioned systemic etiologies. Novel therapies are also reviewed. Our aim is to shed light on this unexplored area of pediatric dermatology and instigate further research.

Effects of odevixibat on pruritus and bile acids in children with cholestatic liver disease: Phase 2 study

PURPOSE

Ileal bile acid transporter inhibition is a novel therapeutic concept for cholestatic pruritus and cholestatic liver disease progression. Odevixibat, a potent, selective, reversible ileal bile acid transporter inhibitor, decreases enteric bile acid reuptake with minimal systemic exposure. Oral odevixibat safety, tolerability, and efficacy in pediatric patients with cholestatic liver disease and pruritus were evaluated.

PATIENTS AND METHODS

In this phase 2, open-label, multicenter study, children received 10‒200 μg/kg oral odevixibat daily for 4 weeks. Changes in serum bile acid levels (primary efficacy endpoint), pruritus, and sleep disturbance were explored.

RESULTS

Twenty patients were enrolled (8 females; 1‒17 years; 4 re-entered at a different dose). Diagnoses included progressive familial intrahepatic cholestasis (n = 13; 3 re-entries), Alagille syndrome (n = 6), biliary atresia (n = 3), and other intrahepatic cholestasis causes (n = 2; 1 re-entry). Mean baseline serum bile acid levels were high (235 µmol/L; range, 26‒564) and were reduced in the majority (-123.1 μmol/L; range, -394 to 14.5, reflecting reductions of up to 98%). Patient-reported diary data documented improved pruritus (3 scales) and sleep. With 100 μg/kg, mean (SEM) decrease was 2.8 (1.1) points for pruritus (visual analogue itch scale 0-10) and 2.9 (0.9) points for sleep disturbance (Patient-Oriented Scoring Atopic Dermatitis scale 0-10). Reduced pruritus correlated significantly with reduced serum bile acids (P ≤ 0.007). Significant correlations were also observed between autotaxin levels and pruritus. All patients completed the study. No serious adverse events were treatment related; most adverse events, including increased transaminases, were transient.

CONCLUSIONS

Orally administered odevixibat was well tolerated, reduced serum bile acids, and improved pruritus and sleep disturbance in children with cholestatic diseases.

Partial Biliary Diversion May Promote Long-Term Relief of Pruritus and Native Liver Survival in Children with Cholestatic Liver Diseases

INTRODUCTION

 Rare cholestatic liver diseases may cause debilitating pruritus in children. Partial biliary diversion (PBD) may relieve pruritus and postpone liver transplantation which is the only other alternative when conservative treatment fails. The aim was to report long-term outcome after PBD in a population of 26 million people during a 25-year period.

MATERIALS AND METHODS

 This is an international, multicenter retrospective study reviewing medical journals. Complications were graded according to the Clavien-Dindo classification system.

RESULTS

 Thirty-three patients, 14 males, underwent PBD at a median of 1.5 (0.3-13) years at four Nordic pediatric surgical centers. Progressive familial intrahepatic cholestasis was the most common underlying condition. Initially, all patients got external diversion, either cholecystojejunostomy (25 patients) or button placed in the gallbladder or a jejunal conduit. Early complications occurred in 14 (42%) patients, of which 3 were Clavien-Dindo grade 3. Long-term stoma-related complications were common (55%). Twenty secondary surgeries were performed due to stoma problems such as prolapse, stricture, and bleeding, or conversion to another form of PBD. Thirteen children have undergone liver transplantation, and two are listed for transplantation due to inefficient effect of PBD on pruritus. Serum levels of bile acids in the first week after PBD construction were significantly lower in patients with good relief of pruritus than in those with poor effect (13 [2-192] vs. 148 [5-383] μmol/L; p = 0.02).

CONCLUSION

 PBD may ensure long-term satisfactory effect on intolerable pruritus and native liver survival in children with cholestatic liver disease. However, stoma-related problems and reoperations are common.

Surgical diversion of enterohepatic circulation in pediatric cholestasis

Progressive familial intrahepatic cholestasis (PFIC) and Alagille syndrome (AS) are conditions caused by either an autosomal recessive or an autosomal dominant genetic defect, and they are both characterized by cholestasis, jaundice, and severe debilitating pruritus refractory to medical management. Before the advent of liver transplantation, most PFIC patients would die from end-stage liver disease in the first decade of life. Although liver transplantation has led to patients' survival, disease recurrence (PFIC-2) and severe extra-hepatic manifestations of the disease (PFIC-1) occurred post transplant. In the late 1980s, Whitington described the use of partial external biliary diversion in PFIC and AS patients as a successful way to improve symptoms and decrease circulating bile acid serum concentrations. Since then, other diversion techniques have been described (ileal exclusion and partial internal biliary diversion). These techniques have the benefit of avoiding a stoma, but equivalent results have not been demonstrated (recurrence of cholestasis after ileal exclusion, limited follow up after internal biliary diversion). Overall, studies have showed that biliary diversions in children with cholestasis are safe procedures with low morbidity and mortality, and that they can reduce inflammation and ongoing liver injury, therefore delaying or avoiding the need for liver transplantation in some patients.

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

Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC) are rare, inherited cholestatic liver disorders that manifest in infants and children and are associated with impaired bile flow (ie cholestasis), pruritus and potentially fatal liver disease. There are no effective or approved pharmacologic treatments for these diseases (standard medical treatments are supportive only), and new, noninvasive options would be valuable. Typically, bile acids undergo biliary secretion and intestinal reabsorption (ie enterohepatic circulation). However, in these diseases, disrupted secretion of bile acids leads to their accumulation in the liver, which is thought to underlie pruritus and liver-damaging inflammation. One approach to reducing pathologic bile acid accumulation in the body is surgical biliary diversion, which interrupts the enterohepatic circulation (eg by diverting bile acids to an external stoma). These procedures can normalize serum bile acids, reduce pruritus and liver injury and improve quality of life. A novel, nonsurgical approach to interrupting the enterohepatic circulation is inhibition of the ileal bile acid transporter (IBAT), a key molecule in the enterohepatic circulation that reabsorbs bile acids from the intestine. IBAT inhibition has been shown to reduce serum bile acids and pruritus in trials of paediatric cholestatic liver diseases. This review explores the rationale of inhibition of the IBAT as a therapeutic target, describes IBAT inhibitors in development and summarizes the current data on interrupting the enterohepatic circulation as treatment for cholestatic liver diseases including ALGS and PFIC.

Systematic Review and Meta-analysis: Partial External Biliary Diversion in Progressive Familial Intrahepatic Cholestasis

OBJECTIVES

We assessed available data on impact of partial external biliary diversion (PEBD) surgery on clinical outcomes in patients with progressive familial intrahepatic cholestasis (PFIC).

METHODS

We performed a systematic literature review (PubMed) and meta-analysis to evaluate relationships between liver biochemistry parameters (serum bile acids, bilirubin, and alanine aminotransferase [ALT]) and early response (pruritus improvement) or long-term outcomes (need for liver transplant) in patients with PFIC who underwent PEBD.

RESULTS

Searches identified 175 publications before September 2018; 16 met inclusion criteria. Receiver operating characteristic (ROC) analysis examined ability of liver biochemistry parameters to discriminate patients who demonstrated early and long-term response to PEBD from those who did not. Regarding pruritus improvement in 155 included patients in aggregate, 104 (67%) were responders, 14 (9%) had partial response, and 37 (24%) were nonresponders. In ROC analyses of individual patient data, post-PEBD serum concentration of bile acids, in particular, could discriminate responders from nonresponders for pruritus improvement (area under the curve, 0.99; P < 0.0001; n = 42); to a lesser extent, this was also true for bilirubin (0.87; P = 0.003; n = 31), whereas ALT could not discriminate responders from nonresponders for pruritus improvement (0.74; P = 0.06; n = 28). Reductions from pre-PEBD values in serum bile acid concentration (0.89; P = 0.0003; n = 32) and bilirubin (0.98; P = 0.002; n = 18) but not ALT (0.62; P = 0.46; n = 18) significantly discriminated decreased aggregate need for liver transplant.

CONCLUSION

Changes in bile acids seem particularly useful in discriminating early and long-term post-PEBD outcomes and may be potential biomarkers of response to interruption of enterohepatic circulation in patients with PFIC.

Ileal bile acid transporter inhibition as an anticholestatic therapeutic target in biliary atresia and other cholestatic disorders

Biliary atresia is a rare cholestatic liver disease that presents in infants and rapidly advances to death in the absence of intervention. As a result of blockage or destruction of the biliary tract, bile acids accumulate and drive inflammation, fibrosis, and disease progression. The standard of care, Kasai portoenterostomy (KPE), is typically performed shortly after diagnosis (currently at ~ 2 months of age) and aims to restore bile flow and relieve cholestasis. Nevertheless, most patients continue to experience liver injury from accumulation of bile acids after KPE, since there are no known effective therapeutics that may enhance survival after KPE. Improving cholestasis via interruption of the enterohepatic circulation of bile acids may directly attenuate hepatic bile acid retention and reduce the risk of early organ failure. Directly addressing intrahepatic accretion of bile acids to avoid inherent bile acid toxicities provides an attractive and plausible therapeutic target for biliary atresia. This review explores the novel therapeutic concept of inhibiting the sole ileal bile acid transporter (IBAT), also known as ASBT (apical sodium-bile acid transporter, encoded by SLC10A2), as a means to reduce hepatic bile acid concentration after KPE. By reducing return of bile acids to the cholestatic liver, IBAT inhibitors may potentially lessen or delay liver damage associated with the hepatotoxicity and cholangiopathy of bile acid accumulation. The clinical programs of 2 IBAT inhibitors in development for the treatment of pediatric cholestatic liver diseases, maralixibat and odevixibat, are highlighted.

Ileal exclusion for pruritus treatment in children with progressive familial intrahepatic cholestasis and other cholestatic diseases

BACKGROUND

Pruritus is a major health-related quality-of-life burden in progressive familial intrahepatic cholestasis (PFIC) and other childhood cholestatic liver diseases. Several nontransplant surgical techniques were developed in an attempt to ameliorate symptoms and slow disease progression. Very few case-series have been published on a particular intervention, ileal exclusion (IE), which has been considered to be inferior to the other approaches.

METHODS

We conducted a single-center retrospective chart-review case-series of patients submitted to IE as the first-line surgical treatment at our institution from 1995 to 2018. The primary goal was pruritus relief, followed by survival with the native liver and improvement in biochemical parameters.

RESULTS

Eleven patients were submitted to IE, with a mean follow-up of 60 months. Complete resolution or significant reduction of pruritus was obtained in 72.7% (n = 8) of patients. One patient (9.1%) had a major postoperative complication that required surgery. No other morbidities were reported. Two cases progressed to end-stage liver disease (ESLD) within the short-term and one year after surgery.

CONCLUSIONS

This case series study shows that IE provided excellent results in pruritus control and permitted survival with the native liver. We believe IE is a safe procedure, with few associated morbidities, and should be considered more often as primary surgical treatment for PFIC and other cholestasis.

LEVEL OF EVIDENCE

IV.

Genotype correlates with the natural history of severe bile salt export pump deficiency

BACKGROUND & AIMS

Mutations in ABCB11 can cause deficiency of the bile salt export pump (BSEP), leading to cholestasis and end-stage liver disease. Owing to the rarity of the disease, the associations between genotype and natural history, or outcomes following surgical biliary diversion (SBD), remain elusive. We aimed to determine these associations by assembling the largest genetically defined cohort of patients with severe BSEP deficiency to date.

METHODS

This multicentre, retrospective cohort study included 264 patients with homozygous or compound heterozygous pathological ABCB11 mutations. Patients were categorized according to genotypic severity (BSEP1, BSEP2, BSEP3). The predicted residual BSEP transport function decreased with each category.

RESULTS

Genotype severity was strongly associated with native liver survival (NLS, BSEP1 median 20.4 years; BSEP2, 7.0 years; BSEP3, 3.5 years; p <0.001). At 15 years of age, the proportion of patients with hepatocellular carcinoma was 4% in BSEP1, 7% in BSEP2 and 34% in BSEP3 (p = 0.001). SBD was associated with significantly increased NLS (hazard ratio 0.50; 95% CI 0.27-0.94: p = 0.03) in BSEP1 and BSEP2. A serum bile acid concentration below 102 μmol/L or a decrease of at least 75%, each shortly after SBD, reliably predicted NLS of ≥15 years following SBD (each p <0.001).

CONCLUSIONS

The genotype of severe BSEP deficiency strongly predicts long-term NLS, the risk of developing hepatocellular carcinoma, and the chance that SBD will increase NLS. Serum bile acid parameters shortly after SBD can predict long-term NLS.

LAY SUMMARY

This study presents data from the largest genetically defined cohort of patients with severe bile salt export pump deficiency to date. The genotype of patients with severe bile salt export pump deficiency is associated with clinical outcomes and the success of therapeutic interventions. Therefore, genotypic data should be used to guide personalized clinical care throughout childhood and adulthood in patients with this disease.

Odevixibat and partial external biliary diversion showed equal improvement of cholestasis in a patient with progressive familial intrahepatic cholestasis

Untreated progressive familial intrahepatic cholestasis (PFIC) type 2, or bile salt exporter protein deficiency, frequently leads to severe pruritus, impaired growth and progressive liver fibrosis with risk of organ failure. We describe a 15-month-old male patient with severe pruritus diagnosed with PFIC type 2 enrolled in an open-label phase 2 study who received 4 weeks of treatment with odevixibat, an ileal bile acid transporter inhibitor under development for cholestatic liver disease treatment. The patient experienced reductions in serum bile acids and improvement in itching and sleep scores, and odevixibat was well tolerated. After the odevixibat study, symptoms returned and the patient underwent partial external biliary diversion (PEBD). Odevixibat treatment and PEBD produced similar normalisation of serum bile acid levels and improvements in pruritus and sleep disruptions. Thus, odevixibat appeared to be as effective as invasive PEBD in treating serum bile acids and cholestatic pruritus in this patient.

Changes in plasma bile acid profiles after partial internal biliary diversion in PFIC2 patients

Background

We ask if plasma bile acid profiles can be used to monitor the effectiveness of partial internal biliary diversion (PIBD) for treating uncontrolled cholestasis in progressive familial intrahepatic cholestasis type 2 (PFIC2) patients.

Methods

Plasma bile acids were profiled in 3 cases of ATP-binding cassette, sub-family B member 11 (ABCB11)-mutated PFIC2 children before and after PIBD compared to healthy controls and 8 PFIC2 patients. The quantitation of bile acids was performed by reversed-phase ultrahigh-performance liquid chromatography/multiple-reaction monitoring-mass spectrometry (UPLC/MRM-MS) with negative ion detection.

Results

Before PIBD, all three patients presented with >50-fold higher levels of total plasma bile acids, 2-7 folds higher ratios of taurine: glycine conjugated primary bile acids, and unchanged secondary bile acids levels compared to healthy controls. After PIBD, only one of the three patients (P3) showed relief of cholestasis. The bile acid profiles of the two nonresponding patients showed little change while that of the responding patient showed a 5-fold reduction in total plasma primary bile acids, a reduced taurine: glycine conjugate ratio, and an unexpected 26- and 12-fold increase in secondary bile acids DCA and LCA respectively. One year later, the responder suffered a recurrence of cholestasis, and the bile acid profile shifted back to a more pre-PIBD-like profile.

Conclusions

Plasma bile acid profiles may potentially be useful as sensitive biomarkers for monitoring the clinical course of PIBD patients. Relief of cholestasis after PIBD appears to be associated with significantly increased circulating toxic secondary bile acids and this may limit the utility of PIBD in PFIC2 patients in the long run.

First report of successful transplantation of a pediatric donor liver graft after hypothermic machine perfusion

One of the main limiting factors in pediatric liver transplantation is donor availability. For adults, DCD liver grafts are increasingly used to expand the donor pool. To improve outcome after DCD liver transplantation, ex situ machine perfusion is used as an alternative organ preservation strategy, with the supplemental value of providing oxygen to the graft during preservation. We here report the first successful transplantation of a pediatric DCD liver graft after hypothermic oxygenated machine perfusion. The full-size liver graft was derived from a 13-year-old, female DCD donor and was end-ischemic pretreated with dual hypothermic oxygenated machine perfusion. Arterial and portal pressures were set at 18 and 4 mm Hg, slightly lower than protocolized settings for adult livers. During 2 hours of machine perfusion, portal and arterial flows increased from 100 to 210 mL/min and 30 to 63 mL/min, respectively. The pretreated liver graft was implanted in a 16-year-old girl with progressive familial intrahepatic cholestasis type 2. Postoperative AST, ALT, and prothrombin time normalized within a week. The recipient quickly recovered and was discharged from the hospital after 18 days. One year after transplantation, she is in excellent condition with a completely normal liver function and histology. This case is the first report of successful transplantation of a pediatric DCD liver graft after hypothermic oxygenated machine perfusion and illustrates the potential role of ex situ machine perfusion in expanding the donor pool and improving outcome after pediatric liver transplantation.

Systematic review of progressive familial intrahepatic cholestasis

BACKGROUND AND AIMS

Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of rare genetic disorders associated with bile acid secretion or transport defects. This is the first systematic review of the epidemiology, natural history and burden of PFIC.

METHODS

MEDLINE and Embase were searched for publications on PFIC prevalence, incidence or natural history, and the economic burden or health-related quality of life (HRQoL) of patients with PFIC. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed.

RESULTS

Of 1269 records screened, 20 were eligible (epidemiology, 17; humanistic burden, 5; both, 2). Incidence of intrahepatic cholestasis, including but not limited to PFIC, was 1/18 000 live births in one study that did not use genetic testing. In two studies of infants and children (2-18 years) with cholestasis, 12-13% had genetically diagnosed PFIC. Of the three main PFIC subtypes, PFIC2 was the most common (21-91% of patients). Common symptoms (e.g. pruritus, jaundice, hepatomegaly, splenomegaly) generally appeared at about 3 months of age and tended to emerge earliest in patients with PFIC2. Patients reported that pruritus was often severe and led to dermal damage and reduced HRQoL. Disease progression led to complications including liver failure and hepatocellular carcinoma, with 20-83% of patients requiring liver transplantation. Mortality was 0-87% across 10 studies (treatment varied among studies), with a median age at death of ~4 years in one study.

CONCLUSIONS

Patients with PFIC face debilitating symptoms and poor prognosis. Further research is needed to inform patient management and clinical trial design. Published data on the epidemiology and socioeconomic burden of PFIC is limited.

Two Cases of Progressive Familial Intrahepatic Cholestasis Type 2: Role of Surgery with Brief Review of Literature

Progressive familial intrahepatic cholestasis (PFIC) is a rare bile acid transporter defect and autosomal recessive disorder with type 2 being the most common type. Partial internal or external biliary diversion delays its progression to end-stage liver disease. Here, we discuss two cases of type 2 PFIC.

Progressive familial intrahepatic cholestasis: diagnosis, management, and treatment

Progressive familial intrahepatic cholestasis (PFIC) is a group of autosomal recessive cholestatic liver diseases which are subgrouped according to the genetic defect, clinical presentation, laboratory findings and liver histology. Progressive liver fibrosis, cirrhosis, and end stage liver disease (ESLD) may eventually develop. PFIC was first described in Amish descendants of Jacob Byler, therefore it was originally called Byler disease. But it can be seen anywhere on the globe. This review summarizes the main features of the subtypes of the disease and discusses the current available diagnosis, conservative and surgical therapeutic options.

Clinical Variability After Partial External Biliary Diversion in Familial Intrahepatic Cholestasis 1 Deficiency

OBJECTIVES

Familial intrahepatic cholestasis 1 (FIC1) deficiency is caused by a mutation in the ATP8B1 gene. Partial external biliary diversion (PEBD) is pursued to improve pruritus and arrest disease progression. Our aim is to describe clinical variability after PEBD in FIC1 disease.

METHODS

We performed a single-center, retrospective review of genetically confirmed FIC1 deficient patients who received PEBD. Clinical outcomes after PEBD were cholestasis, pruritus, fat-soluble vitamin supplementation, growth, and markers of disease progression that included splenomegaly and aspartate aminotransferase-to-platelet ratio index.

RESULTS

Eight patients with FIC1 disease and PEBD were included. Mean follow-up was 32 months (range 15-65 months). After PEBD, total bilirubin was <2 mg/dL in all patients at 8 months after surgery, but 7 of 8 subsequently experienced a total of 15 recurrent cholestatic events. Subjective assessments of pruritus demonstrated improvement, but itching exacerbation occurred during cholestatic episodes. High-dose fat-soluble vitamin supplementation persisted, with increases needed during cholestatic episodes. Weight z scores improved (-3.4 to -1.65, P < 0.01). Splenomegaly did not worsen or develop and 1 patient developed an aminotransferase-to-platelet ratio index score of >0.7 suggesting development of fibrosis 24 months after PEBD.

CONCLUSIONS

Clinical variability is evident among genetically defined FIC1 deficient patients after PEBD, even among those with identical mutations. Recurrent, self-limited episodes of cholestasis and pruritus are reminiscent of the benign recurrent intrahepatic cholestasis phenotype. Despite diversion of bile from the intestinal lumen, weight gain improved while fat-soluble vitamin requirements persisted. Significant progression of liver disease was not evident during follow-up.

Outcomes following partial external biliary diversion in patients with progressive familial intrahepatic cholestasis

BACKGROUND/PURPOSE

PFIC is a family of bile acid (BA) transport disorders that may result in serious liver disease requiring transplantation. We reviewed our experience with PEBD as a method to improve liver function and avoid transplantation.

METHODS

All patients with PFIC were reviewed. Outcomes included changes in serum BA, conversion to ileal bypass (IB), and survival without transplantation. Statistics were obtained using paired t-test and Wilcoxon test.

RESULTS

Thirty-five patients with PFIC were identified. Data were available in 24. Twenty-four children (12 males) underwent PEBD: 10 PFIC-1, 13 PFIC-2, and one PFIC-3. BA levels decreased in PFIC-1 patients (1724±3215 to 11±6μmol/L, P=0.03) and in the single PFIC-3 patient (821 to 11.2μmol/L), but not significantly in PFIC-2 patients (193±99 to 141±118μmol/L, P=0.15). Seven patients were converted to IB. There were no significant changes in BA levels following conversion. Five-year transplant-free survival was 100% in PFIC-1 and PFIC-3, but only 38% (5/13) in PFIC-2 (P=0.004).

CONCLUSION

PEBD is an effective procedure to reduce total BA levels and improve symptoms in PFIC patients. However, it appears to be less efficacious in the PFIC-2 group. The higher BA levels could contribute to ongoing liver damage, and thus a higher transplant rate in PFIC-2 patients.

LEVEL OF EVIDENCE

Level IV.

Biliary atresia and other cholestatic childhood diseases: Advances and future challenges

Biliary Atresia and other cholestatic childhood diseases are rare conditions affecting the function and/or anatomy along the canalicular-bile duct continuum, characterised by onset of persistent cholestatic jaundice during the neonatal period. Biliary atresia (BA) is the most common among these, but still has an incidence of only 1 in 10-19,000 in Europe and North America. Other diseases such as the genetic conditions, Alagille syndrome (ALGS) and Progressive Familial Intrahepatic Cholestasis (PFIC), are less common. Choledochal malformations are amenable to surgical correction and require a high index of suspicion. The low incidence of such diseases hinder patient-based studies that include large cohorts, while the limited numbers of animal models of disease that recapitulate the spectrum of disease phenotypes hinders both basic research and the development of new treatments. Despite their individual rarity, collectively BA and other cholestatic childhood diseases are the commonest indications for liver transplantation during childhood. Here, we review the recent advances in basic research and clinical progress in these diseases, as well as the research needs. For the various diseases, we formulate current key questions and controversies and identify top priorities to guide future research.

Liver transplantation and the management of progressive familial intrahepatic cholestasis in children

Progressive familial intrahepatic cholestasis (PFIC) is a constellation of inherited disorders that result in the impairment of bile flow through the liver that predominantly affects children. The accumulation of bile results in progressive liver damage, and if left untreated leads to end stage liver disease and death. Patients often present with worsening jaundice and pruritis within the first few years of life. Many of these patients will progress to end stage liver disease and require liver transplantation. The role and timing of liver transplantation still remains debated especially in the management of PFIC1. In those patients who are appropriately selected, liver transplantation offers an excellent survival benefit. Appropriate timing and selection of patients for liver transplantation will be discussed, and the short and long term management of patients post liver transplantation will also be described.

Total biliary diversion as a treatment option for patients with progressive familial intrahepatic cholestasis and Alagille syndrome

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) with low gamma-glutamyl transpeptidase (GGT) and Alagille syndrome are associated with persistent cholestasis and severe pruritus. Various types of biliary diversion have been used to reduce this pruritus and prevent liver dysfunction. We report our experience concerning the efficacy and safety of total biliary diversion (TBD) as an additional treatment option.

METHODS

TBD was performed in four PFIC patients and one patient with Alagille syndrome, and was accomplished by anastomosing a jejunal segment to the choledochal duct terminating as an end stoma, or by disconnecting the choledochal duct after previous cholecystojejunocutaneostomy.

RESULTS

TBD resulted in a marked improvement of symptoms and biochemical parameters in all PFIC patients. Despite relief of pruritus, cholestasis persisted in the Alagille patient. During 5-15years of follow-up, no clinical signs of fat malabsorption such as diarrhea or weight loss were encountered. However, to maintain adequate levels of fat-soluble vitamins, especially of vitamin K, substantial supplementation was necessary.

CONCLUSIONS

Total biliary diversion can be a useful surgical treatment option for patients with low-GGT PFIC and possibly also Alagille syndrome, when partial biliary diversion is insufficient. It can be performed without inducing clinical signs of fat malabsorption although individualized supplementation of fat-soluble vitamins with careful monitoring is warranted.

Bile acid pool dynamics in progressive familial intrahepatic cholestasis with partial external bile diversion

OBJECTIVES

Partial external bile diversion (PEBD) is an established therapy for low-γ-glutamyl transferase (GGT) progressive familial intrahepatic cholestasis (PFIC). This study sought to determine whether the dynamics of the cholic acid (CA) and chenodeoxycholic acid (CDCA) pools in subjects with low-GGT-PFIC with successful PEBD were equivalent to those achieved with successful liver transplantation (LTX).

METHODS

The kinetics of CA and CDCA metabolism were measured by stable isotope dilution in plasma samples in 5 subjects with PEBD, all with intact canalicular bile salt export pump expression and compared with subjects with low-GGT-PFIC with successful LTX. Stomal loss of bile acids was measured in subjects with PEBD.

RESULTS

The fractional turnover rate for CA in the PEBD group ranged from 0.5 to 4.2/day (LTX group, range 0.2-0.9/day, P = 0.076) and for CDCA from 0.7 to 4.5/day (LTX group 0.3-0.4/day, P = 0.009). The CA and CDCA pool sizes were equivalent between groups; however, pool composition in PEBD was somewhat more hydrophilic. The CA/CDCA ratio in PEBD ranged from 0.9 to 19.5, whereas in LTX it ranged from 0.5 to 2.6. Synthesis rates computed from isotope dilution correlated well with timed output for both CA (r2 = 0.760, P = 0.024) and CDCA (r2 = 0.690, P = 0.021).

CONCLUSIONS

PEBD results in bile acid fractional turnover rates greater than LTX, pool sizes equivalent to LTX, and pool composition that is at least as hydrophilic as produced by LTX.

Partial internal biliary diversion in progressive familial intrahepatic cholestasis: introduction of a new approach

INTRODUCTION

Facilitation of biliary salts secretion represents the mainstay of treatment for progressive familial intrahepatic cholestasis (PFIC). The purpose of this study was to introduce a new approach for the treatment of progressive familial intrahepatic cholestasis (PFIC) to avoid ostoma.

CASE PRESENTATION

An 11-year-old girl with the diagnosis of PFIC underwent cholecystoappendicostomy with myotomy operation. Because of anastomosis stricture, she was reoperated with cholecystojejunocolic anastomosis and intussuscepted valve surgery. She was followed for 9 months. Despite disappointing outcomes of internal drainage with cholecystoappendicostomy, results of cholecystojejunocolic anastomosis with intussuscepted valve surgery were promising.

DISCUSSION

The cholecystojejunocolic anastomosis with intussuscepted valve surgery could be considered as a forthcoming approach in the treatment of intrahepatic cholestasis.

Laparoscopic cholecystocolostomy: a novel surgical approach for the treatment of progressive familial intrahepatic cholestasis

OBJECTIVE

Conventionally, liver transplantation, ileoileal bypass, and partial external or internal biliary diversion are used in the treatment of progressive familial intrahepatic cholestasis (PFIC). However, postoperative recurrence, chronic diarrhea, and permanent stoma are the major concerns. We present a novel approach of laparoscopic cholecystocolostomy with antireflux Y-loop for the management of children with PFIC.

METHODS

Between August 2003 and April 2011, 20 children with PFIC (median age: 1.47 years; range: 10.8 months to 5.11 years) successfully underwent laparoscopic cholecystocolostomies for bile diversions. Gallbladder was incised longitudinally for cholecystocolostomy. Transverse colon was divided proximal to splenic flexure. End-to-side anastomosis was established between distal transverse colon and mid-descending colon. The mobilized splenic flexure and proximal descending colon, that is, the stem of the Y-loop, was anastomosed to the gallbladder.

RESULTS

The mean operative time was 2.02 ± 0.18 hours (range: 2-2.5 hours). The mean postoperative hospital stay was 8 days (range: 5-10 days). Average time for full resumption of diet was 3 days (range: 2-4 days). Average Y-loop length was 17.65 cm (range: 15-20 cm). The median follow-up period was 54 months (range: 12-104 months). All patients were jaundice free after 7 to 20 days and pruritus subsided in 3 to 14 days. Liver function parameters significantly improved postoperatively. Success rate (normalization of serum bile acids at postoperative 12 months) was 85%. No mortality or morbidities associated with diarrhea, cholangitis, or intrahepatic reflux were observed.

CONCLUSIONS

The novel approach of laparoscopic cholecystocolostomy offers a safe and effective treatment option for PFIC in children with good success rates and minimal morbidity.

Management of cholestatic pruritus in paediatric patients with alagille syndrome: the King's College Hospital experience

OBJECTIVES

The aims of the study were to perform a retrospective observational review of the present management and outcome of cholestatic pruritus in children with Alagille syndrome (AGS) at King's College Hospital and to use results to inform appropriate guidelines.

METHODS

A retrospective review of 62 patients diagnosed as having AGS from January 1995 to November 2010 treated at King's College Hospital was performed. The departmental database of the Paediatric Liver Centre was searched to identify all patients and the clinical records were then analysed.

RESULTS

Fifty-one (82.3%) patients experienced pruritus and 50 (80.6%) received antipruritic medication. Ursodeoxycholic acid was the most prescribed drug (n = 40). Other drugs prescribed were rifampicin (n = 39), cholestyramine (n = 18), naltrexone (n = 14), alimemazine (n = 13), nonsedating antihistamine agents (n = 7), ondansetron (n = 5), and phenobarbitone (n = 1). Albumin dialysis using the molecular adsorbent recirculation system was used in 1 patient. Sixteen patients (25.8%) were listed for liver transplantation, and 11 had undergone transplantation by November 2010. Patient survival was high at 95.2%. Pruritus resolved permanently in 39.2% (n = 20) of patients. Fifty-five percent (n = 11) of such patients had undergone liver transplantation. Pruritus was controlled by medication in 41.2% (n = 21). Itching remained a significant problem, affecting quality of life in 19.6% of patients (n = 10).

CONCLUSIONS

The management of cholestatic pruritus in AGS is difficult and often suboptimal. Pruritus may remain intractable even with combination medical treatment, and at this stage, surgery or liver transplantation is indicated. At our centre, pruritus was successfully treated in 80.4% of patients with medical and surgical management.

Recovery of graft steatosis and protein-losing enteropathy after biliary diversion in a PFIC 1 liver transplanted child

PFIC 1 is a genetic disorder characterized by hepatic and gastrointestinal disease, often requiring LT during childhood. Extrahepatic symptoms, such as diarrhea and malabsorption, do not improve or may be aggravated after LT, as graft steatosis or steatohepatitis as consequences of the interaction between transplanted liver and native bowel. We describe a patient with PFIC 1 who presented with cholestasis in infancy, who developed intractable pruritus and liver fibrosis. The child underwent living donor LT at 3.6 yr of age, and he early developed severe refractory diarrhea, secondary malabsorption with protein-losing enteropathy, and an early fatty liver disease trough graft steatohepatitis. As the response to cholestyramine was unsatisfactory, we decided to perform an EBD by using the jejunal loop used for the cholangiojejunostomy. Diarrhea resolved rapidly after surgery. He remained well after six months following biliary diversion, with normal stool output and no protein loss. We documented a dramatic improvement of graft steatosis at histology as well as normalization of liver function test. EBD can be considered a valuable treatment option to avoid organ disfunction and loss in PFIC 1 transplanted patients who develop graft steatohepatitis.

Normalization of serum bile acids after partial external biliary diversion indicates an excellent long-term outcome in children with progressive familial intrahepatic cholestasis

BACKGROUND/PURPOSE

The surgical treatment for patients with progressive familial intrahepatic cholestasis (PFIC) is either liver transplantation (LTX) or partial external biliary diversion (PEBD). Both procedures achieve a good short-term outcome. However, the treatment strategy for these children remains controversial because the long-term outcome after PEBD is unknown. The aim of our study was to assess the long-term outcome and complications after PEBD in our institution.

METHODS

We retrospectively analyzed the characteristics of all patients with PFIC undergoing PEBD in our department from 1994 to 2008. The course of serum bile acids, pruritus, and liver enzymes was assessed in a regular follow-up.

RESULTS

Twenty-four patients underwent PEBD. Thirteen patients (54%) improved significantly, with a normalization of serum bile acids (P < .001 vs postoperatively) and lessened pruritus (P < .05 vs preoperatively) at 12 months after PEBD. None of these patients showed progression of cholestasis during a median follow-up of 9.8 years (range, 1.6-14.3 years). Partial external biliary diversion failed to normalize bile acids in 11 patients, of whom 9 required secondary LTX at a 1-year follow-up, with a median interval of 1.9 years (range, 0.5-3.8 years). All 7 patients (100%) with liver cirrhosis at the time of PEBD and 2 of 17 patients without cirrhosis (12%) required secondary LTX (P < .001).

CONCLUSIONS

Clinical improvement with normalization of serum bile acids within 1 year was associated with an excellent long-term outcome in patients with PEBD. The presence of liver cirrhosis at the time of PEBD indicated an unfavorable outcome. Thus, we recommend primary LTX only in PFIC patients with liver cirrhosis.

Familial cholestasis: progressive familial intrahepatic cholestasis, benign recurrent intrahepatic cholestasis and intrahepatic cholestasis of pregnancy

Progressive familial intrahepatic cholestasis (PFIC) type 1, 2 and 3 are due to mutations in ATP8B1, ABCB11 and ABCB4, respectively. Each of these genes encodes a hepatocanalicular transporter, which is essential for the proper formation of bile. Mutations in ABCB4 can result in progressive cholestatic disease, while mutations in ATP8B1 and ABCB11 can result both in episodic cholestasis, referred to as benign recurrent intrahepatic cholestasis (BRIC) type 1 and 2, as well as in progressive cholestatic disease. This suggests a clinical continuum and these diseases are therefore preferably referred to as ATP8B1 deficiency and ABCB11 deficiency. Similarly PFIC type 3 is designated as ABCB4 deficiency. Heterozygous mutations in each of these transporters can also be associated with intrahepatic cholestasis of pregnancy. This review summarizes the pathophysiology, clinical features and current as well as future therapeutic options for progressive familial- and benign recurrent intrahepatic cholestasis as well as intrahepatic cholestasis of pregnancy.

Long-term outcome after partial external biliary diversion for progressive familial intrahepatic cholestasis

BACKGROUND

Though patients with progressive familial intrahepatic cholestasis (PFIC) typically require liver transplantation, initial surgical treatment includes partial biliary diversion (PBD) to relieve jaundice-associated pruritus. This study was undertaken to describe long-term PFIC outcome data, which are currently sparsely reported.

METHODS

Retrospective review of 7 patients diagnosed with PFIC who underwent PBD between 2004 and 2008 was directed toward long-term postoperative outcome including resolution of jaundice/pruritus, stoma complications, interval to transplantation, and death.

RESULTS

Six patients who underwent PBD experienced short-term resolution of jaundice and pruritus. Four patients experienced persistent stoma-related complications requiring a total of 14 revisions. Three symptom-free patients have not yet required liver transplantation post-PBD (average, 70 months; range, 59-78 months). Two patients underwent orthotopic liver transplantation (average, 44 +/- 18 months post-PBD). Two patients died at home because of gastroenteritis-associated dehydration before transplantation.

CONCLUSION

Partial biliary diversion for PFIC is effective as a bridge to liver transplantation in improving jaundice and pruritus but may be associated with a high incidence of stoma-related complications. Persistent or recurrent pruritus after PFIC is associated with an increased risk of stoma prolapse or reflux. Insufficiently replaced stomal losses over time may increase the risk of dehydration-related complications in association with gastroenteritis.

ATP8B1 and ABCB11 analysis in 62 children with normal gamma-glutamyl transferase progressive familial intrahepatic cholestasis (PFIC): phenotypic differences between PFIC1 and PFIC2 and natural history

Progressive familial intrahepatic cholestasis (PFIC) types 1 and 2 are characterized by normal serum gamma-glutamyl transferase (GGT) activity and are due to mutations in ATP8B1 (encoding FIC1) and ABCB11 (encoding bile salt export pump [BSEP]), respectively. Our goal was to evaluate the features that may distinguish PFIC1 from PFIC2 and ease their diagnosis. We retrospectively reviewed charts of 62 children with normal-GGT PFIC in whom a search for ATP8B1 and/or ABCB11 mutation, liver BSEP immunostaining, and/or bile analysis were performed. Based on genetic testing, 13 patients were PFIC1 and 39 PFIC2. The PFIC origin remained unknown in 10 cases. PFIC2 patients had a higher tendency to develop neonatal cholestasis. High serum alanine aminotransferase and alphafetoprotein levels, severe lobular lesions with giant hepatocytes, early liver failure, cholelithiasis, hepatocellular carcinoma, very low biliary bile acid concentration, and negative BSEP canalicular staining suggest PFIC2, whereas an absence of these signs and/or presence of extrahepatic manifestations suggest PFIC1. The PFIC1 and PFIC2 phenotypes were not clearly correlated with mutation types, but we found tendencies for a better prognosis and response to ursodeoxycholic acid (UDCA) or biliary diversion (BD) in a few children with missense mutations. Combination of UDCA, BD, and liver transplantation allowed 87% of normal-GGT PFIC patients to be alive at a median age of 10.5 years (1-36), half of them without liver transplantation.

CONCLUSION

PFIC1 and PFIC2 differ clinically, biochemically, and histologically at presentation and/or during the disease course. A small proportion of normal-GGT PFIC is likely not due to ATP8B1 or ABCB11 mutations.

Liver disease associated with canalicular transport defects: current and future therapies

Bile formation at the canalicular membrane is a delicate process. This is illustrated by inherited liver diseases due to mutations in ATP8B1, ABCB11, ABCB4, ABCC2 and ABCG5/8, all encoding hepatocanalicular transporters. Effective treatment of these canalicular transport defects is a clinical and scientific challenge that is still ongoing. Current evidence indicates that ursodeoxycholic acid (UDCA) can be effective in selected patients with PFIC3 (ABCB4 deficiency), while rifampicin reduces pruritus in patients with PFIC1 (ATP8B1 deficiency) and PFIC2 (ABCB11 deficiency), and might abort cholestatic episodes in BRIC (mild ATP8B1 or ABCB11 deficiency). Cholestyramine is essential in the treatment of sitosterolemia (ABCG5/8 deficiency). Most patients with PFIC1 and PFIC2 will benefit from partial biliary drainage. Nevertheless liver transplantation is needed in a substantial proportion of these patients, as it is in PFIC3 patients. New developments in the treatment of canalicular transport defects by using nuclear receptors as a target, enhancing the expression of the mutated transporter protein by employing chaperones, or by mutation specific therapy show substantial promise. This review will focus on the therapy that is currently available as well as on those developments that are likely to influence clinical practice in the near future.