Plasma immune signatures can predict rejection-free survival in the first year after pediatric liver transplantation.

BACKGROUND & AIMS: After pediatric liver transplantation (pLT), children undergo life-long immunosuppression since reliable biomarkers for the assessment of rejection probability are scarce. In the multicenter (n = 7) prospective clinical cohort "ChilSFree" study, we aimed to characterize longitudinal dynamics of soluble and cellular immune mediators during the first year after pLT and identify early biomarkers associated with outcome. METHODS: Using a Luminex-based multiplex technique paired with flow cytometry, we characterized longitudinal dynamics of soluble immune mediators (SIMs, n = 50) and immune cells in the blood of 244 patients at eight visits over 1 year: before, and 7/14/21/28 days and 3/6/12 months after pLT. RESULTS: The unsupervised clustering of patients based on SIM profiles revealed six unique SIM signatures associated with clinical outcome. From three signatures linked to improved outcome, one was associated with 1-year-long rejection-free survival and stable graft function and was characterized by low levels of pro-inflammatory SIMs (CXCL8/9/10/12, CCL7, SCGF-ß, sICAM-1), and high levels of regenerative (SCF, TNF-ß) and pro-apoptotic (TRAIL) SIMs (all, p <0.001, fold change >100). Of note, this SIM signature appeared 2 weeks after pLT and remained stable over the entire year, pointing towards its potential as a novel early biomarker for minimizing or weaning immunosuppression. In the blood of these patients, a higher frequency of CD56bright natural killer cells (p <0.01), a known hallmark also associated with operationally tolerant pLT patients, was detected. The concordance of the model for prediction of rejection based on identified SIM signatures was 0.715, and 0.795, in combination with living-related transplantation as a covariate, respectively. CONCLUSIONS: SIM blood signatures may enable the non-invasive and early assessment of rejection risks in the first year after pLT, paving the way for improved clinical management. IMPACT AND IMPLICATIONS: ChilSFree represents the largest pediatric liver transplant (pLT) cohort with paired longitudinal data on soluble immune mediators (SIMs) and immune phenotyping in the first year after pLT. SIM signatures allow for the selection of rejection-free patients 2 weeks after pLT independently of patient diagnosis, sex, or age. The SIM signatures may enable the non-invasive and early assessment of rejection risks, paving the way for minimization or withdrawal of immunosuppression after pLT.

Discrimination of Etiologically Different Cholestasis by Modeling Proteomics Datasets.

Cholestasis is characterized by disrupted bile flow from the liver to the small intestine. Although etiologically different cholestasis displays similar symptoms, diverse factors can contribute to the progression of the disease and determine the appropriate therapeutic option. Therefore, stratifying cholestatic patients is essential for the development of tailor-made treatment strategies. Here, we have analyzed the liver proteome from cholestatic patients of different etiology. In total, 7161 proteins were identified and quantified, of which 263 were differentially expressed between control and cholestasis groups. These differential proteins point to deregulated cellular processes that explain part of the molecular framework of cholestasis progression. However, the clustering of different cholestasis types was limited. Therefore, a machine learning pipeline was designed to identify a panel of 20 differential proteins that segregate different cholestasis groups with high accuracy and sensitivity. In summary, proteomics combined with machine learning algorithms provides valuable insights into the molecular mechanisms of cholestasis progression and a panel of proteins to discriminate across different types of cholestasis. This strategy may prove useful in developing precision medicine approaches for patient care.

Molecular basis of progressive familial intrahepatic cholestasis 3. A proteomics study.

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a severe rare liver disease that affects between 1/50,000 and 1/100,000 children. In physiological conditions, bile is produced by the liver and stored in the gallbladder, and then it flows to the small intestine to play its role in fat digestion. To prevent tissue damage, bile acids (BAs) are kept in phospholipid micelles. Mutations in phosphatidyl choline transporter ABCB4 (MDR3) lead to intrahepatic accumulation of free BAs that result in liver damage. PFIC3 onset usually occurs at early ages, progresses rapidly, and the prognosis is poor. Currently, besides the palliative use of ursodeoxycholate, the only available treatment for this disease is liver transplantation, which is really challenging for short-aged patients. To gain insight into the pathogenesis of PFIC3 we have performed an integrated proteomics and phosphoproteomics study in human liver samples to then validate the emerging functional hypotheses in a PFIC3 murine model. We identified 6246 protein groups, 324 proteins among them showing differential expression between control and PFIC3. The phosphoproteomic analysis allowed the identification of 5090 phosphopeptides, from which 215 corresponding to 157 protein groups, were differentially phosphorylated in PFIC3, including MDR3. Regulation of essential cellular processes and structures, such as inflammation, metabolic reprogramming, cytoskeleton and extracellular matrix remodeling, and cell proliferation, were identified as the main drivers of the disease. Our results provide a strong molecular background that significantly contributes to a better understanding of PFIC3 and provides new concepts that might prove useful in the clinical management of patients.

Early steroids after pediatric liver transplantation protect against T-cell-mediated rejection: Results from the ChilSFree study.

Steroid-free immunosuppression protocols gained popularity in pediatric liver transplantation (pLT) after the introduction of IL-2-receptor blockade for induction therapy. We analyzed the clinical and immunologic outcome data of the multicenter prospective observational ChilSFree study to compare the impact of steroid-free versus steroid-containing immunosuppressive therapy following pLT in a real-life scenario. Two hundred forty-six children [55.3% male, age at pLT median: 2.4 (range: 0.2-17.9) y] transplanted for biliary atresia (43%), metabolic liver disease (9%), acute liver failure (4%), hepatoblastoma (9%), and other chronic end-stage liver diseases (39%) underwent immune monitoring and clinical data documentation over the first year after pLT. Patient and graft survival at 1 year was 98.0% and 92.7%, respectively. Primary immunosuppression was basiliximab induction followed by tacrolimus (Tac) monotherapy (55%), Tac plus steroid tapering over 3 months (29%), or cyclosporine and steroid tapering (7%). One center used intraoperative steroids instead of basiliximab followed by Tac plus mycophenolate mofetil (7% of patients). N = 124 biopsy-proven T-cell-mediated rejections were documented in n = 82 (33.3%) patients. T-cell-mediated rejection occurred early (median: 41 d, range: 3-366 d) after pLT. Patients initially treated with Tac plus steroids experienced significantly fewer episodes of rejection than patients treated with Tac alone (chi-square p <0.01). The use of steroids was associated with earlier downregulation of proinflammatory cytokines interferon (IFN)-γ, Interleukin (IL)-6, CX motif chemokin ligand (CXCL)8, IL-7, and IL-12p70. Both primary immunosuppression with Tac plus steroids and living donor liver transplantation were independent predictors of rejection-free survival 1 year after pLT on logistic regression analysis. Adjunctive steroid therapy after pLT leads to earlier suppression of the post-pLT proinflammatory response and significantly reduced rejection rates during the first year after pLT (15.9%). Fifty-one percent of patients initially treated without steroids remain steroid-free over the first 12 months without rejection.

∆4-3-oxo-5ß-reductase deficiency: favorable outcome in 16 patients treated with cholic acid.

BACKGROUND: Oral cholic acid therapy is an effective therapy in children with primary bile acid synthesis deficiencies. Most reported patients with this treatment have 3ß-hydroxy-Δ5-C27-steroid oxidoreductase deficiency. The aim of the study was the evaluation of cholic acid therapy in a cohort of patients with the rarer Δ4-3-oxosteroid 5ß-reductase (Δ4-3-oxo-R) deficiency. METHODS: Sixteen patients with Δ4-3-oxo-R deficiency confirmed by AKR1D1 gene sequencing who received oral cholic acid were retrospectively analyzed. RESULTS: First symptoms were reported early in life (median 2 months of age), with 14 and 3 patients having cholestatic jaundice and severe bleeding respectively. Fifteen patients received ursodeoxycholic acid before diagnosis, with partial improvement in 8 patients. Four patients had liver failure at the time of cholic acid initiation. All 16 patients received cholic acid from a median age of 8.1 months (range 3.1-159) and serum liver tests normalized in all within 6-12 months of treatment. After a median cholic acid therapy of 4.5 years (range 1.1-24), all patients were alive with their native liver. Median daily cholic acid dose at last follow-up was 8.3 mg/kg of body weight. All patients, but one, had normal physical examination and all had normal serum liver tests. Fibrosis, evaluated using liver biopsy (n = 4) or liver elastography (n = 9), had stabilized or improved. Cholic acid therapy enabled a 12-fold decrease of 3-oxo-∆4 derivatives in urine. Patients had normal growth and quality of life. The treatment was well tolerated without serious adverse events and signs of hepatotoxicity. CONCLUSIONS: Oral cholic acid therapy is a safe and effective treatment for patients with Δ4-3-oxo-R deficiency.

Quantitative Lipid Profiling Reveals Major Differences between Liver Organoids with Normal Pi*M and Deficient Pi*Z Variants of Alpha-1-antitrypsin.

Different mutations in the SERPINA1 gene result in alpha-1 antitrypsin (AAT) deficiency and in an increased risk for the development of liver diseases. More than 90% of severe deficiency patients are homozygous for Z (Glu342Lys) mutation. This mutation causes Z-AAT polymerization and intrahepatic accumulation which can result in hepatic alterations leading to steatosis, fibrosis, cirrhosis, and/or hepatocarcinoma. We aimed to investigate lipid status in hepatocytes carrying Z and normal M alleles of the SERPINA1 gene. Hepatic organoids were developed to investigate lipid alterations. Lipid accumulation in HepG2 cells overexpressing Z-AAT, as well as in patient-derived hepatic organoids from Pi*MZ and Pi*ZZ individuals, was evaluated by Oil-Red staining in comparison to HepG2 cells expressing M-AAT and liver organoids from Pi*MM controls. Furthermore, mass spectrometry-based lipidomics analysis and transcriptomic profiling were assessed in Pi*MZ and Pi*ZZ organoids. HepG2 cells expressing Z-AAT and liver organoids from Pi*MZ and Pi*ZZ patients showed intracellular accumulation of AAT and high numbers of lipid droplets. These latter paralleled with augmented intrahepatic lipids, and in particular altered proportion of triglycerides, cholesterol esters, and cardiolipins. According to transcriptomic analysis, Pi*ZZ organoids possess many alterations in genes and cellular processes of lipid metabolism with a specific impact on the endoplasmic reticulum, mitochondria, and peroxisome dysfunction. Our data reveal a relationship between intrahepatic accumulation of Z-AAT and alterations in lipid homeostasis, which implies that liver organoids provide an excellent model to study liver diseases related to the mutation of the SERPINA1 gene.

Urea cycle disorders and indications for liver transplantation.

Urea cycle disorders (UCD) are inborn errors of metabolism caused by deficiency of enzymes required to convert nitrogen from ammonia into urea. Current paradigms of treatment focus on dietary manipulations, ammonia scavenger drugs, and liver transplantation. The aim of this study was to describe the characteristics and indication of liver transplantation in UCD in a tertiary hospital. We performed a retrospective study of children with UCD seen in the period 2000-2021. Data was collected on clinical onset, hyperammonemia severity, evolution and liver transplantation. There were 33 patients in the study period, whose diagnosis were: ornithine transcarbamylase (OTC, n = 20, 10 females), argininosuccinate synthetase (ASS, n = 6), carbamylphosphate synthetase 1 (CPS1, n = 4), argininosuccinate lyase (ASL, n = 2) and N-acetylglutamate synthetase (NAGS, n = 1) deficiency. Thirty one were detected because of clinical symptoms (45% with neonatal onset). The other 2 were diagnosed being presymptomatic, by neonatal/family screening. Neonatal forms (n = 14) were more severe, all of them presented during the first week of life as severe hyperammonemia (mean peak 1,152 µmol/L). Seven patients died (6 at debut) and all survivors received transplantation. There was no mortality among the late forms. Of the 27 patients who did not die in the neonatal period, 16 (59%) received liver transplantationwith 100% survival, normal protein tolerance and usual need of citrulline supplementation. The transplant's metabolic success was accompanied by neurologic sequelae in 69%, but there was no progression of brain damage. Decision of continuous medical treatment in 11 patients appeared to be related with preserved neurodevelopment and fewer metabolic crises.

Mortality predictive factors in congenital hepatic hemangioma: a case-control study.

Congenital hepatic hemangiomas (CHHs) are benign vascular tumors whose clinical, histological, and genetic correlation has recently been described in patients with long-term survival, although no mortality risk factors have been identified to date. The aim of this study is to analyze predictors of mortality in patients with CHH. A retrospective single-center case-control study of consecutive CHH patients diagnosed in our institution between 1991 and 2021 was performed, who were classified into two groups according to their survival. Demographic, gestational, imaging, and laboratory data at diagnosis were collected and compared between both groups. A total of 29 patients were included (12 males; 17 females) of whom 5 died as a result of CHH evolution due to cardiac failure and coagulopathy, with a median age of 11 days until death. No differences in demographic or gestational data were reported. There were neither differences when comparing imaging tests, nor in location, number of affected liver segments, or CHH estimated volume. Upon laboratory data at diagnosis, deceased patients had a significant elevation of median liver enzymes [glutamic-oxaloacetic transaminase (359 u/L vs. 45 u/L; p < 0.01) and glutamic-pyruvic transaminase (313 u/L vs. 20 u/L; p < 0. 01)], as well as a decreased median platelet count (85,250/µL vs. 337,000/µL; p < 0.01), prothrombin activity (54% vs. 93%; p < 0.01), and fibrinogen (131 mg/dL vs. 284 mg/dL; p < 0.01), with no differences in blood count or biochemistry data. CONCLUSIONS: CHH clinical behavior can be innocuous or life-threatening. Thrombocytopenia, coagulation disorders, and increased liver enzymes at diagnosis seem to be the main predictors of mortality. WHAT IS KNOWN: • Congenital Hepatic Hemangiomas (CHHs) are benign vascular tumors whose clinical behavior can be innocuous or life-threatening. WHAT IS NEW: • Thrombocytopenia, coagulation disorders and increased liver enzymes at diagnosis seem to be the main predictors of mortality in these patients.

Genotype-phenotype relationships of truncating mutations, p.E297G and p.D482G in bile salt export pump deficiency.

Background & Aims: Bile salt export pump (BSEP) deficiency frequently necessitates liver transplantation in childhood. In contrast to two predicted protein truncating mutations (PPTMs), homozygous p.D482G or p.E297G mutations are associated with relatively mild phenotypes, responsive to surgical interruption of the enterohepatic circulation (siEHC). The phenotype of patients with a compound heterozygous genotype of one p.D482G or p.E297G mutation and one PPTM has remained unclear. We aimed to assess their genotype-phenotype relationship. Methods: From the NAPPED database, we selected patients with homozygous p.D482G or p.E297G mutations (BSEP1/1; n = 31), with one p.D482G or p.E297G, and one PPTM (BSEP1/3; n = 30), and with two PPTMs (BSEP3/3; n = 77). We compared clinical presentation, native liver survival (NLS), and the effect of siEHC on NLS. Results: The groups had a similar median age at presentation (0.7-1.3 years). Overall NLS at age 10 years was 21% in BSEP1/3 vs. 75% in BSEP1/1 and 23% in BSEP3/3 (p <0.001). Without siEHC, NLS in the BSEP1/3 group was similar to that in BSEP3/3, but considerably lower than in BSEP1/1 (at age 10 years: 38%, 30%, and 71%, respectively; p = 0.003). After siEHC, BSEP1/3 and BSEP3/3 were associated with similarly low NLS, while NLS was much higher in BSEP1/1 (10 years after siEHC, 27%, 14%, and 92%, respectively; p <0.001). Conclusions: Individuals with BSEP deficiency with one p.E297G or p.D482G mutation and one PPTM have a similarly severe disease course and low responsiveness to siEHC as those with two PPTMs. This identifies a considerable subgroup of patients who are unlikely to benefit from interruption of the enterohepatic circulation by either surgical or ileal bile acid transporter inhibitor treatment. Impact and implications: This manuscript defines the clinical features and prognosis of individuals with BSEP deficiency involving the combination of one relatively mild and one very severe BSEP deficiency mutation. Until now, it had always been assumed that the mild mutation would be enough to ensure a relatively good prognosis. However, our manuscript shows that the prognosis of these patients is just as poor as that of patients with two severe mutations. They do not respond to biliary diversion surgery and will likely not respond to the new IBAT (ileal bile acid transporter) inhibitors, which have recently been approved for use in BSEP deficiency.

Diagnosing Acute Cellular Rejection after Paediatric Liver Transplantation-Is There Room for Interleukin Profiles?

BACKGROUND: The current gold standard to diagnose T-cell-mediated acute rejection (TCMR) requires liver histology. Using data from the ChilSFree study on immune response after paediatric liver transplantation (pLT), we aimed to assess whether soluble cytokines can serve as an alternative diagnostic tool in children suspected to have TCMR. METHODS: A total of n = 53 blood samples obtained on the day of or up to 3 days before liver biopsy performed for suspected TCMR at median 18 days (range 7-427) after pLT in n = 50 children (38% female, age at pLT 1.8 (0.5-17.5) years) were analysed for circulating cytokine levels using Luminex-based Multiplex technology. Diagnostic accuracy of cytokine concentrations was assessed using a multivariable model based on elastic net regression and gradient boosting machine analysis. RESULTS: TCMR was present in 68% of biopsies. There was strong evidence that patients with TCMR had increased levels of soluble CXCL8, CXCL9, CXCL10, IL-16, IL-18, HGF, CCL4, MIF, SCGF-ß, and HGF before biopsy. There was some evidence for increased levels of sCD25, ICAM-1, IL-6, IL-3, and CCL11. Diagnostic value of both single cytokine levels and a combination of cytokines and clinical markers was poor, with AUROCs not exceeding 0.7. CONCLUSION: Patients with TCMR showed raised levels of cytokines and chemokines reflective of T-cell activation and chemotaxis. Despite giving insight into the mechanisms of TCMR, the diagnostic value of soluble cytokines for the confirmation of TCMR in a clinical scenario of suspected TCMR is poor.

Humoral and cellular immune responses to Pfizer-BioNTech BNT162b2 SARS-CoV-2 vaccine in adolescents with liver transplantation: Single center experience.

Background: Immune responses to vaccines against severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 are variable. In the absence of disease, youngsters are expected to better react to vaccines than adults. Nevertheless, chronic immunosuppression in transplant recipients may impair their capability to generate protection. We aim to explore immune responses after BNT162b2 SARS-CoV-2 vaccination in our cohort of young liver-transplanted patients. Methods: A prospective study of adolescent liver-transplanted patients (n=33) in the long-term follow-up was performed. Immune responses after receiving Pfizer-BioNTech BNT162b2 vaccine were analyzed at two time-points: baseline and 30 days after the second dose. Humoral responses were measured by fluoroenzyme-immunoassay and T-cell responses by interferon-γ-release assay. Post-vaccine coronavirus disease (COVID-19) events were recorded by a survey. Results: Pre-vaccine SARS-CoV-2-specific antibodies were undetectable in 27/32 (84.4%), negative/indeterminate in 3/32 (9.4%) and positive in 2/32 (6.3%) patients. Cellular responses at baseline were negative in 12/18 (66.6%), positive in 3/18 (16.6%) and indeterminate in 3/18 (16.6%) recipients. None of the baseline positives recalled any symptoms. Post-vaccine antibodies were detected in all patients and 92.6% showed levels >816 BAU/mL. Twenty (71.4%) recipients had positive T-cell responses. Regarding post-vaccine SARS-Cov-2 infection, 10 (30.3%) patients reported COVID-19 without hospitalization and 21 (63.6%) did not notify any infection. Negative and positive cell-response groups after vaccination showed statistically significant differences regarding COVID-19 cases (62.5% vs 22.2%, respectively; p=0.046). Conclusions: Adolescents and young adults with liver transplantation responded to SARS-Cov-2 vaccine, generating both humoral and cellular responses. Recipients developing cellular responses after vaccination had a lower incidence of COVID-19.

Consensus Statement on Hemostatic Management, Anticoagulation, and Antiplatelet Therapy in Liver Transplantation.

Anticoagulation and antiplatelet therapies are increasingly used in liver transplant (LT) candidates and recipients due to cardiovascular comorbidities, portal vein thrombosis, or to manage posttransplant complications. The implementation of the new direct-acting oral anticoagulants and the recently developed antiplatelet drugs is a great challenge for transplant teams worldwide, as their activity must be monitored and their complications managed, in the absence of robust scientific evidence. In this changing and clinically heterogeneous scenario, the Spanish Society of Liver Transplantation and the Spanish Society of Thrombosis and Haemostasis aimed to achieve consensus regarding the indications, drugs, dosing, and timing of anticoagulation and antiplatelet therapies initiated from the inclusion of the patient on the waiting list to post-LT surveillance. A multidisciplinary group of experts composed by transplant hepatologists, surgeons, hematologists, transplant-specialized anesthesiologists, and intensivists performed a comprehensive review of the literature and identified 21 clinically relevant questions using the patient-intervention-comparison-outcome format. A preliminary list of recommendations was drafted and further validated using a modified Delphi approach by a panel of 24 transplant delegates, each representing a LT institution in Spain. The present consensus statement contains the key recommendations together with the core supporting scientific evidence, which will provide guidance for improved and more homogeneous clinical decision making.

Impact of muscle mass on the prognosis of liver transplantation for infants with biliary atresia.

Background: Sarcopenia in adult cirrhotic patients is associated with increased morbidity and mortality whereas in children it is still being studied. Anthropometric variables in cirrhotic children are not reliable for assessing muscle mass as they may be altered by ascites, edema, and organomegaly. Measuring the area of the psoas showed good correlation with muscle mass in adults. We aimed to study in cirrhotic infants undergoing liver transplantation the association of the psoas area with liver transplant prognosis as well as with several analytical and anthropometric parameters used to evaluate nutritional status. Methods: Retrospective cohort of 29 infants with cirrhosis due to biliary atresia who underwent abdominal CT scan as a pre-transplant study. We measured the psoas muscle index (PMI) at L4-L5 since it best correlates with muscle mass in pediatric patients. As there are no validated cut-off points to define sarcopenia in children under one year of age, PMI was recorded as a continuous variable and correlated with different prognostic, clinical, and analytical variables. The SPSS 17.0 package was used for statistical analysis and a P < 0.05 was considered significant. Results: 29 infants (10 boys, 19 girls) were studied. 62% were Caucasian and the rest were South American. The mean age at CT scan was 8.5 months (range 3-15 months). There was a negative correlation between PMI and days of admission prior to liver transplant, previous infections, and bone fractures. Among the analytical parameters, cholinesterase, albumin, and prealbumin correlated positively with PMI (P < 0.05). No relationship was observed with anthropometric parameters: weight, height, BMI, brachial perimeter, or bioimpedance. During surgery, patients with lower PMI had a greater need for plasma transfusion, and in the immediate postoperative period, there was a longer stay in intensive care, more days of mechanical ventilation, and more days of hospital admission (P < 0.05). On the contrary, no relationship was found with other complications: bleeding, re-interventions, biliary leaks, rejection, thrombosis, re-transplantation, or infections. Conclusions: The decrease in muscle mass is associated with increased morbidity in infants with biliary atresia undergoing liver transplantation. Muscle mass in these patients cannot be adequately assessed with anthropometric measurements commonly used in the clinic.

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.

Pharmacokinetics, Safety, and Efficacy of Glecaprevir/Pibrentasvir in Children With Chronic HCV: Part 2 of the DORA Study.

BACKGROUND AND AIMS: Glecaprevir/pibrentasvir (GLE/PIB) has shown high efficacy and safety in chronic HCV-infected adults and adolescents; data in children were limited. DORA part 2 is a phase 2/3, nonrandomized, open-label study evaluating the pharmacokinetics, efficacy, and safety of a pediatric formulation of GLE and PIB in children ages 3 to < 12 years. APPROACH AND RESULTS: Children with chronic HCV infection, genotype 1-6, with or without compensated cirrhosis, were divided into three cohorts by age-cohort 2 (9 to < 12 years), cohort 3 (6 to < 9 years), and cohort 4 (3 to < 6 years)-and given weight-based doses of GLE and PIB for 8, 12, or 16 weeks. Primary endpoints were sustained virologic response at posttreatment week 12 (SVR12) and steady-state exposure; secondary endpoints were rates of persistent viremia, relapse, and reinfection. Safety and laboratory abnormalities were assessed. Final pediatric dosages determined to be efficacious were 250 mg GLE + 100 mg PIB (in children weighing ≥ 30 to < 45 kg), 200 mg GLE + 80 mg PIB (≥ 20 to < 30 kg), and 150 mg GLE + 60 mg PIB (12 to < 20 kg). Of 80 participants enrolled and dosed, 96% (77/80) achieved SVR12. One participant, on the initial dose ratio, relapsed by posttreatment week 4; no participants had virologic failures on the final dose ratio of GLE 50 mg/PIB 20 mg. Two nonresponders prematurely discontinued the study. Most adverse events (AEs) were mild; no drug-related serious AEs occurred. Pharmacokinetic exposures were comparable to those of adults. CONCLUSIONS: A pediatric formulation of GLE/PIB was highly efficacious and well tolerated in chronic HCV-infected children 3 to < 12 years old.

Impact of Genotype, Serum Bile Acids, and Surgical Biliary Diversion on Native Liver Survival in FIC1 Deficiency.

BACKGROUND AND AIMS: Mutations in ATPase phospholipid transporting 8B1 (ATP8B1) can lead to familial intrahepatic cholestasis type 1 (FIC1) deficiency, or progressive familial intrahepatic cholestasis type 1. The rarity of FIC1 deficiency has largely prevented a detailed analysis of its natural history, effects of predicted protein truncating mutations (PPTMs), and possible associations of serum bile acid (sBA) concentrations and surgical biliary diversion (SBD) with long-term outcome. We aimed to provide insights by using the largest genetically defined cohort of patients with FIC1 deficiency to date. APPROACH AND RESULTS: This multicenter, combined retrospective and prospective study included 130 patients with compound heterozygous or homozygous predicted pathogenic ATP8B1 variants. Patients were categorized according to the number of PPTMs (i.e., splice site, frameshift due to deletion or insertion, nonsense, duplication), FIC1-A (n = 67; no PPTMs), FIC1-B (n = 29; one PPTM), or FIC1-C (n = 34; two PPTMs). Survival analysis showed an overall native liver survival (NLS) of 44% at age 18 years. NLS was comparable among FIC1-A, FIC1-B, and FIC1-C (% NLS at age 10 years: 67%, 41%, and 59%, respectively; P = 0.12), despite FIC1-C undergoing SBD less often (% SBD at age 10 years: 65%, 57%, and 45%, respectively; P = 0.03). sBAs at presentation were negatively associated with NLS (NLS at age 10 years, sBAs < 194 µmol/L: 49% vs. sBAs ≥ 194 µmol/L: 15%; P = 0.03). SBD decreased sBAs (230 [125-282] to 74 [11-177] µmol/L; P = 0.005). SBD (HR 0.55, 95% CI 0.28-1.03, P = 0.06) and post-SBD sBA concentrations < 65 µmol/L (P = 0.05) tended to be associated with improved NLS. CONCLUSIONS: Less than half of patients with FIC1 deficiency reach adulthood with native liver. The number of PPTMs did not associate with the natural history or prognosis of FIC1 deficiency. sBA concentrations at initial presentation and after SBD provide limited prognostic information on long-term NLS.

Epidemiological pattern, incidence, and outcomes of COVID-19 in liver transplant patients.

BACKGROUND & AIMS: The incidence and outcomes of coronavirus disease 2019 (COVID-19) in immunocompromised patients are a matter of debate. METHODS: We performed a prospective nationwide study including a consecutive cohort of liver transplant patients with COVID-19 recruited during the Spanish outbreak from 28 February to 7 April, 2020. The primary outcome was severe COVID-19, defined as the need for mechanical ventilation, intensive care, and/or death. Age- and gender-standardised incidence and mortality ratios (SIR and SMR) were calculated using data from the Ministry of Health and the Spanish liver transplant registry. Independent predictors of severe COVID-19 among hospitalised patients were analysed using multivariate Cox regression. RESULTS: A total of 111 liver transplant patients were diagnosed with COVID-19 (SIR = 191.2 [95% CI 190.3-192.2]). The epidemiological curve and geographic distribution overlapped widely between the liver transplant and general populations. After a median follow-up of 23 days, 96 patients (86.5%) were admitted to hospital and 22 patients (19.8%) required respiratory support. A total of 12 patients were admitted to the ICU (10.8%). The mortality rate was 18%, which was lower than in the matched general population (SMR = 95.5 [95% CI 94.2-96.8]). Overall, 35 patients (31.5%) met criteria of severe COVID-19. Baseline immunosuppression containing mycophenolate was an independent predictor of severe COVID-19 (relative risk = 3.94; 95% CI 1.59-9.74; p = 0.003), particularly at doses higher than 1,000 mg/day (p = 0.003). This deleterious effect was not observed with calcineurin inhibitors or everolimus and complete immunosuppression withdrawal showed no benefit. CONCLUSIONS: Being chronically immunosuppressed, liver transplant patients have an increased risk of acquiring COVID-19 but their mortality rates are lower than the matched general population. Upon hospital admission, mycophenolate dose reduction or withdrawal could help in preventing severe COVID-19. However, complete immunosuppression withdrawal should be discouraged. LAY SUMMARY: In liver transplant patients, chronic immunosuppression increases the risk of acquiring COVID-19 but it could reduce disease severity. Complete immunosuppression withdrawal may not be justified. However, mycophenolate withdrawal or temporary conversion to calcineurin inhibitors or everolimus until disease resolution could be beneficial in hospitalised patients.

Pediatric transplantation in Europe during the COVID-19 pandemic: Early impact on activity and healthcare.

The current pandemic SARS-CoV-2 has required an unusual allocation of resources that can negatively impact chronically ill patients and high-complexity procedures. Across the European Reference Network on Pediatric Transplantation (ERN TransplantChild), we conducted a survey to investigate the impact of the COVID-19 outbreak on pediatric transplant activity and healthcare practices in both solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT). The replies of 30 professionals from 18 centers in Europe were collected. Twelve of 18 centers (67%) showed a reduction in their usual transplant activity. Additionally, outpatient visits have been modified and restricted to selected ones, and the use of telemedicine tools has increased. Additionally, a total of 14 COVID-19 pediatric transplanted patients were identified at the time of the survey, including eight transplant recipients and six candidates for transplantation. Only two moderate-severe cases were reported, both in HSCT setting. These survey results demonstrate the limitations in healthcare resources for pediatric transplantation patients during early stages of this pandemic. COVID-19 disease is a major worldwide challenge for the field of pediatric transplantation, where there will be a need for systematic data collection, encouraging regular discussions to address the long-term consequences for pediatric transplantation candidates, recipients, and their families.

Endoscopic Retrograde Cholangiopancreatography in Infants: Availability Under Threat: A Survey on Availability, Need, and Clinical Practice in Europe and Israel.

Endoscopic retrograde cholangiopancreatography (ERCP) in infants (younger than 1 year of age) is a highly specialized procedure. Since 2014 opportunities to maintain or purchase duodenoscopes for ERCP in infants have disappeared. In a survey among European hepatology centers (including Israel) we evaluated the availability, need, indications, and practice of ERCP procedures in infants. It shows that infant ERCP is a low-volume procedure (median 5 procedures/year) in the 14 centers that perform this procedure. Since 2014 several centers no longer have an infant ERCP duodenoscope due to breakdown. In addition, substantial differences exist between centers in indications, types of interventions performed, and practical execution of ERCP procedures in infants. We conclude that a concerted effort by the pediatric hepatology community is needed to secure the future availability of infant ERCP. In addition, consensus on the indications and optimal use of infant ERCP could improve the quality of ERCP care for infants.

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.