Apical Sodium-Dependent Transporter Inhibitors in Primary Biliary Cholangitis and Primary Sclerosing Cholangitis

Bile acids (BAs) have gained mainstream attention since the discovery of their key role as signalling molecules in health and disease. The apical sodium-dependent transporter (ASBT) protein located in the terminal ileum plays an important physiological role in the enterohepatic circulation of BAs and therefore essential for the BA homeostasis. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), the 2 most common cholestatic liver diseases are characterised by altered BA flow and BA composition, which contribute to disease progression and symptom (pruritus) development. Therefore, changing the circulating BA pool in patients with PBC and PSC may have therapeutic implications. To this end, pharmacological inhibition of ASBT is fast emerging as an interesting target. In this review, we discuss the recent evidence for potential therapeutic use of ASBT inhibitors to treat PBC and PSC patients.</jats:p

A composite biomarker using multiparametric magnetic resonance imaging and blood analytes accurately identifies patients with non-alcoholic steatohepatitis and significant fibrosis

Non-alcoholic steatohepatitis (NASH) is major health burden lacking effective pharmacological therapies. Clinical trials enrol patients with histologically-defined NAFLD (non-alcoholic fatty liver disease) activity score (NAS) ≥ 4 and Kleiner-Brunt fibrosis stage (F) ≥ 2; however, screen failure rates are often high following biopsy. This study evaluated a non-invasive MRI biomarker, iron-corrected T1 mapping (cT1), as a diagnostic pre-screening biomarker for NASH. In a retrospective analysis of 86 biopsy confirmed NAFLD patients we explored the potential of blood and imaging biomarkers, both in isolation and in combination, to discriminate those who have NAS ≥ 4 and F ≥ 2 from those without. Stepwise logistic regression was performed to select the optimal combination of biomarkers, diagnostic accuracy was determined using area under the receiver operator curve and model validated confirmed with and fivefold cross-validation. Results showed that levels of cT1, AST, GGT and fasting glucose were all good predictors of NAS ≥ 4 and F ≥ 2, and the model identified the combination of cT1-AST-fasting glucose (cTAG) as far superior to any individual biomarker (AUC 0.90 [0.84–0.97]). This highlights the potential utility of the composite cTAG score for screening patients prior to biopsy to identify those suitable for NASH clinical trial enrolment

Reduction and stabilization of bilirubin with obeticholic acid treatment in patients with primary biliary cholangitis

Total bilirubin is a predictor of survival in primary biliary cholangitis, with the main elevated component being direct bilirubin. The purpose of this post hoc analysis was to assess the efficacy and safety of obeticholic acid across quartiles of varying baseline levels of direct bilirubin in the phase 3, randomized, placebo-controlled Primary Biliary Cholangitis Obeticholic Acid International Study of Efficacy. This analysis assessed patients on the basis of their baseline direct bilirubin level (divided by quartile). Biochemistry and safety outcomes were evaluated within each quartile over time. In the quartile with the highest baseline direct bilirubin (>5.47 µmol/L), there was a significant reduction in both direct and total bilirubin at Month 12 compared with placebo. Least squares mean (standard error) change from baseline in direct bilirubin at Month 12 was 4.17 (1.42) µmol/L for placebo, −3.48 (1.63) µmol/L for obeticholic acid 5-10 mg and −3.66 (1.51) µmol/L for obeticholic acid 10 mg (P < .0001, obeticholic acid vs placebo); the corresponding values for total bilirubin at Month 12 were 4.38 (1.55) µmol/L for placebo, −4.53 (1.83) µmol/L for obeticholic acid 5-10 mg and −5.06 (1.64) µmol/L for obeticholic acid 10 mg (P < .0001, obeticholic acid vs placebo). Obeticholic acid treatment was associated with significant reductions in total and direct bilirubin, particularly in patients with high baseline direct bilirubin. Because raised direct bilirubin levels, even within the normal range, are predictive of survival in primary biliary cholangitis, these results suggest substantial benefits of obeticholic acid in at-risk patients

Quantitative MRCP and metrics of bile duct disease over time in patients with primary sclerosing cholangitis:A prospective study

Background: Imaging markers of biliary disease in primary sclerosing cholangitis (PSC) have potential for use in clinical and trial disease monitoring. Herein, we evaluate how quantitative magnetic resonance cholangiopancreatography (MRCP) metrics change over time, as per the natural history of disease. Methods: Individuals with PSC were prospectively scanned using non‐contrast MRCP. Quantitative metrics were calculated using MRCP+ post‐processing software to assess duct diameters and dilated and strictured regions. Additionally, a hepatopancreatobiliary radiologist (blinded to clinical details, biochemistry and quantitative biliary metrics) reported each scan, including ductal disease assessment according to the modified Amsterdam Cholangiographic Score (MAS). Results: At baseline, 14 quantitative MRCP+ metrics were found to be significantly different in patients with PSC (N = 55) compared to those with primary biliary cholangitis (N = 55), autoimmune hepatitis (N = 57) and healthy controls (N = 18). In PSC specifically, baseline metrics quantifying the number of strictures and the number and length of bile ducts correlated with the MAS, transient elastography and serum ALP values (p &lt; 0.01 for all correlations). Over a median 371‐day follow‐up (range: 364–462), 29 patients with PSC underwent repeat MRCP, of whom 15 exhibited quantitative changes in MRCP+ metrics. Compared to baseline, quantitative MRCP+ identified an increasing number of strictures over time (p &lt; 0.05). Comparatively, no significant differences in biochemistry, elastography or the MAS were observed between timepoints. Quantitative MRCP+ metrics remained stable in non‐PSC liver disease. Conclusion: Quantitative MRCP+ identifies changes in ductal disease over time in PSC, despite stability in biochemistry, liver stiffness and radiologist‐derived cholangiographic assessment (trial registration: ISRCTN39463479)

Post-prophylaxis Toxoplasma chorioretinitis following donor-recipient mismatched liver transplantation

Toxoplasmosis may be transferred by organ transplantation. The most common clinical presentation is with multisystem disease, although isolated ocular toxoplasmosis has been described. Many centers have suggested that universal use of co‐trimoxazole prophylaxis obviates the need for specific Toxoplasma testing. We report a case of donor‐acquired ocular toxoplasmosis after liver transplantation despite co‐trimoxazole prophylaxis. The diagnosis was confirmed by Toxoplasma polymerase chain reaction assay in conjunction with seroconversion. The fact that the infection was donor acquired was confirmed by serological mismatch and the absence of sporozoite‐specific antigen antibody in the recipient

BAT117213: Ileal bile acid transporter (IBAT) inhibition as a treatment for pruritus in primary biliary cirrhosis: study protocol for a randomised controlled trial

Background: Pruritus (itch) is a symptom commonly experienced by patients with cholestatic liver diseases such as primary biliary cholangitis (PBC, previously referred to as primary biliary cirrhosis). Bile acids (BAs) have been proposed as potential pruritogens in PBC. The ileal bile acid transporter (IBAT) protein expressed in the distal ileum plays a key role in the enterohepatic circulation of BAs. Pharmacological inhibition of IBAT with GSK2330672 may reduce BA levels in the systemic circulation and improve pruritus. Methods: This clinical study (BAT117213 study) is sponsored by GlaxoSmithKline (GSK) with associated exploratory studies supported by the National Institute for Health Research (NIHR). It is a phase 2a, multi-centre, randomised, double bind, placebo controlled, cross-over trial for PBC patients with pruritus. The primary objective is to investigate the safety and tolerability of repeat doses of GSK2330672, and explore whether GSK2330672 administration for 14 days improves pruritus compared with placebo. The key outcomes include improvement in pruritus scores evaluated on a numerical rating scale and other PBC symptoms in an electronic diary completed twice daily by the patients. The secondary outcomes include the evaluation of the effect of GSK2330672 on total serum bile acid (BA) concentrations, serum markers of BA synthesis and steady-state pharmacokinetics of ursodeoxycholic acid (UDCA). Discussion: BAT117213 study is the first randomised controlled crossover trial of ileal bile acid transporter inhibitor, a novel class of drug to treat pruritus in PBC. The main strengths of the trial are utility of a novel, study specific, electronic symptom diary as patient reported outcome to measure the treatment response objectively and the crossover design that allows estimating the treatment effect in a smaller number of patients. The outcome of this trial will inform the trial design of future development phase of the IBAT inhibitor drug. The trial will also provide opportunity to conduct metabonomic and gut microbiome studies as explorative and mechanistic research in patients with cholestatic pruritus

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist

Autotaxin, bile acid profile and effect of ileal bile acid transporter inhibition in primary biliary cholangitis patients with pruritus

Background and Aims Pruritus is a common symptom in patients with primary biliary cholangitis (PBC) for which ileal bile acid transporter (IBAT) inhibition is emerging as a potential therapy. We explored the serum metabonome and gut microbiota profile in PBC patients with pruritus and investigated the effect of GSK2330672, an IBAT inhibitor. Methods We studied fasting serum bile acids (BAs), autotaxin and faecal microbiota in 22 PBC patients with pruritus at baseline and after 2 weeks of GSK2330672 treatment. Control group included 31 asymptomatic PBC patients and 18 healthy volunteers. BA profiling was done by ultra performance liquid chromatography coupled to a mass spectrometry (UPLC‐MS). Faecal microbiomes were analysed by 16S ribosomal RNA gene sequencing. Results \ud In PBC patients with pruritus, serum levels of total and glyco‐conjugated primary BAs and autotaxin were significantly elevated. Autotaxin activity correlated significantly with tauro‐ and glyco‐conjugated cholic acid (CA) and chenodeoxycholic acid (CDCA), both at baseline and after GSK2330672. GSK2330672 significantly reduced autotaxin and all tauro‐ and glyco‐ conjugated BAs and increased faecal levels of CA (P = 0.048) and CDCA (P = 0.027). Gut microbiota of PBC patients with pruritus was similar to control groups. GSK2330672 increased the relative abundance of Firmicutes (P = 0.033) and Clostridia (P = 0.04) and decreased Bacteroidetes (P = 0.033) and Bacteroidia (P = 0.04). Conclusions Pruritus in PBC does not show a distinct gut bacterial profile but is associated with elevated serum bile acid and autotaxin levels which decrease after IBAT inhibition. In cholestatic pruritus, a complex interplay between BAs and autotaxin is likely and may be modified by IBAT inhibition

Bacterial and metabolic phenotypes associated with inadequate response to ursodeoxycholic acid treatment in primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease with ursodeoxycholic acid (UDCA) as first-line treatment. Poor response to UDCA is associated with a higher risk of progressing to cirrhosis, but the underlying mechanisms are unclear. UDCA modulates the composition of primary and bacterial-derived bile acids (BAs). We characterized the phenotypic response to UDCA based on BA and bacterial profiles of PBC patients treated with UDCA. Patients from the UK-PBC cohort (n = 419) treated with UDCA for a minimum of 12-months were assessed using the Barcelona dynamic response criteria. BAs from serum, urine, and feces were analyzed using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry and fecal bacterial composition measured using 16S rRNA gene sequencing. We identified 191 non-responders, 212 responders, and a subgroup of responders with persistently elevated liver biomarkers (n = 16). Responders had higher fecal secondary and tertiary BAs than non-responders and lower urinary bile acid abundances, with the exception of 12-dehydrocholic acid, which was higher in responders. The sub-group of responders with poor liver function showed lower alpha-diversity evenness, lower abundance of fecal secondary and tertiary BAs than the other groups and lower levels of phyla with BA-deconjugation capacity (Actinobacteriota/Actinomycetota, Desulfobacterota, Verrucomicrobiota) compared to responders. UDCA dynamic response was associated with an increased capacity to generate oxo-/epimerized secondary BAs. 12-dehydrocholic acid is a potential biomarker of treatment response. Lower alpha-diversity and lower abundance of bacteria with BA deconjugation capacity might be associated with an incomplete response to treatment in some patients