A Phase 3 Trial of Seladelpar in Primary Biliary Cholangitis.

BACKGROUND: Effective treatments for patients with primary biliary cholangitis are limited. Seladelpar, a peroxisome proliferator-activated receptor delta agonist, has potential benefits. METHODS: In this phase 3, 12-month, double-blind, placebo-controlled trial, we randomly assigned (in a 2:1 ratio) patients who had had an inadequate response to or who had a history of unacceptable side effects with ursodeoxycholic acid to receive oral seladelpar at a dose of 10 mg daily or placebo. The primary end point was a biochemical response, which was defined as an alkaline phosphatase level less than 1.67 times the upper limit of the normal range, with a decrease of 15% or more from baseline, and a normal total bilirubin level at month 12. Key secondary end points were normalization of the alkaline phosphatase level at month 12 and a change in the score on the pruritus numerical rating scale (range, 0 [no itch] to 10 [worst itch imaginable]) from baseline to month 6 among patients with a baseline score of at least 4 (indicating moderate-to-severe pruritus). RESULTS: Of the 193 patients who underwent randomization and treatment, 93.8% received ursodeoxycholic acid as standard-of-care background therapy. A greater percentage of the patients in the seladelpar group than in the placebo group had a biochemical response (61.7% vs. 20.0%; difference, 41.7 percentage points; 95% confidence interval [CI], 27.7 to 53.4, P<0.001). Normalization of the alkaline phosphatase level also occurred in a greater percentage of patients who received seladelpar than of those who received placebo (25.0% vs. 0%; difference, 25.0 percentage points; 95% CI, 18.3 to 33.2, P<0.001). Seladelpar resulted in a greater reduction in the score on the pruritus numerical rating scale than placebo (least-squares mean change from baseline, -3.2 vs. -1.7; least-squares mean difference, -1.5; 95% CI, -2.5 to -0.5, P = 0.005). Adverse events were reported in 86.7% of the patients in the seladelpar group and in 84.6% in the placebo group, and serious adverse events in 7.0% and 6.2%, respectively. CONCLUSIONS: In this trial involving patients with primary biliary cholangitis, the percentage of patients who had a biochemical response and alkaline phosphatase normalization was significantly greater with seladelpar than with placebo. Seladelpar also significantly reduced pruritus among patients who had moderate-to-severe pruritus at baseline. The incidence and severity of adverse events were similar in the two groups. (Funded by CymaBay Therapeutics; RESPONSE ClinicalTrials.gov number, NCT04620733; EudraCT number, 2020-004348-27.).

Efficacy and Safety of Elafibranor in Primary Biliary Cholangitis.

BACKGROUND: Primary biliary cholangitis is a rare, chronic cholestatic liver disease characterized by the destruction of interlobular bile ducts, leading to cholestasis and liver fibrosis. Whether elafibranor, an oral, dual peroxisome proliferator-activated receptor (PPAR) α and δ agonist, may have benefit as a treatment for primary biliary cholangitis is unknown. METHODS: In this multinational, phase 3, double-blind, placebo-controlled trial, we randomly assigned (in a 2:1 ratio) patients with primary biliary cholangitis who had had an inadequate response to or unacceptable side effects with ursodeoxycholic acid to receive once-daily elafibranor, at a dose of 80 mg, or placebo. The primary end point was a biochemical response (defined as an alkaline phosphatase level of <1.67 times the upper limit of the normal range, with a reduction of ≥15% from baseline, and normal total bilirubin levels) at week 52. Key secondary end points were normalization of the alkaline phosphatase level at week 52 and a change in pruritus intensity from baseline through week 52 and through week 24, as measured on the Worst Itch Numeric Rating Scale (WI-NRS; scores range from 0 [no itch] to 10 [worst itch imaginable]). RESULTS: A total of 161 patients underwent randomization. A biochemical response (the primary end point) was observed in 51% of the patients (55 of 108) who received elafibranor and in 4% (2 of 53) who received placebo, for a difference of 47 percentage points (95% confidence interval [CI], 32 to 57; P<0.001). The alkaline phosphatase level normalized in 15% of the patients in the elafibranor group and in none of the patients in the placebo group at week 52 (difference, 15 percentage points; 95% CI, 6 to 23; P = 0.002). Among patients who had moderate-to-severe pruritus (44 patients in the elafibranor group and 22 in the placebo group), the least-squares mean change from baseline through week 52 on the WI-NRS did not differ significantly between the groups (-1.93 vs. -1.15; difference, -0.78; 95% CI, -1.99 to 0.42; P = 0.20). Adverse events that occurred more frequently with elafibranor than with placebo included abdominal pain, diarrhea, nausea, and vomiting. CONCLUSIONS: Treatment with elafibranor resulted in significantly greater improvements in relevant biochemical indicators of cholestasis than placebo. (Funded by GENFIT and Ipsen; ELATIVE ClinicalTrials.gov number, NCT04526665.).

Seladelpar treatment reduces IL-31 and pruritus in patients with primary biliary cholangitis.

BACKGROUND AND AIMS: Pruritus is a debilitating symptom for many people living with primary biliary cholangitis (PBC). In studies with seladelpar, a selective peroxisome proliferator-activated receptor-delta agonist, patients with PBC experienced significant improvement in pruritus and reduction of serum bile acids. Interleukin-31 (IL-31) is a cytokine known to mediate pruritus, and blocking IL-31 signaling provides relief in pruritic skin diseases. This study examined the connection between seladelpar's antipruritic effects and IL-31 and bile acid levels in patients with PBC. APPROACH AND RESULTS: IL-31 levels were quantified in serum samples from the ENHANCE study of patients with PBC receiving daily oral doses of placebo (n = 55), seladelpar 5 mg (n = 53) or 10 mg (n = 53) for 3 months, and for healthy volunteers (n = 55). IL-31 levels were compared with pruritus using a numerical rating scale (NRS, 0-10) and with bile acid levels. Baseline IL-31 levels closely correlated with pruritus NRS ( r = 0.54, p < 0.0001), and total ( r = 0.54, p < 0.0001) and conjugated bile acids (up to 0.64, p < 0.0001). Decreases in IL-31 were observed with seladelpar 5 mg (-30%, p = 0.0003) and 10 mg (-52%, p < 0.0001) versus placebo (+31%). Patients with clinically meaningful improvement in pruritus (NRS ≥ 2 decrease) demonstrated greater dose-dependent reductions in IL-31 compared to those without pruritus improvement (NRS < 2 decrease). Strong correlations were observed for the changes between levels of IL-31 and total bile acids ( r = 0.63, p < 0.0001) in the seladelpar 10 mg group. CONCLUSIONS: Seladelpar decreased serum IL-31 and bile acids in patients with PBC. The reductions of IL-31 and bile acids correlated closely with each other and pruritus improvement, suggesting a mechanism to explain seladelpar's antipruritic effects.

Hypercholesterolemia Is Associated With Dysregulation of Lipid Metabolism and Poor Prognosis in Primary Biliary Cholangitis.

BACKGROUND & AIMS: Hypercholesterolemia is frequently diagnosed in patients with primary biliary cholangitis (PBC). However, its association with the prognosis and lipid metabolism is unknown. In this study, we aimed to investigate the prognostic value of baseline total cholesterol (TC) levels in PBC and characterized the associated lipid metabolism. METHODS: Five hundred and thirty-one patients with PBC without prior cirrhosis-related complications were randomly divided into the derivation and validation cohorts at a ratio of 7:3. Complete clinical data were obtained and analyzed. The endpoints were defined as liver-related death, liver transplantation, and cirrhosis-related complications. Lipidomics was performed in 89 patients and 28 healthy controls. RESULTS: Baseline TC was independently associated with poor liver-related outcomes, and adjusted C-statistics were 0.80 (95% confidence interval [CI]: 0.74-0.85) and 0.88 (95% CI: 0.78-0.91) in the derivation and validation cohorts, respectively. The predictive ability of TC for disease outcomes was stable over time and comparable with the Globe score. The 200 mg/dL cut-off optimally divided patients into low- and high-TC groups. A combination of TC and Globe score provided a more accurate stratification of patients into risk subgroups. Lipidomics indicated an up-regulation of lipid families in high-TC patients. Pathway analysis of 66 up-regulated lipids revealed the dysregulation of glycerophospholipid and sphingolipid metabolism in high-TC patients, which were associated with poor liver-related outcomes. CONCLUSIONS: Our results indicate that patients with PBC having baseline TC levels above 200 mg/dL have unique lipidome characteristics and are at a higher risk of poor liver-related outcomes.

Anti-integrin αvß6 autoantibodies are increased in PSC patients with concomitant IBD and correlate with liver disease severity.

BACKGROUND AND AIMS: Anti-integrin αvß6 autoantibodies (anti-αvß6) are found in more than 50% of individuals with ulcerative colitis (UC). We aimed to determine the prevalence of anti-αvß6 in patients with primary sclerosing cholangitis (PSC) and their association with liver disease severity. METHODS: Four cohorts of pre-liver transplant PSC patients were recruited. Patients with inflammatory bowel disease (IBD) and healthy controls (HC) served as comparators. Total IgG and anti-αvß6 levels were measured using enzyme-linked immunosorbent assay (ELISA). Olink® inflammation panel was run on a subset of samples. Multivariable linear regression analysis was performed to assess the association between anti-αvß6 and indices of liver disease severity. RESULTS: A total of 137 PSC patients (including 76 with PSC-UC, 33 with PSC-Crohn's disease (CD) and 28 with PSC alone) and 160 controls (including 91 with IBD and 69 HC) were enrolled. Anti-αvß6 levels were significantly higher in PSC-UC and PSC-CD compared to PSC alone (p<0.0001 and 0.003) and HC (p<0.0001 and p<0.0001). However, anti-αvß6 levels in PSC alone were not increased compared to HC. In patients with PSC-IBD, anti-αvß6 levels correlated with markers of liver disease severity including alkaline phosphatase level (r=0.32, p=0.004), the revised Mayo PSC risk score (r=0.25, p=0.02) and liver stiffness measurement (r=0.43, p=0.008) after adjusting for age, gender, race/ethnicity and IBD subtype. Additionally, anti-αvß6 levels were associated with markers of systemic inflammation and tissue remodeling. CONCLUSION: Anti-αvß6 autoantibodies identify a subset of PSC patients with concomitant IBD.

COBALT: A Confirmatory Trial of Obeticholic Acid in Primary Biliary Cholangitis With Placebo and External Controls.

INTRODUCTION: Obeticholic acid (OCA) treatment for primary biliary cholangitis (PBC) was conditionally approved in the phase 3 POISE trial. The COBALT confirmatory trial assessed whether clinical outcomes in patients with PBC improve with OCA therapy. METHODS: Patients randomized to OCA (5-10 mg) were compared with placebo (randomized controlled trial [RCT]) or external control (EC). The primary composite endpoint was time to death, liver transplant, model for end-stage liver disease score ≥15, uncontrolled ascites, or hospitalization for hepatic decompensation. A prespecified propensity score-weighted EC group was derived from a US healthcare claims database. RESULTS: In the RCT, the primary endpoint occurred in 28.6% of OCA (n = 168) and 28.9% of placebo patients (n = 166; intent-to-treat analysis hazard ratio [HR] = 1.01, 95% confidence interval = 0.68-1.51), but functional unblinding and crossover to commercial therapy occurred, especially in the placebo arm. Correcting for these using inverse probability of censoring weighting and as-treated analyses shifted the HR to favor OCA. In the EC (n = 1,051), the weighted primary endpoint occurred in 10.1% of OCA and 21.5% of non-OCA patients (HR = 0.39; 95% confidence interval = 0.22-0.69; P = 0.001). No new safety signals were identified in the RCT. DISCUSSION: Functional unblinding and treatment crossover, particularly in the placebo arm, confounded the intent-to-treat estimate of outcomes associated with OCA in the RCT. Comparison with the real-world EC showed that OCA treatment significantly reduced the risk of negative clinical outcomes. These analyses demonstrate the value of EC data in confirmatory trials and suggest that treatment with OCA improves clinical outcomes in patients with PBC.

IL-31 levels correlate with pruritus in patients with cholestatic and metabolic liver diseases and is farnesoid X receptor responsive in NASH.

BACKGROUND AND AIMS: Pruritus is associated with multiple liver diseases, particularly those with cholestasis, but the mechanism remains incompletely understood. Our aim was to evaluate serum IL-31 as a putative biomarker of pruritus in clinical trials of an farnesoid X receptor (FXR) agonist, cilofexor, in patients with NASH, primary sclerosing cholangitis (PSC), and primary biliary cholangitis (PBC). APPROACH AND RESULTS: Serum IL-31 was measured in clinical studies of cilofexor in NASH, PSC, and PBC. In patients with PSC or PBC, baseline IL-31 was elevated compared to patients with NASH and healthy volunteers (HVs). IL-31 correlated with serum bile acids among patients with NASH, PBC, and PSC. Baseline IL-31 levels in PSC and PBC were positively correlated with Visual Analog Scale for pruritus and 5-D itch scores. In patients with NASH, cilofexor dose-dependently increased IL-31 from Week (W)1 to W24. In patients with NASH receiving cilofexor 100 mg, IL-31 was higher in those with Grade 2-3 pruritus adverse events (AEs) than those with Grade 0-1 pruritus AEs. IL-31 weakly correlated with C4 at baseline in patients with NASH, and among those receiving cilofexor 100 mg, changes in IL-31 and C4 from baseline to W24 were negatively correlated. IL-31 messenger RNA (mRNA) was elevated in hepatocytes from patients with PSC and NASH compared to HVs. In a humanized liver murine model, obeticholic acid increased IL-31 mRNA expression in human hepatocytes and serum levels of human IL-31. CONCLUSIONS: IL-31 levels correlate with pruritus in patients with cholestatic disease and NASH, with FXR agonist therapy resulting in higher serum levels in the latter group. IL-31 appears to derive in part from increased hepatocyte expression. These findings have therapeutic implications for patients with liver disease and pruritus.

Seladelpar efficacy and safety at 3 months in patients with primary biliary cholangitis: ENHANCE, a phase 3, randomized, placebo-controlled study.

BACKGROUND AND AIMS: ENHANCE was a phase 3 study that evaluated efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor-δ (PPAR) agonist, versus placebo in patients with primary biliary cholangitis with inadequate response or intolerance to ursodeoxycholic acid (UDCA). APPROACH AND RESULTS: Patients were randomized 1:1:1 to oral seladelpar 5 mg (n=89), 10 mg (n=89), placebo (n=87) daily (with UDCA, as appropriate). Primary end point was a composite biochemical response [alkaline phosphatase (ALP) < 1.67×upper limit of normal (ULN), ≥15% ALP decrease from baseline, and total bilirubin ≤ ULN] at month 12. Key secondary end points were ALP normalization at month 12 and change in pruritus numerical rating scale (NRS) at month 6 in patients with baseline score ≥4. Aminotransferases were assessed. ENHANCE was terminated early following an erroneous safety signal in a concurrent, NASH trial. While blinded, primary and secondary efficacy end points were amended to month 3. Significantly more patients receiving seladelpar met the primary end point (seladelpar 5 mg: 57.1%, 10 mg: 78.2%) versus placebo (12.5%) ( p < 0.0001). ALP normalization occurred in 5.4% ( p =0.08) and 27.3% ( p < 0.0001) of patients receiving 5 and 10 mg seladelpar, respectively, versus 0% receiving placebo. Seladelpar 10 mg significantly reduced mean pruritus NRS versus placebo [10 mg: -3.14 ( p =0.02); placebo: -1.55]. Alanine aminotransferase decreased significantly with seladelpar versus placebo [5 mg: 23.4% ( p =0.0008); 10 mg: 16.7% ( p =0.03); placebo: 4%]. There were no serious treatment-related adverse events. CONCLUSIONS: Patients with primary biliary cholangitis (PBC) with inadequate response or intolerance to UDCA who were treated with seladelpar 10 mg had significant improvements in liver biochemistry and pruritus. Seladelpar appeared safe and well tolerated.

Recent Advances in the Management of Primary Sclerosing Cholangitis.

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by fibroinflammatory damage to the biliary tree, typically in the setting of inflammatory bowel disease, with an increased risk of liver failure and cholangiocarcinoma. A complex pathophysiology, heterogeneity in clinical features, and the rare nature of the disease have contributed to the lack of effective therapy to date. However, recent innovations in the characterization and prognostication of patients with PSC, in addition to new tools for medical management and emerging pharmacologic agents, give rise to the potential for meaningful progress in the next several years. This review summarizes current concepts in PSC and highlights particular areas in need of further study.

GLIMMER: A Randomized Phase 2b Dose-Ranging Trial of Linerixibat in Primary Biliary Cholangitis Patients With Pruritus.

BACKGROUND & AIMS: GLIMMER assessed dose-response, efficacy, and safety of linerixibat, an ileal bile acid transporter inhibitor in development for cholestatic pruritus associated with primary biliary cholangitis (PBC). METHODS: GLIMMER was a Phase 2b, multicenter, randomized, parallel-group study in adults with PBC and moderate-to-severe pruritus (≥4 on 0-10 numerical rating scale [NRS]). After 4 weeks of single-blind placebo, patients with NRS ≥3 were randomized (3:1) to double-blind linerixibat/placebo for 12 weeks (to week 16), followed by single-blind placebo (to week 20). The primary objective was to investigate dose-related changes in mean worst daily itch (MWDI) score. RESULTS: One hundred forty-seven patients received placebo (n = 36) or linerixibat (once daily: 20 mg, n = 16; 90 mg, n = 23; 180 mg, n = 27; twice daily: 40 mg, n = 23; 90 mg, n = 22). Linerixibat groups exhibited ≥2-point mean reductions in MWDI from baseline at week 16; however, differences from placebo were not significant. Post hoc analysis of change from baseline in monthly itch score over the treatment period (Phase 3 endpoint) showed significant differences between placebo and linerixibat 180 mg once daily (P = .0424), 40 mg twice daily (P = .0105), and 90 mg twice daily (P = .0370). A significant relationship between total daily dose and response was observed post hoc in the per protocol population (P = .0542). Consistent with mechanism of action, diarrhea was the most frequent adverse event, and incidence increased with dose. CONCLUSIONS: Linerixibat effect on itch was not significantly different versus placebo in the primary intent-to-treat analysis but was associated with a significant dose-dependent reduction in itch in the per protocol population. A well-tolerated dose was identified for Phase 3 investigation for cholestatic pruritus in PBC. CLINICALTRIALS: gov ID: NCT02966834.

Safety and Sustained Efficacy of the Farnesoid X Receptor (FXR) Agonist Cilofexor Over a 96-Week Open-label Extension in Patients With PSC.

BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) is a major unmet medical need in clinical hepatology. Cilofexor is a nonsteroidal farnesoid X receptor agonist being evaluated for the treatment of PSC. Here, we describe the safety and preliminary efficacy of cilofexor in a 96-week, open-label extension (OLE) of a phase II trial. METHODS: Noncirrhotic subjects with large-duct PSC who completed the 12-week, blinded phase of a phase II study (NCT02943460) were eligible, after a 4-week washout period, for a 96-week OLE with cilofexor 100 mg daily. Safety, liver biochemistry, and serum markers of fibrosis, cellular injury, and pharmacodynamic effects of cilofexor (fibroblast growth factor 19, C4, and bile acids [BAs]) were evaluated. RESULTS: Among 52 subjects enrolled in the phase II study, 47 (90%) continued in the OLE phase (median age, 44 years; 60% male patients, 60% with inflammatory bowel disease, and 45% on ursodeoxycholic acid [UDCA]). At OLE baseline (BL), the median serum alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) were 368 U/L (interquartile range [IQR], 277-468 U/L) and 417 U/L (IQR, 196-801 U/L), respectively. Of the 47 subjects enrolled, 15 (32%) discontinued treatment prematurely (pruritus [n = 5], other adverse events [n = 5], subject decision/investigator discretion [n = 5]). At week 96, reductions in liver biochemistry parameters occurred, including serum ALP (median, -8.3% [IQR, -25.9% to 11.0%]; P = .066), GGT (-29.8% [IQR, -42.3% to -13.9%]; P < .001), alanine aminotransaminase (ALT) (-29.8% [IQR, -43.7% to -6.6%]; P = .002), and aspartate aminotransaminase (AST) (-16.7% [IQR, -35.3% to 1.0%]; P = .010), and rebounded after 4 weeks of untreated follow-up. ALP response (≥20% reduction from BL to week 96) was similar in the presence or absence of UDCA therapy (29% vs 39%; P = .71). At week 96, cilofexor treatment was associated with a significant reduction in serum 7α-hydroxy-4-cholesten-3-one (C4) (-29.8% [IQR, -64.3% to -8.5%]; P = .001). In subjects with detectable serum BAs at BL (n = 40), BAs decreased -23.9% (IQR, -44.4% to -0.6%; P = .006) at week 48 (n = 28) and -25.7% (IQR, -35.9% to 53.7%; P = .91) at week 96 (n = 26). Serum cytokeratin 18 (CK18) M30 and M65 were reduced throughout the OLE; significant reductions were observed at week 72 (CK18 M30, -17.3% [IQR, -39.3% to 8.8%]; P = .018; CK18 M65, -43.5% [IQR, -54.9% to 15.3%]; P = .096). At week 96, a small, but statistically significant absolute increase of 0.15 units in Enhanced Liver Fibrosis score was observed compared with BL (median, 9.34 vs 9.53; P = .028). CONCLUSIONS: In this 96-week OLE of a phase II study of PSC, cilofexor was safe and improved liver biochemistry and biomarkers of cholestasis and cellular injury. CLINICALTRIALS: gov identifier: NCT02943460.

Greater Transplant-Free Survival in Patients Receiving Obeticholic Acid for Primary Biliary Cholangitis in a Clinical Trial Setting Compared to Real-World External Controls.

BACKGROUND & AIMS: The Primary Biliary Cholangitis (PBC) Obeticholic Acid (OCA) International Study of Efficacy (POISE) randomized, double-blind, placebo-controlled trial demonstrated that OCA reduced biomarkers associated with adverse clinical outcomes (ie, alkaline phosphatase, bilirubin, aspartate aminotransferase, and alanine aminotransferase) in patients with PBC. The objective of this study was to evaluate time to first occurrence of liver transplantation or death in patients with OCA in the POISE trial and open-label extension vs comparable non-OCA-treated external controls. METHODS: Propensity scores were generated for external control patients meeting POISE eligibility criteria from 2 registry studies (Global PBC and UK-PBC) using an index date selected randomly between the first and last date (inclusive) on which eligibility criteria were met. Cox proportional hazards models weighted by inverse probability of treatment assessed time to death or liver transplantation. Additional analyses (Global PBC only) added hepatic decompensation to the composite end point and assessed efficacy in patients with or without cirrhosis. RESULTS: During the 6-year follow-up, there were 5 deaths or liver transplantations in 209 subjects in the POISE cohort (2.4%), 135 of 1381 patients in the Global PBC control (10.0%), and 281 of 2135 patients in the UK-PBC control (13.2%). The hazard ratios (HRs) for the primary outcome were 0.29 (95% CI, 0.10-0.83) for POISE vs Global PBC and 0.30 (95% CI, 0.12-0.75) for POISE vs UK-PBC. In the Global PBC study, HR was 0.20 (95% CI, 0.03-1.22) for patients with cirrhosis and 0.31 (95% CI, 0.09-1.04) for those without cirrhosis; HR was 0.42 (95% CI, 0.21-0.85) including hepatic decompensation. CONCLUSIONS: Patients treated with OCA in a trial setting had significantly greater transplant-free survival than comparable external control patients.

Application of the Latest Advances in Evidence-Based Medicine in Primary Biliary Cholangitis.

Primary biliary cholangitis (PBC) is a chronic, cholestatic, autoimmune liver disease that can progress to end-stage liver disease and its complications. A previous expert review panel collaborated on a consensus document for gastroenterologists and other healthcare professionals regarding the care of patients with PBC. Subsequently, there have been several recent important developments in the diagnosis, treatment, and monitoring of patients with PBC. These include updates to prognostic models on risk stratification, new noninvasive tools for staging of disease, updates to the appropriate use of and long-term treatment results with obeticholic acid as a second-line treatment, the emerging therapeutic role of fibrates, and the advancement of investigational agents for managing PBC. In this updated expert consensus document, we provide updates on staging, the use of noninvasive prognostic tools, and a treatment algorithm to provide evidence-based and practical tools for clinicians who manage PBC, with the ultimate goal to improve the long-term outcomes for patients with this chronic liver disease.

The gut ecosystem and immune tolerance.

The gastrointestinal tract is home to the largest microbial population in the human body. The gut microbiota plays significant roles in the development of the gut immune system and has a substantial impact on the maintenance of immune tolerance beginning in early life. These microbes interact with the immune system in a dynamic and interdependent manner. They generate immune signals by presenting a vast repertoire of antigenic determinants and microbial metabolites that influence the development, maturation and maintenance of immunological function and homeostasis. At the same time, both the innate and adaptive immune systems are involved in modulating a stable microbial ecosystem between the commensal and pathogenic microorganisms. Hence, the gut microbial population and the host immune system work together to maintain immune homeostasis synergistically. In susceptible hosts, disruption of such a harmonious state can greatly affect human health and lead to various auto-inflammatory and autoimmune disorders. In this review, we discuss our current understanding of the interactions between the gut microbiota and immunity with an emphasis on: a) important players of gut innate and adaptive immunity; b) the contribution of gut microbial metabolites; and c) the effect of disruption of innate and adaptive immunity as well as alteration of gut microbiome on the molecular mechanisms driving autoimmunity in various autoimmune diseases.

PRIMIS: design of a pivotal, randomized, phase 3 study evaluating the safety and efficacy of the nonsteroidal farnesoid X receptor agonist cilofexor in noncirrhotic patients with primary sclerosing cholangitis.

BACKGROUND: Primary sclerosing cholangitis (PSC) is a chronic progressive liver disease leading to biliary fibrosis and cirrhosis. Cilofexor is a nonsteroidal farnesoid X receptor agonist that demonstrated significant improvements in liver biochemistry and markers of cholestasis in patients with PSC in a phase 2 study. We describe here the rationale, design, and implementation of the phase 3 PRIMIS trial, the largest placebo-controlled trial in PSC. METHODS: Adults with large-duct PSC without cirrhosis are randomized 2:1 to receive oral cilofexor 100 mg once daily or placebo for up to 96 weeks during the blinded phase. Patients completing the blinded phase are eligible to receive open-label cilofexor 100 mg daily for up to 96 weeks. The primary objective is to evaluate whether cilofexor reduces the risk of fibrosis progression compared with placebo. Liver biopsy is performed at screening and Week 96 of the blinded phase for histologic assessment of fibrosis. The primary endpoint-chosen in conjunction with guidance from the U.S. Food and Drug Administration-is the proportion of patients with ≥ 1-stage increase in fibrosis according to Ludwig histologic classification at week 96. Secondary objectives include evaluation of changes in liver biochemistry, serum bile acids, liver fibrosis assessed by noninvasive methods, health-related quality of life, and safety of cilofexor. CONCLUSION: The phase 3 PRIMIS study is the largest randomized, double-blind, placebo-controlled trial in PSC to date and will allow for robust evaluation of the efficacy and safety of cilofexor in noncirrhotic patients with large-duct PSC. TRIAL REGISTRATION: ClinicalTrials.gov NCT03890120; registered 26/03/2019.

A phase II, randomized, open-label, 52-week study of seladelpar in patients with primary biliary cholangitis.

BACKGROUND & AIMS: We examined the efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor-delta agonist, in adults with primary biliary cholangitis (PBC) at risk of disease progression (alkaline phosphatase [ALP] ≥1.67xupper limit of normal [ULN]) who were receiving or intolerant to ursodeoxycholic acid. METHODS: In this 52-week, phase II, dose-ranging, open-label study, patients were randomized (1:1) to seladelpar 5 mg/day (n = 53) or 10 mg/day (n = 55) or assigned to 2 mg/day (n = 11; United Kingdom sites after interim analysis) for 12 weeks. Doses could then be uptitrated to 10 mg/day. The primary efficacy endpoint was ALP change from baseline to Week 8. RESULTS: Mean baseline ALP was 300, 345, and 295 U/L in the 2 mg, 5 mg, and 10 mg cohorts, respectively. Twenty-one percent of patients had cirrhosis, 71% had pruritus. At Week 8, mean ± standard error ALP reductions from baseline were 26 ± 2.8%, 33 ± 2.6%, and 41 ± 1.8% in the 2 mg (n = 11), 5 mg (n = 49), and 10 mg (n = 52) cohorts (all p ≤0.005), respectively. Responses were maintained or improved at Week 52, after dose escalation in 91% and 80% of the 2 mg and 5 mg cohorts, respectively. At Week 52, composite response (ALP <1.67xULN, ≥15% ALP decrease, and normal total bilirubin) rates were 64%, 53%, and 67%, and ALP normalization rates were 9%, 13%, and 33% in the 2 mg, 5 mg, and 10 mg cohorts, respectively. Pruritus visual analog scale score was decreased in the 5 mg and 10 mg cohorts. There were no treatment-related serious adverse events, and 4 patients discontinued due to adverse events. CONCLUSIONS: Seladelpar demonstrated robust, dose-dependent, clinically significant, and durable improvements in biochemical markers of cholestasis and inflammation in patients with PBC at risk of disease progression. Seladelpar appeared safe and well tolerated and was not associated with any increase in pruritus. GOV NUMBER: NCT02955602 CLINICALTRIALSREGISTER. EU NUMBER: 2016-002996-91 LAY SUMMARY: Current treatment options for patients living with primary biliary cholangitis (PBC) are not optimal due to inadequate effectiveness or undesirable side effects. Patients with PBC who took seladelpar, a new treatment being developed for PBC, at increasing doses (2, 5, or 10 mg/day) for 1 year had clinically significant, dose-dependent improvements in key liver tests. Treatment appeared safe and was not associated with any worsening in patient self-reported itch scores.

Epidemiology, Natural History, and Outcomes of Primary Sclerosing Cholangitis: A Systematic Review of Population-based Studies.

BACKGROUND & AIMS: The aim of this study was to quantify the global epidemiology of primary sclerosing cholangitis (PSC), alongside the incidence of liver transplantation, cancer, and death, through robust systematic review of population-based data. METHODS: We searched MEDLINE and EMBASE up to and including June 30, 2020 to identify population-based studies reporting the incidence and/or prevalence of PSC. Studies that did not report original data, or of exclusively pediatric-onset disease (diagnosis age <16 years) or exclusively PSC-associated with inflammatory bowel disease were excluded. RESULTS: Of 4922 published studies, 17 fulfilled inclusion criteria; 16 documenting incidence and 14 prevalence. The highest reported incidence of PSC was reported in Northern Europe (Finland, 1.58 and Norway, 1.3 per-100,000 population, respectively) and North America (Minnesota, 1.47); with the lowest being observed across the Mediterranean Basin (Italy, 0.1). Prevalence ranged from 31.7 in Finland and 23.99 in Minnesota, to 1.33 in Singapore and 0.0 in Alaska. Of studies reporting temporal occurrence, an increase in disease incidence was observed across North America and Northern Europe (4 studies), alongside an increase in prevalence over time (4 studies). The incidence and risks for clinical outcomes were presented by 9 of the included studies. Median transplant-free survival ranged from 9.7 (United States) to 20.6 years (Netherlands), with standardized mortality ratios of 2.5 and 4.2 compared with the control population. The standardized incidence of cholangiocarcinoma ranged from 235 (Finland) to 398 (Netherlands). CONCLUSIONS: Estimates of PSC incidence and prevalence vary, with most studies conducted in North America and Western Europe; the latter showing a steady increase in disease occurrence over time. Further research is needed to understand changes in disease epidemiology, including etiological drivers, the implications of rising case burden on health care policy, and better appreciation of PSC in the developing world.

A Fibrosis-Independent Hepatic Transcriptomic Signature Identifies Drivers of Disease Progression in Primary Sclerosing Cholangitis.

BACKGROUND AND AIMS: Primary sclerosing cholangitis (PSC) is a heterogeneous cholangiopathy characterized by progressive biliary fibrosis. RNA sequencing of liver tissue from patients with PSC (n = 74) enrolled in a 96-week clinical trial was performed to identify associations between biological pathways that were independent of fibrosis and clinical events. APPROACH AND RESULTS: The effect of fibrosis was subtracted from gene expression using a computational approach. The fibrosis-adjusted gene expression patterns were associated with time to first PSC-related clinical event (e.g., cholangitis, hepatic decompensation), and differential expression based on risk groups and Ingenuity Pathway Analysis were performed. Baseline demographic data were representative of PSC: median age 48 years, 71% male, 49% with inflammatory bowel disease, and 44% with bridging fibrosis or cirrhosis. The first principle component (PC1) of RNA-sequencing data accounted for 18% of variance and correlated with fibrosis stage (ρ = -0.80; P < 0.001). After removing the effect of fibrosis-related genes, the first principle component was not associated with fibrosis (ρ = -0.19; P = 0.11), and a semisupervised clustering approach identified two distinct patient clusters with differential risk of time to first PSC-related event (P < 0.0001). The two groups had similar fibrosis stage, hepatic collagen content, and α-smooth muscle actin expression by morphometry, Enhanced Liver Fibrosis score, and serum liver biochemistry, bile acids, and IL-8 (all P > 0.05). The top pathways identified by Ingenuity Pathway Analysis were eukaryotic translation inhibition factor 2 (eIF2) signaling and regulation of eIF4/p70S6K signaling. Genes involved in the unfolded protein response, activating transcription factor 6 (ATF6) and eIF2, were differentially expressed between the PSC clusters (down-regulated in the high-risk group by log-fold changes of -0.18 [P = 0.02] and -0.16 [P = 0.02], respectively). Clinical events were enriched in the high-risk versus low-risk group (38% [12/32] vs. 2.4% [1/42], P < 0.0001). CONCLUSIONS: Removing the contribution of fibrosis-related pathways uncovered alterations in the unfolded protein response, which were associated with liver-related complications in PSC.

Seladelpar improved measures of pruritus, sleep, and fatigue and decreased serum bile acids in patients with primary biliary cholangitis.

BACKGROUND & AIMS: Primary biliary cholangitis (PBC) can result in life-altering cholestatic pruritus and fatigue, but treatment options are limited. Seladelpar, a peroxisome proliferator-activated receptor-delta (PPARδ) agonist, has demonstrated potent anti-cholestatic effects in clinical studies. This open-label, uncontrolled phase 2 study in PBC patients evaluated the effects of 1-year of seladelpar treatment on measures of pruritus and quality of life. METHODS: Self-reported experiences of 101 PBC patients were collected at baseline and after 1 year of seladelpar treatment using the pruritus visual analog scale (VAS), 5D-itch scale, and PBC-40 questionnaires along with bile acid profiles. RESULTS: In patients with moderate-to-severe pruritus, substantial improvement in pruritus was seen in 58% and 93% of patients in 5/10 mg and 10 mg treatment groups, respectively. After 1 year, patients reporting improvement substantially outnumbered those who worsened in the total 5-D itch (including individual domains) and PBC-40 (itch and fatigue domains) questionnaires. Improvement in sleep disturbance at 1-year was reported in 81% (5/10 mg) and 78% (10 mg) of the patients with baseline itch-related sleep disturbance by 5-D itch score with similar results using the PBC-40 sleep questionnaire. Seladelpar-treated patients had significant reductions of 46% (5/10 mg) and 31% (10 mg) in the serum bile acid precursor C4 and reductions of up to 38% in serum bile acids. CONCLUSIONS: Seladelpar treatment for 1 year led to consistent improvement in both symptom burden and biochemical response, suggesting its potential as a single agent to address two key unmet needs in PBC patients.

Dynamic Risk Prediction of Response to Ursodeoxycholic Acid Among Patients with Primary Biliary Cholangitis in the USA.

BACKGROUND: Ursodeoxycholic acid (UDCA) remains the first-line therapy for primary biliary cholangitis (PBC); however, inadequate treatment response (ITR) is common. The UK-PBC Consortium developed the modified UDCA Response Score (m-URS) to predict ITR (using alkaline phosphatase [ALP] > 1.67 times the upper limit of normal [*ULN]) at 12 months post-UDCA initiation). Using data from the US-based Fibrotic Liver Disease Consortium, we assessed the m-URS in our multi-racial cohort. We then used a dynamic modeling approach to improve prediction accuracy. METHODS: Using data collected at the time of UDCA initiation, we assessed the m-URS using the original formula; then, by calibrating coefficients to our data, we also assessed whether it remained accurate when using Paris II criteria for ITR. Next, we developed and validated a dynamic risk prediction model that included post-UDCA initiation laboratory data. RESULTS: Among 1578 patients (13% men; 8% African American, 9% Asian American/American Indian/Pacific Islander; 25% Hispanic), the rate of ITR was 27% using ALP > 1.67*ULN and 45% using Paris II criteria. M-URS accuracy was "very good" (AUROC = 0.87, sensitivity = 0.62, and specificity = 0.82) for ALP > 1.67*ULN and "moderate" (AUROC = 0.74, sensitivity = 0.57, and specificity = 0.70) for Paris II. Our dynamic model significantly improved accuracy for both definitions of ITR (ALP > 1.67*ULN: AUROC = 0.91; Paris II: AUROC = 0.81); specificity approached 100%. Roughly 9% of patients in our cohort were at the highest risk of ITR. CONCLUSIONS: Early identification of patients who will not respond to UDCA treatment using a dynamic prediction model based on longitudinal, repeated risk factor measurements may facilitate earlier introduction of adjuvant treatment.