The relationship between disease activity and UDCA response criteria in primary biliary cholangitis: A cohort study

A low baseline serum myostatin concentration is associated with poor clinical outcome in patients with primary biliary cholangitis

BACKGROUND AND AIM

Primary biliary cholangitis (PBC) is an autoimmune-mediated cholestatic liver disease that can progress to biliary cirrhosis and liver-related death. The associations between baseline myostatin levels and clinical outcomes in PBC patients are unknown. We aimed to clarify the influence of myostatin levels on the clinical outcomes of PBC patients.

METHODS

A total of 119 PBC patients were analyzed in this study. Myostatin levels were measured in stored sera before ursodeoxycholic acid treatment, and their associations with the clinical features and prognosis of PBC patients were analyzed. We analyzed the correlation between serum myostatin and chemokines/cytokines.

RESULTS

Serum myostatin was significantly lower in PBC patients (2343 pg/mL) than in healthy controls (4059 pg/mL, P < 0.001). The prevalence of patients with low myostatin levels increased according to the severity of histological fibrosis. The serum myostatin concentration was negatively correlated with the IL-6 and leucine-rich α2 glycoprotein levels, but the chemokine concentration was not correlated with the myostatin concentration. Low myostatin in PBC patients was associated with shorter survival without liver-related complications (hazard ratio [HR], 3.598; 95% confidence interval [CI], 1.27-10.1; P = 0.015) and shorter transplant-free survival (HR, 3.129; 95% CI, 1.02-9.56; P = 0.045) independent of pretreatment GLOBE score. Patients with both high pretreatment GLOBE scores and low myostatin levels had poor prognoses (log-rank test: P < 0.001).

CONCLUSIONS

A low serum myostatin concentration at diagnosis was associated with poor clinical outcomes. Assessment of circulating myostatin levels may improve the prediction of outcomes in patients with PBC.

Primary biliary cholangitis drug evaluation and regulatory approval: Where do we go from here?

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease. The management landscape was transformed 20 years ago with the advent of ursodeoxycholic acid. Up to 40% of patients do not, however, respond adequately to ursodeoxycholic acid and therefore still remain at risk of disease progression to cirrhosis. The introduction of obeticholic acid as a second-line therapy for patients failing ursodeoxycholic acid has improved outcomes for patients with PBC. There remains, however, a need for better treatment for patients at higher risk. The greatest threat facing our efforts to improve treatment in PBC is, paradoxically, the regulatory approval model providing conditional marketing authorization for new drugs based on biochemical markers on the condition that long-term, randomized placebo-controlled outcome trials are performed to confirm efficacy. As demonstrated by the COBALT confirmatory study with obeticholic acid, it is difficult to retain patients in the required follow-on confirmatory placebo-controlled PBC outcome trials when a licensed drug is commercially available. New PBC therapies in development, such as the peroxisome proliferator-activated receptor agonists, face even greater challenges in demonstrating outcome benefit through randomized placebo-controlled studies once following conditional marketing authorization, as there will be even more treatment options available. A recently published EMA Reflection Paper provides some guidance on the regulatory pathway to full approval but fails to recognize the importance of real-world data in providing evidence of outcome benefit in rare diseases. Here we explore the impact of the EMA reflection paper on PBC therapy and offer pragmatic solutions for generating evidence of long-term outcomes through real-world data collection.

Incomplete response to ursodeoxycholic acid in primary biliary cholangitis: criteria, epidemiology, and possible mechanisms

INTRODUCTION

As a common autoimmune disease with the characteristic of early complication, primary biliary cholangitis (PBC) leads to an increasing number of mortalities among people with end-stage liver disease (ESLD) waiting for liver transplantation. Ursodeoxycholic acid (UDCA) is the only approved first-line medicine for PBC, and a good response to treatment could acquire an ideal prognosis. Patients with poor UDCA response usually have more adverse outcomes and worse survival, therefore, the management of this group become a major consideration.

AREAS COVERED

Due to the complexity of race and environment for PBC, different criteria for UDCA response exhibit various predictive performances. Factors affecting UDCA response conditions include gender, age, ethnicity, serum indicators, auto-antibodies, and autoimmune comorbidities, while no agreement has been reached. In this review, we mainly focus on cellular senescence, immune-mediated damage, and vitamin D deficiency as possible mechanisms for UDCA non-responders.

EXPERT OPINION

The pathogenesis of PBC has yet to be clarified. Immunology-related mechanisms and therapy targets ought to be the main effort made for further study. Irrespective of the response condition, UDCA is recommended for routine administration in all PBC patients without contraindication. Ongoing clinical trials of second-line and additional therapy exhibit promising prospects.