Clinical bottom line
Serum Mac-2 binding protein glycosylation isomer (M2BPGi) is an emerging noninvasive biomarker with promising utility for staging liver fibrosis and prognosticating outcomes across a range of chronic liver diseases, including hepatitis C virus (HCV) infection, nonalcoholic fatty liver disease (NAFLD), and metabolic dysfunction-associated liver disease (MAFLD). Multiple studies and meta-analyses suggest that M2BPGi correlates well with histologic fibrosis stage and may help identify patients at risk for fibrosis progression or liver-related complications. However, variability in cutoff values, disease-specific performance, and limited longitudinal data warrant cautious interpretation. M2BPGi may complement existing fibrosis assessment tools and guide clinical decision-making but requires further validation before routine adoption.
What the evidence shows
M2BPGi is a glycosylation isomer of Mac-2 binding protein, a secreted glycoprotein involved in liver fibrogenesis and inflammation. Its serum levels increase with advancing fibrosis, reflecting extracellular matrix remodeling and hepatic stellate cell activation (Shirabe et al., 2018).
A comprehensive meta-analysis by Gong et al. (2024) evaluated M2BPGi’s diagnostic accuracy across liver diseases, reporting pooled sensitivity and specificity values exceeding 80% for detecting significant fibrosis (≥F2) and cirrhosis (F4). The area under the receiver operating characteristic curve (AUROC) ranged from 0.82 to 0.91, indicating good discriminatory power. This meta-analysis highlighted M2BPGi’s consistency across etiologies but noted heterogeneity in cutoff thresholds.
In hepatitis C, Chang et al. (2024) demonstrated that serum M2BPGi levels decreased significantly after achieving sustained virologic response (SVR), paralleling fibrosis regression. This dynamic change suggests M2BPGi may monitor treatment response and residual fibrosis risk post-SVR.
In metabolic liver disease, Sotoudeheian Mohammadjavad et al. (2025) reviewed M2BPGi’s role in MAFLD, underscoring its potential to noninvasively stage fibrosis and predict progression. Similarly, Cheng et al. (2021) found M2BPGi effectively identified mild and significant fibrosis in NAFLD patients, with AUROCs around 0.80, supporting its use in this growing patient population.
Screening studies in asymptomatic populations also support M2BPGi’s utility. Nah et al. (2020) reported that M2BPGi detected advanced fibrosis in health checkup cohorts with reasonable accuracy, suggesting a role in early identification of high-risk individuals.
Choi et al. (2019) noted correlations between M2BPGi and metabolic parameters such as hemoglobin A1c, indicating potential links between fibrosis biomarker levels and systemic metabolic status.
Caveats and uncertainty
Despite encouraging data, several limitations temper enthusiasm for widespread clinical use. The optimal M2BPGi cutoff values vary by liver disease etiology, assay platform, and population, complicating standardization (Gong et al., 2024; Sotoudeheian Mohammadjavad et al., 2025).
Most studies are cross-sectional or retrospective, limiting assessment of M2BPGi’s predictive value for fibrosis progression or clinical outcomes. Longitudinal prospective cohorts are needed to establish its role in monitoring disease course and guiding therapy.
M2BPGi levels may be influenced by comorbid conditions, inflammation, or hepatic necroinflammation, potentially confounding fibrosis assessment (Shirabe et al., 2018). Its performance relative to established noninvasive markers such as transient elastography or serum fibrosis panels requires further head-to-head comparison.
Finally, cost-effectiveness and accessibility of M2BPGi assays remain to be defined, especially in resource-limited settings.
How this may change practice
M2BPGi offers a promising adjunct to current noninvasive fibrosis assessment strategies, potentially improving early detection of significant fibrosis and cirrhosis without biopsy. It may be particularly useful in monitoring fibrosis regression after antiviral therapy in HCV or tracking fibrosis progression in metabolic liver disease.
Clinicians might consider incorporating M2BPGi testing alongside elastography and serum fibrosis scores to enhance diagnostic confidence, especially when results are discordant or biopsy is contraindicated. However, given current uncertainties, M2BPGi should not replace established diagnostic algorithms but rather complement them.
Future integration of M2BPGi into clinical practice guidelines will depend on further validation in diverse populations, standardization of assay methods, and demonstration of impact on patient outcomes.