Loss of mucosal tolerance to glycoprotein 2 isoform 1 is a potential novel diagnostic biomarker for cholangiocarcinoma.

Background: Anti-glycoprotein 2 (anti-GP2) IgA and antineutrophil-cytoplasmic antibodies to proteinase 3 (PR3-ANCA) have been reported as predictive markers of cholangiocarcinoma (CCA) in patients with primary sclerosing cholangitis (PSC), but their prevalence in CCA patients without PSC remains unclear.
Methods: This study involved Asian discovery (n = 118) and European validation (n = 38) cohorts of CCA patients without PSC, alongside 49 Asian and 82 European pancreatic ductal adenocarcinoma (PDAC) patients, 21 with benign pancreatic neoplasms (BPN) and 45 with hepatocellular carcinoma (HCC), and 157 healthy controls (HC) from Asia and Europe. We analyzed the prevalence of PR3-ANCA, IgA and IgG against GP2 ₁ and GP2 ₄ , and the CA19-9 levels.
Results: Anti-GP2 ₁ IgA was the most prevalent in both CCA cohorts (discovery: 55.1 %; validation: 42.1 %) and significantly higher than in other groups except PDAC (all p < 0.05). It demonstrated the best diagnostic performance in distinguishing CCA from disease controls and HC, outperforming tumor markers. No significant correlation was found between anti-GP2 ₁ IgA levels and CA19-9 levels.
Conclusion: Our findings show that anti-GP2 ₁ IgA revealing the loss of mucosal tolerance is a potential novel diagnostic biomarker for CCA.
Competing Interests: Declaration of competing interest Dirk Roggenbuck has ownership of Medipan and GA Generic Assays corporation stocks and profits earned from the stocks. The other authors declare that they have no conflicts of interest.
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