CXCL13 as a Predictive Biomarker for Response to Methotrexate Monotherapy in Rheumatoid Arthritis.

This prospective study investigated the utility of baseline CXCL13 levels in predicting methotrexate response and monitoring disease activity in 50 treatment-naive early rheumatoid arthritis (RA) patients (2010 American College of Rheumatology/European League Against Rheumatism criteria) treated with methotrexate. Participants were categorized into methotrexate responders (MTX-R, n = 29) and nonresponders (MTX-NR, n = 21) at 12 weeks. Baseline CXCL13 levels were significantly higher in MTX-R compared with MTX-NR (P = 0.035). Receiver operating characteristic curve analysis identified a baseline CXCL13 cutoff of >100 pg/mL for predicting methotrexate response, with 69% sensitivity, 52% specificity, and 62% accuracy. Posttreatment, CXCL13 levels decreased significantly in MTX-R (P < 0.001) but remained unchanged in MTX-NR. Disease activity parameters (eg, DAS-28) correlated with CXCL13 dynamics, though specific coefficients were not detailed. The study highlights CXCL13 as a potential biomarker for stratifying methotrexate therapy, with higher baseline levels favoring therapeutic response and posttreatment reductions reflecting clinical improvement. While moderate diagnostic accuracy limits standalone use, CXCL13 may complement existing tools to guide early personalized treatment. Further validation in larger cohorts is warranted to confirm its role in optimizing RA management.