Refractory anti-synthetase syndrome-associated interstitial lung disease (ASyS-ILD) lacks targeted therapy. Interleukin-6 drives both inflammation and fibrosis. We evaluated the real-world efficacy and safety of tocilizumab, an IL-6 receptor antagonist.
This single-center retrospective cohort study included patients with refractory ASyS-ILD treated between January 2020 and July 2025. Tocilizumab recipients were compared with those receiving standard of care (SOC) immunosuppressants. Overlap weighting based on propensity scores was used to balance 11 baseline variables. The primary outcome was improvement in symptoms and HRCT findings at ≥3 months. Secondary outcomes included changes in biomarkers and pulmonary function, progression-free survival (PFS), and adverse events. Cox regression identified independent predictors of symptom progression. Generalized additive models (GAM) explored nonlinear relationships, and XGBoost-SHAP machine learning assessed variable importance.