IFIH1 and interstitial lung disease: Because anti-MDA5 antibody-positive rapidly progressive ILD is the most severe phenotype in PM-/DM-/CADM-ILD with the poorest prognoses, a combined immunosuppressive regimen, including high-dose GCs, oral calcineurin inhibitors (CNIs), and intravenous cyclophosphamide (IVCY) pulse, is recommended [18,20,42].