This study aimed to assess the clinical utility of serum interferon-lambda 3 (IFN-λ3) as a sequential biomarker for treatment response and disease control in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (DM)-associated interstitial lung disease (ILD). The gene discussed is IFIH1; the disease is interstitial lung disease.