A Study of Pirfenidone in Patients With Unclassifiable Progressive Fibrosing Interstitial Lung Disease

Inclusion Criteria: * Age \>= 18-85 years * Confirmed fibrosing ILD which, following multidisciplinary team review, cannot be classified with either high or moderate confidence as a specific idiopathic interstitial pneumonia or other defined ILD * Progressive disease as considered by the investigator as participants deterioration within the last 6 months, which is defined as a rate of decline in forced vital capacity (FVC) \>5% or a significant symptomatic worsening not due to cardiac, pulmonary vascular or other causes * Extent of fibrosis \>10% on high-resolution computed tomography * Forced vital capacity \>= 45% of predicted value * Diffusing capacity of the lung for carbon monoxide (DLco) \>= 30% of predicted value * Forced expiratory volume in 1 second/FVC ratio \>= 0.7 * Able to do 6-minute walk distance (6MWD) \>= 150 meters * For women of childbearing potential: agreement to remain abstinent or use a non-hormonal or hormonal contraceptive method with a failure rate of \< 1% per year during the treatment period and for at least 90 days after the last dose of pirfenidone * For men, agreement to remain abstinent or use contraceptive measures, and agreement to refrain from donating sperm Exclusion Criteria: * Diagnosis with moderate or high confidence of nonspecific interstitial pneumonia and any ILD with an identifiable cause such as connective tissue disease-ILD, chronic hypersensitivity pneumonitis, or others * Diagnosis of idiopathic pulmonary fibrosis independent…