Progressive fibrosing interstitial lung diseases: A new concept and indication of nintedanib

Many interstitial lung diseases (ILDs) are characterized by chronic progressive fibrosis. The antifibrotic agents may prevent disease progression of these diseases. Nintedanib is a triple tyrosine kinase inhibitor and has an antifibrotic effect. The proven beneficial effects of nintedanib in idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc)-associated ILD, nintedanib was intended for use in many other fibrotic lung diseases consistent with the concept described below. With this trial, the concept and definition of progressive fibrosing ILD (PF-ILD) were created, a type of fibrosing diseases that progresses with fibrosis measured in forced vital capacity and high-resolution CT findings and worsening of respiratory symptoms at a certain rate or faster. PF-ILDs are composed of idiopathic interstial pneumonias such as non-specific interstitial pneumonia and unclassifiable interstitial pneumonia and inhalation lung diseases such as chronic hypersensitivity pneumonia and connective tissue disease-associated ILD such as rheumatoid arthritis-related ILD and SSc-related ILD and sarcoidosis and so on. Nintedanib significantly reduced the annual rate of decline in forced vital capacity over 52 weeks compared with placebo. Nintedanib received marketing approval in the United States and Japan for the treatment of PF-ILDs. This review summarizes the new concept of PF-ILDs and effectiveness of nintedanib to PF-ILDs and discussion points to be solved in the future when using nintedanib for PF-ILDs.