Abstract Rationale No recommended therapy exists for chronic fibrosing interstitial lung diseases (CF-ILD) with disease progression despite ongoing treatment with nintedanib or pirfenidone. Pamufetinib (also known as TAS-115) is a novel oral antifibrotic tyrosine kinase inhibitor in development for CF-ILD with a progressive phenotype. Objective We sought to evaluate the dose-response of pamufetinib monotherapy in patients with CF-ILD including idiopathic pulmonary fibrosis (IPF) with a progressi