AJ303 is a novel compound under development for the treatment of idiopathic pulmonary fibrosis (IPF). It decreased IPF-related inflammatory cytokines, such as IL-6, MCP1, and GM-CSF in vitro, that delays the progression of pulmonary fibrosis in bleomycin-induced pulmonary injury model in mice. AJ303 has a favorable plasma to pulmonary ratio of tissue distribution after oral administration. Its potential efficacy in treating patients with IPF will be investigated clinically in 2021.