A Study to Test Whether BI 1819479 Improves Lung Function in People With Idiopathic Pulmonary Fibrosis (IPF)

This study is open to adults 40 years or older with idiopathic pulmonary fibrosis (IPF). People can join the study if they are not on any treatment for IPF are on stable treatment for at least 3 months before starting the study. The purpose of this study is to find out whether a medicine called BI 1819479 helps people with IPF. 3 different doses of BI 1819479 are tested in this study. Participants are put into 4 groups by chance. Participants in 3 groups get different doses of BI 1819479. Participants in 1 group get placebo. Placebo tablets look like BI 1819479 tablets, but do not contain any medicine. Participants take the treatment for 6 months to 1 year. Participants are in the study for up to 1 year and 2 months. During this time, they visit the study site between 10 and 12 times and get up to 11 phone calls from the site staff. At site visits doctors regularly perform breathing tests that measure how well the lungs are working. Researchers compare the results between participants who take BI 1819479 and placebo. The doctors also regularly check participants' health and take note of any unwanted effects.