A Study to Find Out Whether BI 765423 Has an Effect on Lung Function in People With Idiopathic Pulmonary Fibrosis (IPF) With or Without Standard Treatment

This study is open to adults who are at least 40 years old and have idiopathic pulmonary fibrosis (IPF). People can participate in the study if they have a forced vital capacity (FVC) greater than or equal to 45% of the predicted value and fibrosis of 20% or more confirmed by a high-resolution computed tomography (HRCT) scan. The purpose of this study is to find out if a medicine called BI 765423 can improve lung function in people with IPF. The study will compare BI 765423 with a placebo to see if there is a difference in lung capacity after 3-6 months of treatment and will also look at changes in certain markers related to lung health. Participants are put into two groups randomly, which means by chance. One group receives the study medicine, and the other group receives a placebo. Placebo looks like BI 765423 but does not contain any study medicine. The study medicine is given as an infusion into a vein every four weeks. Participants are in the study for up to 11 months. During the study, participants may continue their regular treatment for IPF. During the study they visit the study site several times for screening, treatment, and follow-up. Doctors regularly test lung function by measuring FVC and take blood samples to measure study endpoints. The results are compared between the two groups to see whether the treatment works. The doctors also check participants' health and take note of any unwanted effects.