A Study to Test Different Doses of BI 730357 and Find Out Whether They Reduce Symptoms in People With Active Psoriatic Arthritis

This study is open to adults with active psoriatic arthritis who have tender and swollen joints. The purpose of this study is to find out whether a medicine called BI 730357 helps to reduce symptoms and to prevent damage to joints. Three different doses of BI 730357 are tested. Participants are put into 4 groups by chance. Participants in 3 of the 4 groups take BI 730357. Participants in the fourth group take placebo. Participants take BI 730357 or placebo as tablets once a day. Placebo tablets look like BI 730357 tablets but do not contain any medicine. Participants are in the study for about 4.5 months. During this time, they visit the study site about 8 times. At these visits, doctors check whether the swelling of inflamed joints has changed. The results between the BI 730357 and placebo groups are then compared. Doctors also regularly check the general health of the participants.