BI-706321

This study is open to adults, aged 18-75 years, with moderate to severe Crohn's disease.
The purpose of this study is to find out whether BI 706321 combined with ustekinumab helps people with Crohn's disease. BI 706321 is a medicine being developed to treat Crohn's disease. Ustekinumab is a medicine already used to treat Crohn's disease.
Participants are put into 2 groups randomly, which means by chance. One group gets BI 706321 and ustekinumab. The other group gets placebo and ustekinumab.
Participants take BI 706321 or placebo as tablets every day. Placebo tablets look like BI 706321 tablets but do not contain any medicine. Ustekinumab is given as an infusion into a vein once at the beginning of the study. After that, ustekinumab is given as an injection under the skin every 2 months. Participants take BI 706321 or placebo in combination with ustekinumab for 3 months. After that, participants receive only ustekinumab for another 9 months.
Participants are in the study for about 1 year. During this time, they visit the study site about 13 times. At 3 of the visits, doctors do a colonoscopy to examine the bowel. The results from the colonoscopies are compared between the 2 groups. The doctors also regularly check participants' health and take note of any unwanted effects.

To investigate the pharmacokinetics of a single oral dose of BI 706321 when given alone or in combination with itraconazole.