Summary: The purpose of this protocol is to evaluate the efficacy (how well it works), safety and tolerability of oral icotrokinra as therapy in adult and adolescent participants with moderately to severely active ulcerative colitis (UC, a chronic disease of the large intestine in which the lining of the colon becomes inflamed and develops tiny open ulcers).

Summary: The purpose of this study is to evaluate the efficacy of icotrokinra (JNJ-77242113) compared to placebo in biologic-experienced and biologic-naive participants with active psoriatic arthritis (PsA) by assessing the reduction in signs and symptoms of PsA.

Summary: The purpose of this study is to evaluate how-well icotrokinra works (clinical efficacy) and how safe it is (safety) in participants with moderately to severely active Crohn's disease (CD; a long-term condition causing severe inflammation of the intestinal tract).