ROSETTA Study: This study is testing a medicine called Rosnilimab for people with moderate to severe ulcerative colitis (UC). Ulcerative colitis is a condition where the colon, or the large intestine, becomes swollen and develops sores. This study is Phase 2, which means it’s looking more closely at how well the medicine works and how safe it is. The study is randomized and double-blind, so neither the participants nor the doctors know who is getting the real medicine or a placebo, which is like a sugar pill. It will also look at how the body processes the medicine, which is called pharmacokinetics (PK), and how the medicine affects the body, called pharmacodynamics (PD).

• Participants must be 18 or older with moderate to severe UC.
• The study will take place across multiple centers.
• Participants cannot have certain other conditions, like Crohn's disease.