Mk7240-008

Researchers are looking for a new way to treat people with Crohn’s disease (CD) that is causing symptoms (called active). Crohn’s disease (CD) is an inflammatory bowel disease (IBD) that causes swelling and ulcers (sores) in the digestive tract. Symptoms of CD include pain, loose and watery stools (diarrhoea), feeling tired, mouth sores, and weight loss. CD symptoms can come and go, with periods of few or no CD symptoms (called remission) between periods of CD symptoms. Researchers want to learn if tulisokibart, the study medicine, can treat CD. The goals of this study are to learn if more people who receive tulisokibart will go into remission (CD symptoms go away) or respond (CD symptoms lessen or go away) to treatment compared to those who receive placebo (looks like the study medicine but has no study medicine in it). Using a placebo helps researchers better understand the effects of a study treatment. About 1,200 people with active, moderate to severe CD will be in the study. They will be ages 16 to 75 years and:• Have moderate to severe CD based on symptoms, physical examinations, and lab tests• Have had CD for at least 3 months• Have taken other medicines that either did not help their CD or they did not tolerate the medicine• Do not have ulcerative colitis or another type of IBD People will receive one or both treatments: • Tulisokibart, the study medicine, at different dose levels (amounts) • Placebo Both MK-7240 and placebo will be administered as intravenous (IV) infusion or as an injection.This study is made up of 2 studies (Study 1 and Study 2). For both studies, people whose CD symptoms lessen after treatment may continue to receive treatment with tulisokibart for another 3 years (called an extension).Participants will give samples (blood, urine, stool, and colon tissue), have physical examinations, answer questions, and have imaging tests.Participants may be in the study for about 4 years.