A Study to Evaluate Efficacy and Safety of Tulisokibart (MK-7240) in Participants With Moderately to Severely Active Ulcerative Colitis (MK-7240-001)

Inclusion Criteria:

• Has had ulcerative colitis (UC) (from onset of symptoms) for at least 3 monthsbefore randomization

• Has moderately to severely active UC

• Weight ≥40 kg

• Satisfies at least 1 of the following criteria:

• Has had an inadequate response or loss of response to 1 or moreprotocol-specified UC treatments

• Protocol specified corticosteroid dependence

• Has been intolerant to 1 or more protocol-specified UC treatments

• Is on treatment with any protocol-specified drugs during the study and meets drugstabilization requirements, as applicable

• Adolescent participants ≥16 and <18 years of age can participate if approved by thecountry or regulatory/health authority

• A participant assigned female sex at birth is eligible to participate if notpregnant or breastfeeding and Is not a participant of childbearing potential (POCBP); or is a POCBP and uses an acceptable contraceptive method, or is abstinentfrom penile-vaginal intercourse as their preferred and usual lifestyle (abstinent ona long-term and persistent basis), has a negative highly sensitive pregnancy test (urine or serum) as required by local regulations within 24 hours (for a urine test)or 72 hours (for a serum test) before the first dose of study intervention, medicalhistory, menstrual history, and recent sexual activity has been reviewed by theinvestigator to decrease the risk for inclusion of a POCBP with an early undetectedpregnancy

Exclusion Criteria:

• Has a diagnosis of Crohn's Disease (CD) or indeterminate colitis (inflammatory boweldisease (IBD)-undefined) or other types of colitis or enteritis that may confoundefficacy assessment.

• Has a current diagnosis of fulminant colitis and/or toxic megacolon

• Has UC limited to the rectum (i.e, must have evidence of UC extending beyond therectosigmoid junction, which is ~10 cm from the anal margin)

• Has a current or impending need for colostomy or ileostomy

• Has had a total proctocolectomy or partial colectomy

• Has received fecal microbial transplantation within 4 weeks before randomization

• Has had UC exacerbation requiring hospitalization within 2 weeks before screening

• Has prior or current evidence of definite colonic dysplasia except for low-gradedysplasia that has been completely removed

• Has any active or serious infections without resolution after adequate treatment

• Has had cytomegalovirus infection that resolved less than 4 weeks before screening

• Has a transplanted organ which requires continued immunosuppression

• Has a history of cancer (except fully treated non-melanoma skin cell cancers orcervical carcinoma in situ after complete surgical removal) within the last 5 years

• Is known to be infected with hepatitis B virus (HBV), hepatitis C virus (HCV), orhuman immunodeficiency virus (HIV)

• Has evidence of active tuberculosis (TB), latent TB not successfully treated (perlocal guidelines), or inadequately treated TB (for participants with history of TB)

• Has confirmed or suspected COVID-19

• Has a history of drug or alcohol abuse within 6 months prior to screening

• Has had major surgery within 3 months before screening or has a major surgeryplanned during the study

• Is currently receiving or is planning to receive total parenteral nutrition at anytime during study treatment

• Has received UC-related antibiotics and has not been on stable doses for at least 14days before randomization or has discontinued these medications within 14 days ofrandomization

• Requires treatment with a therapy that does not adhere to the protocol-specifiedguidance parameters

• Has received protocol-specified prohibited medications

• Has had prior exposure to tulisokibart or another anti-tumor necrosis factor-likecytokine 1A (TL1A) antibody