The main purpose of this study is to evaluate the efficacy and safety of mirikizumab and placebo compared with mirikizumab and concomitantly administered tirzepatide in adult participants with moderately to severely active CD and obesity, or overweight.

The maximum duration of this study is up to 61 weeks.

Inclusion Criteria:

• Have a confirmed diagnosis of Crohn's disease (CD) or perianal fistulizing CD

• Have obesity body mass index 30 kilograms per meter squared (BMI ≥30 kg/m²), or overweight (BMI ≥27 kg/m2 to <30 kg/m²) and in the presence of at least 1 weight-related comorbid conditions:

  • hypertension
  • Type 2 diabetes mellitus (T2DM)
  • dyslipidemia
  • obstructive sleep apnea, or
  • cardiovascular disease.

• Have moderately to severely active CD defined by a CDAI score of at least 220 at baseline.

• Have a centrally read Simple Endoscopic Score for Crohn's Disease (SES-CD) score ≥6 for patients with ileal-colonic or ≥4 for patients with isolated ileal disease within 21 days before the first dose of study treatment.

• Participants with a history of CD for ≥8 years involving only or predominantly the colon must have documented negative results for colorectal dysplasia and cancer within 1 year prior to baseline.

• Demonstrated inadequate response, loss of response or intolerance to at least one protocol-specified conventional or advanced CD therapy

Exclusion Criteria:

• Have a current diagnosis of Ulcerative Colitis (UC), inflammatory bowel disease-unclassified (formerly known as indeterminate colitis), or primary sclerosing cholangitis.
• Have more than 2 missing segments of the following 5 segments: terminal ileum, ·right colon, transverse colon, ·left colon, and rectum.
• Currently have or are suspected to have an abscess.
• Have a stoma, ileoanal pouch, or ostomy.
• Have a history of more than 3 small bowel resections, total resection of small bowel greater than 100 centimeters (cm), diagnosis of short bowel syndrome, or any intestinal or non-intestinal intra-abdominal surgery within 3 months of baseline.
• Have a diagnosis of Type 1 Diabetes Mellitus (T1DM) or have insulin-treated T2DM.
• Have a history of severe hypoglycemia and/or hypoglycemia unawareness within the 6 months prior to screening.
• Have had more than 5% body weight change in the past 3 months
• Have a current or recent acute, active infection.

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication and approval of the indication studied in the US and EU, whichever is later. Data will be indefinitely available for requesting.

A research proposal should be approved by an independent review panel and researchers should sign a data sharing agreement.

Mirikizumab will be open label, tirzepatide and placebo to match will be blinded.