The purpose of this study is to assess the effect of vedolizumab subcutaneous (vedolizumab SC) as maintenance treatment in participants with moderately to severely active CD who achieved clinical response following administration of vedolizumab intravenous (vedolizumab IV) induction therapy.

The drug being tested in this study is called vedolizumab SC. Vedolizumab SC is being tested to treat people who have moderate to severely active CD. This study will look at clinical remission, as well as enhanced clinical response and corticosteroid-free remission in participants with CD who receive vedolizumab SC maintenance therapy after having achieved a clinical response to vedolizumab IV induction therapy.

The study will enroll approximately 824 participants. All participants will enter a 6 week Induction Phase where they will be administered open-label vedolizumab IV 300 mg via IV infusion at Week 0 (Day 1) and Week 2 (Day 15), and will then be assessed for a clinical response at Week 6. Participants who achieve a clinical response at Week 6 will be randomly assigned to one of the two treatment groups:

• Vedolizumab SC 108 mg Maintenance Arm
• Placebo SC Maintenance Arm

Participants who do not achieve a clinical response will not be randomized into the Maintenance Period, and instead will receive a third infusion of vedolizumab IV 300 mg at Week 6.

This multi-center trial will be conducted worldwide. The overall time to participate in this study is up to 71 weeks. Participants will make multiple visits to the clinic, plus a final visit 18 weeks after last dose of study drug for a follow-up assessment. Participants will also participate in a long-term safety follow-up, by phone, at 6 months after the last dose of study drug.

Inclusion Criteria:

1. Diagnosis of CD established at least 3 months prior to screening by clinical and endoscopic evidence corroborated by a histopathology report.

2. Moderately to severely active CD as determined by a CDAI score of 220 to 450 and 1 of the following:

   • C-reactive protein (CRP) level greater than (>) 2.87 milligram per liter (mg/L) OR
   • Ileocolonoscopy with photographic documentation of a minimum of 3 nonanastomotic ulcerations (each >0.5 centimeter [cm] in diameter) or 10 aphthous ulcerations (involving a minimum of 10 contiguous cm of intestine) consistent with CD OR
   • Fecal calprotectin >250 microgram per gram (mcg/g) stool during the screening period in conjunction with computed tomography enterography (CTE), magnetic resonance enterography (MRE), contrast-enhanced small bowel radiography, or wireless capsule endoscopy revealing CD ulcerations (aphthae not sufficient).

3. CD involvement of the ileum and/or colon, at a minimum.

4. Inadequate response with, loss of response to, or intolerance to corticosteroids, immunomodulators, or Tumor necrosis factor-alpha (TNF-α) antagonists.

Exclusion Criteria:

1. Evidence of abdominal abscess at Screening.
2. Extensive colonic resection, subtotal or total colectomy.
3. History of >3 small bowel resections or diagnosis of short bowel syndrome.
4. Ileostomy, colostomy, or known fixed symptomatic stenosis of the intestine.
5. Prior exposure to investigational or approved non-biologic therapies (example, cyclosporine, tacrolimus, thalidomide, or tofacitinib) for the treatment of underlying disease within 30 days or 5 half-lives of screening (whichever is longer).
6. Prior exposure to any investigational or approved biologic or biosimilar agent within 60 days or 5 half-lives of screening (whichever is longer).
7. Prior exposure to vedolizumab.
8. Surgical intervention for CD required at any time during the study.
9. History or evidence of adenomatous colonic polyps that have not been removed, or of colonic mucosal dysplasia.
10. Suspected or confirmed diagnosis of ulcerative colitis, indeterminate colitis, ischaemic colitis, radiation colitis, diverticular disease associated with colitis, or microscopic colitis.
11. Active infections.
12. Chronic hepatitis B virus (HBV) or C (HCV) infection, tuberculosis (TB) (active or latent), or congenital or acquired immunodeficiency. HBV immune participants (that is, being hepatitis B surface antigen [HBsAg] negative and hepatitis B antibody positive) may, however, be included.
13. History of any major neurological disorders, including stroke, multiple sclerosis, brain tumor, or neurodegenerative disease.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/ For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.