Safety and Efficacy of Adalimumab Versus Ustekinumab for One Year

The purpose of this study is to compare the efficacy of treatment with ustekinumab or adalimumab in biologic naive participants with moderately-to-severely active Crohn's disease (CD) who have previously failed or were intolerant to conventional therapy (corticosteroids and/or immunomodulators, such as azathioprine, 6-mercaptopurine, or methotrexate), as measured by clinical remission at one year.

This study compares the safety and efficacy of ustekinumab versus adalimumab. It will consist of screening (within 1- 5 weeks prior to Week 0), treatment phase (Weeks 0 to 52), and follow-up phase (up to Week 76). The primary hypothesis is that ustekinumab is superior to adalimumab as measured by clinical remission after one year of treatment. Study assessments will include Crohn's disease activity index (CDAI), video ileocolonoscopy; CD-related healthcare utilization; patient-reported outcomes (PROs); laboratory evaluations; biomarkers; review of concomitant medications and adverse events (AEs); and evaluation of serum concentrations of study agent as well as development of antibodies to study agent. All participants will randomly be assigned to receive either ustekinumab or adalimumab. No participants will be treated with placebo only.

Eligibility Criteria:
Inclusion Criteria:

* Has Crohn's Disease (CD) or fistulizing CD of at least 3 months' duration, with colitis, ileitis, or ileocolitis, confirmed at some time in the past by radiography, histology, and/or endoscopy
* Has moderately-to-severely active CD with a baseline Crohn's disease activity index (CDAI) score of greater than or equal to (\>=) 220 and less than or equal to (\<=) 450
* Has one or more ulceration on screening ileocolonoscopy (which by definition, would result in an Simple Endoscopic Score for Crohn's Disease \[SES-CD\] of at least 3)
* Has failed or was intolerant to conventional therapy (corticosteroids, azathioprine \[AZA\], 6-mercaptopurine \[6-MP\] and/or methotrexate \[MTX\]) at adequate doses or is corticosteroid dependent
* Has not previously received an approved biologic for Crohn's Disease (i.e., infliximab, adalimumab, certolizumab pegol, ustekinumab, natalizumab, vedolizumab or approved biosimilars of these agents)
* Participants on oral corticosteroids (e.g., prednisone, budesonide) at a prednisone-equivalent dose of \<=40 or milligram/day (mg/day) or \<=9 mg/day of budesonide are budesonide \<=9 mg/day are permitted if doses are stable for 3 weeks prior to baseline
* Participants on AZA, 6-MP, or MTX at screening (or recently prior), must discontinue these medications at least 3 weeks prior to baseline

Exclusion Criteria:

* Has complications of CD that are likely to require surgery or would confound the ability to assess the effect of ustekinumab or adalimumab treatment using the CDAI, such as: active stoma; short-gut syndrome and severe or symptomatic strictures or stenosis
* Currently has, or is suspected to have, an abscess. Recent cutaneous and perianal abscesses are not exclusionary if drained and adequately treated at least 3 weeks prior to baseline, or 8 weeks prior for intra-abdominal abscesses, if there is no anticipated need for any further surgery. Participants with active fistulas may be included if there is no anticipation of a need for surgery and there are currently no abscesses present
* Has had any kind of bowel resection within 6 months prior to baseline or other intra-abdominal surgery or a hospital admission for bowel obstruction within 3 months prior to baseline
* Has a stool culture or other examination positive for an enteric pathogen, including Clostridium difficile toxin, in the last 4 months unless a repeat examination is negative and there are no signs of ongoing infection with that pathogen
* Has received a Bacillus Calmette-Guerin (BCG) vaccination within 12 months or any other live bacterial or live viral vaccination within 2 weeks of baseline
* Has a history of, or ongoing, chronic or recurrent infectious disease, including but not limited to, chronic renal infection, chronic chest infection, recurrent urinary tract infection (eg, recurrent pyelonephritis or chronic nonremitting cystitis), or infected skin wounds or ulcers