Safety and Efficacy Study of JNJ-64304500 in Participants With Moderately to Severely Active Crohn's Disease

Inclusion Criteria:

- Have Crohn's disease or fistulizing Crohn's disease of at least 3 months' duration,
with colitis, ileitis, or ileocolitis, confirmed at any time in the past by
radiography, histology, and/or endoscopy

- A woman of childbearing potential must have a negative highly sensitive serum
(beta-human chorionic gonadotropin [b-hCG]) pregnancy test result at screening and a
negative urine pregnancy test result at Week 0

- Adhere to the following requirements for concomitant medication for the treatment of
Crohn's disease, which are permitted provided that doses meeting these requirements
are stable, or have been discontinued, for at least 3 weeks before baseline (Week 0),
unless otherwise specified: a) Oral 5-aminosalicylic acid (5-ASA) compounds, b) Oral
corticosteroids at a prednisone-equivalent dose at or below 40 milligram per day
(mg/day), or 9 mg/day of budesonide, or 5 mg/day beclomethasone dipropionate, c)
Antibiotics being used as a primary treatment of Crohn's disease, d) Conventional
immunomodulators (that is, azathioprine (AZA), 6-mercaptopurine (6-MP), or
Methotrexate (MTX)): participants must have been taking them for at least 12 weeks and
at a stable dose for at least 4 weeks before baseline

- A participant who has had extensive colitis for greater than or equal to (>=) 8 years,
or disease limited to the left side of the colon for >= 12 years, must either have had
a colonoscopy to assess for the presence of dysplasia within 1 year before the first
administration of study agent or a colonoscopy to assess for the presence of
malignancy at the screening visit, with no evidence of malignancy

- Have active Crohn's disease, defined as a baseline Crohn's Disease Activity Index
(CDAI) score of >= 220 but <= 450

Exclusion Criteria:

- Participants who have received intravenous (IV) corticosteroids less then (<)3 weeks
or have received tumor necrosis factor-alpha (TNF-alpha) antagonist biologic agents
(example, monoclonal antibody [mAb] therapies) or other agents intended to suppress or
eliminate tumor necrosis factor-alpha (TNF-alpha) <8 weeks or have received
Vedolizumab <16 weeks before the first administration of study drug

- Woman who is pregnant or planning pregnancy or is a man who plans to father while
randomized in the study or within 16 weeks after the last administration of study
agent

- Participants with certain complications of Crohn's disease that would make it hard to
assess response to study drug

- Participants with a history of or ongoing chronic or recurrent infectious disease

- Has previously received a biologic agent targeting interleukin (IL)-12 or IL-23,
including but not limited to ustekinumab or briakinumab (ABT-874)