A Study of the Efficacy and Safety of Guselkumab in Participants With Moderately to Severely Active Crohn's Disease

The purpose of this study is to evaluate the clinical efficacy (GALAXI 1), clinical and endoscopic efficacy (GALAXI 2 and GALAXI 3) and safety of guselkumab in participants with Crohn's disease.

Inclusion Criteria: * Have Crohn's disease (CD) or fistulizing Crohn's disease of at least 3 months duration (defined as a minimum of 12 weeks), with colitis, ileitis, or ileocolitis, confirmed at any time in the past by radiography, histology, and/or endoscopy * Have moderate to severe CD as assessed by CDAI, stool frequency (SF), and abdominal pain (AP) scores, and Simple Endoscopic Score for Crohn's Disease (SES-CD) * Have screening laboratory test results within the protocol specified parameters * A female participant of childbearing potential must have a negative urine pregnancy test result at screening and baseline * Demonstrated intolerance or inadequate response to conventional or to biologic therapy for CD Exclusion Criteria: * Current diagnosis of ulcerative colitis or indeterminate colitis * Has complications of Crohn's disease, such as symptomatic strictures or stenoses, short gut syndrome, or any other manifestation * Unstable doses of concomitant Crohn's disease therapy * Receipt of Crohn's disease approved biologic agents, investigational agents, or procedures outside of permitted timeframe as specified in the protocol * Any medical contraindications preventing study participation