A Study to Evaluate the Safety and Efficacy of Ustekinumab in Patients With Moderately to Severely Active Crohn's Disease Who Have Failed or Are Intolerant to Tumor Necrosis Factor (TNF) Antagonist Therapy (UNITI-1)

• Clinical Response [ Time Frame: Week 6 ] [ Designated as safety issue: No ]
  The number of patients in clinical response, as measured by the reduction from baseline in the Crohn's Disease Activity Index (CDAI), which is assessed by collecting information on extra-intestinal manifestations, abdominal mass, weight, hematocrit, total number of liquid stools, abdominal pain/cramping, use of antidiarrheal drug(s) and/or opiates, and general well-being.
  
  

• Clinical remission [ Time Frame: Week 8 ] [ Designated as safety issue: No ]
  The number of patients in clinical remission, as assessed by the CDAI.
  
  
• Clinical improvement/response [ Time Frame: Study visits through Week 8 ] [ Designated as safety issue: No ]
  The number of patients experiencing clinical response or improvement, as measured by the reduction from baseline in CDAI score.
  
  

This study (CNTO1275CRD3001 or "UNITI-1") examines ustekinumab (an antibody medication that inhibits the inflammatory proteins IL-12 and IL-23) versus a placebo (otherwise identical except without the ustekinumab antibody) given intravenously (by an IV) in adults with moderately to severely active Crohn's disease who previously did not respond to, lost response to, or could not tolerate TNF-antagonist medications (specifically, infliximab, adalimumab or certolizumab pegol). Ustekinumab (also known as Stelara) is approved as a treatment for the skin condition of moderate to severe plaque-type psoriasis, but this study will examine if ustekinumab can provide benefit in Crohn's disease and also assess for any risks or side effects. Both the positive and negative outcomes of IV placebo versus two different doses of IV ustekinumab will be tracked and compared over eight weeks, in approximately 703 patients. Patients enrolling in this study will be assigned to one of the 3 treatment groups by chance (randomly, like rolling dice), and all will receive a single IV administration of study agent at the first study visit (after the screening period), and then will be asked to return for 3 additional visits through Week 8. Patients who complete this study through the Week 8 visit and remain eligible can enter the maintenance study (CNTO1275CRD3003 or "IM-UNITI"), where they will receive additional study agent, including the administration of ustekinumab in patients who receive placebo in this study and have not had improvement in their Crohn's disease. Patients who do not enter the CNTO1275CRD3003 study will have a final safety follow-up visit approximately 20 weeks after they received study agent when they entered into this study at the Week 0 visit. .All patients will receive a single intravenous (IV) administration of study drug (either placebo or ustekinumab) at the first (week 0) visit when they enter the study.There are 3 treatment groups: Group 1: Placebo; Group 2: ustekinumab 130 mg, Group 3: weight-range based ustekinumab doses approximating ustekinumab 6 mg/kg: 260 mg (weight <= 55 kg), 390 mg (weight > 55 kg and <= 85 kg), and 520 mg (weight > 85 kg).