A Study to Evaluate the Efficacy and Safety of Ustekinumab in the Treatment of Anti-TNFα Naive Participants With Active Radiographic Axial Spondyloarthritis

This is a Phase 3, multicenter (when more than one hospital or medical school team work on a medical research study), randomized (study medication assigned to participants by chance), double-blind (neither the researchers nor the participants know what treatment the participant is receiving), placebo-controlled (an inactive substance; a pretend treatment \[with no drug in it\] that is compared in a clinical trial with a drug to test if the drug has a real effect) study. The study consists of 3 phases; Screening (up to 8 weeks), Treatment phase: placebo-controlled (Week 0 to 24) and active treatment (Week 24 to Week 100), and Safety Follow-up (12 weeks after last dose). Participants will be randomly assigned to 1 of 3 treatment groups: placebo, ustekinumab 45 mg and ustekinumab 90 mg. The total duration of study will be up to 112 weeks. Participants will be primarily assessed for Assessment of SpondyloArthritis International Society (ASAS) 40 response at Week 24. Participants' safety will be monitored throughout the trial.