This study was planned as a Phase II/III seamless, multicenter, randomized, double-blind, placebo-controlled study in patients with AS who were naïve to TNF antagonist therapy. The study consisted of 2 parts, each preceded by a screening visit and followed by a common open-label extension phase. Recruitment into Part 2 commenced after completion of enrollment for Part 1.
Part 1 was designed as a Phase II study exploring the efficacy and safety of tocilizumab therapy versus placebo. Part 1 was intended to determine whether Part 2 of the study would continue, based on a Week 12 analysis.
Part 2 was designed to provide pivotal Phase III efficacy and safety data for tocilizumab in patients with AS. Approximately 400 patients were to be enrolled. Once randomization into Part 1 was complete, randomization into Part 2 of the study was to be initiated.
Based on the results of the Week 12 Part 1 analyses of the primary endpoint (ASAS20) and secondary endpoints, and in consideration of all available safety data, a benefit/risk assessment was made and it was decided to halt the study because of lack of overall efficacy. Most patients did not complete the 24-week double-blind treatment period in Part 2.
