Efficacy and Safety of Tofacitinib in Ankylosing Spondylitis by Baseline C-Reactive Protein Level: Post Hoc Analysis of Phase II and Phase III Clinical Trials.

Regardless of baseline CRP, TOF was more efficacious vs placebo at week 12. The placebo-adjusted efficacy and PRO responses were generally numerically higher in patients with CRP ≥ 5 mg/L and ≥ 10 mg/L vs < 5 mg/L and < 10 mg/L. The higher concomitant NSAID/SSZ exposure may have improved efficacy responses in the baseline < 5 mg/L placebo group, and ultimately affected the TOF treatment effect. Safety was consistent with previous studies of TOF use in AS, with numerically higher incidence rates for TEAEs and "all infections" for TOF vs placebo in patients with CRP < 5 mg/L.