Efficacy and Safety of Adalimumab in Patients with Ankylosing Spondylitis: Results of a Multicenter, Randomized, Double-blind, Placebo-controlled Trial

Objective: To evaluate the safety and efficacy of adalimumab, a fully human recombinant IgG1 monoclonal antibody that specifically targets human tumor necrosis factor, in patients with active ankylosing spondylitis (AS).

Methods: This was a multicenter, randomized (2:1 ratio), double-blind, placebo-controlled study to evaluate a subcutaneous injection of adalimumab, 40 mg every other week, compared with placebo for 24 weeks. The primary efficacy end point was the percentage of patients with a 20% response according to the ASsessment in Ankylosing Spondylitis International Working Group criteria for improvement (ASAS20) at week 12. Secondary outcome measures included the ASAS20 at week 24 and multiple measures of disease activity, spinal mobility, and function, as well as ASAS partial remission.

Results: At week 12, 58.2% of adalimumab-treated patients (121 of 208) achieved an ASAS20 response, compared with 20.6% of placebo-treated patients (22 of 107) (P < 0.001). More patients in the adalimumab group (45.2% [94 of 208]) than in the placebo group (15.9% [17 of 107]) had at least a 50% improvement in the Bath Ankylosing Spondylitis Disease Activity Index at week 12 (P < 0.001). Significant improvements in the ASAS40 response and the response according to the ASAS5/6 criteria at weeks 12 and 24 were also demonstrated (P < 0.001). Partial remission was achieved by more adalimumab-treated patients than placebo-treated patients (22.1% versus 5.6%; P < 0.001). Adalimumab-treated patients reported more adverse events (75.0% versus 59.8% of placebo-treated patients; P < 0.05), but there was no statistically significant difference in the incidence of infections. Most adverse events were mild or moderate in severity.

Conclusion: Adalimumab was well-tolerated during the 24-week study period and was associated with a significant and sustained reduction in the signs and symptoms of active AS.