The Adalimumab Trial Evaluating Long-Term Efficacy and Safety in Ankylosing Spondylitis (AS) or ATLAS trial was a double-blind, phase III, placebo-controlled study to evaluate the ability of adalimumab to reduce signs and symptoms of AS over a one-year period. Patients with active AS refractory to at least one NSAID were given 40 mg adalimumab bi-weekly or placebo for 24 weeks.

Adalimumab efficacy was evaluated by ASsessment in AS (ASAS) 20 Criteria (inflammation, total back pain, function, and patient's global assessment of disease activity). The primary endpoint (ASAS20) was at Week 12, at which point patients had the option to switch to early escape therapy (EET) of open-label 40 mg adalimumab. One-year efficacy of ADA was assessed using the following analyses: 1) a non-responder imputation to Week 52 for patients using EET (any EET patients and dropouts were considered nonresponders), 2) observed data for all patients from baseline, and 3) observed data for only EET patients during the entire 1-year period.

Signs and symptoms of AS were reduced in patients treated with adalimumab in the first 12 weeks and improvements were sustained for 52 weeks. There were 66 placebo patients at week 12, 7 at week 16, and 2 at week 20 that switched to EET. By week 52, 88.6% of the patients remained in the study.