BACKGROUND:Patients with moderately-to-severely active ulcerative colitis (UC) are unlikely to continue anti-TNF therapy in the absence of early therapeutic response. AIM:To assess week 52 efficacy, safety and benefit/risk balance of adalimumab treatment in patients with moderately-to-severely active UC failing conventional therapy who achieved clinical response at week 8 in the 52-week ULTRA 2 trial. METHODS:Patients randomised to adalimumab (160/80 mg, week 0/2; 40 mg, every other week thereafter) in ULTRA 2 who achieved clinical response at week 8 per partial Mayo score (Mayo score without endoscopy subscore) were assessed for week 52 clinical remission, clinical response, mucosal healing, steroid-free remission and steroid discontinuation rates, overall and by prior anti-TNF use. Benefit/risk balance for the overall ITT population (regardless of week 8 responder status) was assessed using 'net efficacy adjusted for risk' (NEAR) odds ratios. Safety was assessed using adverse event rates. RESULTS:Of 248 adalimumab-treated patients, 123 (49.6%) achieved clinical response at week 8. Of these, 30.9%, 49.6%, and 43.1% achieved clinical remission, clinical response, and mucosal healing, respectively, at week 52. Of the week 8 responders using corticosteroids at baseline (N = 90), 21.1% achieved steroid-free remission and 37.8% were steroid-free at week 52. NEAR odds ratios indicated a positive benefit/risk balance for achievement of week 8 and week 52 response or remission without serious adverse events or serious infections. No safety concerns were identified. CONCLUSIONS:Adalimumab treatment was associated with a positive benefit/risk balance in the overall population of patients with moderately-to-severely active ulcerative colitis in ULTRA 2; early response was predictive of a positive outcome at 1 year (NCT00408629).