The objective of this trial was to compare effectiveness of certolizumab pegol added to conventional synthetic DMARDs (csDMARDs) in RA patients, followed by continuing vs discontinuing background csDMARDs after treatment response.
Patients with active RA who had certolizumab pegol added to their existing csDMARD regimen due to inadequate response were eligible. At 3 or 6 months, patients who achieved a change (Δ) in DAS28 of ⩾1.2 were randomized to continue combination therapy (COMBO) or withdraw csDMARD therapy (MONO) (unblinded). The primary outcome was non-inferiority of stopping vs continuing csDMARD(s) in terms of maintaining ΔDAS28 ⩾ 1.2 or achieving DAS28 low disease activity at 18 months (non-inferiority margin: 15 percentile units).
A total of 125 patients were enrolled, 88 randomized to COMBO (n = 43) or MONO (n = 45). No significant differences were observed between groups in baseline age, gender, race, RF status or prior biologics (16% vs 11%). Although the rate of ΔDAS28 ⩾ 1.2 and/or DAS28 low disease activity achievement at 18 months was clinically comparable between the two groups (72% vs 69%), non-inferiority assumptions were not met [absolute risk difference (upper limit of 90% CI): 2.6% (19.1%)]. Similar baseline-adjusted improvements were seen in DAS28 (COMBO vs MONO: -2.3 vs -2.1; P = 0.49) and all endpoints were not statistically different including 59% vs 56% achieved DAS28 low disease activity, 69% vs 59% ΔDAS28 ⩾ 1.2, and 41% each remission.
Among RA patients achieving a therapeutic response on combination therapy with certolizumab pegol and csDMARDs, withdrawing csDMARDs was not non-inferior to maintaining csDMARDs but improvements were sustained in both groups at 18 months.