Background The efficacy and safety of certolizumab pegol in the treatment of adult patients with moderate to severe rheumatoid arthritis (RA), when administered either in combination with methotrexate (MTX) or as monotherapy, has been previously shown in several controlled clinical trials. However, a detailed assessment of certolizumab pegol in combination with a wide range of non-biologic disease-modifying drugs (nbDMARDs) used in real-life routine clinical practice is lacking compared to switching to monotherapy after achieving a response when added to nbDMARD(s).

Objectives The objective is to compare the effectiveness and tolerability of certolizumab pegol given as add-on to nbDMARDs, including MTX and others, or as monotherapy after achieving a DAS28(ESR) improvement of ≥1.2 In this descriptive interim analysis, preliminary data on the effectiveness of certolizumab pegol given in combination nbDMARDs or monotherapy, are presented.

Methods RA patients who had certolizumab pegol added to their existing DMARD regimen due to inadequate response to their nbDMARD(s) were eligible. At 3 or 6 months, those patients who achieved a change in DAS28 of ≥1.2 were randomized to continue combination therapy (Combination group) or withdraw nbDMARD therapy (Monotherapy group) and be followed for 18 months. A sample size of 125 randomized patients per group was calculated to have 100 randomized (50 per group) to find a difference of 15% in response.

Results A total of 121 patients were enrolled, of whom 79 were randomized to continue combination therapy (n=35) or withdraw nbDMARDs (n=44). No significant differences were observed between-groups in baseline age, gender (83% vs. 71% female), race (89% vs. 91% Caucasian), rheumatoid factor status (56% vs. 60% positive), or prior biologic experience (17% vs. 11%).

At 18 months, upon adjusting for baseline scores, similar improvements were observed between groups in DAS28 ESR (-2.1 vs. -2.0). Furthermore, the odds of achieving DAS28 LDA (OR [95% CI]: 0.96 [0.28–3.31]), ΔDAS28>1.2 (0.97 [0.29–3.26]), or both (1.00 [0.29–1.49]), were not different between the Combination and Monotherapy groups. Similarly, no differences were observed between groups at 12 months of treatment with respect to these outcomes.

Conclusions The results of this interim analysis suggest that, among RA patients achieving a therapeutic response when on combination therapy with certolizumab pegol and nbDMARDs, nbDMARDs could be withdrawn without impact on treatment effectiveness over the next year. Additional analyses with the full number of patients will be conducted to confirm this finding.

Disclosure of Interest None declared