Background: Tumour necrosis factor-a (TNFa) inhibitors are one of the most used biological therapy for rheumatoid arthritis (RA) patients without response to conventional disease-modifying antirheumatic drugs (cDMARDs). There is scarce information about biological DMARDs (bDMARDs) effectiveness as monotherapy in real life.

Objectives: To assess the effectiveness of Certolizumab pegol in real-life clinical practice in a cohort of patients with RA and previous failure to cDMARDs who received certolizumab as monotherapy, combined with Methotrexate (MTX), combined with leflunomide (LFN), or both MTX and LFN.

Methods: A retrospective cohort study was conducted at a specialized center for RA management in Colombia. Patients treated with Certolizumab as monotherapy or in combination with MTX, or LFN, or both MTX plus LFN, (2012 – 2020) were included. The indication of certolizumab was a independent decision based on disease activity. Patients could be taking adjuvant medications for pain and/or corticosteroids. Certolizumab was administered 400 mg SC monthly after three induction doses at weeks 0, 2 y 4, as monotherapy or in combination with MTX (until 25 mg/week), LFN (20 mg/day) or both as a first-line treatment after failure with cDMARDs or as a second-line treatment after failure with one or more bDMARDs. Effectiveness was assessed at three, six, and twelve months according to the change in DAS28. Exploratory comparisons of numeric variable data between groups were done (ANOVA). Chi-square test and Fisher’s exact test were used for categorical variables. Multivariate analyses (logistic regressions) were performed to analyse factors related to the response at 6 and 12 months.

Results: Of 181 enrolled patients, 24 received certolizumab as monotherapy, 62 combined with MTX, 47 in combination with LFN and 48 in combination with MTX and LFN. 55.2% of patients were first-line treatment, without significant differences between groups. Mean age of subjects included was 57.87 ± 12.33 with a mean age of around 60 years in patients treated with CERTO+MTX and CERTO+LFN (p=0,014). Women predominated in all groups (84% of the total) (p=0,275). The duration of arthritis on average was 8.27 ± 8.73 years, without significant differences between treatment groups (p=0,871). In terms of disease activity, 78.5% of patients were in moderate or high disease activity, according to DAS28, without significant differences between the groups (p=0,787). Differences in the number of biologicals and corticoid use were observed, patients in the combination groups had used in a higher proportion two or more biological (p=0,046) than in the monotherapy group and had used corticosteroids (p=0,042) more frequently. Overall, there were decreased disease activity, at 3 and 6 months with no significant differences between groups (p=0,08). At 12 months of treatment, there was a higher maintenance in mild activity/remission response in monotherapy group compared to the others (p=0,01). In the multivariate analysis, no differences were observed in the response at 6 and 12 months between the treatment groups. The response at three months was the only variable associated with the 6-month response (OR 5.46; CI 95% 2.08 – 14.32). The response at three months (OR 4.04; CI 95% 1.28-12.69) and positive anti-CCP (OR 3.83; CI 95% 1.11-13.21) were associated with 12-month response.

Conclusion: These exploratory results show a clear trend of Certolizumab being effective as monotherapy in patients previously treated with cDMARDs and even after being treated with one bDMARD. Although results are not statistically different, it seems that certolizumab in monotherapy could be as least as effective as combination therapy. Prospective studies with larger sample size and with a structured follow-up are needed to confirm these findings.

Disclosure of Interests: Paola Osorio: None declared, Laura Villarreal: None declared, Wilberto Rivero: None declared, Linda Ibata: None declared, Susan Martinez: None declared, Adriana Rojas-Villarraga: None declared, Pedro Santos-Moreno Speakers bureau: has received fees for conferences from: Abbvie, Abbott, Biopas-UCB, Bristol, Janssen, Pfizer, Roche, Sanofi, Consultant of: has received fees for counseling, advisory boards from: Abbvie, Abbott, Biopas-UCB, Bristol, Janssen, Pfizer, Roche, Sanofi, Grant/research support from: has received fees for research grants from: Abbvie, Abbott, Biopas-UCB, Bristol, Janssen, Pfizer, Roche, Sanofi