Background Over the past decade, the introduction of biologics has significantly changed the management of rheumatoid arthritis (RA) and ankylosing spondylitis (AS). However, the high cost of biologics imposes limits on their use, particularly in developing countries. The development and commercialization of biosimilars can help address unmet medical needs by improving access to well-established therapeutic interventions while improving healthcare affordability. Biosimilar infliximab (CT-P13) was the first monoclonal antibody biosimilar approved in the EU.

Objectives To demonstrate the safety and effectiveness of CT-P13 when administered in a real-life setting in adults with active RA or AS.

Methods This multicenter, non-interventional, observational study was conducted in Romania, Czech Republic, Poland, Bulgaria and Latvia in patients with active RA with an inadequate response to methotrexate (MTX) or other DMARDs, or active AS with inadequate response to NSAIDs. Patients received CT-P13 at baseline (visit 1), weeks 2 (visit 2), 6 (visit 3), and between weeks 12 and 14 (visit 4: month 3). Dosages were established according to CT-P13 SPC. Safety was assessed by early dropouts and adverse events (AEs). Effectiveness was assessed at baseline and visit 4 (month 3) using the Disease Activity Score (DAS28) for RA patients and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) for AS patients.

Results By January 1st 2016, 122 subjects (49% male, mean [SD] age 48.2 [14.6] years) have been enrolled in the study, with a median follow-up of 165 days. At visit 4 (month 3), mean (SD) CT-P13 doses were 246 (52) mg/3.3 (0.6) mg/kg for RA, and 372 (82) mg/5.1 (0.5) mg/kg for AS. A total of 20 AEs were recorded: 4 definitely related, 3 possibly related, and 13 unrelated to CT-P13 treatment. Among these AEs, 2 were serious (a spontaneous pneumothorax, unrelated to CT-P13, and a dyspnea due to allergic infusion reaction, definitely related to CT-P13; both resolved without sequelae) and a total of 4 dropouts were reported due to AEs (3 definitely-related allergic infusion reactions and 1 possibly related). Currently, 59 patients (RA: 26; AS: 33) have baseline and follow-up primary effectiveness measurements at month 3. Patients who terminated the study prematurely were excluded from effectiveness analyses. After 3 months of CT-P13 treatment, patients showed significant improvements in disease activity relative to baseline in terms of DAS28 (baseline: mean [SD]=6.7 [1.1], month 3: mean [SD]=2.7 [1.4]; t=8.1, df=25, p<0.0001, Cohen's d=2.5) and BASDAI (baseline: mean [SD]=6.5 [1.7], month 3: mean [SD]=2.8 [2.1]; t=10.5, df=32, p<0.0001, Cohen's d=2.0). Patients with RA (baseline: mean [SD]=23 [16.3], month 3: mean [SD]=9.3 [19.8]; t=2.5, df=25, p=0.02, Cohen's d=0.9) or AS (baseline: mean [SD]=26.7 [26.3], month 3: mean [SD]=5.5 [8.6]; t=5, df=38, p<0.0001, Cohen's d=1.2) also showed a significant decrease in C-reactive protein (CRP) levels after 3 months of treatment.

Conclusions Biosimilar infliximab (CT-P13) is safe and effective in a real-life setting in patients with RA or AS.

Disclosure of Interest None declared