Comparison of Efficacy and Safety of Original and Biosimilar Adalimumab in Active Rheumatoid Arthritis in a Real-World National Cohort

Background and Objectives: Real-world evidence should reflect the evidence obtained from controlled trials; therefore, the study aimed to compare biosimilar adalimumab (bADA) to original adalimumab (oADA) in terms of efficacy and safety in a real-life national cohort of rheumatoid arthritis (RA) patients. Materials and Methods: The following study is a prospective observational study in which we analyzed patients treated with reimbursed biologics from the Romanian Registry of Rheumatic Diseases (RRBR). RA cases must fulfill the 2010 classification criteria, as well as specific inclusion and exclusion criteria. The RRBR database was queried for all RA patients starting oADA or bADA (FKB327, GP2017, MSB11022, SB5 available) from 2 May 2019 (the first bADA initiation) until 26 March 2022 (study search date). Results: The study included 441 patients who started oADA (48.3%) or bADA (51.7%) in the same time period. At baseline, patients starting bADA had a significantly higher mean age and lower prevalence of women. After the first six months of treatment, there were no significant differences between the oADA and bADA regarding rates of Boolean (15.0% vs. 12.3%, p = 0.401), DAS28-CRP (32.4% vs. 34.2%, p = 0.686) and SDAI (16.4% vs. 14.0%, p = 0.483) remission rates. There were 107 cases of adverse events (AE): 81.3% on oADA and 18.7% on bADA. Notably, 51.4% of AE were infections. Regarding severity, 49.5% of AEs were mild, 34.6% were moderate, and 15.9% were severe. Conclusion: Biosimilar adalimumab showed similar efficacy and safety to original adalimumab after the first six months of treatment in RA patients from a national registry.