Background Switching patients from originator infliximab (IFX) to biosimilar IFX can reduce healthcare costs. Several studies have shown that switching does not affect the efficacy for rheumatoid arthritis (RA) patients(1,2), however prospectively collected data on pharmacokinetics, immunogenicity and quality of life (QoL) is scarce. Objectives We report data collected from RA patients in clinical remission enrolled in the SECURE study (IFX4501; registered at www.clinicaltrialsregister.eu 2014-004904-31). In SECURE we collected IFX serum concentrations, efficacy, quality of life (QoL) and safety data of patients switched from originator IFX to biosimilar IFX CT-P13 for up to 16 weeks. The IBD cohort of this study has been published elsewhere (3). Methods In this prospective, open-label, interventional, non-inferiority, multi-center, phase IV trial, adult RA patients in clinical remission >30 weeks (DAS Results Between July 2015 and December 2016, 34 RA patients were recruited. Two patients were excluded from the safety population (1 no IMP exposure; 1 no efficacy assessment) and two patients discontinued before week 16 (1 AE: renal colic; 1 personal reasons), leaving 30 patients in the intent to treat population. For 11 patients, blood samples were obtained at baseline and week 16. The IFX ratio at week 16 (biosimilar) compared to baseline (originator) was 107.40 (90% CI 90.35;127.66), indicating non inferiority. The number of included patients was too low for firm conclusions. The mean difference (95% CI) at week 16 compared to baseline was for the CRP -0.22 (-1.80,1.37); for DAS 0.12 (-0.06,0.30), for EQ5D thermometer -3.19 (-9.78,3.41) and EQ5D Health status -0.05 (-0.08,-0.01). These changes were not clinical relevant. In total 76 AEs were reported by 29 (90.6%) patients; 27 of these AEs were related to the study treatment. The most frequently reported AEs (≥5% subjects) were fatigue (9.4%), headache (6.3%), arthralgia (15.6%), back pain (9.4%), cough (6.3%), viral upper respiratory tract infection (15.6%) bursitis (6.3%) and pain in extremity (6.3%). Two non-related serious AEs were reported (ovarian cyst and benign parathyroid tumour). No ADA’s were detected by inclusion or during the follow-up period. Conclusion In this prospective, interventional study in RA patients in clinical remission there were no clinically relevant changes in clinical and biochemical efficacy, quality of life and tolerability 16 weeks after switching to the biosimilar IFX CT-P13 compared to the originator. This study is sponsored by Mundipharma Pharmaceuticals BV. References [1] Park, W. et al. Ann Rheum Dis76,346-354 (2017) [2] Jorgensen, K.K. et al. Lancet389, 2304-2316 (2017) [3] Strik, A.S. et al. Lancet Gastroenterol & Hepatol6(3),404-412 (2018) Disclosure of Interests Michael Nurmohamed Grant/research support from: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Menarini, MSD, Mundipharma, Pfizer, Roche, Sanofi and UCB, Consultant for: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Menarini, MSD, Mundipharma, Pfizer, Roche, Sanofi and UCB, Speakers bureau: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Menarini, MSD, Mundipharma, Pfizer, Roche, Sanofi and UCB, Reinhard Bos Grant/research support from: SUN Pharma, Marc Kok: None declared, Lindy-Anne Korswagen: None declared, Petra Vos: None declared, Joanne Bloemsaat Employee of: Mundipharma Pharmaceuticals B.V, Theo Rispens Grant/research support from: Genmab, Speakers bureau: Pfizer, Abbvie, Regeneron, Yvonne van Megen Employee of: Mundipharma Pharmaceuticals B.V, Gerard D’Haens Consultant for: Abbvie, Ablynx, Amakem, Amgen, AM Pharma, Avaxia, Biogen, Bristol Meiers Squibb, Boerhinger Ingelheim, Celgene/Receptos, Celltrion, Cosmo, Covidien/Medtronics, Ferring, DrFALK Pharma, Eli Lilly, Engene, Galapagos, Genentech/Roche, Gilead, Glaxo Smith Kline, Immunic, Johnson and Johnson, Lamepro, Lycera, Medimetrics, Millenium/Takeda, Mitsubishi Pharma, Merck Sharp Dome, Mundipharma, Nextbiotics, Novonordisk, Otsuka, Pfizer/Hospira, Prometheus laboratories/Nestle, Protagonist, Robarts Clinical Trials, Salix, Samsung Bioepis, Sandoz, Setpoint, Shire, Teva, Tigenix, Tillotts, Topivert, Versant and Vifor; received speaker fees from Abbvie, Biogen, Ferring, Johnson and Johnson, Merck Sharp Dome, Mundipharma, Norgine, Pfizer, Samsung Bioepis, Shire, Millenium/Takeda, Tillotts and Vifor.