LAUSR

Background The first infliximab biosimilar (CT-P13) was introduced in Europe in 2014, followed by a rapid, but differential, uptake across the Nordic countries [1]. Pre and post-marketing randomized controlled trials have shown similar efficacy and safety of originator infliximab (INF) versus CT-P13, but a number of observational studies have indicated potential differences in long-term treatment retention. However, no large observational study has hitherto directly compared the treatment retention of INF with CT-P13 in bio-naïve patients with spondyloarthritis (SpA) starting infliximab during the same calendar-time period. Objectives To compare one- and two-year treatment retention of INF versus CT-P13 in SpA, when used as a first line biologic, and to explore baseline characteristics in the two cohorts. Methods Observational cohort study. Bio-naïve patients with ankylosing spondylitis (AS), non-radiographic axial SpA (nrax-SpA) or undifferentiated SpA (uSpA), starting INF or CT-P13 as their first ever TNFi during the time-period Jan 2014 through Jun 2017 were identified in biological registers in the five Nordic countries. SpA comorbidities were identified through linkage to national registers. Treatment retention of INF versus CT-P13 was assessed through survival probability curves and one- and two-year retention rates. Results In total 1319 bio-naïve patients with SpA started infliximab during the time-period, 24% started INF and 76% CT-P13. Baseline characteristics of patients in the two treatment groups were comparable (Table 1). The survival probability curves were identical for INF compared to CT-P13 (Figure 1), and the proportion of patients remaining on treatment after one and two years were similar: one year INF 62% (95%CI 57-68%), CT-P13 63% (95%CI 60-66%); two years: INF 44% (95%CI: 38-50%) and CT-P13 46% (95%CI: 42-51%). Further confounder-adjusted analyses, are planned and will be presented at the conference.Table 1 Baseline characteristics of infliximab treated SpA patients. INF (N=320) CT-P13 (N=999) Age at start, years 42 (14) 42 (13) Disease duration, years 13 (12) 10 (11) Sex, men,% 57 58 AS,% 57 46 nrax-SpA/uSpA,% 43 54 Psoriasis*,% 6 3 Inflammatory bowel disease*,% 10 11 CRP, mg/L 15 (21) 13 (22) VAS-pain, mm 62 (23) 59 (24) ASDAS 3.37 (1.02) 3.35 (0.97) BASDAI, mm 6.0 (2.0) 5.6 (2.0) BASFI, mm 4.4 (2.5) 4.8 (2.4) Concomitant csDMARD,% 44 31 Numbers are means (standard deviations) unless otherwise stated INF= infliximab originator; CT-P13= infliximab biosimilar. *comorbidities only available from Sweden, Denmark and Finland. csDMARD = conventional synthetic Disease Modifying anti-Rheumatic Drugs. Conclusion We found remarkably similar treatment retentions for the infliximab originator and biosimilar when used as the first line biologic in 1319 patients with SpA. The baseline characteristics of the patients starting the originator and the biosimilar suggest that the cohorts are comparable, and the results thus supports the equivalence of the treatments. Reference [1] Glintborg, et al. Biological treatment in ankylosing spondylitis in the Nordic countries during 2010-2016: a collaboration between five biological registries. Scand J Rheumatol. 2018;47:465-74. Acknowledgement This study received funding from NordForsk and from FOREUM. Disclosure of Interests Ulf Lindström: None declared, Bente Glintborg Grant/research support from: Biogen, Pfizer, AbbVie, Daniela Di Giuseppe: None declared, Johan Askling Grant/research support from: Karolinska Institutet (JA) has or has had research agreements with the following pharmaceutical companies, mainly in the context of the ATRIS national safety monitoring programme for rheumatology biologicals: Abbvie, BMS, MSD, Eli Lilly, Pfizer, Roche, Samsung Bioepis, and UCB., Consultant for: Karolinska Institutet has received remuneration for JA participating in ad boards arranged by Lilly, Novartis, and Pfizer., Dan Nordström Grant/research support from: MSD, Pfizer, Consultant for: AbbVie, BMS, MSD, Novartis, Roche, Pfizer, UCB, Speakers bureau: Novartis, UCB, Sella Aarrestad Provan Consultant for: Novartis, Speakers bureau: Lilly, Björn Gudbjornsson: None declared, Merete L. Hetland Grant/research support from: BMS, MSD, AbbVie, Roche, Novartis, Biogen, Pfizer, Consultant for: Eli Lilly, Speakers bureau: Orion Pharma, Biogen, Pfizer, CellTrion, Merck, Samsung Bioepis, Kalle Aaltonen: None declared, Niels Steen Krogh: None declared, Arni Jon Geirsson: None declared, Lennart T.H. Jacobsson Consultant for: LJ has received lecture and consulting fees from Pfizer, Abbvie, Novartis, Eli-Lily and Janssen