Infliximab biosimilar-to-biosimilar switching in patients with inflammatory rheumatic disease: clinical outcomes in real-world patients from the DANBIO registry

Abstract

Objective: Successful uptake of biosimilars in rheumatology is limited by lack of real-world evidence regarding effectiveness of biosimilar-to-biosimilar switching. We investigated infliximab biosimilars CT-P13-to-GP1111 switching among patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondyloarthritis (AxSpA).

Methods: Observational cohort study from the DANBIO registry. Patients were classified as originator-naïve or originator-experienced. Retention rates of 1-year GP1111 treatment were explored (Kaplan-Meier). We identified baseline factors (at the time of switch) associated with withdrawal of GP1111 (multivariable Cox-regression analyses with HRs including originator treatment history). Changes in subjective and objective measures of disease activity 4 months before and after the switch were assessed in individual patients.

Results: Of 1605 patients (685 RA, 314 PsA and 606 AxSpA, median disease duration was 9 years, 37% in Clinical Disease Activity Index/Ankylosing Spondylitis Disease Activity Score remission), 1171 were originator-naïve. Retention rates at 1-year were 83% (95% CI: 81% to 85%) and 92% (95% CI: 90% to 95%) for the originator-naïve and originator-experienced, respectively. GP1111 retention rates were higher in originator-experienced compared to originator-naïve with RA (HR=0.4 (95% CI: 0.2 to 0.7)) and PsA (HR=0.2 (95% CI: 0.1 to 0.8)), but not significantly for AxSpA: HR=0.6 (95% CI: 0.3 to 1.2). Lower disease activity was associated with higher retention. Changes in disease activity preswitch and postswitch were close to zero.

Conclusion: This real-world observational study of more than 1600 patients with inflammatory arthritis showed high 1-year retention following a nationwide infliximab biosimilar-to-biosimilar switch. Retention was higher in originator-experienced and in patients with low disease activity, suggesting outcomes to be affected by patient-related rather than drug-related factors.

Keywords: arthritis, psoriatic; arthritis, rheumatoid; biosimilar pharmaceuticals; infliximab; spondylitis, ankylosing.

Figure 1

Study population and definition of the two subgroups according to originator infliximab treatment history. *Switched to CT-P13 in the period 1 May 2015 to 1 March 2016. A time gap of 0–120 days between stop of originator and start of biosimilar was allowed to comply with registration practice.**Based on following International Classification of Diseases (ICD)-10 codes: For RA: M05.9, M06.0, M06.9, M13.0, for PsA: M073.A, M073.B, M46.8 in combination with M07.3 and for AxSpA: M45.9, M46.1, M46.8, M46.9, also M45.9 and M46.8 in combination with M02.9, M07.2, M07.4, M07.5 and/or H20.0. Also minimum one visit in DANBIO after 1 April 2019, and aged ≥18 years at the time of treatment start with a biologic disease-modifying antirheumatic drug (bDMARD). ***Switched to GP1111 in the period 1 April 2019 to 1 February 2020. AxSpA, axial spondyloarthritis; PsA, psoriatic arthritis; RA, rheumatoid arthritis.

Figure 2

Kaplan-Meier plots of crude treatment retention rates in GP1111-treated patients ((A) originator-naïve and (B) originator-experienced switchers)*.*The grey shaded area on the figures represents the 95% CI.