P20 Biosimilar use in children and young people with juvenile idiopathic arthritis in a real-world setting in the United Kingdom
Authors: Kearsley-Fleet Lianne , Adam Rebecca , Baildam Eileen , Beresford Michael W. , Foster Helen E. , Southwood Taunton R. , Thomson Wendy , Hyrich Kimme L. 
Published: September 2019

Abstract

Background
Most research concerning biosimilar use in musculoskeletal diseases has been conducted in adults. Little to no data regarding the use of biosimilars in children and young people with juvenile idiopathic arthritis (JIA) exist. Our aim was to describe the characteristics of children and young people with JIA starting biosimilars in the United Kingdom (UK) with musculoskeletal diseases.

Methods
The Biologics for Children with Rheumatic Diseases (BCRD) study is an ongoing prospective UK study recruiting children and young people with JIA starting biologic therapies other than etanercept originator (followed in a separate parallel study) from 2010 onwards. Baseline information is collected via questionnaires completed by the treating physician or affiliated clinical research nurse. Follow-up data including disease activity measures and changes in drug therapy are collected at six months, one year and annually thereafter. From May-2015, data has been captured on anti-TNF biosimilars in the UK.

Results
To 18 June 2019, 159 patients had started a biosimilar; 84 (53%) infliximab (2 products), 60 (38%) etanercept (2 products), and 15 (9%) adalimumab. Of these, 53 (33%) started the biosimilar as their first biologic therapy. Fifty (31%) patients switched from their originator, median (IQR) time on originator before switch was 2.2 (1.1-4.1) years, with most citing cost or hospital policy (n = 22) as the reason and these patients had low disease activity (median active joint count was zero) at point of switch. Fifty-six (35%) patients switched to a biosimilar from a non-originator biologic with 37 (66%) switching for efficacy reasons and 13 (23%) for safety reasons, with higher disease activity reported (median active joint count was three); most (n = 32) switching from adalimumab. Follow-up data was available in 143 patients; median follow-up time was 1.1 (0.7, 1.9) years. Sixty-seven patients switched to another biologic in this period. The majority (n = 38) switched to a non-originator biologic, predominantly adalimumab (n = 22) or tocilizumab (n = 14). Nineteen patients switched between infliximab biosimilars. Ten patients switched to the originator biologic (two due to inefficacy, four due to adverse events, four due to painful injections), although only four of these were on the originator prior to starting biosimilar; overall, in patients who switched from originator to biosimilar, 8% switched back to the originator.

Conclusion
Biosimilars in children and young people with JIA are being used as both first-line and subsequent-line biologic therapy. Patients starting a biosimilar from an originator product had lower disease activity and reported switching due to cost reasons, whilst patient starting a biosimilar from a non-originator were doing so due to inefficacy. Overall tolerance of biosimilar appears to be good so far, with few patients switching back to the originator. It is imperative that these patients continue to be followed within the registers so that effectiveness and safety of these treatments can be captured.

Conflicts of Interest
The authors declare no conflicts of interest.