Etanercept originator versus etanercept biosimilar for the treatment of rheumatoid arthritis as a first biologic: results from the BSRBR-RA.

OBJECTIVES: Etanercept biosimilars show comparable efficacy to their originators among biologic-naïve patients with RA in RCTs. Nationwide guidelines have obligated prescribing of etanercept biosimilars from 2016 resulting in significant cost-savings. This analysis aimed to compare the effectiveness of etanercept originator versus etanercept biosimilar amongst biologic-naïve RA patients treated in routine clinical-practice in the UK.

METHODS: Biologic-naïve RA patients starting etanercept in the BSRBR-RA cohort study from 2010 were included. Data collected at start of therapy includes patient demographics and disease activity. Follow-up data includes changes in disease activity and anti-rheumatic therapy. Six and 12-month primary outcomes include Disease Activity Score for 28-joints (DAS28) remission, EULAR response, and minimal clinically important difference (MCID) in function. Etanercept drug survival was assessed using Kaplan-Meier and Cox-regression, including reasons for treatment withdrawal. Multiple imputation accounted for missing data. Propensity-decile adjustment was used to account for confounding-by-indication.

RESULTS: 1806 biologic-naïve RA patients started etanercept: 1009 originator, 797 biosimilar. At six and 12-months, proportion of patients achieving DAS28 remission, and EULAR response were similar between treatments. During follow-up, 19% originator patients switched onto etanercept biosimilar. Patients were censored at time of switch. Patients on originator were no more likely to stop therapy versus biosimilar; 71% originator and 76% biosimilar patients remained on therapy at one-year.

CONCLUSIONS: In one of the largest analyses of patients with RA, biologic-naïve RA patients treated with etanercept originator showed similar outcomes vs biosimilar using real-world data. Drug survival, and disease activity after six and 12-months of therapy, was similar between cohorts.