Objectives To demonstrate the equivalent efficacy and compare the safety and immunogenicity of an etanercept biosimilar, GP2015, with reference etanercept (ETN) in patients with moderate-to-severe, active rheumatoid arthritis (RA), characterised by an inadequate response to synthetic or biologic disease-modifying antirheumatic drugs (DMARDs). Methods In the EQUIRA study, eligible patients (n=376) were randomised 1: 1 to 50 mg GP2015 or ETN subcutaneously, once weekly, for 24 weeks (treatment period 1). Patients from both groups, with at least moderate European League Against Rheumatism response at week 24, received GP2015 up to week 48 (treatment period 2). All patients continued to receive concomitant methotrexate at a stable dose (10-25 mg/week) until end of the study. The 24-week results are presented here. Results Equivalent efficacy between GP2015 and ETN was demonstrated if the 95% CI for the difference in disease activity score 28-joint count C reactive protein (DAS28-CRP) change from baseline to week 24 between treatment arms was contained within the prespecified equivalence margin range of -0.6 to 0.6. The least squares mean difference (GP2015-ETN) in change from baseline in DAS28-CRP up to week 24 was -0.07 (95% CI -0.26 to 0.12 [primary endpoint)]. The incidence of treatment-emergent adverse events was comparable between GP2015 (43.5%) and ETN (49.5%). None of the GP2015-treated patients developed neutralising anti-drug antibodies (NAbs) whereas 1.6% and 0.6% of patients in ETN group were NAb positive at weeks 4 and 12, respectively. Conclusion In patients with RA who had an inadequate response to DMARDs, GP2015 demonstrated a similar efficacy and a comparable safety and immunogenicity profile with ETN.