Comparative effectiveness and persistence of SB4 and reference etanercept in patients with psoriatic arthritis in Norway.

Abstract

We aim to compare drug effectiveness and persistence between reference etanercept (ETN) and ETN biosimilar SB4 in psoriatic arthritis (PsA) patients naïve to ETN and to investigate drug effectiveness and persistence in those undergoing mandatory non-medical switch from ETN to SB4. Retrospective comparative database study including 1138 PsA patients treated with ETN or SB4 (years 1999-2021) in Norway. Disease activity score in 28 joints (DAS28) and drug persistence were compared between unmatched ETN (n=644) and SB4 (n=252) cohorts and in matched analyses (n=144, both cohorts) at baseline using propensity score (PS) to adjust for confounders. Drug persistence was analyzed with Kaplan-Meier method. In unmatched analyses, difference in change from baseline between ETN (n=140) and SB4 (n=132) for DAS28 at 1 year was mean 0.67 (95% confidence interval [95%CI] 0.38-0.96) in favor of ETN. In PS-matched analyses, difference in change from baseline between ETN (n=54) and SB4 (n=54) was 0.09 (95%CI -0.33-0.50) and mean difference assessed with ANCOVA model 0.01 (95%CI -0.38-0.40), both within predefined equivalence margin (±0.6). Drug persistence at 1 year was 0.75 (95%CI 0.71-0.78) for ETN, 0.58 (95%CI 0.51-0.63) for SB4, HR 2.45 (95%CI 2.02-2.97) in unmatched analysis, and 0.55 (95%CI 0.46-0.63) for ETN, 0.60 (95%CI 0.51-0.67) for SB4, HR 1.29 (95%CI 0.94-1.76) in PS-matched cohorts. At 1 year, outcomes for PsA disease activity and drug persistence were comparable for patients treated with either ETN or SB4. In patients undergoing mandatory non-medical switch from ETN to SB4, drug effectiveness was maintained in 2-year period.