OBJECTIVES: Additional FDA-approved adalimumab biosimilars become available in the US in 2023, potentially yielding significant reductions in treatment cost. However, concerns exist as to whether these biosimilars will have equivalence to originator molecules for efficacy, toxicity, and tolerability. Here we examine experience with existing biosimilars for the purpose of lessening or validating these concerns.

METHODS: Data: PIONEER Rheumatology, an EMR and extracted chart note database specific to patients in care by the American Rheumatology Network. Study criteria: rheumatoid arthritis, first infliximab exposure Apr 2018 to Mar 2021, >360 days history and follow up. Analyses: One-way ANOVA with post hoc Games-Howell (continuous), Pearson’s chi-square with proportions comparisons by z-test with Bonferroni correction (categorical), time to event by Kaplan-Meier and log-rank test.

RESULTS: 569 study patients: 255 INFLIXIMAB (IFX), 111 INFLIXIMAB-ABDA (ABDA), AND 203 INFLIXIMAB-DYYB (DYYB). Groups did not statistically differ by gender, baseline BMI, CDAI, DAS28, RAPID3, ALT, AST, blood glucose or concurrent csDMARD or corticosteroids, but did differ by race, age, payer coverage, baseline eGFR, and prior csDMARD treatment. With censure at 360 days, duration did not differ between groups: IFX estimated mean (median) days 258 (not reached), ABDA 232 (259), DYYB 236 (265) (p=0.129). For patients remaining on therapy for >180 days, disease assessments (CDAI, DAS28, RAPID3) at 180+/-30 days were not significantly different by severity levels, mean scores, change in mean scores, or proportion of patients achieving minimally important reductions. Discontinuation reasons (n=277) by broad classifications of lack of efficacy, clinical conditions related or unrelated to treatment, and non-clinical reasons were not significantly different between groups.

CONCLUSIONS: In this study of infliximab-naïve patients in community practice, infliximab biosimilars did not differ from the originator infliximab in efficacy, the reasons for discontinuation, or tolerability.