Characteristics and 6-Month Outcomes in Patients with Rheumatoid Arthritis Initiating Infliximab Biosimilar IFX-dyyb in a Real-World Setting.

INTRODUCTION: Real-world studies describing biosimilar initiation or switching in patients with rheumatoid arthritis (RA) are limited. The aim of this study was to assess treatment patterns and effectiveness of real-world patients with RA initiating infliximab biosimilar IFX-dyyb (CT-P13; Inflectra®) in the USA. METHODS: This observational study evaluated patients with RA from the CorEvitas RA Registry who initiated IFX-dyyb and had Clinical Disease Activity Index (CDAI) recorded at baseline and 6 months. The primary outcome was reaching low disease activity (LDA; CDAI ≤ 10) at 6 months in patients with moderate or high disease activity (CDAI > 10) at baseline. Secondary outcomes were change at 6 months in CDAI and certain patient-reported outcomes (PROs). Patient data were stratified by prior treatment: biologic/targeted synthetic disease-modifying antirheumatic drug (tsDMARD)-naïve, reference infliximab (IFX-REF) or IFX biosimilar, or a non-IFX biologic or tsDMARD. RESULTS: Of 318 patients initiating IFX-dyyb, 176 had baseline and 6-month CDAI scores; 73 (41%) switched from IFX, 61 (35%) switched from another non-IFX/biologic/tsDMARD, 32 (18%) were naïve to biologics/tsDMARDs, and 10 (6%) switched from an IFX biosimilar. Among patients with moderate or high disease activity at baseline, 32.9% (95% CI 22.9, 42.9) achieved LDA at 6 months. Mean 6-month change from baseline in CDAI was - 1.8 (95% CI - 3.3, - 0.3) overall; - 4.7 (- 7.6, - 1.7) in patients who switched from a non-IFX biologic/tsDMARD, - 4.1 (- 7.8, - 0.3) in biologic/tsDMARD-naïve patients, and 1.1 (- 0.4, 2.6) in patients who switched from IFX-REF/IFX biosimilar. Other clinical outcomes/PROs improved at 6 months. Of the IFX-dyyb initiators, 68% remained on IFX-dyyb at 6 months. CONCLUSION: In this real-world population of patients with RA initiating IFX-dyyb, the majority switched from IFX-REF or a non-IFX biologic/tsDMARD. CDAI remained stable in patients switching from IFX-REF/IFX biosimilar and improved in patients switching from a non-IFX biologic/tsDMARD and in biologic/tsDMARD-naïve patients.

Infliximab is an effective treatment for rheumatoid arthritis (RA). Biosimilars­biologic drugs designed to be very similar to the originator products­are now available that may be more affordable with matching efficacy and safety. IFX-dyyb is a US Food and Drug Administration-approved infliximab biosimilar but little is known about its use in real-world clinical practice in patients with RA in the USA. This study used data from a large observational registry to look at treatment patterns and effectiveness of IFX-dyyb in adults with RA. One hundred and seventy-six patients were included who had data available at both baseline and at 6 months. Most patients (47%) switched to IFX-dyyb from the originator infliximab or another infliximab biosimilar; 35% switched from another RA treatment, and 18% were new to treatment. Six months after starting IFX-dyyb, 68% of patients were still receiving treatment. A measure of clinical disease activity remained stable in patients who switched from originator infliximab or another biosimilar, while this measure improved in patients switching to IFX-dyyb from other treatments or starting treatment for the first time. Other clinical measures and patient-reported outcomes such as pain and fatigue also improved over 6 months with IFX-dyyb. This real-world study of patients with RA initiating IFX-dyyb in the USA adds to our knowledge of the use of biosimilars in this patient population.