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

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. 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. 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. 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). Biosimilars—biologic drugs designed to be very similar to the originator products—are 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.