IFX-dyyb Boosts Rheumatoid Arthritis Outcomes in 6 Months


A new study provides insight into the effectiveness of IFX-dyyb in a real-world US population of RA patients, showing how the biosimilar compares to other treatments.

IFX-dyyb Boosts Rheumatoid Arthritis Outcomes in 6 Months

Joshua F. Baker, MD, MSCE

Credit: Perelman School of Medicine, University of Pennsylvania

A recent study evaluating IFX-dyyb, an infliximab biosimilar, in patients with rheumatoid arthritis (RA) revealed promising outcomes, with notable improvements in disease activity and patient-reported outcomes observed over 6 months, particularly among those switching from non-IFX biologic/tsDMARD or biologic/tsDMARD-naïve patients.1 Improvement stayed the same for patients switching from IFX-REF/IFX biosimilar.

“The present study provides data that are reflective of situations in clinical practice, where patients may switch to a biosimilar from the originator or from other biologic DMARDs or tsDMARDs,” wrote investigators, led by Joshua F. Baker, MD, MSCE, from the University of Pennsylvania. “Our findings suggest that outcomes at 6 months with IFX-dyyb treatment in the real-world setting are comparable with efficacy outcomes in clinical trials.”

Recently, a 2022 real-world study showed IFX-dyyb maintained effectiveness for a year in 394 Japanese patients with RA who were naïve to biological disease-modifying antirheumatic drugs (bDMARDs).2 Although the US Food and Drug Administration (FDA) approved IFX-dybb little was known about the biosimilar’s use in real-world clinical practice in patients with RA in the US.1

Investigators sought to assess the treatment effectiveness of real-world US patients with RA starting the biosimilar IFX-dyyb (CT-P13; Inflectra). They conducted an observational study assessing patients with RA from the large observational CorEvitas RA Registry who initiated IFX-dyyb and had Clinical Disease Activity Index (CDAI) recorded at baseline and 6 months.

The data recorded patient visits from April 5, 2016 to October 31, 2022. Participants in the registry were ≥ 18 years old, diagnosed with RA by a rheumatologist, and were currently receiving an FDA-approved biologic, biosimilar, or Janus kinase (JAK) inhibitor for RA initiated within 365 days of enrollment. The sample was mostly White (75.6%) and female (78.4) with a mean age of 63.6 ± 13.3 years.

The primary outcome was patients with moderate or high disease activity (CDAI > 10) at baseline reaching a low disease activity (LDA)—defined as CDAI ≤ 10—at 6 months. Secondary outcomes included the number of patients achieving remission at 6 months, the change in CDAI at 6 months, the Health Assessment Questionnaire (HAQ), and patient-reported outcomes of pain and fatigue, and if they had a ≥ 20%, 50%, or 70% improvement at 6 months.

Participants 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.

The sample included 176 patients who initiated IFX-dyyb and had baseline and 6-month CDAI scores. Patients with missing scores were excluded.

Investigators observed patients switched to IFX-dyyb from IFX (41%), another non-IFX/biologic/tsDMARD (35%), and an IFX biosimilar (6%). Additionally, 18% of participants initiating IFX-dyyb were previously naïve to biologics/tsDMARDs.

Of participants with moderate or high disease activity at baseline, 32.9% achieved LDA at 6 months (95% confidence interval [CI], 22.9 to 42.9). The mean CDAI change from baseline to 6 months was -1.8 (95% CI, -3.3 to -0.3). More than half (68%) of patients who initiated INFX-dyyb continued taking the biosimilar at 6 months.

The CDAI change from baseline for patients who switched from non-IFX biologic/tsDMARD and IFX-REF/IFX biosimilar was − 4.7 (− 7.6, to − 1.7) and 1.1 (− 0.4 to 2.6), respectively. For biologic/tsDMARD-naïve patients, the CDAI change from baseline was − 4.1 (− 7.8 to − 0.3).

The team also observed clinical outcomes or patient-reported outcomes improved at 6 months.

Most people who initiated IFX-dyyb had switched from IFX-REF or a non-IFX biologic/tsDMARD. Patients improved the CDAI when switching from a non-IFX biologic/tsDMARD and in biologic/tdDMARD-naïve patients. As for patients switching from IFX/REF/IFX biosimilar, the CDAI remained stable.

“This finding is expected since changing from the originator product or other biosimilar product should effectively represent a continuation of therapy,” investigators wrote.

Investigators stated several limitations, such as the observational study design preventing robust data. They also added the findings were limited by not adjusting for confounders, only having a US population, and not evaluating safety outcomes.

“Overall, these data provide insights for clinicians regarding expected disease effectiveness outcomes following switching RA therapy in a real-world setting to IFX-dyyb and potentially alleviate hesitation in its use,” investigators concluded.


  1. Baker JF, Bakewell C, Dikranian A, et al. Characteristics and 6-Month Outcomes in Patients with Rheumatoid Arthritis Initiating Infliximab Biosimilar IFX-dyyb in a Real-World Setting. Rheumatol Ther. Published online March 20, 2024. doi:10.1007/s40744-024-00653-6
  2. Takeuchi T, Nishikawa K, Yamada F, et al. Real-world safety and efficacy of CT-P13, an infliximab biosimilar, in Japanese rheumatoid arthritis patients naive to or switched from biologics. Mod Rheumatol. 2022;32:718–27.

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