Study Shows Infliximab Biosimilar is Safe in Patients Undergoing RA Treatment

Research from a recent study demonstrated that patients with rheumatoid arthritis (RA) undergoing treatment with infliximab (Remicade; Janssen Biotech, Inc.) in clinical remission could safely switch to infliximab-dyyb (CT-P13, Remsima, Inflectra; Celltrion), a biosimilar, without an increased risk of relapse. These findings are significant for patients because they present a cost-effective alternative for treatment.¹

Infliximab is an FDA-approved monoclonal antibody that targets tumor necrosis factor-alpha (TNF-α) to address inflammatory conditions, including Crohn disease, ulcerative colitis, RA, ankylosing spondylitis, psoriatic arthritis, and severe plaque psoriasis. In addition to these indications, it is used off label to treat Bechet disease, relapsing polychondritis, juvenile idiopathic arthritis, and hidradenitis suppurativa, among other conditions. Infliximab may be administered in combination with methotrexate to avoid potential immunologic responses, which could decrease or blunt the drug's effect. Treatment for RA is the indication the FDA requires concurrent methotrexate use.²

Infliximab is a biological therapy/immunotherapy medication designed to stimulate the body's immune system and treat certain diseases. It has a high affinity for TNF-α, which is responsible for several physiological responses, including inducing proinflammatory cytokines (eg, IL-1 and IL-6), increasing adhesion molecule release, and enhancing the migration of leukocytes from blood vessels in the surrounding tissue.²

CT-P13’s initial approval was based on the results of 2 clinical trials in which CT-P13 was shown to be equivalent to reference infliximab in terms of pharmacokinetic properties in patients with ankylosing spondylitis and efficacy in patients with RA. In both studies, CT-P13 had a similar tolerability profile to that of its reference product. Immunogenicity evaluations showed that the proportion of patients developing antidrug antibodies was similar with each agent. Additionally, preliminary data from trial extensions demonstrated that patients who switched from reference infliximab to CT-P13 had sustained efficacy and had similar outcomes to those treated continuously with the biosimilar.³

For this current study, which was published in Drug Discoveries & Therapeutics¹, the investigators aimed to assess the efficacy and safety of switching from reference infliximab to the biosimilar CT-P13 in patients with RA. This was determined with musculoskeletal ultrasound (MSUS) and clinical disease activity indices. The prospective, open-label, interventional, single-arm clinical trial included a 24-week follow-up and enrolled patients with RA who had achieved clinical remission during treatment with originator infliximab. The biosimilar was switched from the reference product with an unchanged dosing regimen for 24 weeks. Further, the study utilized both clinical disease activity indices and MSUS and serum cytokines/chemokines.¹

A total of 18 patients were evaluated during the study period. From baseline to week 24, approximately 11.1% (n = 2) of patients experienced clinical relapse (95% CI 3.1–32.8). There were no changes observed in the MSUS score, including total grayscale and power Doppler scores, Disease Activity Score 28 (DAS28)-erythrocyte sedimentation rate, DAS28-C-reactive protein, Health Assessment Questionnaire-Disability Index, and van der Heijde-modified total Sharp score from baseline to week 24. Of note, serum levels of multiple cytokines and chemokines showed no apparent changes.¹

Three nonserious adverse events (AEs) occurred, but importantly, there were no study discontinuations as a result of AEs. With these positive efficacy and safety findings, most patients with RA who underwent treatment with originator infliximab in clinical remission could safely switch to CT-P13 without an increased risk of relapse, as supported by MSUS, clinical indices, and biomarker levels.¹

“This study highlighted the potential for cost-effective biosimilars to maintain remission in patients with RA, suggesting significant implications for reducing treatment costs and improving accessibility,” concluded the study authors.¹

REFERENCES
1. Shimizu T, Kawashiri SY, Koga T, et al. Switching from originator infliximab to biosimilar infliximab in Japanese patients with rheumatoid arthritis achieving clinical remission (the IFX-SIRIUS study I): An interventional, multicenter, open-label, single-arm clinical trial with clinical, ultrasound and biomarker assessments. Drug Discov Ther. 2025;19(4):253-261. doi:10.5582/ddt.2025.01044

2. Fatima R, Bittar k, Aziz M. Infliximab. National Library of Medicine. Updated March 21, 2024. Accessed October 7, 2025. https://www.ncbi.nlm.nih.gov/books/NBK500021/

3. McKeage K. A review of CT-P13: an infliximab biosimilar. BioDrugs. 2014;28(3):313-321. doi:10.1007/s40259-014-0094-1