A new study published in Arthritis & Rheumatology reports that 24% of patients who switched from infliximab (reference) to CT-P13 (infliximab biosimilar) discontinued treatment during 6 months of follow-up primarily due to subjective health complaints.
Study authors aimed to assess the pharmacokinetics, efficacy, immunogenicity, safety, and drug discontinuation after switching from infliximab (Remicade) to the biosimilar CT-P13 in 192 patients with rheumatoid arthritis, psoriatic arthritis or ankylosing spondylitis in daily practice. The multicenter, prospective cohort study measured changes in Disease Activity Score 28 C-Reactive Protein (DAS28-CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), CRP and (anti-) infliximab levels after 6 months. Adverse events were recorded and survival and prognostic factors were evaluated using regression analyses.
During the 6 months of follow-up, nearly a quarter of patients (24%) discontinued CT-P13. Thirty-seven patients restarted Remicade, 7 transitioned to another biologic, and 3 took no biologic. The DAS28-CRP, CRP, and (anti-) infliximab levels remained stable from baseline to Month 6. BASDAI, however, increased from 3.8 at baseline to 4.3 at Month 6 (difference +0.5, 95% CI: 0.1–0.9).
The authors note that right before CT-P13 was discontinued, the tender joint count component of DAS28-CRP, patients’ global disease activity, and BADAI were higher compared to baseline. Having a shorter Remicade infusion interval at baseline was a predictor of discontinuing CT-P13 therapy (hazard rate 0.77, 95% CI: 0.62–0.95).
Arthralgia, fatigue, pruritus, and myalgia were the most commonly reported adverse events.
The authors attribute the CT-P13 discontinuation to possible nocebo and/or incorrect causal attribution effect. “As a result, communication between clinicians and patients seems to be the determining factor of the success of transitioning to a biosimilar in daily practice,” said lead author Dr. Lieke Tweehuysen, of Sint Maartenskliniek, in the Netherlands.
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