medwireNews: Results of two independent studies suggest that patients with inflammatory arthritis can be switched from infliximab to the biosimilar CT-P13 without compromising the effectiveness of treatment.
In the phase IV NOR-SWITCH trial, 482 Norwegian patients receiving stable treatment with infliximab for any approved indication were randomly assigned to either continue with their treatment regimen or switch to CT-P13.
A total of 19% of the study participants had spondyloarthritis, 16% had rheumatoid arthritis (RA), and 6% had psoriatic arthritis (PsA), while the remaining patients had Crohn’s disease (32%), ulcerative colitis (19%), or chronic plaque psoriasis (7%).
As reported in The Lancet, the researchers found that disease worsening – as measured by disease-specific composite measures or consensus between healthcare provider and patient leading to a change in treatment – occurred in 26% of 202 patients receiving originator infliximab over 52 weeks of follow-up, compared with 30% of 206 who switched to CT-P13, giving a difference of –4.4% after adjustment for diagnosis and treatment duration at baseline.
The 95% confidence interval of the adjusted treatment difference, at –12.7% to 3.9%, was within the predefined non-inferiority margin of 15%, explain the researchers, suggesting “that CT-P13 is not inferior to infliximab originator.”
Similar numbers of patients in the infliximab originator and CT-P13 groups experienced treatment-emergent adverse events (TEAEs; 70 vs 68%) and serious TEAEs (10 vs 9%), with infections being the most common side effect.
“These results support those from earlier observational studies and suggest that switching to CT-P13 is not associated with any safety concerns,” say Tore Kvien (Diakonhjemmet Hospital, Oslo, Norway) and study co-authors.
Commenting on the NOR-SWITCH findings, Richard Veselý and Peter Richardson, both from the European Medicines Agency in London, UK, note that “[a]lthough the study’s design does not allow for conclusions on individual diseases, its results support the idea that infliximab originator can be replaced during treatment with a biosimilar.”
In the second study, Bente Glintborg (Rigshospitalet, Glostrup, Denmark) and colleagues used the nationwide DANBIO registry to compare disease activity before and after switching from infliximab to CT-P13 among patients with inflammatory arthritis in Denmark.
“A national guideline [issued in] May 2015 dictated a non-medical switch, that is, all patients treated with [infliximab] should switch to CT-P13 for economic reasons,” write the authors in the Annals of the Rheumatic Diseases.
They found that disease activity was “largely unchanged” in most patients at 3 months before versus 3 months after the switch, with “no clinically meaningful differences observed.” For example, the median 28 Joint Disease Activity Score was 2.2 points at both timepoints among 403 patients with RA, and was 2.5 and 2.4 points before and after switching, respectively, among 120 patients with PsA.
And in the 279 patients with axial spondyloarthritis, the median Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was 23 points before switching to CT-P13 and 25 points after switching, and the corresponding Ankylosing Spondylitis Disease Activity Scores (ASDAS) were 1.8 and 2.0.
While there was no significant difference in 1-year unadjusted retention rates between patients who switched to CT-P13 and a historic cohort of infliximab-treated patients (84.1 vs 86.2%), these rates were significantly different after adjustment for factors including age, gender, and comorbidities (83.4 vs 86.8%), and patients who switched had a significant 1.3-fold increased risk for treatment withdrawal.
However, the authors note that “[t]his difference is not necessarily attributable to CT-P13, but could also represent a ‘nocebo-effect’, that is, negative expectations towards the drug or residual confounding.”
And they conclude that “a nationwide non-medical switch to CT-P13 had no negative impact on disease activity.”
By Claire Barnard
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