Among patients with rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis, a full 24% discontinued treatment with biosimilar infliximab (CT-P13) within 6 months of transitioning from original infliximab (REM), primarily because of increases in subjective tender joint count and patient global disease activity, as well as subjective adverse events (AEs), according to results of a study published in Arthritis & Rheumatology.
This high rate of discontinuation, noted researchers, was perhaps due to the awareness of both clinicians and patients of the transition, which may cause negative expectations and result in negative symptoms and incorrect causal attributions.
“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 Lieke Tweehuysen, MD, Department of Rheumatology, Sint Maartenskliniek, Nijmegen, The Netherlands.
With this multicenter, prospective cohort study, Dr. Tweehuysen and colleagues assessed drug survival, effectiveness, pharmacokinetics, immunogenicity, and safety in patients with rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis transitioned from REM treatment to CT-P13.
In all, 192 of the 222 patients treated with REM agreed to transition to CT-P13. After 6 months, researchers assessed changes in Disease Activity Score 28-joint count C reactive protein (DAS28-CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), C reactive protein (CRP), and (anti-) infliximab levels, and documented all adverse events (AEs). Using Kaplan-Meier and Cox regression analyses, they analyzed drug survival and prognostic factors.
During the 6-month follow-up, 24% of patients discontinued CT-P13. Thirty-seven patients restarted REM, 7 switched to another biologic, and 3 stayed biologic-free.
From baseline to month 6, DAS28-CRP remained stable (2.2 to 2.2; difference: 0.0; 95% CI: 0.1, 0.2). During this time, BASDAI increased from 3.8 to 4.3 (difference: +0.5; 95% CI: 0.1, 0.9). CRP and (anti-) infliximab levels did not change.
Before patients discontinued CT-P13 discontinuation, researchers observed increases in the DAS28-CRP components of tender joint count and patient global disease activity, and increases in BASDAI compared to baseline. The most common AEs included arthralgia, fatigue, pruritus, and myalgia.
Finally, Dr. Tweehuysen and fellow researchers found that a shorter REM infusion interval at baseline was predictive of CT-P13 discontinuation (HR: 0.77; 95% CI: 0.62, 0.95).