Switching from originator infliximab to biosimilar CT-P13 in real-life: The weight of patient acceptance.

OBJECTIVE: To explore acceptance and retention rate of biosimilar CT-P13 after switching from originator infliximab (OI) in patients with various rheumatic diseases.

METHODS: Patients with stable rheumatoid arthritis (RA), ankylosing spondylitis (AS) or psoriatic arthritis (PsA) under OI were proposed to switch to CT-P13 at the same regimen. A prospective cohort of infliximab-naïve patients beginning CT-P13 and a retrospective cohort of patients treated with OI were used as controls. The primary outcome was to evaluate the retention rate of CT-P13. Secondary outcomes were the switch acceptance rate, reasons of failure and safety.

RESULTS: Switch was proposed to 100 patients and accepted by 89 of them (63 AS, 12 PsA and 14 RA). After a median follow-up of 33 weeks, 72% of patients were still treated with CT-P13. This retention rate was significantly lower than the one found in our retrospective and prospective control cohorts: 88% and 90% respectively (P-value=0.0002). Within patients who asked to be reswitched to OI, 13/25 (52%) presented clinical disease activity, one developed serum sickness and 11 (44%) presented no objective activity. A subanalysis excluding these 11 patients abrogated difference in retention rates between the 3 cohorts (P-value=0.453). After reswitching to OI, patients without objective disease activity claimed to recover original efficacy.

CONCLUSIONS: Retention rate was lower after switching from OI to CT-P13 compared to our control cohorts. However, this difference faded after excluding patients without objective clinical activity, suggesting a reluctance of patients to the switch and a negative perception of the biosimilar.