Background: Switching from infliximab originator (Remicade®, RMC) to CT-P13 has been shown to be safe in patients with inflammatory bowel disease (IBD). There are few data confirming that switching is not related to higher immunogenicity than continuing RMC, and the role of anti-infliximab antibodies (ADA) formation in IBD patient clinical outcomes.
Methods: We prospectively analysed 3 cohorts of consecutive IBD patients (43 Crohn's disease, 43 ulcerative colitis, 15 unclassified colitis) treated with RMC, CT-P13, or switchers from RMC to CT-P13. A total of 564 consecutive trough sera were collected just before the infusion to all patients. All samples were frozen for subsequent testing with ELISA Promonitor®-IFX and Promonitor® Anti-IFX (Progenika, Spain). The ADA positivity rate (presence of stable ADA in at least two consecutive samples), trough IFX levels (TL), and the correlation between ADA and infusion reactions (IR) and secondary loss of response (sLoR) was analysed with survival curves and log-rank test, and logistic regression, and compared in the three groups. Statistical significance was set as p<0.05.
Results: One-hundred IBD patients treated with infliximab (RMC (n=30), CT-P13 (n=52), or switchers from RMC to CT-P13 (n=18)) were enrolled. In the entire population, 34 patients developed ADA in the follow-up (FU) time (13 RMC, 9 CT-P13 and 12 switchers, p=0.5). Forty-nine patients (49%) had suboptimal levels of IFX TL in the FU time without differences between the three groups (19% RMC, 18% CT-P13, 12% switchers, p=0.14). Fifteen patients (15%) had sLoR (4% RMC, 9% CT-P13, 2% switchers, p=0.19) in the FU time. Seven patients (7%) had IR in the FU time (1% RMC, 5% CT-P13, 1% switchers, p=0.15). There was significant difference (p<0.001) in the ADA levels between patients having IR (median ATI=37 AU/mL) and those without IR (median ATI = 0.0 AU/mL), regardless of the cohort (p=0.003).
Conclusions: Patients switching from RMC to CT-P13 are not at higher risk for immunogenicity compared to those exposed to RMC or CT-P13 alone. Although ADA formation was related to IR, no significant increase in ADA formation was found in patients who were switched. Switching from RMC to CT-P13 is safe in IBD patients.