Background: The biosimilar of infliximab, CT-P13, recently entered the European market. It has been approved for the same indications held by the infliximab reference product. Clinical data on switching from originator infliximab to CT-P13 in inflammatory bowel disease (IBD) are scarce. The aim of this study was to assess the efficacy, safety, bioavailability profile and factors associated with relapse after switching in IBD patients.
Methods: Remicade®-treated IBD patients for at least 6 months and in clinical remission for at least 3 months (Harvey-Bradshaw index of ≤4 points and partial Mayo score of <2 points) who switched to CT-P13 were included in this retrospective observational study. Epidemiological, clinical and analytical data, including C-reactive protein (CRP), infliximab trough level (TL) and antidrug antibodies (ADAs), were collected. The incidence of relapse, adverse effects and possible changes in bioavailability after switching were evaluated. A multivariate analysis was performed, using Cox proportional hazards regression to identify factors associated with the relapse.
Results: 36 patients were included, 58.3% women, mean age 41.3 years (SD ±15.7), 23 Crohn's disease (CD) and 13 ulcerative colitis (UC). The mean follow-up was 8.4 months (SD ±3.5). 13.9% of the patients lost efficacy during follow-up with a mean time to relapse of 2.4 months (SD ±1.9). In the multivariate analysis, the factors that were associated with a lower risk of relapse were: longer clinical remission time before switching (HR 0.54, 95% CI 0.29–0.98, p=0.04) and detectable infliximab levels at the time of switching (HR 0.03, 95% CI 0.001–0.89, p=0.04). The disease duration, time on treatment with infliximab reference product, previous intensification and Non-detectable ADAs, were not associated with the risk of relapse. No differences were found between infliximab levels at the time of switching, at week 8 and 16 after switching (p=0.94). During the follow-up, 8.3% of the patients had some adverse effect, motivating in one case the suspension of biosimilar for severe pneumonia.
Conclusions: Switching from Remicade® to CT-P13 in a real-life cohort of IBD patients in clinical remission did not have a significant impact on short-term clinical outcomes. The factors associated with relapse were similar to those expected during follow-up in patients continuing with infliximab reference product. However, until prospective and controlled data are available, this clinical practice should be evaluated with caution.