Objective Switching patients from the originator infliximab to a biosimilar is a measure to expand access to treatments and counteract its negative impact on healthcare budgets. However, industry-independent long-term studies on the effect of switching in real life to support the lack of switch-related problems in inflammatory bowel disease (IBD) patients are sparse, as are studies addressing infliximab pharmacokinetic behaviour. The objectives were to investigate the effectiveness and the pharmacokinetics of CT-P13 after switching from originator infliximab in a real-world population of IBD patients with a follow-up of 2 years.

Method Prospective, single-centre, observational 2 year study conducted in IBD adult patients with stable disease treated with the originator infliximab who were switched to CT-P13. Four time points were defined for follow-up: prior to the switch, 4–8 weeks after the switch, 8 months later, and 2 years later. Outcome measures were the proportion of patients with clinical, endoscopic and biochemical remission, and changes in biochemical inflammation markers (albumin, C-reactive protein, faecal calprotectin) and infliximab clearance.

Results 42 IBD patients were switched, of which 36 (85.7%) remained on CT-P13 throughout the 2 year study period. Only two patients discontinued CT-P13 due to loss of response. The proportion of patients who displayed clinical, endoscopic and biochemical remission were unchanged during the follow-up (p<0.05) and no statistically significant changes were observed in the biochemical markers of disease activity. The median (IQR) clearance estimated for the infliximab originator before the change was 0.364 (0.321–0.415) L/day, and for the CT-P13 biosimilar it was 0.361 (0.323–0.415) L/day 4–8 weeks after the change, and 0.370 (0.334–0.419) L/day 2 years after (p=0.395).

Conclusion Switching from originator infliximab to biosimilar CT-P13 did not affect the long-term clinical outcomes or the pharmacokinetic behaviour. This information provides the clinician more evidence for the success of switching and supports non-medical switching in adult IBD patients.