Objective: Currently, a biosimilar of Remicade is available (CT-P13). Switching patients from Remicade to a biosimilar is still under debate, especially for patients with inflammatory bowel disease (IBD). In a retrospective study, we investigated the feasibility and safety of switching patients with IBD from Remicade to a biosimilar infliximab. Patients and

Methods: At two large general hospitals in The Netherlands, adult patients with a diagnosis of Crohn's disease or ulcerative colitis being treated with Remicade were asked to switch to the biosimilar infliximab (CT-P13). After switching, patients were closely monitored by assessing disease activity and evaluating disease-specific measures (serum C-reactive protein and fecal calprotectin). Adverse effects were recorded and serum infliximab concentrations measured. All parameters were assessed at baseline (t=0) and after two infusions with biosimilar infliximab (±week 16).

Results: Among 197 patients with IBD switched to the biosimilar infliximab (∼77%), and no difference in disease activity was observed. Disease-specific measures did not differ between baseline and after two infusions with the biosimilar. Apart from one infusion-related reaction, no serious or unexpected adverse reactions were reported. Serum trough concentrations did not differ between baseline and after switching [median: 4.1 µg/ml (range: 0.03-22 µg/ml) vs. 4.6 µg/ml (range: 0.03-22 µg/ml); P=0.08, n=98].

Conclusion: These data suggest that switching patients with IBD to the biosimilar infliximab is safe in clinical practice. After the switch, no clinically relevant differences were observed in disease activity, adverse effects, and serum infliximab concentrations.