Drug Discontinuation and Persistent Symptoms Among Initiators of Bio-Originator and Biosimilar anti–Tumor Necrosis Factor Drugs in Inflammatory Bowel Disease: Real-World Contemporary Data From the CAnadian Network for Advanced Interdisciplinary Methods/CIRC Registry

Background and aims: Biosimilars and their originator anti-tumor necrosis factor drugs remain important in inflammatory bowel diseases (IBDs). We assessed drug discontinuation, IBD symptoms, and quality of life (QoL) in adults after initiating infliximab and adalimumab bio-originators or biosimilars. Methods: Six Canadian IBD sites enrolled initiators of these drugs, between January 2019 and February 2024. We determined drug discontinuation, concomitant medications, and symptoms and QoL (using the Short Inflammatory Bowel Disease Questionnaire and 5-level EuroQol-5D) at 12 months after initiating therapy, and assessed differences between bio-originator and biosimilar users. Results: We evaluated 205 initiators of infliximab (N = 151) or adalimumab (N = 54) who had completed at least 12 months of follow-up. Within this time, 21.5% (n = 44) discontinued drug use. There were significant reductions in corticosteroid use, abdominal pain and bowel urgency among both bio-originator and biosimilar users. Significant reduction in overall pain/discomfort and fatigue was detected among biosimilar users only. There was a significant improvement in QoL on the Short Inflammatory Bowel Disease Questionnaire both in the bio-originator (mean difference 9.0, 95% confidence interval: 4.0-15.0) and biosimilar (9.0, 95% confidence interval: 6.0-12.0) groups. Conclusion: About 80% of individuals initiating infliximab or adalimumab for IBD were still on these drugs at 12 months. Benefits (including less corticosteroid use, abdominal pain, bowel urgency, and improved QoL) were seen in individuals initiating both biosimilar and bio-originators.