P0676Safety and Effectiveness of Multi-Switch between Adalimumab Originator and Biosimilars in Inflammatory Bowel Disease: A Multicenter (SUSTAIN) Study

Abstract Background Biologic therapies have transformed the management of inflammatory bowel disease (IBD), but their high cost has prompted the introduction of biosimilars (1). Although switching from originator biologics to biosimilars is increasingly common, real-world evidence remains limited (2). We aimed to explore the safety and efficacy of switching between biologics originator and biosimilars. Methods We conducted retrospective chart review of patients with IBD between 2015 and 2025. Adult patients receiving adalimumab-adaz, or adalimumab-atto were included. Patients who were non-medically switched once from adalimumab originator (Humira) to any biosimilar were classified as group A. Patients who also switched back to originator (multiple switches) were classified as group B. Primary outcome was safety of biosimilar including any adverse events (AEs) and serious AEs. Secondary outcome was efficacy including sustained clinical remission and sustained normalization ofinflammatory markers. Logistic regression identified predictors of biosimilar switching. Results A total of 237 patients were included in the study. The number of patients in group A and group B was 208 and 58 patients, respectively. Sustained clinical remission was achieved in 198 (95.4%) of Group A and 54 (93.6%) of Group B participants. Sustained normalization of inflammatory markers was also comparable, occurring in 190 (91.5%) of Group A and 54 (92.3%) of Group B (figure 1). No treatment-emergent adverse events (AEs), infections, or treatment discontinuations were reported in either group (0%). Local or mild AEs were rare, occurring in 3 (1.2%) of Group A and 1 (2%) of Group B, with no other AEs reported (0% in both groups). Regression analysis identified older age and prior immunomodulator use as significant predictors of switching. Conclusion Multiple switches of adalimumab biosimilars can be safely undertaken without increasing the risk of adverse reactions, or treatment failure. Our study provides meaningful evidence to guide policy, resource allocation, and clinician confidence in biosimilar interchangeability as a sustainable therapeutic strategy in IBD mansagement. References: 1. Danese, S., Vuitton, L., & Peyrin-Biroulet, L. (2015). Biologic agents for IBD: practical insights. Nature reviews Gastroenterology & hepatology, 12(9), 537-545.2. 2. Raffals, L. E., Nguyen, G. C., & Rubin, D. T. (2019). Switching between biologics and biosimilars in inflammatory bowel disease. Clinical Gastroenterology and Hepatology, 17(5), 818-823. Conflict of interest: Dr. Shehab, Mohammad: No conflict of interest Almajdi, Anwar: No conflict of interest Abdullah, Israa: No conflict of interest Alrashed, Fatema: No conflict of interest