Poster Session II - A282 CLINICAL OUTCOMES AND DRUG SUSTAINABILITY AFTER NON-MEDICAL SWITCH FROM USTEKINUMAB ORIGINATOR TO BIOSIMILARS IN INFLAMMATORY BOWEL DISEASE

Abstract Background Biologic therapies have transformed the management of inflammatory bowel disease (IBD), yet their high cost poses substantial challenges for healthcare systems. Biosimilars offer a cost-effective alternative, with extensive evidence supporting the safety and efficacy of non-medical switching for infliximab and adalimumab. However, real-world data on ustekinumab biosimilars in IBD remain limited. Given increasing mandates for non-medical switches in Canada, evaluating clinical outcomes is critical to ensure patient safety and treatment sustainability. We hypothesized that switching from originator ustekinumab to a biosimilar would preserve clinical efficacy, safety, and drug persistence in patients with IBD. Aims To evaluate clinical efficacy, drug sustainability, biomarker activity and adverse events (AEs) in IBD patients who underwent non-medical biosimilar switching from ustekinumab originator to a biosimilar. Methods This was an observational study of consecutive IBD patients who underwent biosimilar switch. Disease activity, biomarkers, drug sustainability, and AEs were captured 8 weeks before switch, at the time of switch (baseline), 12 and 24 weeks after the switch. Results 81 patients were included [85.2% had Crohn’s disease (CD), the median age at inclusion: 42 years (IQR 29-61)]. Previous biological exposure was 82.7% and a dose optimization of the originator ustekinumab was performed in 63% before the switch. Drug sustainability at 12 and 24 weeks of switch was 96.3% and 95%, regardless of disease type or phenotype. The discontinuation rate was 4.9%. There was no significant difference in the rates of clinical remission at week 8 before switch, baseline, week 12, and 24 after switch: 87%, 85.9%, 84.3%, and 92.7%, p=NS. The biomarker activity was not significantly different for CRP, hemoglobin, albumin and fecal calprotectin (p=NS). All patients who stopped therapy after the non-medical switch needed a dose optimisation of the originator ustekinumab and had previous biological therapy prior to starting the ustekinumab originator. Conclusions Despite prior biologic exposure and frequent dose escalation, switching to ustekinumab biosimilar showed stable efficacy, unchanged biomarkers, and high drug sustainability. Funding Agencies None