P708 Multiple Biosimilar Infliximab Switching is Not Associated with Adverse Outcomes in Inflammatory Bowel Disease: A Real-World Effectiveness Analysis in a National U.S. Cohort

Infliximab (IFX) biosimilars are available for inflammatory bowel disease (IBD). Many options of IFX biosimilars exist, however there is a paucity of data on the safety and efficacy of switching between multiple IFX biosimilars. The goal of this study is to evaluate the safety and outcomes in patients who received multiple IFX biosimilars in a National U.S. Cohort of patients with IBD. We conducted a retrospective cohort study of IBD patients on maintenance IFX originator from 2017- 2019 in the national Veterans Affairs (VA) healthcare system. Crohn’s disease (CD) and ulcerative colitis (UC) patients were identified using a previously validated algorithm. Cases, exposures and outcomes were confirmed by chart review. Patents on IFX originator were identified by dispensed medication from the VA Corporate Data Warehouse. Patients were classified as no-switch (NS)- receiving originator but no biosimilar during study period, Single Switch (SS)- switch from originator to one biosimilar, or Double Switch (DS)-switch from IFX originator to two different biosimilars. Primary outcome was IBD flare, defined as escalation of steroid, IBD-related Emergency department visit or hospitalization within 12 months. Secondary outcomes were immunogenicity, serious infection, and infusion reaction. Event rates of the DS group were compared to NS and SS groups using univariate and multivariate (MV) logistic regression models adjusting for patient and non-patient factors. 789 patients (487 CD, 298 UC) on maintenance IFX originator were identified. Of these, 410 patients were categorized as NS, 249 as SS, and 130 as DS. Overall, the rate of flare within 12 months was 19.9% (22.2% NS, 15.3% SS, 21.5% DS, p= 0.08), rate of infection was 11.2% (11.5% NS, 8% SS, 16.2% DS, p= 0.056). No statistically significant differences in rates of immunogenicity or infusion reaction were identified between the DS and NS or SS groups. In MV logistic regression including age, race, gender, medication, comorbidity and VA priority status, no significant differences in flares at 12 months was observed between DS (ref) and NS (aOR 1.12, 95% CI 0.68-1.84), or SS groups (aOR 0.64, 95% CI 0.36-1.12). In MV analyses, SS was associated with lower rate of infection compared to DS (aOR 0.41, 95% CI 0.21-0.82). In a national U.S. cohort of patients with IBD, multiple IFX biosimilar switching was not associated with flare at 12 months compared to patients continued on IFX originator or with a single IFX biosimilar switch. However, DS was associated with increased odds of infection compared to single switch. These findings provide reassurance that multiple IFX biosimilar switching for IBD is effective but further study on infection risks may be warranted.