S1570 Prior Biologic or Janus Kinase Inhibitor Therapy Does Not Impact Colectomy Rates Among Patients Needing Infliximab Rescue Therapy for Acute Severe Ulcerative Colitis

Introduction: Infliximab (IFX) is recommended for steroid-refractory patients hospitalized with acute severe ulcerative colitis (ASUC). However, limited data exist on its efficacy in patients with prior exposure to advanced therapies (AT), including biologics or janus kinase (JAK) inhibitors. This study examines the efficacy of IFX rescue therapy in ASUC patients with and without prior AT exposure. Methods: We conducted a health system-wide retrospective cohort study of hospitalized patients aged ≥17 years who received inpatient IFX rescue therapy for ASUC between January 2017 and December 2024. The primary endpoint was colectomy rates among AT-naïve vs AT-exposed patients during index hospitalization and within 3 months following inpatient IFX treatment. Secondary endpoints included the impact of inpatient IFX dosing strategy (standard vs accelerated), post-discharge IFX persistence at 1 year, use of other AT during follow-up, and colectomy rate at 1 year. Results: A total of 75 patients received IFX rescue therapy (AT-naïve = 52, AT-exposed = 23). Among AT-exposed, 65% had received 1 prior therapy, 30% had received 2, and 4% had received ≥ 3; 16 patients (28%) were actively on AT at the time of index hospitalization. UC duration, CRP, and albumin levels on admission did not differ between groups. AT-naïve patients were more likely to have a Mayo endoscopic subscore of 3 (87% vs 65% AT-exposed, P = 0.03). No significant differences were observed for inpatient (P > 0.99) or 3-month (P = 0.16) colectomy rates between AT-naïve and AT-exposed patients . Infliximab dosing strategy, whether standard or accelerated (increased frequency, dosing, or both), did not differ between groups and was not independently associated with the primary outcome. AT-exposed patients were more likely to continue IFX at 1 year (52% vs 11%, P <0.01). Colectomy rates at 1 year were similar (21.7% for AT-exposed vs 21.2% for AT-naïve, P > 0.99). Conclusion: Prior exposure to biologic or JAK inhibitors does not appear to impact short-term colectomy rates following IFX rescue therapy for ASUC, suggesting that IFX remains an effective salvage option regardless of prior treatment history. Future studies are needed to evaluate long-term clinical outcomes.