S1991 Long-Term Comparative Outcomes of TNF-α Antagonists vs Vedolizumab as First-Line Therapy for Refractory Ulcerative Proctitis: A Propensity-Matched Study

Introduction: Ulcerative proctitis (UP), is a type of ulcerative colitis defined by inflammation limited to the rectum. A subset of patients with UP refractory to mesalamine may need biologic therapy. Patients with UP are frequently excluded from clinical trials of biologic therapies for UC, resulting in limited data to guide their use. This study evaluates the clinical outcomes of refractory UP patients treated with tumor necrosis factor inhibitor (TNFi) or vedolizumab (VDZ) as first-line biologic therapy. Methods: We identified adults with isolated UP on TriNetx using International Classification of Diseases-10 codes (Appendix). UP patients receiving TNFi or VDZ as first-line advanced therapy between 1/1995 to 1/2024 were included. Patients with left-sided colitis, pancolitis, Crohn’s disease, and autoimmune diseases were excluded. Complications of UP, defined as corticosteroid use, all-cause ER visits and hospitalizations, or colectomy, assessed at 6, 12, and 24 months after initiation of either TNFi or VDZ. Secondary outcomes included a sensitivity analysis of outcomes between adalimumab (ADA) and VDZ, and assessing the usage patterns of biologics in UP patients. Statistical analysis was done via TriNetX. Propensity score matching (PSM) was done for all known confounders. Adjusted odds ratios with 95% confidence intervals were calculated. Results: Among 641 patients with UP exposed to advanced therapy, the most commonly used treatments were ADA (39%), infliximab (27%), and VDZ (26%). Ustekinumab was used in 12% of patients; tofacitinib and upadacitinib were each used in 6%. 328 patients were treated with TNFi and 135 with VDZ. Among TNFi, 192 received ADA and 136 received infliximab. Demographic and clinical characteristics were similar between groups. TNFi-treated patients had lower odds of ED visits and/or hospitalizations compared to VDZ at 6-months (14.3% vs 25%, P = 0.03) and 12 months [16.1% vs 35.2%, P = 0.01), before and after matching. No significant differences were observed between TNFi and VDZ in steroid use or colectomy. In 132 matched patients on ADA and VDZ, a similarly reduced risk of ED visits and/or hospitalizations at 6 and 12 months was seen in the ADA group. Conclusion: In conclusion, TNFi and VDZ demonstrate comparable risk of complications for refractory UP. TNFi may offer benefits in reducing ER visits and/or hospitalizations at 6 and 12-months, likely due to the faster onset of action. This finding was also seen for ADA vs VDZ. The rate of surgery in UP patients was low which may be expected due to limited disease.