Second-line infliximab therapy for ulcerative colitis (SLIT-UC): a retrospective cohort study

BACKGROUND: Infliximab's efficacy as a second-line agent in moderate or severe ulcerative colitis after prior advanced therapy failure is unclear. Registration trials for infliximab did not assess its efficacy after exposure to other advanced therapies, a sequence in which it is increasingly used. We evaluate infliximab's second-line effectiveness, identify predictors of response, and compare outcomes to its first-line use. METHODS: We conducted a retrospective cohort study of adults with ulcerative colitis treated with infliximab at a tertiary care center. Patients were categorized by line of therapy. Clinical and endoscopic outcomes at 1 year were compared between first-line and second-line users. Multivariable logistic regression was used to assess predictors of 1-year clinical remission. RESULTS: Among 225 included patients, 143 received infliximab first-line and 82 as second-line or subsequent therapy. Clinical response at 1 year was significantly lower in second-line users (odds ratio 0.53, 95% confidence interval: 0.28-0.99, P = 0.049) and remained significantly lower after adjustment for biosimilar and concurrent steroid use. Dose escalation was more common with second-line use (57.3% vs. 42.0%, P = 0.026). Endoscopic and histologic remission was numerically lower in second-line users (47.7% vs. 33.3% and 27.0% vs. 41.7%, respectively), though these were not statistically significant ( P = 0.180 and 0.099, respectively). CONCLUSION: Infliximab remains effective as a second-line agent in ulcerative colitis, though with reduced response and higher rates of dose escalation as compared to use first-line. These findings support its continued use while highlighting the need for optimized patient selection and treatment strategies in therapy-exposed populations.