Achievement of clinical, endoscopic, and histologic outcomes in patients with ulcerative colitis treated with etrasimod, and association with fecal calprotectin and C-reactive protein: results from the Phase 2 OASIS trial.

BACKGROUND AND AIMS:Etrasimod is an oral, selective sphingosine 1-phosphate receptor 1,4,5 [S1P1,4,5] modulator in development for ulcerative colitis [UC]. This post hoc analysis of the phase 2 OASIS trial [NCT02447302] evaluated its efficacy for endoscopic improvement-histologic remission [EIHR] and assessed correlation between fecal calprotectin [FCP] and C-reactive protein [CRP] levels with efficacy outcomes. METHODS:156 adults with moderately to severely active UC received once-daily etrasimod [1 mg [n=52]; 2 mg [n=50]] or placebo [n=54] for 12 weeks. Clinical, endoscopic, and histologic variables were evaluated at baseline and Week 12. EIHR was defined as achievement of endoscopic improvement [endoscopic subscore ≤1, without friability] and histologic remission [Geboes score <2.0]. Outcomes included the relationships between FCP and CRP concentration and clinical, endoscopic, and histologic variables. RESULTS:Achievement of EIHR was significantly higher in patients who received etrasimod 2 mg versus placebo [19.5% vs 4.1%; Mantel-Haenszel estimated difference, 15.4%; p=0.010]. In the etrasimod 2-mg group, median FCP and CRP levels at Week 12 were significantly lower in patients who achieved clinical remission, endoscopic improvement, histologic remission, and EIHR versus patients who did not [all p<0.05]. An FCP concentration cutoff of 250 μg/g achieved optimum sensitivity and specificity for efficacy, including EIHR [0.857 and 0.786, respectively; κ coefficient, 0.3584]. Higher proportions of patients with FCP ≤250 μg/g achieved efficacy outcomes at Week 12 versus patients with FCP >250 μg/g. CONCLUSIONS:Etrasimod was effective for inducing EIHR in patients with UC. FCP and CRP may be useful, noninvasive biomarkers to monitor treatment response.