Achievement of Clinical, Endoscopic, and Histological Outcomes in Patients with Ulcerative Colitis Treated with Etrasimod, and Association with Faecal Calprotectin and C-reactive Protein: Results From the Phase 2 OASIS Trial.

Background and aims: Etrasimod is an oral, once-daily, selective sphingosine 1-phosphate (S1P)1,4,5 receptor modulator for the treatment of moderately to severely active 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 faecal calprotectin [FCP] and C-reactive protein [CRP] levels with efficacy outcomes.

Methods: In total, 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.

Clinicaltrials.gov number: NCT02447302.