Early Intestinal Ultrasound Response to Biologic and Small Molecule Therapy is Accurate to Predict Treat-To-Target Endoscopic Outcomes in Children with Ulcerative Colitis: Results from the Prospective Super Sonic-UC Study

Abstract Background and Aims Stride-II recommends monitoring early biomarker targets to achieve treat-to-target (T2T) endoscopic remission (ER) in ulcerative colitis (UC). Predictive capabilities of intestinal ultrasound (IUS) for ER remain unknown. We evaluated IUS response to predict ER in children with UC. Methods Prospective longitudinal cohort study of children with UC (Mayo endoscopic score (MES>2) starting advanced therapy undergoing IUS (including Milan Ultrasound Criteria (MUC), Civitelli Ulcerative Colitis Index (CUCI) and International Bowel Ultrasound Group Segmental Activity Score (IBUS-SAS)), fecal calprotectin (FC), C-reactive protein (CRP), and Pediatric Ulcerative Colitis Activity Index (PUCAI) at baseline, week 8, and T2T. Primary outcome was accuracy to predict T2T ER (MES=0) for change in bowel wall thickness (BWT) from baseline to week 8, and absolute BWT at week 8. Logistic regression with forward selection determined an optimal prediction model for endoscopic outcomes. Results Of 42 children, 21 (50%) achieved ER. Week 8 BWT < 2.7 mm (OR 6.4 [95% CI 1.8-27.0], p=0.007), MUC < 6.0 (OR 5.7 [95% CI 1.5-25.3], p=0.015), and FC < 177 (OR 4.5 [95% CI 1.1-23.6], p=0.049) were associated with ER. Conclusions Combining non-invasive biomarkers of BWT and the MUC on IUS, and FC, is a feasible tight control monitoring strategy in children with UC that is predictive of endoscopic outcomes. Larger, multicenter validation studies are needed to understand how an IUS and FC monitoring strategy may improve outcomes in children with UC.