P295 Early sonographic improvement predicts the middle-term efficacy of molecular-targeted medications for Ulcerative Colitis

Today molecular-targeted medications (MTMs) are widely used for ulcerative colitis (UC). Predicting the efficacy of MTMs early after induction remains a crucial clinical challenge. Intestinal ultrasound (IUS) is now considered a non-invasive, promising monitoring tool for UC. It can assess the disease activity of UC in the whole colon safely and repeatedly. Here, we hypothesized that over time IUS assessment can predict the MTM efficacy early, contribute to early clinical decision-making on whether to continue or switch MTMs, and reduce the burden of colonoscopy (CS) recommended to be scheduled at around 6 months after the induction. We analyzed 44 patients who started an MTM for active UC, underwent IUS at baseline and 3 months, and took CS at 6 months after the induction. The clinical disease activity and endoscopic activity at 6 months were assessed with Lichtiger index (LI) and Mayo endoscopic subscore (MES), respectively. Clinical remission was defined as a LI ≤ 3. Endoscopic improvement (EI) was defined as a MES = 0 or 1. In addition to the assessment of sonographic findings, such as bowel wall thickness (BWT), bowel wall stratification including submucosa index (SMI), bowel wall flow with modified Limberg score (mLS), Milan Ultrasound Criteria (MUC), UC-IUS index (UII), Kyorin Ultrasound Criterion for UC (KUC-UC; BWT<3.8mm with SMI<50%) were evaluated. Patients who achieved steroid-free clinical remission (SFCR) showed better improvement in BWT, %BWT, and mLS in 3 months compared to those who did not achieve SFCR (p<0.01 for each). The improvement in MUC and UII was also observed in patients who achieved SFCR at 6 months (p<0.001 for both). In ROC analyses, the area under the curve for SFCR at 6 months was 0.80 with BWT, 0.80 with %BWT, 0.81 with mLS, 0.85 with MUC, and 0.85 with UII. Among the 44 patients, 7 patients achieved MUC≤ 6.2, estimating MES=0/1, at 3 months, and 6 out of 7 patients demonstrated EI at 6 months (positive predictive value [PPV]=87.5%). Meanwhile, 4 patients satisfied KUC-UC at 3 months and all of them achieved SFCR and EI at 6 months (PPV=100%). Our study suggests that patients who achieved sonographic improvement in 3 months can continue an ongoing MTM therapy and that patients who demonstrated sonographic findings estimating EI at 3 months can postpone CS at 6 months.