S1454 Long-Term Efficacy and Safety of Intravenous (IV) Tulisokibart in Patients With Ulcerative Colitis (UC): Results From the Open-Label Extension (OLE) Period of the Phase 2 ARTEMIS-UC Study

Introduction: Tumor necrosis factor–like cytokine 1A (TL1A) is a regulator of inflammation and fibrosis in inflammatory bowel disease. Tulisokibart, an anti-TL1A monoclonal antibody, demonstrated efficacy without clinically meaningful safety findings vs placebo after a 12-week induction in adults with moderately to severely active UC in the multicenter, double-blind, placebo-controlled phase 2 ARTEMIS-UC study. We report long-term efficacy and safety of tulisokibart among cohort 1 induction responders at week 50 from the OLE period of ARTEMIS-UC. Methods: Cohort 1 of ARTEMIS-UC enrolled participants regardless of genetic-based diagnostic test status. After the 12-week induction period, in which randomized participants received IV tulisokibart (1000 mg on day 1; 500 mg at weeks 2, 6, 10) or placebo, participants had the option to continue in the OLE. Participants were classified as induction responders (defined as reduction of ≥2 points and ≥30% in modified Mayo score from baseline with a reduction ≥1 in rectal bleeding [RB] subscore or absolute RB subscore ≤1 at week 12) or induction nonresponders. Cohort 1 induction responders in the tulisokibart group were randomized to receive open-label IV tulisokibart 100 or 250 mg every 4 weeks at 14–170 weeks. Efficacy outcomes are reported for induction responders from the tulisokibart group. Safety is reported for induction responders from tulisokibart and placebo groups. Descriptive statistics were used to summarize observed data. Results: 47 cohort 1 induction responders in the tulisokibart group were randomized to receive tulisokibart 250 mg (n=25) or 100 mg (n=22). Improvements in clinical, endoscopic, and biomarker outcomes observed with tulisokibart were generally maintained through week 50 in both dose groups (Table 1). A greater proportion of patients achieved clinical and endoscopic outcomes with tulisokibart 250 vs 100 mg. In the safety population, (tulisokibart 250 mg, n=35; 100 mg, n=30), through week 50, AEs occurred in 63% and 77% of participants receiving tulisokibart 250 and 100 mg, respectively; most were mild to moderate in severity. Serious AEs occurred in 1 (3%) and 2 (7%) participants in the tulisokibart 250 and 100 mg groups, respectively. Conclusion: At week 50, maintenance of treatment effect was generally observed in cohort 1 induction responders. A trend for higher efficacy with tulisokibart 250 vs 100 mg was observed. Tulisokibart was well tolerated with no identified safety signals. Larger trials are needed to confirm these findings. Table 1. - Clinical, endoscopic, and biomarker outcomes at week 12 in the cohort 1 tulisokibart group and at week 50 among cohort 1 induction responders in the tulisokibart group Week 12TulisokibartInduction(n=68) Week 50Tulisokibart100 mg(n=22) Week 50Tulisokibart250 mg(n=25) Clinical remission,a % 26 32 48 Endoscopic improvement,b % 37 36 48 Clinical response,c % 66 59 68 Symptomatic remission,d % 19 23 32 Histologic-endoscopic mucosal improvement,e % n = 6531 n = 1547 n = 2050 High-sensitivity C-reactive protein fold change from baseline, geometric LS mean (95% CI) n = 650.56 (0.48–0.66) n = 170.51 (0.22–1.19) n = 240.56 (0.26–1.19) Fecal calprotectin fold change from baseline, geometric LS mean (95% CI) n = 540.21 (0.16–0.27) n = 130.28 (0.09–0.88) n = 170.27 (0.10–0.77) LS least squares; mMS, 3-component modified Mayo score; SF stool frequency.aClinical remission per mMS was defined as endoscopic subscore of 0 or 1, RB subscore of 0, and SF subscore of 0 or 1 and not greater than baseline.bEndoscopic improvement was defined as endoscopy subscore ≤1 with no friability.cClinical response per mMS was defined as reduction from baseline ≥2 points and ≥30% in mMS, accompanied by a reduction ≥1 in RB subscore or absolute RB subscore ≤1.dSymptomatic remission was defined as SF subscore of 0 and RB subscore of 0.eHistologic-endoscopic mucosal improvement was defined as Geboes score ≤3.1 and endoscopy subscore ≤1.

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