Abstract Background CT-P13 subcutaneous (SC) infliximab formulation was developed to provide patients with a convenient option for treatment. Previous studies have shown efficacy and safety of CT-P13 SC comparable to CT-P13 intravenous (IV) in inflammatory bowel disease (IBD)1 and rheumatoid arthritis2. This study aimed to demonstrate superiority of CT-P13 SC over placebo in maintenance therapy after induction therapy of CT-P13 IV in patients with ulcerative colitis (UC). Methods Patients with moderately to severely active UC (modified Mayo score 5 to 9 with endoscopic subscore of ≥ 2 points) were enrolled LIBERTY-UC (NCT04205643) and treated with open label CT-P13 IV 5 mg/kg at Weeks 0, 2 and 6 as induction therapy. At Week 10, patients who had a clinical response, defined as decrease in modified Mayo score from baseline of at least 2 points and at least 30%, with an accompanying decrease in the rectal bleeding subscore of at least 1 point or an absolute rectal bleeding subscore of 0 or 1 point, were randomised in a 2:1 ratio to receive either CT-P13 SC 120 mg (CT-P13 SC) or placebo SC arms every 2 weeks up to Week 54. The primary endpoint was clinical remission at Week 54. The key secondary endpoints of clinical response, endoscopic-histologic mucosal improvement, and corticosteroid-free remission were assessed at Week 54. Safety was evaluated up to Week 54. Results A total of 548 patients were enrolled. Among them, 438 patients (79.9%) responded to CT-P13 IV induction dosing and were randomised (294 in CT-P13 SC arm and 144 in placebo arm, respectively) at Week 10. The rate of clinical remission at Week 54 was significantly greater in CT P13 SC (43.2%) compared to placebo (20.8%) (P<0.0001). Clinical response, endoscopic-histologic mucosal improvement and corticosteroid-free remission also showed statistically greater improvement with CT-P13 SC treatment group, compared to placebo treatment group (Table 1). The safety profile during maintenance phase was generally comparable between CT-P13 SC and placebo arms (table 2). No deaths were reported. Conclusion CT-P13 SC was more effective than placebo for clinical remission, clinical response, endoscopic histologic mucosal improvement, and corticosteroid-free remission at Week 54 in patients with moderately to severely active UC. No new safety concerns were identified. These results demonstrate that the CT-P13 SC provides both a robust clinical benefit and the convenience of SC administration to patient with moderately to severely active UC. 1 Schreiber et al., 2021. Gastroenterology 2021;160:2340–23 2 Westhovens et al., 2020. Rheumatology 2020;00:1