P585 Effectiveness of Switching to Subcutaneous Infliximab in Ulcerative Colitis Patients Experiencing Intravenous Infliximab Failure

Studies on elective switching to the subcutaneous (SC) formulation of infliximab revealed comparable efficacy and safety and higher infliximab level than those exhibited by intravenous (IV) infliximab. However, no studies have reported on the effectiveness of SC switching in ulcerative colitis (UC) patients who experienced IV infliximab failure during maintenance treatment. This retrospective study included UC patients who had been switched to SC infliximab because of IV infliximab failure, between January 2021 and January 2023. Group A was defined as having clinically and biochemically active UC (secondary loss of response), and group B consisted of patients with stable symptoms but biochemically active UC. Twenty-three patients met the inclusion criteria: 15 in group A and 8 in group B. The serum infliximab levels significantly increased after SC switching in both groups. Electively switched group also exhibited increased infliximab levels after SC switching. Group A showed improved partial Mayo score with a significant decrease in faecal calprotectin (FC) and C-reactive protein after switching. In group B, the FC level significantly decreased without clinical relapse after switching. A high proportion of patients (≥ 80%) in both groups achieved clinical and/or biochemical response at last follow-up. During the follow-up period, only two patients in group A discontinued SC infliximab, and only one complained of severe injection site reaction. In UC patients who experience IV infliximab failure during maintenance treatment, switching to SC infliximab may be a promising option because of its efficacy and safety.