P921 Maintenance of clinical, biochemical and transmural remission in inflammatory bowel disease patients switching from intravenous to subcutaneous infliximab

Abstract

Abstract Background Subcutaneous (SC) infliximab (IFX) effectively maintains biochemical, clinical and endoscopic remission in inflammatory bowel disease (IBD) with a comparable safety profile to intravenous (IV) formulation. Transmural healing is considered a desirable long-term treatment endpoint in IBD, especially in Crohn’s disease (CD). Whether switching from intravenous to SC-IFX effectively maintains transmural remission in IBD is still unknown. Methods This is a preliminary report from a prospective multicentre cohort study on IBD patients in clinical and endoscopic remission on IV-IFX treatment switched to SC-IFX. Enrolled patients were followed-up for 12 months, with fecal calprotectin (FC), C-reactive protein (CRP), infliximab trough levels and anti-drug antibodies (ADAs) measured at baseline, at 3, 6 and 12 months. Intestinal ultrasound (IUS) was performed at baseline and every six months. At month 12 a full colonoscopy was performed for mucosal healing assessment. Remission rates and safety profile were subsequently recorded. T-Test and ANOVA for mean comparisons and Kaplan-Meier estimates were used for survival curves. Results 43 IBD patients (69% males) were enrolled, 58% with CD, of whom 52% reported a history of perianal disease. Median disease duration and IFX therapy were 6 (IQR 3-12) and 5 (IQR 2-9) years, respectively. During a median follow-up of 311 (range 122-489) days, clinical remission rate was 98% (Harvey-Bradshaw Index <5 and Mayo score <2). No reactivation of perianal disease was reported. FC and CRP remained stable at each time point (p> 0.05). The median baseline infliximab level was 10.02 ( range 0.1- 41.84) ug/ml. Undetectable infliximab levels (<1 ug/ml) and positive ADAs were found in 6 and 14 patients, respectively; at 3 months, a significant increase in infliximab levels (mean increase 27.5 ng/ml; ± 12.5 SD; p< 0.001) and a progressive decrease of ADAs titer were observed, despite unchanged SC-IFX dose. At baseline, all patients had normal bowel wall thickness (i.e. ileum ≤ 3mm, colon≤4 mm) and a Limberg score ≤1at IUS; reactive lymphadenopathies were reported in 5 patients and a mild abdominal effusion in 1. No significant changes were shown during follow-up. Mild endoscopic activity was found in 2 out 30 patients who performed follow-up endoscopy. Regarding safety profile 12 mild infectious events, 2 mild cutaneous injection site reaction and 1 non-IBD related hospital admission were observed. Conclusion Switching from IV to SC infliximab in a selected cohort of IBD patients confirmed to be safe and effective in maintaining clinical, biochemical, and transmural remission. IUS is a useful, non-invasive and low-cost tool for periodic disease assessment in this subset of patients.