P027 Could Fecal Calprotectin Guide the Therapeutic Regimen of Infliximab in Inflammatory Bowel Disease?

Abstract

BACKGROUND: Infliximab is a monoclonal antibody against tumor necrosis factor α approved for induction and maintenance of remission in inflammatory bowel disease (IBD). Therapeutic monitoring, with determination of infliximab levels, allows to guide therapeutic decisions and helps to prevent loss of response. AIM: To identify predictive factors of non-therapeutic infliximab levels (<0.50 µg/mL) in IBD patients. METHODS: Retrospective single-center study including patients treated with infliximab with at least one determination of infliximab levels and with a minimum follow-up of six months. Clinical and demographic data obtained included disease phenotype, surgical background, duration of infliximab therapy, presence of anti-infliximab antibodies at the time of analysis, concomitant immunomodulator therapy, compliance, occurrence of an infusion reaction and biochemical assessment at the time of first induction infusion. RESULTS: 104 patients were included, 56 females (53.8%) with a mean age of 38.2 ± 13.1 years. The overall prevalence of non-therapeutic infliximab levels was 29.8%. In the majority (90.4%) of the patients, the first determination was performed during maintenance therapy. 29.0% of the patients with non-therapeutic levels had simultaneously positive antibodies, and of the remainder, 27.3% acquired antibodies in a subsequent analysis. It was found that patients with non-therapeutic levels had significantly higher fecal calprotectin values at the initiation of treatment with infliximab (1184 ± 679 vs 708 ± 621, P = 0.02). No statistically significant association was found with other analytical parameters, like haemoglobin (12.7 ± 1.7 vs 12.9 ± 1.6, P = 0.55), C-reactive protein (11.2 ± 12.2 vs 15.9 ± 20.0, P = 0.22), sedimentation rate (22.4 ± 20.7 vs 23.7 ± 19.3, P = 0.76), ferritin (138.3 ± 128.2 vs 165.5 ± 166.6, P = 0.42) or albumin (3.50 ± 0.45 vs 3.56 ± 0.47, P = 0.54). CONCLUSION(S): Patients with non-therapeutic levels of infliximab have higher values of calprotectin prior to treatment, which may be related to increased inflammatory activity. In these cases infliximab regimens with higher and/or more frequent doses may be considered.