Trough s-infliximab and antibodies towards infliximab in a cohort of 79 IBD patients with maintenance infliximab treatment

Abstract Background and Aims The anti-TNF antibody infliximab is effective in inducing remission in Crohn's disease as well as in ulcerative colitis and many patients are treated for several years with sustained clinical remission. However, the role of monitoring s-infliximab and antibodies towards infliximab during maintenance treatment remains unclear. Our aim was to correlate serum drug levels and antibodies to clinical activity, CRP, albumin and concomitant immunosuppression in a cohort on maintenance infliximab treatment. Methods We included 79 patients with Crohn's disease or ulcerative colitis who had responded to infliximab and received maintenance treatment (4–69 infusions) in this retrospective study. Infliximab levels and antibodies towards the drug were analyzed with in-house-developed ELISA assays. Results The mean s-infliximab was significantly higher in patients in remission (4.1 μg/mL) as compared with disease flare (mean 1.8 μg/mL); p  Conclusions The trough level 4.1 μg/mL may serve as cut-off for clinical remission. Drug trough levels decreased during treatment and almost all patients with undetectable s-infliximab and monotherapy had developed antibodies against the drug.