Definition of a therapeutic range for predicting long-term infliximab response in patients with inflammatory bowel disease.

ABSTRACT

INTRODUCTION: Monitoring plasma levels of Infliximab plays an important role in optimising treatment in patients with inflammatory bowel disease (IBD). The aim of the following study has been to determine the predictive potential of monitoring infliximab plasma levels for sustained clinical response and evaluate its usefulness to improve treatment efficacy and symptom control, in patients with IBD. METHODS: This single-centre retrospective study (2017-2019) included patients diagnosed with IBD treated with infliximab. Serum levels and the occurrence of drug-associated immunogenicity were analysed at Week 8 post-induction and 6, 12 and 24 months. Clinical parameters and inflammatory markers were recorded such as subjective global assessment (SGA), C-reactive protein (CRP) and faecal calprotectin (FC). Factors associated with early discontinuation and dose intensification of infliximab were determined. RESULTS: Multivariate analysis determined that IFX concentrations>7µg/mL at week 8, and at 6 months, are associated with inflammatory remission (p=0.046, 0.045). IFX>7µg/mL at 12 months predicted remission at 18 months of treatment (p=0.006). IFX values>3µg/mL at 12 months are associated with stable SGA at 18 months (p=0.001). Such values at 18 months are associated with stable SGA at 24 months (p=0.044). CONCLUSIONS AND RELEVANCE The predictive potential of monitoring IFX plasma levels as a strategy to evaluate sustained long-term clinical response was confirmed. Our results highlight the importance of its introduction into routine clinical practice to enable early identification of non-responders, treatment optimisation, relapse prevention and improve long-term therapy maintenance.