P338 Early proactive drug monitoring strategy of infliximab as monotherapy for inflammatory bowel disease in paediatric patients is associated with good sustained clinical remission

Abstract

Abstract Background Monotherapy with infliximab (IFX) could be as efficient as combotherapy with immunomodulators in the treatment and maintenance of remission for children with inflammatory bowel disease (IBD) if a proactive therapeutic drug monitoring strategy is adequately performed. This strategy may allow optimization of blood levels of IFX in order to obtain a sustained clinical response. Methods A retrospective study was conducted amongst children with IBD, aged from, 2 to, 18 years old and diagnosed between January, 2018 and June, 2020. All patients were treated with IFX less than, 30 days after diagnosis. Data concerning disease activity was collected at diagnosis, at one year after diagnosis. Close monitoring of IFX blood levels were collected before the third and fourth dose and regularly thereafter. Adjustments in IFX dose per infusion were made according to blood levels and clinical response. The primary outcome was clinical remission, defined by a PUCAI or shortPCDAI score <, 10 without the need of corticosteroid, at one year after diagnosis. The secondary outcomes measured were the median (interquartile range (IQR)) dose of IFX (in mg/kg) after a year of treatment, the median (IQR) number of changes of IFX dose, the time intervals between IFX infusions over a year, and the median (IQR) number of blood levels of IFX done in a year. Results A total of, 91 patients were included (81% Crohn’s disease; mean age at diagnosis was, 13.2 years (IQR = 11.3 to, 15.15)). After one year of treatment, 76 patients (83.5%) reached clinical remission. IFX was discontinued in, 13 patients:, 6 due to antibody occurrence, 5 because of treatment failure, 1 due to psoriasis and, 1 due to autoimmune hepatitis. In total, 61.5% of patients needed two or more IFX dose/interval optimization over the course of a year. At one year after diagnosis, the median IFX dose per infusion was, 8.78 mg/kg (IQR = 7.5 mg/kg to, 9.9 mg/kg) with infusions given, 6 weeks apart or less in, 82% of the patients. Patients who were diagnosed before the age of, 10 had a median IFX dose of, 9.43 mg/kg. The median number of IFX blood level dosage was, 4 per patient over a year (IQR=, 3.5 to 6). Conclusion Early treatment for IBD with IFX as monotherapy and a proactive optimization strategy is associated with a good sustained steroid free clinical remission. Most patients needed an increase of IFX dose during the first year of treatment. We therefore recommend to proactively monitor blood levels of IFX before the third and fourth dose of IFX and thereafter, in order to lower the risk of treatment failure and anti-infliximab antibodies occurrence.