Retrieval of Serum Infliximab Level by Shortening the Maintenance Infusion Interval Is Correlated with Clinical Efficacy in Crohnʼs Disease

Abstract

Infliximab has shown beneficial effects in the treatment of Crohn's disease (CD). The aim of this study was to assess 1) the clinical efficacy of shortening the infusion interval from 8 to 4 weeks when patients had shown loss of response during maintenance therapy, and 2) the association between the serum trough level and clinical efficacy. This was an open-label prospective multicenter study. Infliximab was administered at 5 mg/kg to patients with active CD at weeks 0, 2, and 6. Week 10 responders received infliximab every 8 weeks thereafter. In those with loss of response after week 14 the interval was switched to every 4 weeks. Co-primary endpoints were the rate of patients achieving clinical response and remission at week 54. Serum level of infliximab was measured at each visit. Fifty-seven patients who responded to induction treatment received maintenance therapy after week 14. Thirty-seven patients continued at the 8-week interval and 20 patients were switched to a 4-week interval. The overall clinical response and remission rates at week 54 were 82.5% and 61.4%, respectively. For those with loss of response, treatment at the 4-week interval resulted in clinical response and remission rates of 83.3% (15/18) and 55.6% (10/18), respectively, at week 54. A correlation between clinical efficacy and serum trough level was found (P < 0.01, overall). A treatment strategy with an option of shortening the dosing interval of infliximab retrieves its trough level and may be useful for maintaining its efficacy.