Subcutaneous Infliximab Monotherapy Versus Combination Therapy with Immunosuppressants in Inflammatory Bowel Disease: A Post Hoc Analysis of a Randomised Clinical Trial

Background and Objective Whether benefits and risks of intravenous (IV) infliximab combotherapy with immunosuppressants versus infliximab monotherapy apply to subcutaneous (SC) infliximab is unknown. This post hoc analysis of a pivotal randomised CT-P13 SC 1.6 trial aimed to compare SC infliximab monotherapy with combotherapy in inflammatory bowel disease (IBD). Methods Biologic-naive patients with active Crohn's disease or ulcerative colitis received CT-P13 IV 5 mg/kg at Week (W) 0 and 2 (dose-loading phase). At W6, patients were randomised (1:1) to receive CT-P13 SC 120 or 240 mg (patients < 80 or >= 80 kg) every 2 weeks until W54 (maintenance phase), or to continue CT-P13 IV every 8 weeks until switching to CT-P13 SC from W30. The primary endpoint-non-inferiority of trough serum concentrations-was assessed at W22. We report a post hoc analysis comparing pharmacokinetic, efficacy, safety and immunogenicity outcomes up to W54 for patients randomised to CT-P13 SC, stratified by concomitant immunosuppressant use. Results Sixty-six patients were randomised to CT-P13 SC (37 monotherapy, 29 combotherapy). At W54, there were no significant differences in the proportions of patients achieving target exposure (5 mu g/mL; 96.6% monotherapy vs 95.8% combotherapy; p > 0.999) or meeting efficacy or biomarker outcomes including clinical remission (62.9% vs 74.1%; p = 0.418). Monotherapy and combotherapy groups had comparable immunogenicity (anti-drug antibodies [ADAs]: 65.5% vs 48.0% [p = 0.271], neutralising antibodies [in ADA-positive patients]: 10.5% vs 16.7% [p = 0.630], respectively). Conclusions Pharmacokinetics, efficacy and immunogenicity were potentially comparable between SC infliximab mono therapy and combotherapy in biologic-naive IBD patients.