Subcutaneous infliximab in the treatment of refractory Crohn‘s disease patients – a pilot study of drug immunogenicity

Introduction: Despite infliximab (IFX) still being the “gold standard” of biological therapy for Crohn’s disease (CD), its effectiveness may vary depending on many factors. One of these factors is the individual patient’s reaction to the drug. A significant clinical problem is the immunogenicity of IFX, where up to 60% of treated patients may develop antibodies against the drug, leading to a loss of response to treatment and/or adverse reactions to therapy. Since 2020, subcutaneous infliximab (IFX-SC) has been available for treating CD patients, characterized by its stable and high trough level (TL) concentration in blood. It is possible that one consequence of this property of IFX-SC is its lower rate of immunogenicity. We present a prospective study of patients diagnosed with CD with severe to refractory courses, treated with IFX-SC. The aim of the study was to monitor the immunogenicity of IFX-SC, including the dynamics of TL and anti-drug antibodies (anti-IFX). The dynamics of clinical, imaging, and laboratory markers of CD over one year of monitoring and treatment are described. Materials and methods: The study included 23 patients diagnosed with CD who had failed 2 to 6 previous lines of biological therapy, one of which was intravenous infliximab (IFX-IV). Patients were divided into two arms of induction therapy based on the presence of anti-IFX. Maintenance therapy consisted of 120 mg s.c. every 14 days, and intensification was 240 mg s.c. every 14 days if necessary. Patients were monitored at weeks W0, W4, W14, W30, and W52, recording Harvey-Bradshaw Index (HBI), serum C-reactive protein (CRP), fecal calprotectin (FC) concentrations, drug trough levels (TL IFX) and serum anti-drug antibodies (anti-IFX). Endoscopic and ultrasonographic disease scores (SES-CD and IUS) were determined, and HLA DQA1*05 haplotype was examined in all patients. Data were analyzed using MedCalc® Statistical Software with non-parametric statistical methods and binary logistic regression. Results: 52-week persistence on IFX-SC treatment was recorded in 13 out of 23 patients (56.5%), with a significant decrease in all monitored clinical, imaging, and laboratory markers of CD activity. During the therapy, 8 out of 16 initially anti-IFX positive individuals seroconverted to negative anti-IFX (50%). None of the patients treated with IFX-SC in W52 needed concomitant immunomodulator treatment. No new sensitization to infliximab was recorded in the cohort during the 52-week therapy. Conclusion: The subcutaneous route of infliximab administration may be a suitable and successful solution in situations where reinduction of infliximab therapy is desired, including patients with the presence of neutralizing antibodies against the drug.