P1127 Comparative study of Subcutaneous and Intravenous Infliximab in Inflammatory Bowel Disease: Interim analysis of a prospective single center cohort (The SWITCH study)
Authors: Liefferinckx C , Minsart C , Husson C , Helman C , Wambacq V , Amininejad L , Cremer A , Franchimont D 
Published: January 2025

Abstract

Background
Randomized control studies have demonstrated the efficacy of subcutaneous infliximab (IFX SC) compared to placebo. However, real-life evidence remains scarce on the impact of this switch on effectiveness, safety, pharmacokinetics (PK), and quality of life in IBD management.

Methods
This is a 1 year longitudinal prospective single center cohort study (EC: P2021/570) comparing 2 groups: IBD patients remaining on IFX Intravenous (IV) (IV group) and patients switching from IFX IV to SC (SC group). The study population included patients in clinical, biological and endoscopic remission on IFX IV maintenance. Decision to switch to SC or to remain on IV was based on patient preference. The primary outcome was the proportion of IBD patients with drug sustainability. Drug sustainability was defined as the absence of treatment interruption or modifications in the IFX regimen. The secondary outcomes were safety, PK and quality of life (via IBDQ). At each timepoint, IFX Trough Levels (TL) were measured using ELISA.

Results
Sixty-eight IBD patients met the inclusion criteria with 42 patients switching to SC. At last IV infusion, all patients were treated at 5 mg/kg with regimen of every 8 (n=49), 6 (n=9) and 4 (n=10) weeks. Demographics of SC and IV groups were comparable as shown in Table 1. At the time of this interim analysis, the mean follow-up was 37 weeks ± 20. Drug sustainability was not different in the 2 groups (p=0.45). The reasons for loss of drug sustainability were flare disease (n=4), neoplasia (n=1), pregnancy (n= 1) or patient choice (n=4). At last IV infusion and baseline, both IV and SC groups had similar TL distributions but as soon as patients were switched to SC (SC group), IFX TL were significantly different from patients maintained in IV (IV group) at each timepoint (Figure 1a). Strikingly, in the SC group, median IFX TL at week 8 was significantly lower in patients failing drug sustainability (Figure 1b) (10.7 μg/mL, IQR (7.3-14.1) vs 27.5 μg/mL, IQR (25.8-45), (p= 0.007)).
Neither the overall quality of life assessed via IBDQ nor the specific IBDQ domains (GI, systemic, social, or emotional) showed significant differences between the SC and IV groups.
Although the incidence of IFX-related adverse events was higher in the SC group, the difference was not statistically significant (74% vs 41%; p=0.07). Injection site reactions were the most common and specific adverse event in the SC group.

Conclusion
This study demonstrates comparable drug sustainability between IFX SC and IV in a remitter IBD population. Among SC patients, week 8 IFX levels were predictive of drug sustainability. While SC treatment showed a trend toward higher adverse events, injection site reactions were the most common and specific to the SC group

References
This interim analysis of SWITCH study demonstrates comparable drug sustainability between IFX SC and IV in a remitter IBD population. Among patients switched to SC, week 8 IFX trough levels were predictive of drug sustainability. While SC treatment showed a trend toward higher adverse events, injection site reactions were the most common and specific to the SC group.