What question did this study set out to answer?

This study aims to compare treatment persistence and serum drug levels between subcutaneous and intravenous infliximab in patients with inflammatory bowel disease.

January 23, 2026

P1179Switching from intravenous to subcutaneous infliximab is equally effective and increases the serum drug levels

Key Points

This study aims to compare treatment persistence and serum drug levels between subcutaneous and intravenous infliximab in patients with inflammatory bowel disease.
Prospective cohort design comparing patients on subcutaneous infliximab to those on intravenous therapy.
Participants included those who switched from intravenous to subcutaneous infliximab and those who continued on intravenous therapy.
Serum infliximab trough levels were measured before and after switching.
Treatment continuation rates were analyzed for both routes of administration.
Treatment continuation rates were similar between subcutaneous (77.8% for primary-sc and 91.7% for switch) and intravenous regimens (87.5% for primary and 89.3% for switch).
92.3% of patients switching to subcutaneous infliximab showed an increase in serum infliximab levels after treatment.
The median serum infliximab level increased significantly from 11.1μg/ml before the switch to 20μg/ml after switching (P = 0.007).

Abstract

Abstract Background Infliximab (IFX) is a monoclonal antibody against tumor necrosis factor-α (TNF-α), approved for the treatment of moderate to severe inflammatory bowel disease (IBD). Its subcutaneous (sc) formulation has been approved as maintenance therapy at a dose of 120mg or 240 mg every 1 or 2 weeks. The aim of the present study is to compare treatment persistence and serum drug levels between patients receiving sc IFX and those on intravenous (iv) IFX maintenance therapy. Methods This prospective cohort study included patients with IBD who received sc IFX as maintenance treatment. The “primary-sc” cohort consisted of patients who initiated sc IFX following iv induction and were compared to patients who received iv induction since January 2024, achieved clinical remission and continued on iv IFX for maintenance (control A). The “switch” group consisted of patients who were on maintenance iv IFX for at least 6 months and then switched to sc IFX and were compared to patients who remained on iv maintenance (control B). The “switch” cohort was further classified as “optimal switch” and “non optimal switch”, depending on the presence of endoscopic remission at the time of switch. The primary end-point was treatment continuation. Secondary end-point, only for the “switch”, was the comparison of serum IFX trough levels before (at their last iv treatment) and after switching to sc (after at least 3 sc doses), measured using a point-of-care assay (range:0.4-20μg/ml). Results As of October 2025, 42 patients mean age, 39 years (SD = 14.1), 26 were male (61.9%) and 21 patients had CD had received sc IFX 18 “primary-sc” and 24 “switch” (14 “optimal”, 10 “non optimal”). The median treatment duration was 8 months (IQR:5-15.3). Forty (95.2%) were treated with 120 mg every 2 weeks and 2 (4.7%) with 120 mg every week. Six patients discontinued treatment, 4 due to an adverse event and 2 due to secondary loss of response. Treatment continuation rates are comparable between sc and iv regimens in both cohorts “primary sc” 14/18 (77.8%) vs 14/16 (87.5%) P=0.458; “switch” 22/24 (91.7%) vs 50/56 (89.3%) P=0.745). No difference is observed between “optimal” (13/14) and “non optimal” (9/10) switch groups. Among 14 patients with trough IFX levels before and after switching, 13 (92.3%) showed an increase in IFX concentration (median before:11.1μg/ml [IQR:8.1-20 vs after:20μg/ml IQR:16.4-20 P = 0.007) Figure 1. Conclusion Subcutaneous IFX demonstrated comparable persistence to the iv regimen as maintenance treatment for IBD. Patients switching from iv to sc IFX achieved higher serum drug levels. Our results support the safety and efficacy of sc IFX administration as a treatment for moderate-to-severe IBD. Conflict of interest: Dr. Avatziadis, Panagiotis: No conflict of interest Kokkotis, Georgios: No conflict of interest Chalakatevaki, Konstantina: No conflict of interest Kitsou, Vasiliki: No conflict of interest Gkizis, Michalis: No conflict of interest Laoudi, Effrosyni: No conflict of interest Koutsounas, Ioannis: No conflict of interest Bamias, Giorgos: Grants: Grants from Takeda, AbbVie, Mylan/Viatris/Biocon, Genesis Pharma, Ferring, Vianex, and Aenorasis Consulting Fees and Speaker Honoraria: AbbVie, Adacyte Therapeutics, Amgen, Bristol Myers Squibb, Faran, Ferring, Galenica, Genesis Pharma, J&ampJ, Lilly, MSD, Mylan/Viatris/Biocon, Pfizer, Shattuck Labs, Takeda, Vianex

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