Comparison of subcutaneous and intravenous infliximab in patients with inflammatory bowel disease showed no differences in immunogenicity or treatment persistence at 1 year

Background Infliximab (IFX) effectiveness in inflammatory bowel disease (IBD) can be impaired by antidrug antibodies (ADA). Subcutaneous IFX has a different pharmacokinetic profile compared with intravenous administration, potentially affecting immunogenicity. Methods Retrospective audit of adult patients starting IFX between January 2019 and June 2022. All participants received induction with three intravenous doses, followed by either maintenance subcutaneous IFX every 2 weeks (from 2021) or maintenance intravenous IFX (historic control). We compared ADA levels, IFX trough levels and treatment persistence between groups after 12 months of treatment. Results 101 patients receiving maintenance subcutaneous IFX were compared with 108 patients with maintenance intravenous IFX. At 12 months, prevalence of ADA positivity was similar in both groups (48.1% subcutaneous vs 50.6% intravenous; p=0.775). There were no differences in detectable IFX trough levels and treatment persistence between both groups. Patients receiving combination therapy with IFX and immunomodulators (34.8%) had less often ADA (65.2%; OR 0.28 (95% CI 0.13 to 0.58); p=0.001) irrespective of route of IFX administration. Treatment persistence was higher in those receiving combination therapy compared with monotherapy at 12 months (73.3% vs 51.9%; p=0.004). Conclusions There were no significant differences in ADA levels, IFX levels and treatment persistence between the subcutaneous and intravenous routes of IFX administration after 12 months. Concurrent use of immunomodulators was associated with reduced immunogenicity and better treatment persistence. Clinicians should advise patients on the benefits of immunomodulator combination therapy regardless of route of administration.