P1021 Comparison of subcutaneous and intravenous infliximab in patients with inflammatory bowel disease showed no differences in immunogenicity or treatment persistence at one year

Abstract

Abstract Background The effectiveness of infliximab (IFX) in inflammatory bowel disease (IBD) can be impaired by the formation of anti-drug antibodies (ADA). Subcutaneous (SC) IFX has a different pharmacokinetic profile compared to intravenous (IV) administration. These differences may affect the risk of immunogenicity and we sought to explore this in a retrospective study. Methods We performed a retrospective study in Leeds, United Kingdom. Adult patients starting IFX for the first time between January 2019 and June 2022 were identified. All received standard induction with three IV doses followed by either: 1) maintenance SC IFX 2-weekly (standard practice from 2021), or 2) maintenance IV IFX (standard practice until 2021). We compared ADA levels, IFX trough levels and treatment persistence between groups after 12-months of treatment. ADA levels above 10 AU/ml were considered positive and ADA levels above 50 AU/ml as clinically relevant. Results After excluding 41 patients (16 stopped IFX after IV induction, 24 moved to SC after >4 IV doses, and 1 lost to follow-up), 101 patients receiving maintenance SC IFX were compared to 108 patients continuing with maintenance IV IFX. At 12-months, prevalence of ADA positivity was similar in both groups (48.1% SC vs 50.6%; p=0.775). Clinically relevant ADA levels (>50 AU/ml) were also similar (21.1% SC vs 26.5% IV; p=0.481). Additionally, there were no statistically significant differences in terms of detectable IFX trough levels and treatment persistence after 12-months of treatment between the two groups. Patients receiving combination therapy with IFX and immunomodulators showed a significant reduction in ADA formation irrespective of the route of IFX administration. 34.8% of patients receiving combination therapy had detectable ADA compared to 65.2% receiving IFX monotherapy (OR 0.28 (95% CI 0.13-0.58; p=0.001)). Treatment persistence was also significantly higher in those receiving combination therapy compared with monotherapy at 12-months (73.3% vs. 51.9%; p=0.004). The proportion of patients with detectable drug levels at 12-months was also higher with combination therapy (91.3% vs. 72.7%; p=0.005). Conclusion There were no significant differences in ADA levels, IFX levels, and treatment persistence between the SC and IV routes of IFX administration after 12 months of treatment. Concurrent use of immunomodulators was associated with reduced immunogenicity and better treatment persistence regardless of the route of maintenance IFX. Clinicians should advise patients on the benefits of immunomodulator combination therapy when initiating IFX regardless of route of administration.