Introduction
Subcutaneous infliximab (SC IFX, CT-P13) delivers more stable trough levels and lower immunogenicity than IV infliximab, and has become standard IBD therapy across Europe; yet long-term real-world data comparing newly initiated versus switched patients, particularly from Central-Eastern Europe, remain scarce.1,2,3
Aims & Methods
To assess two-year effectiveness, persistence, pharmacokinetics, immunogenicity and safety of SC IFX in IBD stratified by switch status, we used an internal patient list maintained at a tertiary centre that tracks all IBD patients by current biologic therapy; all consecutive adults with Crohn's disease (CD) or ulcerative colitis (UC) started on SC IFX between January 2023 and December 2024 were retrieved from this list and their clinical data extracted and analysed through 104 weeks. All received 120 mg SC every 2 weeks; any dose escalation was counted as a persistence event. Patients were either newly initiated on SC IFX after two IV induction doses, or switched from maintenance IV IFX. HBI, partial Mayo score (pMayo), CRP, faecal calprotectin (FCP), IFX trough level, antibodies to infliximab (ATI) levels and concomitant azathioprine (AZA) were assessed at baseline, weeks 12, 26, 52, 78 and 104. Clinical remission: HBI<4 (CD) or pMayo<2 (UC); biochemical: FCP<200 µg/g; combined: both. Persistence was analysed by Kaplan–Meier, with escalation, loss of response, adverse event (AE) or biologic switch as events. Adjusted effects of time, switch status, sex and IBD type on remission were estimated by mixed-effects logistic regression (glmmTMB) with random intercept per patient.
Results
120 patients (97 CD, 23 UC; 56 newly initiated, 64 switched [81% from 5 mg/kg IV q8w]; 61% male; median age 38 years; BMI 25.7 kg/m²; perianal involvement: 28% of CD; AZA: 32%; smokers: 17%) were enrolled. Kaplan–Meier persistence of SC IFX 120 mg q2w was 79% at week 52 and 67% at 104, with 41 events (16 AEs, 14 dose intensifications, 8 secondary loss of response, 3 other). Persistence was markedly higher in switched than in newly initiated patients (W104 82% vs 47%; p<0.001) and numerically higher with concomitant AZA (W104 74% vs 63% without; p=0.121). Clinical, biochemical (FCP<200) and combined remission rates were 89%, 95% and 84% at W52 and 95%, 91% and 87% at W104. Among patients still on drug at W104, combined remission was 78% in newly initiated vs 91% in switched; the GLMM, which models the whole cohort, predicted 11% vs 60% (time × switch-status interaction adjusted OR 153, 35–674, p<0.001). Median IFX level was comparable between switched and newly initiated patients (W52: 15.1 vs 12.3 µg/mL, p=0.296; W104: 15.1 vs 14.6 µg/mL, p=0.538). Higher IFX level was associated with combined remission (W52 in- vs non-remission 14.4 vs 9.3 µg/mL, p=0.009; ROC AUC 0.76, cut-off ≈12.8 µg/mL). Baseline BMI was inversely correlated with IFX level from W52 onwards (W104 ρ=−0.50, p<0.001); obese patients (BMI≥30) had lower IFX at W104 (9.8 vs 20.2 µg/mL, p<0.001). ATI positivity was observed in 22% and contributed to treatment discontinuation in 9 patients. AEs occurred in 23 patients (19%, 29% new vs 11% switched, p=0.02), predominantly cutaneous; 16 led to treatment discontinuation.
Conclusion
In this Slovak two-year real-world cohort, subcutaneous infliximab at 120 mg q2w performed markedly better in patients switched from IV maintenance than in those newly initiated — with higher persistence, higher sustained combined remission and lower immunogenicity. Combined remission was linked to higher, BMI-dependent IFX levels, supporting trough-guided management of SC IFX.
References
1. Schreiber, S. et al. Randomized Controlled Trial: Subcutaneous vs Intravenous Infliximab CT-P13 Maintenance in Inflammatory Bowel Disease. Gastroenterology 160, 2340–2353 (2021).
2. Buisson, A. et al. Effectiveness of Switching From Intravenous to Subcutaneous Infliximab in Patients With Inflammatory Bowel Diseases: the REMSWITCH Study. Clinical Gastroenterology and Hepatology 21, 2338-2346.e3 (2023).
3. Iborra, M. et al. Subcutaneous Infliximab Cutoff Points in Patients With Inflammatory Bowel Disease: Data From the ENEIDA Registry. Journal of Crohn’s and Colitis jjae127 (2024) doi:10.1093/ecco-jcc/jjae127.
Disclosure
MP has served as clinical trial investigator for Ventyx, Reason, and Amalthea, and has received speaker honoraria from Johnson & Johnson, AbbVie, Takeda, Celltrion, Sandoz, and Biocon. JB has received speaker honoraria from AbbVie, Takeda, Celltrion and Sandoz. PL has served as a clinical trial investigator for Ventyx and has received speaker honoraria from AbbVie, Takeda, Celltrion and Sandoz and has acted as an advisory board member (consultant) for AbbVie, Johnson & Johnson, Takeda and Elli Lilly.