What question did this study set out to answer?

To evaluate the persistence of treatment and safety outcomes between intravenous and subcutaneous infliximab in IBD patients.

January 23, 2026

P0919A Propensity Score Weighted Comparison of Intravenous and Subcutaneous Infliximab as Maintenance Treatment in Patients with Inflammatory Bowel Disease: the CISI Study

Key Points

To evaluate the persistence of treatment and safety outcomes between intravenous and subcutaneous infliximab in IBD patients.
Retrospective observational study design
Patients with Crohn’s disease or ulcerative colitis in stable remission included
Comparison of two arms: switched from IV to SC infliximab vs. continued IV therapy
Propensity score weighting used to mitigate selection bias
Primary endpoint: treatment persistence without steroids, secondary endpoints: adverse events and clinical activity over 24 months.
251 patients included: 134 on IV infliximab, 117 switched to subcutaneous CT-P13
At month 12, retention rates: 63.6% IV vs. 78.5% SC. No significant difference in Kaplan-Meier analysis (p = 0.10)
Higher discontinuation risk associated with female sex (HR 2.59; p < 0.001)
Adverse event incidence rate: 6.16 per 100 person-years for IV and 4.42 for SC
No significant differences in clinical activity scores or CRP levels between groups at any time point.

Abstract

Abstract Background The subcutaneous (SC) formulation of the infliximab (IFX) biosimilar CT-P13 is increasingly used in inflammatory bowel disease (IBD). A direct comparison between patients switched from intravenous (IV) IFX to SC CT-P13 and those who remained on IV IFX may provide valuable insights for clinical practice. Methods The CISI study is a retrospective, observational study conducted at the IBD Unit of “Villa Sofia-Cervello” Hospital, Palermo, Italy. Consecutive adult patients with Crohn’s disease (CD) or ulcerative colitis (UC) in stable, steroid-free clinical remission (Harvey-Bradshaw Index 5 for CD or partial Mayo score 2 for UC, without steroid use for ≥4 months) while on maintenance IV IFX (5 mg/kg every 8 weeks) were included. Two arms were compared. Arm 1: patients in stable, steroid-free remission who were switched from IV IFX to SC CT-P13; Arm 2: patients in stable, steroid-free remission who continued IV IFX. A propensity score-weighted analysis using inverse probability of treatment weighting (IPTW) with stabilized weights was applied to reduce selection bias. The primary endpoint was treatment persistence without steroids. Secondary endpoints included the incidence rate (IR) of adverse events (AEs) and the clinical activity at 6, 12, and 24 months. Results Overall, 251 patients were included (CD: 53.8%, UC: 46.2%): 134 remained on IV IFX and 117 were switched to SC CT-P13. Mean follow-up was 24.7 ± 29.8 months for IV IFX and 20.9 ± 14.9 months for SC CT-P13 (p = 0.41). At month 12, retention rates were 63.6% for IV IFX and 78.5% for SC CT-P13. Kaplan–Meier analysis showed no significant difference (log-rank p = 0.10 – figure 1). In the multivariable Cox model, female sex was independently associated with higher discontinuation risk (HR 2.59; 95% CI 1.66–4.04; p 0.001). A significant time-dependent effect was detected for the SC CT-P13 (p = 0.005). During the first months after switching, patients on SC CT-P13 showed a higher probability of treatment discontinuation compared with those maintained on IV therapy. However, this excess risk progressively decreased and crossed unity around month 8, after which the likelihood of persistence became higher for SC CT-P13. The AE IR was 6.16 (95% CI 3.59–9.87) per 100 person-years for IV IFX and 4.42 (95% CI 2.02–8.39) for SC CT-P13. The IPTW-adjusted IR ratio (SC/IV) was 0.95 (95% CI 0.38–2.42; p = 0.92). No significant differences between the two arms were observed in HBI, partial Mayo score, or CRP levels at 6, 12, or 24 months. Conclusion Switching from IV IFX to SC CT-P13 demonstrated comparable persistence, safety, and disease control to continued IV therapy in IBD patients with stable remission. In the long term, the SC formulation may be associated with greater treatment persistence. Conflict of interest: Dr. Macaluso, Fabio Salvatore: Advisory board and/or lecture fees for: AbbVie, MSD Galapagos, Sandoz, Takeda, Janssen, Eli-Lilly, Pfizer, Alfasigma, Giuliani Funding: The CISI study is an investigator-initiated study funded through an unrestricted educational grant provided by Celltrion Healtchare Italy s.r.l. Calderone, Silvia: No conflict of interest Renna, Sara: SR served as an advisory board member or received lecture grants from AbbVie, Johnson and Johnson, Pfizer, Alfasigma, Takeda, Eli Lilly. Casà, Angelo: No conflict of interest Orlando, Rosalba: No conflict of interest Orlando, Emanuele: No conflict of interest Li Voti, Raffaele: No conflict of interest Vastarella, Josephine: No conflict of interest Armetta, Samuele: No conflict of interest Morello, Simona: No conflict of interest Orlando, Ambrogio: Advisory board and/or lecture fees for: AbbVie, Galapagos, Celltrion, MAD, Sofar, Pfizer, Takeda, Cadigroup, Sandoz, Janssen, Eli-Lilly, Alfasigma

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