Jaakko Rautakorpi*[1], Sara Kolehmainen*[2], Eliisa Löyttyniemi[3], Clas-Göran af Björkesten[2], Perttu Arkkila[2], Taina Sipponen[2], Kimmo Salminen[1]

Affiliates

1 University of Turku and Turku University Hospital, Abdominal Center- Gastroenterology, Turku, Finland2 University of Helsinki and Helsinki University Hospital, Abdominal Center- Gastroenterology, Helsinki, Finland3 Department of Biostatistics, University of Turku and Turku University Hospital, Turku, Finland

Abstract

Background
Stable disease activity and low relapse rates have been observed in relatively small real-world cohorts of inflammatory bowel disease (IBD) patients who switched from established intravenous (IV) maintenance infliximab (IFX) therapy to subcutaneous (SC) IFX therapy. Studies with larger patient populations are needed to confirm these results. Aims of the study were to assess real-world treatment persistence, clinical outcomes, IFX concentrations and safety after switching from established IV IFX treatment to SC IFX in a comprehensive group of IBD patients.

Methods
This retrospective register-based study included adult Crohn’s disease (CD) and ulcerative colitis (UC) patients who switched from IV IFX maintenance therapy to SC IFX therapy in two tertiary centres from 1 January 2021 to 31 May 2023. The only exclusion criterion was a follow-up time on SC therapy of less than 6 months. Study data were collected from the hospitals’ IBD registers and electronic patient records, managed using REDCap electronic data capture tools, and combined by Finnish data permit authority Findata. Data were collected at baseline and at the time points of 3, 6, 12 and 18 months after switching to SC therapy. Clinical remission was defined as Harvey-Bradshaw Index (HBI) < 5 or Partial Mayo Score (PMS) < 2, and faecal calprotectin (FC) < 100 was considered normal.

The data analysis was generated using SAS studio, Version 3.81, Basic Edition (SAS Institute Inc., Cary, NC, USA). Categorical variables were summarized with counts and percentages, continuous variables with median together with range or lower and upper quartile (marked with IQR). Continuous measurements, which were measured over time (baseline – 12 months), were analysed with Friedman’s test or linear mixed model. Logarithmic transformation was used to fulfil assumptions for the model. Compound symmetry covariance structure and Kenward-Roger corrections for degrees of freedom was used.

Results
A total of 274 patients (104 CD, 170 UC) were included. Of all patients, 19.3% (n=53) had a shortened (less than 8 weeks) IV IFX infusion interval and 7.3% (n=20) had an escalated IV IFX dose of 10 mg/kg. Most patients (96.7%) started SC treatment with 120mg dose every other week, and the rest of the patients with a shortened interval. After switching, treatment persistence at 12 months was 94.8% in CD patients and 88.8% in UC patients. During a median follow-up of 79 weeks, 11.3% (n=9 CD and n=22 UC) of patients discontinued the treatment. Thirteen patients discontinued the treatment due to either inadequate response or loss of response. Compared to baseline, no statistically significant change occurred in disease activity at timepoints 3, 6, and 12 months based on HBI, PMS or FC (p=0.792, p=0.462 and p=0.20). The median IBD-VAS score remained at 1 after the switch and during follow-up. IFX concentrations were significantly (p<0.0001) higher during SC treatment (median 16.75 µg/ml) compared to IV trough levels before switching (median 6.71 µg/ml). Antibodies to IFX were detected in six patients at some point after switching. During follow-up, 10.2% (n=28) of patients needed shortening of SC administration interval. In total, 13.5% (n=37) reported mild adverse events and 1.5% (n=4) serious adverse events during SC IFX treatment.

Conclusion
Switching to SC IFX maintenance treatment was associated with high treatment persistence, stable disease course, increased IFX concentrations and acceptable safety profile.

Poster_P4_Kolehmainen