Introduction
The clinical efficacy of subcutaneous (S/C) infliximab as maintenance treatment in IBD has been demonstrated in multiple studies. REMSWITCH identified that patients receiving higher intravenous (IV) doses were at increased risk of clinical relapse. However, there is conflicting data regarding the efficacy of S/C infliximab in maintaining disease remission in both high-dose and standard-dose groups.
Aims & Methods
Aim: To assess disease stability following a switch from IV to S/C infliximab, evaluate outcomes with higher versus standard IV dosing and monitor disease activity throughout the study.
Methods: Baseline clinical data was prospectively collected including age, gender, disease subtype, disease extent as well as infliximab dose, faecal calprotectin (FCP) and infliximab trough levels( ITLs) pre/post-switch. Data was also collected from quality-of-life questionnaires (IBD disk and EQ-5D-5L), along with baseline intestinal ultrasound (IUS) and IUS at 12 months post S/C switch. Additionally, patients who required escalation of therapy were evaluated.
Results
Reporting results of the first 67 patients recruited in the IRESWITCH study, 49% of patients were female with a median age of 40 years. 72% had UC, 28% had CD.
Median ITLs pre-switch were 6.87mg/ml(IQR 4.8) and 15.05mg/ml(IQR 8.35) 3 months post-switch (p<0.001). Median CRP levels were 1mg/L pre-switch(IQR 1.3) and 1.3ml/L 3 month post-switch(IQR 1.78). Median FCP level pre switch was 38mg/g(IQR 66) and 29mg/g(IQR 115) 3 months post-switch. FCP levels did not significantly change after switching from IV to S/C. Median baseline IUS SAS(Segmental Activity Score) was 8.4(IQR 3.6),n=59. There was no significant change in the median IUS SAS score post-switch, p=0.5 (n=15).
Median EQ-5D-5L scores at baseline (n=39) were 80 (IQR 85) suggesting a high self-reported health status. Median IBD-Disk Scores(n=37) were 20(IQR 32) suggesting a low to mild level of IBD-related disability. On repeat IBD-Disk score at 3 months, 8/18(44%) had a lower IBD-Disk score, 4/18(22%) had the same score and 6/18(33%) had a higher score.
17/67(25%) were on standard IV dosing at 5mg/kg 8 weekly(8WE). 50/67(75%) were on doses >5mg/kg 8WE, with 29/67(43%) on 10mg/kg.
In total, 3 patients returned to IV infliximab. 2 were for patient preference, 1 patient(1.5%) due to clinical activity and was on 10mg/kg 8WE pre-switch.
3/67 (4%) required dose escalation. 2/3 received dose escalation at 240mg S/C for 12 weeks and returned to standard dosing. Both of these patients had been on standard 5mg/kg 8WE pre-switch.
| Baseline Characteristics | N=67 | % |
| Age, median | 40 |
|
| Female | 33 | 49 |
| UC | 48 | 72 |
| 5mg/kg 8WE | 17 | 25 |
| 7.5mg/kg | 17 | 25 |
| 10mg/kg | 29 | 43 |
| Baseline CRP, median (mg/L) | 1 |
|
| Baseline FCP, median (mg/g) | 38 |
|
| Baseline IUS SAS, median | 8.4 |
|
Table 1. Baseline demographics and clinical characteristics of patients prior to switching from IV to S/C infliximab
Conclusion
Switching from IV to S/C infliximab is as effective in high-dose patients as in those on standard dosing.
Combined non-invasive monitoring with FCP, CRP and IUS demonstrates stability of disease control with IV to S/C switch in early results from the IRESWITCH study.
References
1. Buisson A, Nachury M, Reymond M, Yzet C, Wils P, Payen L, Laugie M, Manlay L, Mathieu N, Pereira B, Fumery M. Effectiveness of Switching From Intravenous to Subcutaneous Infliximab in Patients With Inflammatory Bowel Diseases: the REMSWITCH Study. Clin Gastroenterol Hepatol. 2023 Aug;21(9):2338-2346.e3. doi: 10.1016/j.cgh.2022.08.011. Epub 2022 Aug 17. PMID: 35987302.
2. Chetwood JD, Tran Y, Subramanian S, Smith PJ, Iborra M, Buisson A, Paramsothy S, Leong RW. Intravenous Versus Subcutaneous Infliximab in Inflammatory Bowel Disease: A Systematic Review and Meta-analysis. J Crohns Colitis. 2024 Sep 3;18(9):1440-1449. doi: 10.1093/ecco-jcc/jjae059. PMID: 38656784.