P613 Switch from intravenous to subcutaneous maintenance infliximab in real world IBD cohort

Background

During the COVID-19 pandemic, there has been concern regarding patients attending hospitals for intravenous (IV) infusions due to increased COVID-19 exposure risk and demand on hospital resources. Data on switching patients from escalated dosing of IV infliximab (IFX) are limited. We describe a real-world experience of electively switching a cohort of patients on maintenance IV IFX for inflammatory bowel disease (IBD), at both standard and escalated dosing, to subcutaneous CT-P13 (Remsima®).

Methods

Adult patients with IBD on IV IFX at Royal Adelaide Hospital were invited to switch to fortnightly dosing of subcutaneous IFX. We collected demographic data using medical records, and prospectively measured clinical assessment scores (CDAI/HBI for Crohn's disease (CD) and partial Mayo/SCCAI for Ulcerative Colitis (UC)), faecal calprotectin (FCal), CRP and trough IFX levels prior to switching to subcutaneous IFX, and at 6 months post switch. Clinical remission was defined as CDAI≤150/HBI≤4 (CD) or partial Mayo≤3 (no subscore>1)/SCCAI≤2 (UC).

Results

29 patients were switched from IV IFX to subcutaneous CT-P13 between March 2021 and May 2022 (see Table 1 for baseline demographics). 23 had Crohn's disease (79%). 10/29 patients (31%) were on intensified IV dosing at baseline prior to switch. The majority of patients, 25/29 (86%) were in remission pre-switch.

Of 19 patients with paired trough IFX levels, these increased significantly from baseline to 6 months post-switch (5.9mg/ml to 13.9mg/ml, respectively (p=0.0003), see Fig 1). The median FCal did not change pre- vs post switch (73mcg/g vs 80mcg/g, p=0.540), see Fig 2). Median CRP did not change pre- vs. post switch (1 µg/ml vs 2 µg/ml). Clinical assessment scores remained stable pre- vs. post-switch (CDAI 31 vs 31, (p=0.316) see Fig 3; HBI. 1 vs 2 (p=0.940); partial Mayo 0 vs 0, (p>0.999); and SCCAI 1 vs 2 (p=0.5000)).

Regarding the subset of patients on escalated dosing at baseline, all patients were in clinical remission at 6 months post-switch. There was no significant change in IFX levels (8.4 vs 13.3, p=0.253). FCal did not significantly change (76mcg/g vs 79mcg/g (p=0.563), nor did median CDAI (37 vs 21 (p=0.5312) and median HBI (2 vs 2 (p=0.750)). 

Overall, only 1/29 (3%) patients were not in remission at 6 month follow-up. No patients in required steroids or surgery. Of the 9 patients with perianal disease, none had a flare. All patients with weight>100kg (n=4) remained in remission.