EFFICACY AND SAFETY OF SWITCHING FROM INTRAVENOUS TO SUBCUTANEOUS IFX (CT-P13): A MULTI-CENTRE COHORT STUDY

Objective

Intravenous (IV) infliximab (IFX) is a well-established therapy for IBD patients. A subcutaneous (SC) IFX (CT-P13) formulation has recently been shown to be as effective as IV IFX in a randomised trial but there are no data to support elective switching of patients on maintenance IV IFX therapy. We aimed to assess the effectiveness of an elective switching program to SC CT-P13 in patients treated with IV IFX.

Design

Patients on maintenance IV IFX who switched to SC CT-P13 were included in this retrospective multi-centre cohort study. Disease activity was monitored serially with HBI, SCCAI, Faecal calprotectin (FCP), C-reactive protein (CRP) for up to 12 months at baseline and then months 3, 6 and 12. IFX trough levels were measured at the same time points following switch. The primary outcome measure was treatment persistence. Secondary outcome measures included IFX pharmacokinetics (PK), safety and need for corticosteroid rescue therapy/surgery.

Results

We included 181 patients of whom 115 (63.5%) had CD. 72.4% were on 8-weekly dosing of intravenous IFX prior to switching and 59.1% were on concomitant immunomodulators. The majority of patients (CD: N=106, 92.2%, UC: N=46, 76.7% and IBD-U: N=5, 83.3%) were in clinical remission. Treatment persistence rates were 92.3% (N=167). 7.7% stopped treatment during the follow-up period. There was no significant difference between baseline and repeat measurements for HBI, SCCAI, CRP or FCP. 21.7% of patients had perianal CD. Only 2 patients (8%) had worsening of perianal CD. Mean IFX levels increased from a baseline mean of 9.6 µg/dl to 15.3 µg/dl (P<0.001) at 3 months and remained stable at 6 months (mean 15.2 µg/dl) and 12 months (mean 15.3 µg/dl, both P<0.001 compared to baseline). Among the variables examined, only antibodies to IFX (ATI) was associated with IFX levels (OR -13.369, 95% CI -15.405, -11.333, P<0.001). 7.7% patients developed ATI of which 64.3% were on concomitant immunomodulators. Immunomodulatory therapy was not significantly associated with development of ATI (P=0.15). Patient acceptance and satisfaction rates with SC CT-P13 were high.

Conclusions

Among patients on IV IFX maintenance therapy switched to SC CT-P13, we observed high treatment persistence rates and low rates of immunogenicity with no change in clinical disease activity indices or biomarkers. IFX levels increased after switch to SC CT-P13 and only ATI was associated with serum IFX levels.