P890 Usefulness of subcutaneous Infliximab in patients with Inflammatory Bowel Disease in clinical practice: are increased levels associated with clinical benefit?

Abstract

Abstract Background Switch from intravenous Infliximab (IFXiv) to subcutaneous Infliximab (IFXsc) in Inflammatory Bowel Disease (IBD) has been associated with an increase in trough levels. However, whether this increase is correlated with additional clinical benefit has not thus far been evaluated in clinical practice. Methods Single-center retrospective study of IBD patients who switched from IFXiv to IFXsc (for at least 3 months), between July 2021 and August 2023, due to unfavorable pharmacokinetics (IFX serum levels <3 +/- anti-IFX antibodies). Disease activity was defined as clinically: Simple Clinical Colitis Activity Index (SCCAI) ≥2 for Ulcerative Colitis (UC), Harvey Bradshaw Index (HBI) ≥5 for Crohn´s Disease (CD) or perianal fistulae with active drainage; and biochemical: C-reactive protein (CRP) >5 mg/L and/or fecal calprotectin (FC) >250 µg/g in UC and >150 µg/g in CD. Primary endpoint was to evaluate the effectiveness of IFXsc switch: achieving clinical response (decrease of SCCAI ≥2, IHB ≥3 or ≥50% in fistula drainage) or remission (SCCAI ≤1, IHB ≤4 or absence of active fistula drainage) with biomarkers normalization, or maintenance of remission, in patients with and without previous activity, respectively. Secondary endpoints were to assess IFX levels change and safety of IFXsc switch. Results Twenty-five patients (23 CD, 2 UC) were included (Table 1). Previous IFXiv therapy lasted for a median of 55 (20.6-74.1) months (100% with intensified dose and 48% with combined therapy). Median baseline IFX level was 1.7 (0.4-3) μg/mL, with anti-IFX antibodies in two cases. At baseline, 7 patients were in remission and 18 had active disease: 15/18 clinical or both clinical and biochemical (3/15 luminal, 11/15 perianal or 1/15 both), and 3/18 biochemical only. Median follow-up was 15.2 (10.2-19.2) months. After IFXsc switch, an increase of IFX level was achieved in 96% of cases, with a median final level of 12.4 μg/mL (9.2-18) (Figure 1). None of the patients in remission at the beginning relapsed during follow-up. Of patients with previous clinical activity, 66.6% achieved clinical remission (53.3%) or response (13.3%), which was seen in 50% of patients with luminal and 66.7% with perianal activity, after a median of 79 (75-210) days. CRP and FC normalization was reported in 53.3% of patients with previous biochemical activity. Treatment was discontinued only in one patient due to inefficacy. IFXsc was intensified in 8% and concomitant treatment could be withdrawn in four patients. No adverse events we reported. Conclusion Switching to IFXsc in patients with previous therapy with intensified IFXiv is not only associated with a more favorable pharmacokinetic profile but also with a greater effectiveness.