Higher serum infliximab concentrations following subcutaneous dosing are associated with deep remission in patients with inflammatory bowel disease.

ABSTRACT

BACKGROUND: The relationship between SC-IFX concentrations and favorable therapeutic outcomes in patients with Crohn's disease (CD) and ulcerative colitis (UC) remain elusive. PATIENTS AND METHODS: This cross-sectional trial study included consecutive IBD adult patients with IBD treated with SC-IFX at maintenance dose of 120mg/2 weeks. Investigated therapeutic outcomes included sustained clinical remission; composite clinical and biomarker remission [clinical remission and CRP < 5mg/L]; biochemical remission [FC < 250 µg/g]; and deep remission [clinical, biological and biochemical remission]. RESULTS: Of 91 patients identified, 71 patients qualified for inclusion in the study (70% with CD; 27% with concomitant immunomodulators). At the time of drug concentration measurement (median 13.5 months after switch), 55 (77%) patients had sustained clinical remission; n=44 (62%) composite clinical and biomarker remission; n=40 (56%) biochemical remission; and n=31 (43%) patients deep remission. The mean SC-IFX concentrations were significantly higher in patients with sustained clinical remission [p=0.014]; composite clinical and biomarker remission [p=0.003]; biochemical remission [p<0.001] and deep remission [p<0.001] compared to patients without having these outcomes. In multivariate analysis, SC-IFX concentration was the only factor independently associated with sustained clinical remission [odds ratio (OR) 4.7, 95% CI 3.1-12.2, p=0.005)]; clinical and biomarker remission (OR 9.21, 95%CI 6.09-18.7, p=0.006); biochemical remission (OR 37, 95%CI 14-39.3), p<0.001); and deep remission (OR 29, 95%CI15.7-37.4, p<0.001). The optimal SC-IFX concentration cut-off associated with deep remission based on ROC analysis was 20µg/mL (sensitivity 0.91, specificity 0.80, accuracy 0.85). Combination with an IMM failed to improve SC-IFX pharmacokinetics. CONCLUSION: Higher SC-IFX concentrations are associated with higher rates of favorable therapeutic outcomes in IBD patients. Serum SC-IFX concentrations higher than 20µg/mL were significantly associated with deep remission.