1. Infliximab trough levels above 7 μg/mL in inflammatory bowel disease treated with infliximab: Better control of inflammation without increased risk of infections
Drobne D, Kurent T, Golob S, et al.
Slides compiled by Sharyle Fowler
UEGW 2017

2. Introduction Background and objectives Methods
The IFX target trough level for optimal control is not clear; previous studies have suggested 3–7 μg/mL1
Objective: To explore whether IFX trough levels > 7 μg/mL are more effective and still safe compared with lower levels
Methods
Single-centre cohort in Slovenia of 183 patients (CD: 109, UC/IBD-U: 74; adults: 162, children: 21) who received IFX between 2010–2015
Efficacy was assessed using FCP, CRP and endoscopy
Infection rates were assessed over 4-month intervals
IFX trough levels were available in 473/1260 (38%) of the 4-month periods
CD: Crohn’s disease; CRP: C-reactive protein; FC: fecal calprotectin IBD-U: inflammatory bowel disease unclassified ; IFX: infliximab 1. Vande Casteele N, et al. Gastroenterology 2015;148: e3..

3. Infliximab trough levels
Results: Efficacy
Median FCP and CRP were significantly lower in patients with high (≥ 7 μg/mL) compared with low (< 7 μg/mL) IFX trough levels
Median FCP: 66 (IQR 30–257) vs 155 mg/kg (IQR 72–474), p <0.001, respectively
Median CRP: 3 (IQR 3–3) vs 3 mg/L (IQR 3–14.5), p < 0.001, respectively
More patients had increased CRP and FCP with lower IFX levels (< 7 μg/mL)
FCP/CRP normalized in 10/17 patients after dose optimization to increase trough levels from 3–7 to > 7 μg/mL
Infliximab trough levels
 ≥ 7 µg/mL
< 7 µg/mL
p value
Increased CRP (> 3 mg/L), n (%)
20 (20)
113 (40)
< 0.001
Increased FCP(> 100 mg/kg), n (%)
17 (45)
51 (67)
0.022
CRP: C-reactive protein; FCP: fecal calprotectin; IFX: infliximab

4. Results: Safety
During follow-up, there were 160 infections that necessitated postponing IFX infusion
There were no differences in rates of infection between 4-month periods based on IFX levels < 7 vs ≥ 7 μg/mL (9.3% vs 12.4%, p = 0.32) , respectively
There were no differences in median IFX trough levels in 4-month periods with vs without infection (4.25 vs 4.09 μg/mL, p = 0.867)
IFX: infliximab

5. Conclusions & significance to clinical practice
Although the study does not determine a target IFX trough level, it provides evidence that serum trough concentrations above the frequently quoted 3–7 μg/mL target may be beneficial in some patients without increasing risk of adverse events
Significance to clinical practice
IFX: infliximab