Subcutaneous injection of infliximab CT-P13 results in stable drug levels within 14-day treatment cycle in Crohn's disease.

Abstract

CD patients in clinico-biological remission under maintenance therapy with intravenous (iv) IFX/CT-P13 were switched to CT-P13 sc 8weeks (W) after the last infusion. They were treated with CT-P13 sc, 120mg every 2W. Assessments were performed from 8W after starting CT-P13 sc and patients had to attend 6 visits on 2 consecutive cycles of treatment (cycles A and B). Visits were scheduled on days 4-6 (visit 1), days 7-9 (visit 2) and day 14 (visit 3) of each cycle, where days 1 and 14 were the days of sc injection of CT-P13. At each visit, peripheral blood was collected to measure serum IFX levels and anti-drug antibodies. Twenty patients underwent 120 evaluations. Large intra-individual variations of serum drug levels of IFX were observed. When pooling the 120 evaluations, the mean drug level was 11.3±4.9μg/ml, and the median drug level was 10.9μg/ml (IQR 7.5-15.5). During each cycle, the median drug levels were similar between visits 1 and 2 as well as between visits 1 and 3 and between visits 2 and 3. In cycle A, median drug levels were 11.1μg/ml (7.8-14.5), 12.0μg/ml (7.2-16.1) and 11.0μg/ml (7.5-15.1) at V1, V2 and V3, respectively. Similar results were obtained in cycle B, where median drug levels were 11.6μg/ml (7.9-14.9), 11.4μg/ml (8.1-15.2) and 10.9μg/ml (7.9-15.6) at V1, V2 and V3, respectively. In univariate analysis, we failed to identify factors predictive of low drug levels. IFX drug levels are quite stable within 14-day treatment cycle, without trough levels in CD patients in remission during the maintenance therapy with CT-P13 sc. In patients with inactive CD under maintenance therapy with CT-P13 sc, therapeutic drug monitoring of IFX can be performed at any time between two CT-P13 sc injections.