Lize Bollen

Short-term Effect of Infliximab Is Reflected in the Clot Lysis Profile of Patients with Inflammatory Bowel Disease: A Prospective Study

Background:Inflammatory bowel disease (IBD) is recognized as an independent risk factor for thrombosis. First, we investigate whether the concentration of fibrinolysis inhibitors is increased in patients with IBD. Second, we investigate the effect of infliximab induction therapy on the hemostatic profile. Methods:This prospective study included 103 patients with IBD starting infliximab therapy and 113 healthy controls. Plasma was collected before the first infliximab infusion (wk 0) and after induction therapy (wk 14). Patients not showing a clinical response on induction were considered as primary nonresponders. Fibrinolysis inhibitors were measured by enzyme-linked immunosorbent assay. Using a clot lysis assay, the area under the curve (global marker for coagulation/fibrinolysis), 50% clot lysis time (marker for fibrinolytic capacity), and amplitude (indicator for clot formation) were determined. Results:Patients with IBD selected for infliximab treatment have higher area under the curve (median 29 [interquartile range, 20–38]) and amplitude (0.4 [0.3–0.5]) compared with healthy controls (18 [13–24] and 0.3 [0.2–0.3], respectively, P < 0.001). Primary nonresponders showed a decrease neither in inflammatory markers nor in hemostatic parameters, whereas in primary responders, a decrease in inflammatory markers was associated with a decrease in both area under the curve (29 [20–38] (wk 0) to 20 [14–28] (wk 14), P < 0.001) and amplitude (0.4 [0.3–0.5] (wk 0) to 0.3 [0.3–0.4] (wk 14), P < 0.001). Conclusions:This is the first prospective study demonstrating that the clot lysis profile differs between patients with IBD and healthy individuals. On infliximab induction treatment, this clot lysis profile normalizes in responders suggesting that infliximab treatment is advisable for patients with IBD with an activated hemostatic profile.

Rapid Test for Infliximab Drug Concentration Allows Immediate Dose Adaptation

OBJECTIVES: Therapeutic drug monitoring of infliximab improves treatment outcomes, but available assays to monitor infliximab lack speed to implement treatment algorithms immediately. Our aim is to validate a rapid, lateral flow‐based assay (LFA) for quantitative determination of infliximab and to assess thresholds associated with mucosal healing in patients with ulcerative colitis. METHODS: Samples (n=190) from 29 anti‐tumor necrosis factor naive patients with ulcerative colitis starting infliximab induction therapy between June 2010 and February 2012 were prospectively collected. All patients had a Mayo endoscopic sub‐score ≥2 at baseline. Mucosal healing (MH), defined as a Mayo endoscopic sub‐score ≤1, was evaluated at week 10–14. Infliximab trough concentrations (TC) were determined with a novel LFA, which was benchmarked with the RIDASCREEN infliximab Monitoring (ELISA). RESULTS: The LFA showed an excellent agreement with enzyme‐linked immunosorbent assay (ELISA) for quantification of infliximab, as observed from Pearson and intraclass correlation coefficients of 0.95 and 0.95 during induction and 0.93 and 0.87 during maintenance therapy, respectively. In total, 45% of patients achieved MH. Using the LFA, week 14 TC ≥2.1 μg/ml (AUROC: 0.819, P=0.008) were associated with MH. After 2 years follow‐up, 77% of patients with MH were still receiving infliximab therapy vs. 25% of patients without MH. CONCLUSIONS: We validated a LFA for quantification of infliximab and identified TC associated with MH. With a time‐to‐result of 20 min, individual sample analysis and user‐friendliness, the LFA outplays ELISA as a rapid, accurate tool to monitor infliximab concentrations.

Active PAI-1 as marker for venous thromboembolism: Case–control study using a comprehensive panel of PAI-1 and TAFI assays

BACKGROUND Both activated Thrombin Activatable Fibrinolysis Inhibitor (TAFI) and active Plasminogen Activator Inhibitor-1 (PAI-1) attenuate fibrinolysis and may therefore contribute to the pathophysiology of Venous ThromboEmbolism (VTE). Whether increased TAFI and/or PAI-1 concentrations are associated with VTE is unclear. OBJECTIVE To study an association of impaired fibrinolysis and VTE using a comprehensive panel of in-house developed assays measuring intact TAFI, activation peptide of TAFI (AP-TAFI), PAI-1 antigen, endogenous PAI-1:t-PA complex (PAI-1:t-PA) and active PAI-1 levels in 102 VTE patients and in 113 healthy controls (HC). RESULTS Active PAI-1 was significantly higher in VTE patients compared to HC (20.9 [9.6-37.8] ng/ml vs. 6.2 [3.5-9.7] ng/ml, respectively). Active PAI-1 was the best discriminator with an area under the ROC curve and 95% confidence interval (AUROC [95%CI]) of 0.84 [0.79-0.90] compared to 0.75 [0.68-0.72] for PAI-1:t-PA, 0.65 [0.58-0.73] for PAI-1 antigen, 0.62 [0.54-0.69] for AP-TAFI and 0.51 [0.44-0.59] for intact TAFI. Using ROC analysis, we defined an optimal cut-off of 12.8 ng/ml for active PAI-1, with corresponding sensitivity of 71 [61-79] % and specificity of 89 [82-94] %. A lack of association with the time between VTE event and sample collection or with the intake of anticoagulant treatment suggests that active PAI-1 levels are sustainable high in VTE patients. CONCLUSIONS This case-control study emphasizes the clinical importance of measuring active PAI-1 instead of PAI-1 antigen and identifies active PAI-1 as a potential marker of VTE. Prognostic studies will need to address the clinical significance of active PAI-1 as biomarker.

The Occurrence of Thrombosis in Inflammatory Bowel Disease Is Reflected in the Clot Lysis Profile

Background:The occurrence of thromboembolic events (TE) is an important extraintestinal manifestation in patients with inflammatory bowel disease (IBD). The aim of this study was to compare fibrinolysis and clot lysis parameters between (1) patients with IBD and healthy controls and (2) patients with IBD with TE (IBD + TE) and without TE (IBD − TE). Methods:One hundred thirteen healthy controls and 202 patients with IBD, of which 84 patients with IBD + TE and 118 patients with IBD − TE, were included in this case–control study. Three clot lysis parameters (area under the curve, 50% clot lysis time, and amplitude) were determined using a clot lysis assay. Plasminogen activator inhibitor 1 (PAI-1) and thrombin activatable fibrinolysis inhibitor concentrations were determined by enzyme-linked immunosorbent assay. Results:PAI-1 antigen, active PAI-1, and intact thrombin activatable fibrinolysis inhibitor concentrations, as well as 50% clot lysis time and area under the curve, were significantly associated with the presence of IBD (all P < 0.05). The median time between TE and plasma collection was 5.0 (1.8–11.0) years. Comparing IBD + TE versus IBD − TE, active to total PAI-1 ratio (0.36 [0.24–0.61] versus 0.24 [0.13–0.40]), area under the curve (31 [24–49] versus 22 [13-31]), 50% clot lysis time (110 [64–132] versus 95 [70–126] minutes), and amplitude (0.295 [0.222–0.436] versus 0.241 [0.168–0.308]) were significantly higher in IBD + TE (all P <0.05) and remained higher after adjustment for age, gender, C-reactive protein, type of disease, presence of comorbidities, and disease activity. Conclusions:Patients with IBD have an altered clot lysis profile compared with healthy controls. Clot lysis parameters differ significantly between patients with IBD with and without a history of TE and should be included in the risk assessment.

Identification of an inflammatory bowel disease patient with a deep vein thrombosis and an altered clot lysis profile.

Patients with inflammatory bowel diseases (IBD), a chronic inflammatory disease characterized by flares and remission, are prone to develop thrombosis. The mechanism behind this prothrombotic state is not completely understood but is definitely multifactorial and linked with excessive inflammation observed in these patients. So far, no biomarker exists to select among IBD patients those with and increased risk for thrombosis. Corticosteroid therapy, given as rescue IBD treatment, is known to increase the thrombotic risk, whereas for antitumor necrosis factor (TNF)-alpha therapy such as infliximab, given to induce and maintain remission in IBD, the results are inconclusive. Here, we describe a 31-year-old IBD patient who developed a deep vein thrombosis. We determined the clot lysis profiles before and after developing thrombosis. We showed that a global functional clot lysis assay can be used as a tool to identify IBD patients who may benefit from thromboprophylactic therapy.

C0481: Active Plasminogen Activator Inhibitor-1 (PAI-1) Concentrations are Increased in Patients with a Venous Thromboembolism (VTE)

Background: Impaired fibrinolytic activity is associated with an increased risk for venous thromboembolism (VTE). Both activated thrombin activatable fibrinolysis inhibitor (TAFI) and active plasminogen activator inhibitor-1 (PAI-1) attenuate fibrinolysis. Activated TAFI cleaves C-terminal lysine residues of fibrin thereby hampering plasmin generation whereas active PAI-1 inhibits plasminogen activator through complex formation. Aim: Analyze the role of fibrinolysis in patients diagnosed with VTE by comparing TAFI and PAI-1 plasma levels with healthy controls (HC). Methods: Plasma of 102 patients diagnosed with VTE was collected after the VTE event in a time range of 10 to 2868 days with a median of 163 days. Plasma parameters (intact TAFI, activation peptide of TAFI (AP, marker for the extent of TAFI activation), total PAI-1 and active PAI-1) of VTE patients were measured using in-house developed ELISAs and compared with plasma parameters of 113 HC. VTE patients had either a deep vein thrombosis (DVT), a pulmonary embolism (PE) or both (DVT+PE). Results: Median [interquartile range] active PAI-1 and AP concentrations were significantly increased in VTE patients compared to HC (20.8 ng/ml [9.6–37.8] vs. 6.2 ng/ml [3.6–9.7], p vs. 314ng/ml [257–376], p = 0.0027, respectively). The type of VTE (PE, DVT or PE+DVT) had no impact on PAI-1 and/or TAFI levels. Neither did the days between diagnosis of the VTE and plasma sampling. ROC analyses revealed that active PAI-1 was the best parameter to discriminate VTE patients from healthy controls (Area Under Curve (AUC) = 0.84, 95% confidence interval 0.79 to 0.90). Conclusions: Preliminary data show thatactive PAI-1 may function as a good biomarker to distinguish VTE patients from healthy subjects. In a next step the association of other cardiovascular risk factors such as recurrent VTE, age, body mass index, immobilization, contraceptive use, . . . , with PAI-1 and TAFI levels will be analyzed using multivariate analyses.