Background Dosing of replacement therapy with factor VIII concentrate in patients with haemophilia A in the perioperative setting is challenging. Underdosing and overdosing of factor VIII... Show moreBackground Dosing of replacement therapy with factor VIII concentrate in patients with haemophilia A in the perioperative setting is challenging. Underdosing and overdosing of factor VIII concentrate should be avoided to minimise risk of perioperative bleeding and treatment costs. We hypothesised that dosing of factor VIII concentrate on the basis of a patient's pharmacokinetic profile instead of bodyweight, which is standard treatment, would reduce factor VIII consumption and improve the accuracy of attained factor VIII levels.Methods In this open-label, multicentre, randomised, controlled trial (OPTI-CLOT), patients were recruited from nine centres in Rotterdam, Groningen, Utrecht, Nijmegen, The Hague, Leiden, Amsterdam, Eindhoven, and Maastricht in The Netherlands. Eligible patients were aged 12 years or older with severe or moderate haemophilia A (severe haemophilia was defined as factor VIII concentrations of <0.01 IU/mL, and moderate haemophilia as 0.01-0.05 IU/mL), without factor VIII inhibitors, and planned for elective low or medium risk surgery as defined by surgical risk score. Patients were randomly assigned (1:1) using a web-based randomisation system and treatment minimisation, stratified by method of administration of factor VIII concentrate (continuous infusion vs bolus administration) and risk level of surgery (low and medium risk surgery), to the pharmacokinetic-guided or standard treatment group. The primary endpoint was total amount of infused factor VIII concentrate (IU per kg bodyweight) during perioperative period (from day of surgery up to 14 days after surgery). Analysis was by intention to treat and the safety analysis population comprised all participants who underwent surgery with factor VIII concentrate. This study is registered with the Netherlands Trial Registry, NL3955, and is now closed to accrual.Findings Between May 1, 2014, and March 1, 2020, 98 patients were assessed for eligibility and 66 were enrolled in the trial and randomly assigned to the pharmacokinetic-guided treatment group (34 [52%]) or the standard treatment group (32 [48%]). Median age was 49.1 years (IQR 35.0 to 62.1) and all participants were male. No difference was seen in consumption of factor VIII concentrate during the perioperative period between groups (mean consumption of 365 IU/kg [SD 202] in pharmacokinetic-guided treatment group vs 379 IU/kg [202] in standard treatment group; adjusted difference -6 IU/kg [95% CI -88 to 100]). Postoperative bleeding occurred in six (18%) of 34 patients in the pharmacokinetic-guided treatment group and three (9%) of 32 in the standard treatment group. One grade 4 postoperative bleeding event occurred, which was in one (3%) patient in the standard treatment group. No treatment-related deaths occurred.Interpretation Although perioperative pharmacokinetic-guided dosing is safe, it leads to similar perioperative factor VIII consumption when compared with standard treatment. However, pharmacokinetic-guided dosing showed an improvement in obtaining factor VIII concentrations within the desired perioperative factor VIII range. These findings provide support to further investigation of pharmacokinetic-guided dosing in perioperative haemophilia care. Copyright (C) 2021 Elsevier Ltd. All rights reserved. Show less
Recent studies have reported that patients with von Willebrand disease treated perioperatively with a von Willebrand factor (VWF)/factor VIII (FVIII) concentrate with a ratio of 2.4:1 (Humate P... Show moreRecent studies have reported that patients with von Willebrand disease treated perioperatively with a von Willebrand factor (VWF)/factor VIII (FVIII) concentrate with a ratio of 2.4:1 (Humate P/Haemate P) often present with VWF and/or FVIII levels outside of prespecified target levels necessary to prevent bleeding. Pharmacokinetic (PK)-guided dosing may resolve this problem. As clinical guidelines increasingly recommend aiming for certain target levels of both VWF and FVIII, application of an integrated population PK model describing both VWF activity (VWF:Act) and FVIII levels may improve dosing and quality of care. In total, 695 VWF:Act and 894 FVIII level measurements from 118 patients (174 surgeries) who were treated perioperatively with the VWF/FVIII concentrate were used to develop this population PK model using nonlinear mixed-effects modeling. VWF:Act and FVIII levels were analyzed simultaneously using a turnover model. The protective effect of VWF:Act on FVIII clearance was described with an inhibitory maximum effect function. An average perioperative VWF:Act level of 1.23 IU/mL decreased FVIII clearance from 460 mL/h to 264 mL/h, and increased FVIII half-life from 6.6 to 11.4 hours. Clearly, in the presence of VWF, FVIII clearance decreased with a concomitant increase of FVIII half-life, clarifying the higher FVIII levels observed after repetitive dosing with this concentrate. VWF:Act and FVIII levels during perioperative treatment were described adequately by this newly developed integrated population PK model. Clinical application of this model may facilitate more accurate targeting of VWF:Act and FVIII levels during perioperative treatment with this specific VWF/FVIII concentrate (Humate P/Haemate P). Show less
Moort, I. van; Bukkems, L.H.; Heijdra, J.M.; Schutgens, R.E.G.; Laros-van Gorkom, B.A.P.; Nieuwenhuizen, L.; ... ; OPTI-CLOT Study Grp 2020
Background von Willebrand factor (VWF) is crucial for optimal dosing of factor VIII (FVIII) concentrate in hemophilia A patients as it protects FVIII from premature clearance. To date, it is... Show moreBackground von Willebrand factor (VWF) is crucial for optimal dosing of factor VIII (FVIII) concentrate in hemophilia A patients as it protects FVIII from premature clearance. To date, it is unknown how VWF behaves and what its impact is on FVIII clearance in the perioperative setting. Aim To investigate VWF kinetics (VWF antigen [VWF:Ag]), VWF glycoprotein Ib binding (VWF:GPIbM), and VWF propeptide (VWFpp) in severe and moderate perioperative hemophilia A patients included in the randomized controlled perioperative OPTI-CLOT trial. Methods Linear mixed effects modeling was applied to analyze VWF kinetics. One-way and two-way analyses of variance were used to investigate perioperative VWFpp/VWF:Ag ratios and associations with surgical bleeding. Results Fifty-nine patients with median age of 48.8 years (interquartile range: 34.8-60.0) were included. VWF:Ag and VWF:GPIbM increased significantly postoperatively. Blood type non-O or medium risk surgery were associated with higher VWF:Ag and VWF:GPIbM levels compared with blood type O and low risk surgery. VWFpp/VWF:Ag was significantly higher immediately after surgery than 32 to 57 hours after surgery (p < 0.001). Lowest VWF:Ag quartile (0.43-0.92 IU/mL) was associated with an increase of FVIII concentrate clearance of 26 mL/h (95% confidence interval: 2-50 mL/h) compared with highest VWF antigen quartile (1.70-3.84 IU/mL). VWF levels were not associated with perioperative bleedingF(4,227) = 0.54,p = 0.710. Conclusion VWF:Ag and VWF:GPIbM levels increase postoperatively, most significantly in patients with blood type non-O or medium risk surgery. Lower VWF antigen levels did not lead to clinically relevant higher FVIII clearance. VWF:Ag or VWF:GPIbM levels were not associated with perioperative hemorrhage. Show less
Introduction: Many patients with von Willebrand disease (VWD) are treated on demand with von Willebrand factor and factor VIII (FVIII) containing concentrates present with VWF and/or FVIII plasma... Show moreIntroduction: Many patients with von Willebrand disease (VWD) are treated on demand with von Willebrand factor and factor VIII (FVIII) containing concentrates present with VWF and/or FVIII plasma levels outside set target levels. This carries a risk for bleeding and potentially for thrombosis. Development of a population pharmacokinetic (PK) model based on FVIII levels is a first step to more accurate on-demand perioperative dosing of this concentrate. Methods: Patients with VWD undergoing surgery in Academic Haemophilia Treatment Centers in the Netherlands between 2000 and 2018 treated with a FVIII/VWF plasma-derived concentrate (Haemate (R) P/Humate P (R)) were included in this study. Population PK modeling was based on measured FVIII levels using nonlinear mixed-effects modeling (NONMEM). Results: The population PK model was developed using 684 plasma FVIII measurements of 97 VWD patients undergoing 141 surgeries. Subsequently, the model was externally validated and reestimated with independent clinical data from 20 additional patients undergoing 31 surgeries and 208 plasma measurements of FVIII. The observed PK profiles were best described using a one-compartment model. Typical values for volume of distribution and clearance were 3.28 L/70 kg and 0.037 L/h/70 kg. Increased VWF activity, decreased physical status according to American Society of Anesthesiologists (ASA) classification (ASA class >2), and increased duration of surgery were associated with decreased FVIII clearance. Conclusion: This population PK model derived from real world data adequately describes FVIII levels following perioperative administration of the FVIII/VWF plasma-derived concentrate (Haemate (R) P/Humate P (R)) and will help to facilitate future dosing in VWD patients. Show less
