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Thrombophilia management is based on the personal and family history of thrombosis. Current guidelines recommend performing thrombophilia testing only when the results will change clinical management. To investigate to what extent treatment recommendations changed following thrombophilia testing, clinical and laboratory data of 255 patients with and without venous thromboembolism who underwent thrombophilia screening were assessed retrospectively. A local score based on clinical indicators for thrombophilia was used to assess the pretest probability of thrombophilia. A total of 144 patients (57.6%) were found to have a clear thrombophilic phenotype, of which 78 were predicted to have definite thrombophilia and considered for indefinite anticoagulation; 66 were likely to have thrombophilia and were considered for indefinite or prolonged anticoagulation. Eighty-three (32.5%) could not be clearly classified and 28 (11%) were asymptomatic. A thrombophilic risk factor was diagnosed in 98 (38.4%) patients; this included 64 of 144 (44.5%) patients with a clear thrombophilic phenotype and 26 of 83 (31.3%) patients who could not be easily classified. Treatment recommendations changed in 57 of 255 (22%) patients following thrombophilia testing. Eight patients were switched from direct oral anticoagulants to vitamin K antagonists due to confirmed triple-positive antiphospholipid syndrome. In 49 patients, the anticoagulant dose was either increased ( n  = 3) or treatment was prolonged ( n  = 46) following diagnosis of high-risk thrombophilia. Clinically, assessing thrombophilia probability score before thrombophilia testing improves thrombophilia management recommendations., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Background: Von Willebrand disease (VWD), the most prevalent hereditary bleeding disorder, results from deficiency of von Willebrand factor (VWF)., Objectives: This large cohort study aims to offer a comprehensive exploration of mutation spectra and laboratory features in quantitative VWF deficiencies, shedding light on genetic underpinnings and genotype-phenotype associations., Methods: Our cohort consisted of 221 Caucasian index patients with quantitative VWD, along with 47 individuals whose plasma VWF levels fell within the lower normal boundaries (50-70 IU/dL). We conducted comprehensive VWF assays and genetic analyses, encompassing VWF gene sequencing, copy number variation investigations, and bioinformatic assessments., Results: Following International Society on Thrombosis and Haemostasis-Scientific and Standardization Committee VWF guidelines, 77 index patients were characterized as having type 1 VWD (VWF antigen [VWF:Ag] < 30 IU/dL), 111 as having type 1 VWD (VWF:Ag, 30-50 IU/dL), and 33 as having type 3 VWD. Mutation detection rates were 88%, 65%, and 92%, respectively. Notably, blood group O overrepresentation was evident in type 1 with VWF:Ag of 30 to 50 IU/dL, particularly among mutation-negative patients, suggesting a potential causal role of blood group O. A total of 223 VWF variants, comprising 147 distinct variations, were identified in quantitative VWD patients, of which 57 were novel variants (39%). Additionally, approximately 70% of individuals with VWF levels within the lower normal boundaries (50-70 IU/dL) displayed VWF variants., Conclusion: Our data advance our understanding of the molecular mechanisms underlying quantitative VWD, offering valuable insights for future research and clinical management. Distinct mutation patterns were observed among subgroups, particularly the contrast between type 1 VWD (VWF:Ag < 30 IU/dL) and type 1 VWD (VWF:Ag, 30-50 IU/dL), an area with limited prior investigation., Competing Interests: Declaration of competing interests The authors declare that they have no conflicts of interest and do not have anything to disclose., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Sepsis-associated coagulopathy increases risk of mortality. Impairment of the anticoagulant protein C (PC) pathway may contribute to the thrombotic phenotype in coronavirus disease 2019 (COVID-19) sepsis. This study assessed the functionality of this pathway in COVID-19 and non-COVID sepsis by measuring its key enzymes, thrombin and activated PC (APC). The study population included 30 patients with COVID-19, 47 patients with non-COVID sepsis, and 40 healthy controls. In healthy controls, coagulation activation and subsequent APC formation was induced by 15 µg/kg recombinant activated factor VII one hour before blood sampling. APC and thrombin in plasma were measured using oligonucleotide-based enzyme capture assays. The indirect thrombin markers prothrombin-fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) were also measured. Compared with stimulated healthy controls, median thrombin, F1+2, and TAT levels were higher in patients with COVID-19 (up to 6-fold, p < 2 × 10 -6 ) and non-COVID sepsis (up to 4.7-fold, p < 0.010). APC levels were 2.4-fold higher in patients with COVID-19 (7.44 pmol/L, p = 0.011) and 3.4-fold higher in non-COVID sepsis patients (10.45 pmol/L, p = 2 × 10 -4 ) than in controls (3.08 pmol/L). Thrombin markers and APC showed correlation in both COVID-19 (r = 0.364-0.661) and non-COVID sepsis patients (r = 0.535-0.711). After adjustment for PC levels, median APC/thrombin, APC/F1+2, and APC/TAT ratios were 2-fold ( p = 0.036), 6-fold ( p = 3 × 10 -7 ) and 3-fold ( p = 8 × 10 -4 ) lower in the COVID-19 group than in the non-COVID sepsis group, and the latter two were also lower in the COVID-19 group than in stimulated healthy controls. In conclusion, it was found that a comparatively lower anticoagulant APC response in COVID-19 patients as compared to non-COVID sepsis patients, potentially linked to endothelial dysfunction, contributes to the prothrombotic phenotype of COVID-19 sepsis.

Introduction: Lonoctocog alfa is a single-chain factor VIII (FVIII) molecule with high binding affinity to von-Willebrand-factor. While it is well known that its plasma activity is underestimated by one-stage clotting assays (OSCA), there is a lack of knowledge on the post-infusion performance of lonoctocog alfa in global coagulation assays or its potential impact on the haemostatic balance in vivo., Aim: To characterize lonoctocog alfa versus octocog alfa in pre- and post-infusion samples obtained from patients undergoing repeated investigation of incremental recovery (IR)., Methods: Eighteen patients with severe haemophilia A (lonoctocog alfa: 10, octocog alfa: 8) were included. A panel of factor-specific and global coagulation assays was applied, comprising a FVIII OSCA, two FVIII chromogenic substrate assays (CSA), rotational thrombelastography and thrombin generation (TG). Potential activation of coagulation was assessed by measuring plasma thrombin markers and levels of activated protein C., Results: Comparable IRs were found for lonoctocog alfa and octocog alfa (2.36 [IU/dL]/[IU/kg] vs. 2.55 [IU/dL]/[IU/kg], respectively). Lonoctocog alfa activities were found to be underestimated by the FVIII OSCA while also the two FVIII CSAs showed statistically significant assay discrepancies on lonoctocog alfa. Effects of both FVIII products on rotational thrombelastography were less distinct than those on TG parameters. No elevated pre- or significantly shifting post-infusion plasma levels of coagulation biomarkers were detected., Conclusion: Lonoctocog alfa and octocog alfa showed comparable recovery and safety in vivo as well as similar impacts on TG in vitro. Observed assay discrepancies on lonoctocog alfa demonstrated variability of results also between different FVIII CSAs., (© 2024 The Author(s). Haemophilia published by John Wiley & Sons Ltd.)

Introduction:  Atypical sites for thrombosis include deep vein thrombosis (DVT) of the upper extremity (UE-DVT), splanchnic vein thrombosis (SVT), and cerebral venous sinus thrombosis (CVST). In addition to specific pathogenic factors, their underlying mechanisms share similarities with typical venous thromboembolism (VTE), namely, DVT of the lower extremity and/or pulmonary embolism, but are less understood., Methods:  Records of unselected patients with a history of typical VTE ( n  = 2,011), UE-DVT ( n  = 117), SVT ( n  = 83), and CVST ( n  = 82), who were referred to the Institute in Bonn for ambulatory thrombophilia testing, were retrospectively analyzed. Acquired and hereditary thrombosis risk factors were comparatively assessed., Results:  UE-DVT was characterized by a high rate (50.4%) of site-specific acquired risk factors. Compared with typical VTE, SVT was more frequently associated with systemic inflammation, infection, or malignancy (2.2 vs. 12.0%, p  = 3·10 -8 ) and the JAK2  V617F mutation was present in 16.9%. In CVST compared with typical VTE, demographics and higher rates of oral contraception (43.2 vs. 57.6%, p  = 0.011) and pregnancy (4.2 vs. 10.9%, p  = 0.012) suggest a significant hormonal influence on etiology. While the prevalence of inhibitor deficiencies and factor V Leiden mutation did not differ between cohorts, the prevalence of F2 20210G > A was higher in SVT (15.7%, p  = 0.003) and CVST (15.9%, p  = 0.003) than in typical VTE (7.0%)., Conclusion:  The cohorts with thrombosis in atypical sites showed distinctive patterns of acquired risk factors. Further studies are warranted to provide additional mechanistic insight into the role of hormonal influence in CVST and the contribution of F2 20210G > A to the development of SVT and CVST., Competing Interests: JO: Grants or contracts from any entity: Bayer, Biotest, CSL Behring, Octapharma, Pfizer, Swedish Orphan Biovitrum, and Takeda. Consulting fees: Bayer, Biogen Idec, BioMarin, Biotest, Chugai Pharmaceutical Co., Ltd., CSL Behring, Freeline, Grifols, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd., Sanofi, Spark Therapeutics, Swedish Orphan Biovitrum, and Takeda. Payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events: Bayer, Biogen Idec, BioMarin, Biotest, Chugai Pharmaceutical Co., Ltd., CSL Behring, Freeline, Grifols, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd., Sanofi, Spark Therapeutics, Swedish Orphan Biovitrum, and Takeda. Support for attending meetings and/or travel: Bayer, Biogen Idec, BioMarin, Biotest, Chugai Pharmaceutical Co., Ltd., CSL Behring, Freeline, Grifols, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd., Sanofi, Spark Therapeutics, Swedish Orphan Biovitrum, and Takeda. Participation on a Data Safety Monitoring Board or Advisory Board: Bayer, Biogen Idec, BioMarin, Biotest, Chugai Pharmaceutical Co., Ltd., CSL Behring, Freeline, Grifols, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd., Sanofi, Spark Therapeutics, Swedish Orphan Biovitrum, and Takeda.The other authors have no conflict of interest., (Thieme. All rights reserved.)

Background: Recently, we have shown alterations in the anticoagulant response to recombinant activated factor VII (rFVIIa)-induced coagulation activation in patients with thrombophilia., Objectives: This study aimed to extend this in vivo model to fibrinolysis biomarkers., Methods: This interventional in vivo study included 56 patients with thrombophilia and previous venous thromboembolism (VTE+), 38 without VTE (VTE-), and 35 healthy controls. Plasma levels of D-dimer, plasmin-α2-antiplasmin (PAP) complex, and plasminogen activator inhibitor-1 (PAI-1) were monitored for over 8 hours after rFVIIa infusion (15 μg/kg) along with thrombin markers and activated protein C (APC)., Results: Throughout cohorts, median PAP increased by 40% to 52% ( P  < 3.9 × 10 -10 ) and PAI-1 decreased by 59% to 79% ( P  < 3.5 × 10 -8 ). In contrast to thrombin-antithrombin (TAT) complex, which also increased temporarily (44% to 115%, P  < 3.6 × 10 -6 ), changes in PAP and PAI-1 did not reverse during the observation period. The area under the measurement-time curves (AUCs) of PAP and TAT, which are measures of plasmin and thrombin formation, respectively, were each greater in the VTE+ cohort than in healthy controls (median PAP-AUC = 0.48 vs 0.27 ng·h/L [ P  = .003], TAT-AUC = 0.12 vs 0.03 nmol·h/L [ P  = 2.5 × 10 -4 ]) and were correlated with one another ( r  = 0.554). As evidenced by the respective AUCs, asymptomatic factor (F)V Leiden carriers showed less PAP formation (0.22 vs 0.41 ng·h/L, P  = 9 × 10 -4 ), more pronounced PAI-1 decline (0.10 vs 0.18 ng·h/L, P  = .01), and increased APC formation (28.7 vs 15.4 pmol·h/L, P  = .02) than those within the VTE+ group ( n  = 19 each)., Conclusion: rFVIIa-induced thrombin formation is associated with fibrinolysis parameter changes outlasting the concomitant anticoagulant response. Both correlate with thrombosis history in FV Leiden and might help explain its variable clinical expressivity., (© 2024 The Author(s).)

Introduction: Patients with hemophilia A treated with coagulation Factor VIII (FVIII) products are at risk for developing anti-FVIII antibodies. The ABIRISK Consortium aimed to provide knowledge on the formation and detection of anti-drug antibodies against biopharmaceutical products, including FVIII. Accordingly, standardized and validated assays for the detection of binding (total) and neutralizing antibodies are needed., Aim: Two-center validation of an ELISA for the detection of total FVIII-binding IgG-antibodies and Nijmegen-Bethesda assays for the quantification of FVIII-neutralizing antibodies according to consensus validation guidelines., Methods: Validation of assays at both sites was done according to published recommendations and included preanalytics, the determination of key assay parameters, including cut-points, assay sensitivity, precision, and FVIII interference., Results: The validated assays reproducibly detected FVIII-binding and -neutralizing antibodies with comparable performance in both laboratories. Floating screening cut-points were established for both assays. Determined mass-based sensitivity of both assays (all values ≤66 ng/mL) complied with the minimum sensitivity for the detection of anti-drug antibodies as recommended by the FDA (<100 ng/mL). Intra- and inter-assay coefficients of variation did not exceed 25%. Assay validation further revealed that pre-analytical heat treatment led to potentially false-positive ELISA results, while up to 0.15 IU/mL, residual FVIII showed no significant impact. Overall, good agreement of results was found for patient samples analyzed at both study sites., Conclusion: Comprehensive validation of different anti-FVIII-antibody assays in two laboratories gave novel insights into the impact of pre-analytical sample treatment as well as the comparability of test results generated by the use of methodically different assays., (© 2023 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Background: Accurate measurement of emicizumab in the presence of factor (F) VIII is required in patients with severe hemophilia A treated with emicizumab, as well as additional need for FVIII substitution or emicizumab prophylaxis in patients with acquired or moderate to mild hemophilia A. However, the presence of FVIII potentially biases the results., Objectives: To assess the impact of plasma FVIII activity on determined emicizumab levels and evaluate different strategies for correction for or preanalytical inhibition of FVIII., Methods: Evaluated strategies comprised of the following: (1) calculation of actual emicizumab plasma levels based on measured FVIII activities and FVIII-affected emicizumab values, (2) preanalytical heat treatment (56 °C for 40 minutes), and (3) neutralization of FVIII activity using FVIII inhibitors. Emicizumab levels and FVIII activities were measured using a modified FVIII one-stage clotting assay and a chromogenic FVIII assay based on bovine factors, respectively., Results: Spiking experiments revealed a consistent linear association between FVIII activities and determined (FVIII-affected) emicizumab results at different emicizumab input levels (∼0.12 μg/mL per IU/dL of FVIII). This principally allowed for mathematical correction of measured emicizumab levels in the presence of FVIII. While a 40% to 50% activity loss of intrinsic plasma emicizumab through heat treatment was observed in patient samples, emicizumab spiked into FVIII-deficient plasma was not or only marginally affected. Application of inhibitor-based FVIII neutralization led to good agreement of results when compared with direct quantification of emicizumab by liquid chromatography-tandem mass spectrometry., Conclusion: Inhibitor-based FVIII neutralization appears to be a feasible strategy for accurate measurement of plasma emicizumab levels in the presence of FVIII activity., Competing Interests: Declaration of competing interests J.M. has received honoraria from Octapharma and Siemens Healthineers. J.O. has received research funding from Bayer, Biotest, CSL Behring, Octapharma, Pfizer, Swedish Orphan Biovitrum, and Takeda; consultancy, speakers bureau, honoraria, scientific advisory board, and travel expenses from Bayer, Biogen Idec, BioMarin, Biotest, Chugai Pharmaceutical Co, Ltd, CSL Behring, Freeline, Grifols, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd, Sanofi, Spark Therapeutics, Swedish Orphan Biovitrum, and Takeda. N.S.H., A.D., M.v.L., S.G., H.R., C.K., T.A., M.A., and B.P. report no conflicts of interest., (Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Venous thromboembolism is one of the most common vascular diseases. Increased thrombin formation together with reduced blood flow create a hypercoagulable environment that induces thrombus formation. Anticoagulants play a pivotal role in the treatment and secondary prophylaxis of venous thromboembolism because they effectively interrupt this hypercoagulability. A personalized assessment of the thrombotic risk is essential for planning the duration and intensity of secondary prophylaxis. The occurrence of thrombosis outside a typical risk situation, an atypical localization and a family history of thrombosis indicate a thrombophilic state. In these cases, thrombophilia diagnostics are useful for extended risk assessment. If anti-phospholipid antibodies are detected, the risk of recurrence is particularly increased., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Background: The endothelial cell-dependent PC (protein C) pathway is critically involved in the regulation of coagulation, anti-inflammatory, and cytoprotective signaling. Its reactivity shows high interindividual variability, and it contributes to prothrombotic disorders, such as the FVL (factor V Leiden) mutation., Methods: Endothelial colony-forming cells (ECFCs) were isolated from heparinized peripheral blood from healthy individuals and FVL carriers. Confluent monolayers of ECFCs were overlaid with plasma, and thrombin formation was initiated by addition of tissue factor (1 pmol/L). Subsequently, thrombin and APC (activated PC) formation rates were measured over time using oligonucleotide-based enzyme capture assays. To induce downregulation of TM (thrombomodulin) expression, ECFCs were stimulated with IL-1β (interleukin 1β). In vivo APC response rates were monitored in study participants after infusion of low-dose rFVIIa (recombinant activated factor VII)., Results: The median peak APC concentration was 1.12 nmol/L in experiments with IL-1β stimulated ECFCs and 3.66 nmol/L without IL-1β. Although thrombin formation rates were comparable, APC formation rates were significantly higher in FVL carriers (n=6) compared to noncarriers (n=5) as evidenced by a higher ratio between the area under the curve of APC generation to the area under the curve of thrombin generation (median 0.090 versus 0.031, P =0.017). These ex vivo results were correlated with an increased APC response to rFVIIa-induced thrombin formation in FVL carriers in vivo., Conclusions: Patient-specific ex vivo modeling of the PC pathway was achieved using blood-derived ECFCs. The correlation between in and ex vivo APC response rates confirms that the autologous PC model accurately depicts the in vivo situation.

Purpose: Uncontrolled hemorrhage is still the major cause of preventable death after trauma and is aggravated by trauma-induced coagulopathy (TIC). The underlying pathophysiology of TIC is still elusive, but several key effectors such as the thrombin-generation capacity, the protein C (PC) pathway, and the fibrinolytic activity could be identified. The aim of this prospective observational study was to investigate plasma coagulation markers attributed to reflect the course of TIC and to identify the mechanisms being responsible for the coagulopathy after major trauma., Methods: Seventy-three consecutive patients after major trauma and admission to a level-1-trauma unit were included to the study. During early trauma management, extended coagulation testing including the measurement of circulating thrombin markers and activated PC (APC) was performed and correlated with standard shock parameters and the patients' clinical course and outcome., Results: In contrast to standard coagulation parameters, thrombin markers and APC were found to be increased in correlation with injury severity. Even in patients with lower impact mechanisms, early endogenous accumulation of thrombin markers and APC (ISS < 16: 0.5 ng/ml; ISS ≥ 16-26: 1.5 ng/ml; ISS > 26: 4.1 ng/ml) were observed. Furthermore, APC showed ISS- and injury-dependent patterns while ROC curve analysis revealed that especially APC plasma levels were predictive for coagulopathy and general patient outcome., Conclusion: Increased levels of APC and thrombin markers in patients after major trauma were positively correlated with injury severity. APC showed an ISS- and injury-dependent kinetic and might serve as candidate biomarker to identify patients at risk for developing TIC., (© 2022. The Author(s).)

A disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13) is a metalloprotease that regulates the size of circulating von Willebrand factor (vWF) multimers. Severe lack of ADAMTS-13 activity [<10% of normal (0.1 IU/mL)] leads to thrombotic thrombocytopenic purpura (TTP), a specific type of thrombotic microangiopathy (TMA). Timely determination of plasma ADAMTS-13 activity is essential to discriminate TTP from other types of TMA with respect to adequate treatment. Identification of the minimal substrate motif for ADAMTS-13 within the A2 domain of vWF (vWF73) as well as the generation of monoclonal antibodies (mAbs) that specifically recognize the ADAMTS-13 cleavage site enabled the development of a variety of methods for determination of plasma ADAMTS-13 activity. In order to further extend the range of analytical platforms applicable for quantitative determination of plasma ADAMTS-13 activity, a specific, vWF/mAb-based assay with flow cytometric readout was developed and validated. Basic assay characteristics include a total assay time of 80 to 90 min, a near linear dynamic range from 0.005 (lower limit of quantification) to 0.2 IU/mL, and intra- and interassay coefficients of variation below 5 and 30% at input plasma ADAMTS-13 activities of 0.015 and ≤0.050 IU/mL, respectively. When compared to the results obtained with a commercially available quantitative ADAMTS-13 activity ELISA, analysis of 18 plasma samples obtained from patients with suspected TTP revealed full agreement of results with respect to the clinical 0.1 IU/mL TTP threshold. Based on these data, it is assumed that the described assay principle can be successfully transferred to virtually all laboratories that have a flow cytometer available., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Introduction: Activation of the plasmatic coagulation system is a major contributor to acute myocardial infarction (AMI). Markers of plasmatic coagulation and thrombin activation are correlated with clinical, laboratory and outcome parameters. In this study, we sought to evaluate if the catalytically active coagulation factors thrombin and activated protein C (APC) can be measured in patients with AMI and whether there are associations with laboratory or clinical parameters., Methods: Thrombin and APC was quantified using oligonucleotide-enzyme-capture assays (OECAs) in 132 patients presenting with AMI immediately before and 24 h after percutaneous coronary intervention (PCI)., Results: APC was measured above the lower limit of quantification (LLOQ) in 43 (32.6%) patients before PCI (day 0) and in 55 (41.7%) patients on the following day (day 1). Thrombin was measured in 62 (47.0%) patients on day 0 and 60 (45.5%) on day 1. Both APC and thrombin were correlated with markers of thrombin generation including F1 + 2 and TAT. Additionally, APC values correlated with CK and CK-MB while thrombin correlated with CK and troponin I after PCI. APC levels above a cutoff of 0.141 ng/ml after PCI, but not thrombin, predicted 30 day major adverse cerebrovascular events., Conclusion: Both thrombin and APC were elevated above the LLOQ in a subset of patients with AMI before and after PCI and correlated with surrogate markers of myocardial injury. Our results indicate that enzymatically active APC and thrombin are present in the circulation of patients with AMI., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Emicizumab mimics the hemostatic activity of activated factor VIII (FVIIIa) within the tenase complex. Despite functional similarities between FVIIIa and emicizumab, conventional laboratory methods designed for monitoring of FVIII activity are inappropriate for the measurement of emicizumab. At present, a modified one stage (FVIII) assay (mOSA) is mainly used for emicizumab monitoring. Two-stage chromogenic FVIII assays based on human factors can be used, although limited performance due to lack of corresponding optimization might be observed. Furthermore, the presence of FVIII or anticoagulants in the patient sample may falsify assay results. To address these issues, we optimized and evaluated a two-stage chromogenic assay (emi-tenase) for measurement of emicizumab in plasma samples. Heat inactivation of samples was established to abolish the influence of endogenous or substituted FVIII. The lower limit of quantification (LLoQ) was found to be 2 μg/ml in a manual assay format and 9.5 μg/ml on an automated coagulation analyzer. Intra- and inter-assay coefficients of variation (CV) did not exceed 20%. Analysis of 17 patient plasma samples with severe haemophilia A under emicizumab treatment showed good correlation of results between the emi-tenase assay and the mOSA (Cohens Kappa coefficient = 0.9). Taken together, the emi-tenase assay allows specific measurement of emicizumab plasma levels over a broad concentration range (10 μg/ml to 100 μg/ml). The assay can be applied on an automated coagulation analyzer, demonstrating its applicability within a routine laboratory setting., Competing Interests: The authors have declared that no competing interest exist.

Direct oral anticoagulants (DOACs) apixaban and rivaroxaban are broadly used in the management of venous thromboembolism (VTE). Although not routinely required, measurement of their plasma concentration is advised for an increasing number of indications. Due to the lack of therapeutic ranges, current guidelines recommend reporting DOAC plasma levels together with expected levels from previous pivotal studies. The aim of this study was to assess DOAC level variation in a large VTE patient population. Drug concentrations determined by measurement of the anti-Xa-activity using drug-specific calibrators in citrated plasma samples from patients on rivaroxaban (n = 1471) or apixaban (n = 725) were analyzed. Observed 5th-95th percentile ranges of apixaban peak/trough levels (63-299/13-114 ng/mL for 5 mg, 37-161/7-68 ng/mL for 2.5 mg twice daily) were similar to previously reported mass-spectrometry-based reference data, and 10th-90th percentile ranges of rivaroxaban peak/trough levels (98-367/8-55 ng/mL for 20 mg, 51-211/5-27 ng/mL for 10 mg once daily) were even narrower. Age and drug levels correlated weakly (r ≤ 0.330). Drug levels measured repeatedly in subgroups of patients showed a strong correlation (r ≥ 0.773). In conclusion, anti-Xa-activity-based measurement of apixaban and rivaroxaban yields reliable results. However, the paucity of levels off-range underlines the need for evidence-based thresholds to better assist clinical decision making.

Activated protein C (APC) is a serine protease with anticoagulant and cytoprotective activities which make it an attractive target for diagnostic and therapeutic applications. In this work, we present one-step activation of APC from a commercial source of protein C (PC, Ceprotin) followed by rapid and efficient purification using an APC-specific aptamer, HS02-52G, loaded on MyOne superparamagnetic beads. Due to the Ca 2+ -dependent binding of APC to HS02-52G, an efficient capturing of APC was applied in the presence of Ca 2+ ions, while a gentle release of captured APC was achieved in the elution buffer containing low EDTA concentration (5 mM). The captured and eluted APC showed more than 95% purity according to SDS-PAGE gel analysis and an enzyme-linked fluorescent assay (VIDAS Protein C). The purification yield of 45% was calculated when 4.2 µg APC was used, however this yield reduced to 21% if the starting amount of APC increased to 28.5 µg. Altogether, this method is recommended for rapid and efficient PC activation and APC purification. The purified APC can be used directly for downstream processes where high concentration of pure and active APC is needed., (© 2022. The Author(s).)

Elevated D-dimer levels during anticoagulant therapy with vitamin K antagonists (VKA) are associated with an increased risk of thrombosis. It has been hypothesized that elevated D-dimer levels in patients receiving direct oral anticoagulants (DOACs) also indicate an increased risk of thrombosis recurrence, but data on the distribution of D-dimer levels in patients with VTE on DOACs are sparse. In the present study we retrospectively analyzed D-dimer levels in patients taking DOACs after first or recurrent venous thrombosis ( n = 1,716, 1,126 thereof rivaroxaban, 481 apixaban, 62 edoxaban, and 47 dabigatran). Patients on VKA ( n = 402) served as control group. Thrombotic events in the study population were categorized into distal deep venous thrombosis (DVT, n = 552 patients), distal DVT with pulmonary embolism (PE, n = 166), proximal DVT ( n = 685), proximal DVT with PE ( n = 462), PE without DVT ( n = 522), DVT of the upper extremity ( n = 78), cerebral venous sinus thrombosis (CVST, n = 48), and other venous thrombosis ( n = 74). In VKA users a median D-dimer level of 0.20 mg/l was observed. In patients on DOACs D-dimer levels were significantly higher, with 0.26 mg/l for rivaroxaban, 0.31 mg/l for apixaban ( P < 10 -16 each), 0.24 mg/l for edoxaban ( P = 2 × 10 -5 ), and 0.25 mg/l for dabigatran ( P = 4 × 10 -4 ). These differences in comparison to patients on VKA treatment could not be explained by the patients' age, sex, body mass index, and type of thrombosis as these characteristics did not differ significantly between cohorts. Moreover, the prevalence of D-dimer levels above age-adjusted cut-offs [≥0.50 mg/l in ≤50-year-old patients, ≥(age × 0.01) mg/l in >50-year-old patients] was higher in patients on rivaroxaban (13.9%, RR 1.74, 95% CI 1.21-2.50), apixaban (17.0%, RR 2.14, 95% CI 1.45-3.15) and dabigatran (23.4%, RR 2.94, 95% CI 1.59-5.44) than in patients on VKA (8.0%). In patients on edoxaban D-dimer levels above the reference range were observed in 14.5%, but no statistical significance was reached in comparison to the VKA cohort. In conclusion, the obtained data suggest, that the type of oral anticoagulant should be considered in the clinical assessment of D-dimer levels in thrombosis patients. Further studies are warranted to evaluate a potential association between elevated D-dimer levels and thrombosis risk in patients on DOACs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Reda, Thiele Serra, Müller, Hamedani, Oldenburg, Pötzsch and Rühl.)

Aim: Feedback activation of factor XI (FXI) by thrombin is believed to play a critical role in the amplification phase of thrombin generation and to contribute to thrombosis development and hemostasis. However, the activation of FXI by thrombin has been shown in vitro to require a cofactor. In this study, the role of thrombin in activated FXI (FXIa) formation in vivo is investigated., Methods: The study population comprised probands in whom coagulation activation was triggered by low-dose (15 µg/kg) recombinant activated factor VII (rFVIIa, n=89), of whom 34 with (VTE+) and 45 without a history of venous thromboembolism (VTE-), and patients undergoing major orthopedic surgeries (n=45). FXIa was quantified via an enzyme capture assay using a monoclonal FXI-specific antibody. Thrombin formation was monitored using an oligonucleotide-based enzyme capture assay and the thrombin activation markers prothrombin fragment 1＋2 (F1＋2) and thrombin-antithrombin complex (TAT)., Results: In the rFVIIa cohort, FXIa and thrombin remained below their lower limit of quantification of 3.48 and 1.06 pmol/L, respectively. By contrast, during the surgeries, median FXIa levels increased from 3.69 pmol/L pre-operatively to 9.41 pmol/L mid-operatively (P=4·10 -4 ) and remained significantly elevated 24 h thereafter, with 9.38 pmol/L (P=0.001). Peak levels of F1+2 were comparable in the VTE+, VTE-, and surgery cohort (235, 268, and 253 pmol/L), whereas peak TAT levels were higher in the surgery cohort (53.1, 33.9, and 147.6 pmol/L)., Conclusions: Under in vivo conditions, the activation of FXI requires specific local features that are present at the wounded site including potential cofactors of thrombin.

Background: Coronavirus disease 2019 vaccine ChAdOx1 nCov-19 may rarely lead to vaccine-induced thrombotic thrombocytopenia (VITT). Antibody-mediated, platelet factor 4 (PF4)-dependent platelet activation appears to resemble a key mechanism in VITT, partially comparable to heparin-induced thrombocytopenia. The use of PF4/heparin immunoassays has been proposed as part of a diagnostic approach, but their sensitivity has not been established., Methods: Sera from 12 well-defined VITT patients were first studied by two different laboratories in functional assays. Sera where then used for an interlaboratory comparison, in which five different PF4/heparin immunoassays were used by four laboratories., Results: Results for functional testing were highly concordant. VITT antibodies were also reliably detected by PF4/heparin enzyme-linked immunosorbent assays (ELISAs) (92-100%). In contrast, only 25% of VITT antibodies were reactive in a particle gel immunoassay (PaGIA), and 8% in a lateral flow assay (LFA). An automated chemiluminescence immunoassay (CLIA) was negative for all sera tested (0%)., Conclusion: It seems feasible to establish functional antibody testing for the confirmation of VITT. For the initial screening of suspected VITT cases, PaGIA, LFA, and CLIA are useless when applied as single tests. Only ELISA-based PF4/heparin immunoassays are sensitive enough to be incorporated in the diagnostic workup. However, a combination of a positive ELISA and a negative CLIA may be useful to identify VITT antibodies in the absence of confirmatory functional assays., Competing Interests: None declared., (Thieme. All rights reserved.)

Protein C (PC) activity tests are routinely performed in a thrombophilia workup to screen for PC deficiency. Currently used tests combine conversion of PC to activated PC (APC) by the snake venom Protac with subsequent APC detection through hydrolysis of a chromogenic peptide substrate or prolongation of a clotting time. In this prospective cohort study, we analyzed how different modes of PC activation and subsequent APC determination influence the diagnostic accuracy of PC activity testing in a cohort of 31 patients with genetically confirmed PC deficiency. In addition to chromogenic and clot-based measurement, an oligonucleotide-based enzyme capture assay utilizing a basic exosite-targeting aptamer was used for APC detection. To study the influence of the PC activation step on diagnostic sensitivity, PC activation through Protac and through the thrombin-thrombomodulin (TM) complex were compared. Twenty-six (84%) and 24 (77%) PC deficient patients were identified as true-positive using the chromogenic and the clot-based PC activity assay, respectively. True-positive results increased to 27 (87%) when the basic exosite-targeting aptamer approach was used for APC measurement. Additional replacement of the PC activator Protac by thrombin-TM gave true-positive results in all patients. These data indicate that the mode of PC activation is crucial in determining the accuracy of PC activity testing and that diagnostic sensitivity can be significantly improved by replacing the PC activator Protac with thrombin-TM. APC detection using a basic exosite-targeting aptamer achieves high sensitivity toward mutations outside the active center while being less subject to interfering factors than clot-based PC activity assays., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Reda, Rühl, Witkowski, Müller, Pavlova, Oldenburg and Pötzsch.)

Precise control of blood clotting and rapid reversal of anticoagulation are essential in many clinical situations. We were successful in modifying a thrombin-binding aptamer with a red-light photocleavable linker derived from Cy7 by Cu-catalyzed Click chemistry. We were able to show that we can successfully deactivate the modified aptamer with red light (660 nm) even in human blood-restoring the blood's natural coagulation capability., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The COVID-19 pandemic has resulted in significant morbidity and mortality worldwide. To prevent severe infection, mass COVID-19 vaccination campaigns with several vaccine types are currently underway. We report pathological and immunological findings in 8 patients who developed vaccine-induced immune thrombotic thrombocytopenia (VITT) after administration of SARS-CoV-2 vaccine ChAdOx1 nCoV-19. We analyzed patient material using enzyme immune assays, flow cytometry and heparin-induced platelet aggregation assay and performed autopsies on two fatal cases. Eight patients (5 female, 3 male) with a median age of 41.5 years (range, 24 to 53) were referred to us with suspected thrombotic complications 6 to 20 days after ChAdOx1 nCoV-19 vaccination. All patients had thrombocytopenia at admission. Patients had a median platelet count of 46.5 x109/L (range, 8 to 92). Three had a fatal outcome and 5 were successfully treated. Autopsies showed arterial and venous thromboses in various organs and the occlusion of glomerular capillaries by hyaline thrombi. Sera from VITT patients contain high titer antibodies against platelet factor 4 (PF4) (OD 2.59±0.64). PF4 antibodies in VITT patients induced significant increase in procoagulant markers (P-selectin and phosphatidylserine externalization) compared to healthy volunteers and healthy vaccinated volunteers. The generation of procoagulant platelets was PF4 and heparin dependent. We demonstrate the contribution of antibody-mediated platelet activation in the pathogenesis of VITT.

Parkinson's disease (PD) is the second most common age-related neurodegenerative disease. Accumulating evidence demonstrates that alpha-synuclein (α-Syn), an apparently predominant neuronal protein, is a major contributor to PD pathology. As α-Syn is also highly abundant in blood, particularly in red blood cells (RBCs) and platelets, this in turn raises the question on the function of presumably dysfunctional α-Syn in "peripheral" cells and its putative effect on the other enclosed constituents. Herein, we detected the internal variance in erythrocytes of PD patients by Raman spectroscopy, but no measurable amount of erythrocytic behavioural change (eryptosis) or any haemoglobin variation was noticed. An elevated level of plasmin-antiplasmin complexes (PAP) was observed in the plasma of PD patients, indicating activation of the fibrinolytic system, but platelet activation after thrombin stimulation was not altered. Sex-specific patterns were noticed for blood coagulation factor XIII and factor XII activity in PD patients. Additionally, the alterations in homocysteine levels which have often been observed in PD patients were found to be independent from L-DOPA usage and PAP levels. Furthermore, a selective gene expression analysis identified subsets of genes related to different blood-associated compartments (RBCs, platelets, coagulation-fibrinolysis) also involved in PD-related pathways.

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

The COVID-19 pandemic is an ongoing global healthcare crisis. Based on reports of atypically located thromboses following vaccination with the AstraZeneca COVID-19 vaccine, the Society of Thrombosis and Haemostasis Research (GTH) has issued guidance statements on the recognition, diagnosis, and treatment of this rare complication. It shares pathophysiological features with heparin-induced thrombocytopenia (HIT) and is referred to as vaccine-induced prothrombotic immune thrombocytopenia (VIPIT)., Competing Interests: J.O. has received personal fees for lectures or consultancy and/or research support from Bayer, Biogen Idec, Biotest, Chugai, CSL Behring, Grifols, Novo Nordisk, Octapharma, Pfizer, Roche, SOBI, and Takeda, outside the submitted work.R.K. reports grants and personal fees from Bayer, grants and personal fees from LEO Pharma, personal fees from Pfizer, personal fees from Bristol-Myers Squibb, and grants and personal fees from Daiichi Sankyo, outside the submitted work.F.L. has received personal fees for lectures, advisory boards, or consultancy and/or research support from Aspen, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Daiichi Sankyo, LEO Pharma, Pfizer, and Sanofi, outside the submitted work.M.A. has served as a member of the Paediatric Expert Working Group for Boehringer Ingelheim and Daiichi Sankyo, outside the submitted work.C.A. has received personal fees for lectures and/or advisory boards from Bayer, Bristol-Myers Squibb, Daiichi Sankyo, Pfizer, and Sanofi, outside the submitted work.W.K. has received personal fees, research grants, and/or travel support from AxonLab, Bayer, Bristol-Myers Squibb, Daiichi Sankyo, Portola, Sanofi, and SOBI, outside the submitted work.R.E.S. reports grants and personal fees from Bayer HealthCare, personal fees from Bayer Vital, personal fees from CSL Behring, grants and personal fees from Pfizer, and personal fees from Takeda, outside the submitted work.A.G. has received personal fees, grants, and/or travel support from Aspen, Bayer, Boehringer Ingelheim, Biokit, BioMarin/Prosensa, Blau Farmaceutica, Chromatec, DRK-BSD Baden-Württemberg/Hessen, DRK-BSD NSTOB, Ergomed, Gore Inc., Instrumentation Laboratory, Macopharma, ParinGenix, Portola, Roche, Rovi, Sagent, and Sanofi, outside the submitted work.C.v.A. and B.P. declare no conflicts of interest., (Thieme. All rights reserved.)

Abstract: Palliative care is a central component of the therapy in terminally ill patients. During treatment in non-palliative departments this can be realized by consultation.To analyze the change in symptom burden during palliative care consultation.In this observational study, we enrolled all cancer cases (n = 163) receiving inpatient treatment for 2015 to 2018 at our institution. We used the MDASI-questionnaire (0 = 'not present' and 10 = "as bad as you can imagine") and the FAMCARE-6 (1 = very satisfied, 5 = very dissatisfied) to analyze the treatment effect and patient satisfaction, respectively.We examined the association of symptom burden and patient satisfaction using Spearman-correlation. Comparing mean values, we applied the Wilcoxon-test and one-way ANOVA.An improvement in MDASI-core-items after treatment completion was significant (P < .05) in 14/18 symptoms. The change in perception of pain showed the strongest improvement (median: 5 to 3). Initially the MDASI-items "activity" (median = 8) and emotional distress (median = 5 and 6) were viewed as especially incriminating. There was no evidence for a correlation between patients' age, the type of diagnosis and time since diagnosis.The analysis of FAMCARE-6 patient contentment was lower or equal to two in all of the six items. There was a weak negative association between the change in symptom burden of psycho-emotional items "distress/feeling upset" (P = .006, rSp = -0,226), "sadness" and patient satisfaction in FAMCARE-6.A considerable improvement of the extensive symptom burden particularly of pain relief was achieved by integrating palliative consultation in clinical practice., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Inactivation of thrombin by the endogenous inhibitor antithrombin (AT) is a central mechanism in the regulation of hemostasis. This makes hereditary AT deficiency, which is caused by SERPINC1 gene mutations, a major thrombophilic risk factor. Aim of this study was to assess to what extent AT mutations impair thrombin inhibition kinetics. The study population included 36 thrombophilic patients with 19 different mutations and mean AT levels of 65% in a thrombin-based functional assay, and 26 healthy controls. To assess thrombin inhibition kinetics, thrombin (3.94 mU/mL final concentration) was added to citrated plasma. Subsequently, endogenous thrombin inhibition was stopped by addition of the reversible thrombin inhibitor argatroban and the amount of argatroban-complexed thrombin quantified using an oligonucleotide-based enzyme capture assay. The plasma half-life of human thrombin was significantly longer in patients with AT mutations than in the controls (119.9 versus 55.9 s). Moreover, it was disproportionately prolonged when compared with preparations of wild type AT in plasma, in whom a comparable thrombin half-life of 120.8 s was reached at a distinctly lower AT level of 20%. These findings may help to better understand the increased thrombotic risk of SERPINC1 mutations with near normal AT plasma levels in functional assays.

Coagulation factor XIII (FXIII) is a protransglutaminase which plays an important role in clot stabilization and composition by cross-linking the α- and γ-chains of fibrin and increasing the resistance of the clot to mechanical and proteolytic challenges. In this study, we selected six DNA aptamers specific for activated FXIII (FXIIIa) and investigated the functional characterization of FXIIIa after aptamer binding. One of these aptamers, named FA12, efficiently captures FXIIIa even in the presence of zymogenic FXIII subunits. Furthermore, this aptamer inhibits the incorporation of FXIII and α2-antiplasmin (α2AP) into fibrin(ogen) with IC 50 -values of 38 nM and 17 nM, respectively. In addition to FA12, also another aptamer, FA2, demonstrated significant effects in plasma-based thromboelastometry (rotational thromboelastometry analysis, ROTEM)-analysis where spiking of the aptamers into plasma decreased clot stiffness and elasticity ( p < 0.0001). The structure-function correlations determined by combining modeling/docking strategies with quantitative in vitro assays revealed spatial overlap of the FA12 binding site with the binding sites of two FXIII substrates, fibrinogen and α2AP, while FA2 binding sites only overlap those of fibrinogen. Taken together, these features especially render the aptamer FA12 as an interesting candidate molecule for the development of FXIIIa-targeting therapeutic strategies and diagnostic assays.

Aims: In hemolysis, which is accompanied by increased levels of labile redox-active heme and is often associated with hemostatic abnormalities, a decreased activity of activated protein C (APC) is routinely detected. APC is a versatile enzyme that exerts its anticoagulant function through inactivation of clotting factors Va and VIIIa. APC has not been demonstrated to be affected by heme as described for other clotting factors and, thus, is a subject of investigation. Results: We report the interaction of heme with APC and its impact on the protein function by employing spectroscopic and physiologically relevant methods. Binding of heme to APC results in inhibition of its amidolytic and anticoagulant activity, increase of the peroxidase-like activity of heme, and protection of human umbilical vein endothelial cells from heme-induced hyperpermeability. To define the sites that are responsible for heme binding, we mapped the surface of APC for potential heme-binding motifs. T 285 GWGYHSSR 293 and W 387 IHGHIRDK 395 , both located on the basic exosite, turned out as potential heme-binding sites. Molecular docking employing a homology model of full-length APC indicated Tyr 289 and His 391 as the Fe(III)-coordinating amino acids. Innovation: The results strongly suggest that hemolysis-derived heme may directly influence the protein C pathway through binding to APC, conceivably explaining the decreased activity of APC under hemolytic conditions. Further, these results extend our understanding of heme as a multifaceted effector molecule within coagulation and may allow for an improved understanding of disease development in hemostasis under hemolytic conditions. Conclusion: Our study identifies APC as a heme-binding protein and provides insights into the functional consequences.

Background Hypergravity may promote human hemostasis thereby increasing thrombotic risk. Future touristic suborbital spaceflight will expose older individuals with chronic medical conditions, who are at much higher thromboembolic risk compared with professional astronauts, to hypergravity. Therefore, we tested the impact of hypergravity on hemostasis in healthy volunteers undergoing centrifugation. Methods and Results We studied 20 healthy seated men before and after 15 minutes under 3 Gz hypergravity on a long-arm centrifuge. We obtained blood samples for hemostasis testing before, immediately after, and 30 minutes after centrifugation. Tests included viscoelastic thromboelastometry, platelet impedance aggregometry, endothelial activation markers, blood rheology testing, microparticle analyses, and clotting factor analysis. Exposure to hypergravity reduced plasma volume by 12.5% ( P =0.002) and increased the red blood cell aggregation index ( P <0.05). With hypergravity, thrombelastographic clotting time of native blood shortened from 719±117 seconds to 628±89 seconds ( P =0.038) and platetet reactivity increased ( P =0.045). Hypergravity shortened partial thromboplastin time from 28 (26-29) seconds to 25 (24-28) seconds ( P <0.001) and increased the activity of coagulation factors (eg, factor VIII 117 [93-134] versus 151 [133-175] %, P <0.001). Tissue factor concentration was 188±95 pg/mL before and 298±136 pg/mL after hypergravity exposure ( P =0.023). Antithrombin ( P =0.005), thrombin-antithrombin complex ( P <0.001), plasmin-alpha2-antiplasmin complex (0.002), tissue-plasminogen activatior ( P <0.001), and plasminogen activator inhibitor-1 ( P =0.002) increased with centrifugation. Statistical adjustment for plasma volume attenuated changes in coagulation. Conclusions Hypergravity triggers low-level hemostasis activation through endothelial cell activation, increased viscoelasticity, and augmented platelet reactivity, albeit partly counteracted through endogenous coagulation inhibitors release. Hemoconcentration may contribute to the response.

Due to structural differences between extended half-life (EHL) factor VIII (FVIII) or FIX products and equivalent plasma wild-type molecules used for assay calibration, reagent-dependent discrepancies during monitoring of FVIII- and FIX-replacement therapies with EHL products have been described. To assess the performance of available one-stage clotting and chromogenic substrate assays on the Siemens Atellica COAG 360 analyzer, an in vitro study using spiked plasma samples was performed. The described results confirm previously described findings and allowed allocation of each EHL product to an appropriate assay. In addition, corresponding EHL product-specific analytes were defined within the order entry system of the University Hospital Bonn. The requirement of product-specific FVIII and FIX assays complicates patient monitoring and demonstrates the need for both continuous education and communication between treating physicians and the coagulation laboratory., Competing Interests: J.M. reports nonfinancial support from Bayer Vital GmbH, CSL Behring, Novo Nordisk, Sobi, and Takeda, during the conduct of the study; personal fees from Siemens Healthineers, Novo Nordisk, and Bayer Vital GmbH, outside the submitted work., (Thieme. All rights reserved.)