Programme

Professor Cédric Hermans currently leads the Hemostasis and Thrombosis Unit and the Hemophilia Center of the Saint-Luc University Hospital in Brussels, Belgium.
He was appointed Associate Professor at the Medical School of the Catholic University of Louvain in 2003, Full Professor in 2012 and Vice-Dean in 2015.

Professor Hermans has published over 196 original articles in international journals and is a member of several scientific societies and international advisory boards.
He was president of EAHAD and was recently appointed as a member of the Board of Directors of the World Federation of Hemophilia.
In July 2018 prof. Hermans became the new Editor-in-chief of the international scientific journal Haemophilia.

His main research interests lie in the area of hemostasis and thrombosis, especially clinical studies on the treatment of hemophilia, new anticoagulants, and the management of thrombosis.

Professor Peter Verhamme is staff member Vascular Medicine and Haemostasis at the Department of Cardiovascular Diseases, University Hospitals Leuven. He is also associate professor at KU Leuven – University of Leuven, Department of Cardiovascular Sciences; Center for Molecular and Vascular Biology and clinical investigator of the Research Foundation – Flanders.

He is author or co-author of more than 250 publications in the broad field of vascular biology and vascular medicine with focus on Translational Vascular Medicine.

Prof. Verhamme has made Important contributions to the clinical development of new oral anticoagulants and their antidotes with numerous authorships in pivotal studies. He is also member of the writing committee of international guidelines by different leading scientific societies (ISTH, ASH, EHRA) resulting in >100 co-authorships in leading journals.

Dr. Natascha Marquardt has a specialization in hemostasis and transfusion medicine from the University of Bonn. She is senior physician at the institute for experimental hematology and transfusion medicine in the hemophilia center of the University Hospital in Bonn. She has been a sub-investigator in multiple clinical and non-interventional trials and has published articles in her field of expertise. She has a special interest in comorbidities in elderly hemophilia patients and is a member of the ADVANCE working group. Dr Marquardt also has a special interest in ultrasonography of hemophilic joints and was a trainer in the HEAD US European Ultrasound Preceptorship Program. She is a member of the Society for Thrombosis and Haemostasis Research e.V. (GTH).

Dr Philip Maes is a pediatric hemato-oncologist and runs the Pediatric Hematology and Hemostasis and Thrombosis Unit within the Hemophilia Reference Center of the University Hospital of Antwerp (UZA), Belgium.
He is also guest professor at the Medical School of the University of Antwerp.
Dr Maes is a member of several scientific societies and international advisory boards.
His main research interests lies in the area of Benign hematology, hemostasis and thrombosis in children especially clinical studies on the treatment of hemoglobinopathies, hemophilia and new anticoagulants.

Introduction
Bleeding is the most frequent complication in patients with continuous flow mechanical circulatory support (CF-MCS) and linked to the occurrence of acquired von Willebrand syndrome (aVWS). MCS devices cause an increased shear-induced proteolysis of von Willebrand factor (VWF) by ADAMTS13, leading to aVWS. We previously showed that blocking human ADAMTS13 is an efficient way to prevent aVWS in in vitro CF-MCS experiments. The efficacy of this drug in a preclinical animal model has not been investigated yet.

Aims
To investigate if blocking ADAMTS13 using our in-house developed inhibitory anti-ADAMTS13 monoclonal antibody (mAb) 17C7 rescues aVWS in vitro using bovine blood and in a preclinical CF-MCS calf model.

Methods
Bovine blood was circulated through an in vitro Impella 5.5 heart-pump with either mAb 17C7 (20 µg/mL) or PBS and VWF multimers and function (VWF collagen binding activity (VWF:CB/VWF:Ag)) were determined. Next, Impella 5.5 pumps were implanted in calves (n=6) and one dose of mAb 17C7 (600 µg/kg, n=6) or PBS (n=4) was injected seven days after pump implantation. The concentration of mAb 17C7, ADAMTS13 activity, ADAMTS13 antigen, VWF multimers and blood parameters were determined in plasma or whole blood.

Results
Perfusion of bovine blood supplemented with PBS through the in vitro system resulted in the occurrence of aVWS as HMW VWF multimers decreased (54 ± 3% before to 30 ± 4%, 5h after perfusion, p=0.01) which was accompanied by a decrease in VWF:CB/VWF:Ag (0.98 ± 0.13 before versus 0.49 ± 0.19, 5h after perfusion, p=0.04). In contrast, blocking bovine ADAMTS13 using mAb 17C7 could prevent the occurrence of aVWS in the in vitro system as no decrease in HMW VWF multimers (55 ± 4% before versus 50 ± 9%, 5h after perfusion) nor in VWF:CB/VWF:Ag ratio (0.89 ± 0.09 before versus 0.87 ± 0.15, 5h after perfusion) was observed. Implantation of Impella 5.5 pumps in calves resulted in aVWS (52 ± 4% HMW VWF multimers before versus 33 ± 2%, 1 day after pump implantation, p=0.02) and persisted for 7 consecutive days. At day 7, the mAb 17C7 or PBS was injected in the calves and the rescue of aVWS was evaluated. Interestingly, ADAMTS13 inhibition led to a significant rescue of HMW VWF multimers at day 2 after drug injection (HMW VWF multimers increased 13 ± 2%, p=0.01) which persisted until the end of the experiment (day 14). In line with that, the inhibitory mAb could be detected up to 7 days after injection and accordingly, ADAMTS13 activity was inhibited for 7 days after injection (8 ± 9% versus 91 ± 27% before injection, p=0.03). ADAMTS13 antigen levels did not drop after mAb injection, indicating that ADAMTS13 is not cleared by the mAb. Importantly, blocking ADAMTS13 in calves did not lead to thrombocytopenia nor hemolytic anemia, signs observed in patients suffering from thrombotic thrombocytopenic purpura (TTP) probably due to the absence of a secondary trigger in the calves.

Conclusion
Blocking ADAMTS13 rescues CF-MCS-induced VWF proteolysis in calves and could become a promising therapy to treat CF-MCS-induced bleeding in MCS patients.

Introduction
The COVID-19 pandemic emerged in Wuhan, China and spread across the world rapidly. The causative agent has been identified as the Severe acute respiratory coronavirus-2 or SARS-Cov2. The main target of the virus is the lung and the clinical manifestations of the disease range from asymptomatic to severe forms which are characterized by acute respiratory distress syndrome (ARDS) and thrombotic events frequently leading to patient deaths. The pathophysiology of the disease is characterized by an important recruitment of innate immune cells, such as neutrophils and monocytes, a decrease of lymphocytes and a huge amount of cytokine production also named “the cytokine storm”. Nevertheless, the exact contribution of immune cells to ARDS and thrombotic events is still missing.

Aims
Neutrophil Extracellular traps (NETs) are structures released from neutrophils under inflammatory conditions. These structures are implicated in tissue damages and favorize the formation of thrombi. Since severe forms of SARS-Cov2 are characterized by ARDS and coagulopathies and are associated with high amount of neutrophils into the lung, we wondered if neutrophils recruited into the lung during SARS-Cov2 infection released NETs which could shed new light on COVID-19 pathophysiology and represent new therapeutical targets.

Materials and Methods
We investigated the presence of NETs in four lung biopsies of SARS-Cov2 deceased patients and compared them to four lung biopsies of patients deceased at the hospital from a non-lung related disease. To do so, we performed confocal microscopy analyses and identified NETs as extracellular structures containing DAPI, myeloperoxidase (MPO) and citrullinated histone 3 (H3-cit) which are specific components of NETs.

Results
We were only able to observe DAPI+MPO+H3-cit+ structures identified as NETs in lungs of COVID-19 patients. Quantification of co-localization of MPO and H3-cit confirmed a significantly higher amount of NETs in lung of COVID-19 patients as compared to controls. We next sought to investigate precise NETs release locations into the lungs of COVID-19 patients. We identified all the NETs infiltrating areas on our biopsies and reported them on corresponding hematoxylin eosin stained biopsies. We observed NETs in the bronchi of the four COVID patients. NETs were also located in the lung interstitium and in the vascular compartment of three patients and in the alveoli of one patient. Finally, we performed histopathological analysis of NETs infiltrating areas. NETs were mostly associated to macrophages rich areas and fibrine deposition.

Summary and Conclusion
We have demonstrated that SARS-Cov2 infection was associated to an important release of NETs in the four anatomic compartments of the lung: the alveoli, the bronchi, the interstitium and the blood vessels. This observation is of great importance as NETs could be implicated in tissue damages and induce hypoxemia as observed in ARDS and also in thrombi formation as observed in intravascular disseminated coagulopathy, two major causes of death in COVID-19 patients. Thus, NETs represent an important potential target in the treatment of COVID-19 patients. Finally, location of NETs release is of great importance when considering the route of administration of anti-NETs drugs to treat COVID-19 patients.

Background
Ticagrelor is an antiplatelet agent with both in vitro and in vivo bactericidal properties against gram-positive bacteria. The in vitro bactericidal activity of ticagrelor is direct, i.e. not mediated by platelets. Ticagrelor is the only antiplatelet drug with such dual action, which might make it superior to other available drugs through its ability to protect cardiovascular patients against thrombosis and potentially against gram-positive bacterial infections, e.g. infective endocarditis. While the mechanism of action of ticagrelor on platelets has been extensively studied, nothing is known about its direct action on gram-positive bacteria.

Aims
Our study aimed at unveiling the mechanism of action of ticagrelor against gram-positive bacteria.To do so we generated in vitro ticagrelor-resistant mutants of methicillin-resistant Staphylococcus epidermidis RP62A (MRSE). Such clones acquired the capacity to grow at concentrations higher than their initial ticagrelor-inhibitory concentration.Specific aims consisted in: 1) identifying the gene(s) mutated in these ticagrelor-resistant clones; 2) understanding their causality in the ticagrelor-resistance mechanism; 3) generating hypotheses on ticagrelor mechanism of action against gram-positive bacteria and possibly identifying ticagrelor targets.

Methods
A multistep mutant generation of MRSE was undertaken to isolate ticagrelor-resistant clones. Whole Genome Sequencing (WGS) and comparative genomics analysis was performed on such clones and on wild type (wt) bacteria. Genetic mutations were validated by Sanger sequencing.

Membrane phospholipids of wt and mutant bacteria were analysed by thin layer chromatography (TLC) and by Mass Spectrometry (MS). Calcein-encapsulated unilamellar staphylococcus like-liposomes were prepared using the extrusion and ultracentrifugation method. Calcein release assay was performed to assess membrane bilayer disruption. Confocal microscopy was used to visualize ticagrelor effect on Bacillus subtilis, a gram-positive bacteria model.

Results
Four ticagrelor-resistant clones showed a non-synonymous mutation in cdsA, an essential gene for cell membrane phospholipid biosynthesis, suggesting that: 1) compared to the parent strain, clones carrying this mutation could have a different phospholipid composition which would potentially render their membrane impermeable to ticagrelor; 2) ticagrelor might interfere with the stability of bacterial lipid bilayer and act on bacteria as a membrane-targeting/damaging drug. To test the first hypothesis we performed comparative lipid profiles and observed a different lipid composition in the resistant clones compared to wt bacteria. For the second hypothesis we showed that ticagrelor was able to disrupt unilamellar staphylococcus like-liposomes in a calcein-release assay. To strengthen the hypothesis of ticagrelor as membrane-damaging drug, we have treated Bacillus subtilis with ticagrelor and observed by confocal microscopy the disruption of its cytoplasmic membrane.

Conclusions
We identified a genetic mutation in the cdsA gene of MRSE, potentially causing the ticagrelor-resistant phenotype in four isolated S. epidermidis clones. Mutant strains had substantial differences in membrane phospholipid composition as compared to wt strain. Ticagrelor disrupts unilamellar staphylococcus like-liposomes. Hence, ticagrelor may exert bactericidal activity against gram-positive bacteria by disrupting their phospholipid membrane.

Pulmonary embolism (PE) is a common and potentially fatal disease that must be promptly diagnosed and treated. The diagnostic management of patients with suspected acute PE does not rely on a single and definitive test but on the application of integrated diagnostic strategies including clinical probability assessment, D-dimer testing, and imaging tests.

The combination of clinical signs and symptoms with the presence of risk factors for venous thromboembolism allows the classification of patients into different categories of clinical probability, which correspond to an increasing prevalence of confirmed PE. The clinical pre-test probability can be assessed either empirically or by clinical probability scores. Consideration of the probability of PE before testing is a key step of all diagnostic algorithms for PE as it avoids unnecessary testing and is critical to the interpretation of diagnostic tests results.

D-dimer is a sensitive but not specific diagnostic test. In combination with the clinical pre-test probability, D-dimer testing allows the clinician to rule out a PE in approximately one-third of patients with suspected PE without further diagnostic test. More recently, the use of either clinical probability adjusted or age adjusted D-dimer interpretation has led to a further reduction in lung imaging to safely rule out PE.

Computed tomography pulmonary angiography (CTPA) and planar ventilation-perfusion (V/Q) lung scan are well established imaging tests for PE diagnosis. Diagnostic algorithms using one of these two imaging modalities as a cornerstone of the strategy have been validated in large management outcome studies. However, both tests have strengths and drawbacks. Limitations of CTPA include higher radiation exposure especially to the female breast, the use of iodinated contrast media, and a possible over-diagnosis or over-treatment of clinically insignificant PE. Limitations of planar V/Q scan include a high proportion of non-diagnostic tests resulting in more complex diagnostic algorithms, and the inability to provide alternative diagnoses. V/Q single photon emission computed tomography (SPECT), with or without low dose CT, has been described to have greater diagnostic performance and much fewer non-diagnostic tests as compared with planar scintigraphy. However, the test has not yet been validated in prospective management outcome studies.

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Pierre-Yves Le Roux, M.D, Ph.D., is a Professor of Nuclear Medicine at the Western Brittany University, France, a physician in the Department of Nuclear Medicine at the Brest University Hospital, France and a Senior Scientist in the Thrombosis Study Group of Western Brittany (“Groupe d’Etude de la Thrombose de Bretagne Occidentale”, GETBO-EA3878), France.

His primary research interest is the diagnosis and management of pulmonary embolism, especially using V/Q planar and SPECT/CT scintigraphy. His clinical research also focuses on the development of V/Q PET/CT imaging and on cancer-associated thrombosis. He has 70 peer-reviewed publications and has been involved in several multicenter projects on the diagnosis and management of venous thromboembolism.

Pulmonary embolism (PE) is the third most frequent acute cardiovascular syndrome. Annual PE incidence and PE-related mortality rates rise exponentially with age, and consequently the disease burden imposed by PE on the society continues to rise as the population ages worldwide. Recently published trials provided the basis for new or changed recommendations included in the 2019 update of the European Society of Cardiology Guidelines (developed in cooperation with the European Respiratory Society) on the diagnosis and management of acute PE. Refinements in diagnostic algorithms were proposed and validated, increasing the specificity of pre-test clinical probability and D-dimer testing, and thus helping to avoid unnecessary computed tomographic pulmonary angiography. Improved diagnostic strategies were also successfully tested in pregnant women with suspected PE. Non-vitamin K antagonist oral anticoagulants (NOACs) are now the preferred agents for treating the majority of patients with PE, both in the acute phase (with or without a brief lead-in period of parenteral heparin or fondaparinux) and over the long term. Of note, patients with severe renal dysfunction, and those with the antiphospholipid syndrome, are an exception to this recommendation. Primary reperfusion options (systemic thrombolysis, catheter-directed (pharmaco)mechanical treatment, or surgical embolectomy) are reserved for the emergency treatment of haemodynamically unstable patients. Besides, the 2019 Guidelines endorse multidisciplinary teams for coordinating the acute-phase management of high-risk and (in selected cases) intermediate-risk PE. For normotensive patients, physicians are advised to include assessment of the right ventricle on top of clinical severity scores in further risk stratification, especially if early discharge of the patient is envisaged. Further important updates include guidance 1) on extended anticoagulation after PE, taking into account the improved safety profile of NOACs; 2) on the use of NOACs in patients with cancer-associated thrombosis; and 3) on the overall care and follow-up of patients who have suffered PE, with the aim to prevent, detect and treat late sequelae of venous thromboembolism.

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Stavros Konstantinides is Professor for Clinical Trials and Medical Director of the multidisciplinary Center for Thrombosis and Hemostasis (CTH) at the University of Mainz, Germany. The CTH is dedicated to integrated patient care and patient-oriented research, and funded by the federal German government.

Dr Konstantinides is also Professor of Cardiology at the Democritus University of Thrace, Greece.

He completed his clinical training in Cardiology and gained his doctorate thesis at the University of Freiburg, Germany. He has worked as Consultant Cardiologist, Assistant and Associate Professor of Medicine at the Universities of Freiburg and Goettingen, Germany, and as Research Associate and Visiting Scientist at the Department of Vascular Biology, the Scripps Research Institute, La Jolla, CA, USA.

For the past 30 years, his research has been focused on basic mechanisms of thrombosis, and on the risk stratification and risk-adapted antithrombotic management of pulmonary embolism. He has designed and coordinated, and/or has been principal investigator of several high-impact national and international multicentre trials, several of which have been published in the New England Journal of Medicine. He has received several international awards and distinctions. His research is funded by national and European peer-reviewed granting agencies. He is leading member of national and European committees, task forces for international guidelines, and networks focusing on the pulmonary circulation and right ventricular function.

The half-life of conventional factor VIII therapy for haemophilia A is constrained by the von Willebrand factor’s (VWF) chaperone effect, which is believed to limit the time the factor remains in the body.¹

BIVV001 is a novel and investigational recombinant factor VIII therapy that has been shown to break through this VWF-imposed half-life ceiling, thus allowing people with haemophilia A to potentially move toward normal factor activity levels for the majority of the week. BIVV001 builds on the innovative Fc fusion technology by adding a region of von Willebrand factor and XTEN polypeptides to extend its time in circulation.²

Nonclinical studies have shown that the use of BIVV001 results in a half-life of factor VIII that is three to four times as long as that of recombinant factor VIII and restores haemostasis in mice with factor VIII.²

These findings were recently supplemented with the results from a phase 1/2a study in people with severe haemophilia A, showing that a single dose of BIVV001 achieved high sustained factor activity and a similar three- to four-fold increase in half-life when compared to conventional factor VIII replacement therapies.³

BIVV001 was granted orphan drug designation by the US Food and Drug Administration in August 2017 and the European Commission in June 2019. It is currently under clinical investigation. Its safety and efficacy have not been reviewed by any regulatory authority.

Annemieke Willemze will start off this symposium by reviewing the molecular features of BIVV001.

Subsequently, Elena Santagostino will elaborate on the clinical development of BIVV001, including the final results of the Phase 1/2a study, recently published in the New England Journal of Medicine.

References

1. Pipe SW et al. Blood. 2016; 128: 2007-16.
2. Seth Chhabra E et al. 2020;135:1484-96.
3. Konkle BA et al. N Engl J Med. 2020;383:1018-27.

Annemieke Willemze, MD, PhD, joined Sanofi clinical development in 2019 as medical lead for the overall clinical development plan of BIVV001.

Previously she worked as medical director in the Sobi Medical Affairs team for rFIXFc (Alprolix®) and rFVIIIFc (Elocta®), leading phase IV studies for both molecules. Prior to Sobi, she was paediatric haematologist at the Van Creveld hemophilia comprehensive care centre in Utrecht, the Netherlands. As international medical director, she was responsible for the clinical development strategies of several early and late phase projects, including rFVIIa (NovoSeven®) and N8-GP as a subcutaneous administration in Novo Nordisk clinical development in Denmark.

Before Novo Nordisk, Annemieke completed a clinical fellowship of pediatric hematology and of transfusion medicine at the Sophia Children’s Hospital in Rotterdam and the Dutch Blood Supply Sanquin, respectively.

Dr. Willemze earned her MD from the State University of Leiden, the Netherlands, and holds a PhD in acute childhood leukemia and stem cell transplantation from Leiden University. She completed her residency in general pediatrics in the Leiden University Medical Centre.

Elena Santagostino, MD, PhD, has joined Sobi Global Medical Affairs as Clinical Expert this year (2020).

She previously leaded the Haemophilia Unit at Fondazione Ca’ Granda Ospedale Maggiore Policlinico and University of Milan, Italy. She was President of the Italian Association of Haemophilia Centres and Senior Advisor to the Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA). Previously, she was Chair of the Scientific Council of Paediatric Network (PedNet) and co-Chair of both the  International Society on Thrombosis and Haemostasis (ISTH) Scientific and Standardization Committee (SSC) on factor VIII and IX, and the Executive Committee of the European Association for Haemophilia and Allied Disorders (EAHAD). Dr. Santagostino has authored more than 300 articles in peer-reviewed journals.

Dr. Santagostino specialised in experimental haematology and internal medicine at the University of Milan and earned a PhD in the management of haemophilia at Maastricht University, The Netherlands. She returned to the University of Milan as a contract Professor at the School of Clinical and Experimental Haematology and, in 2018, earned the National Scientific Qualification as Full Professor in Haematology and Internal Medicine.

In this Gaston Baele Memorial Lecture I describe the limited knowledge of thrombosis and haemostasis sixty years ago, when Gaston Baele and I entered the field. I start with the presentation of the coagulation tests used at that time to monitor anticoagulant therapy and to distinguish between hemophilia A and B. I discuss the limited tools available to evaluate platelet function and their application for diagnosis. I present starting research on fibrinolysis. I discuss a number of memorable hemorrhagic syndromes at the beginning of my career. I  note that, already sixty years ago, there was Belgian inter-university interaction in thrombosis and haemostasis. Both Gaston Baele and I had the immense privilege to witness the explosive increase in theoretical and practical knowledge of thrombosis and haemostasis in the years that followed,  and to participate in this explosion; I discuss Gaston Baele’s many contributions. Finally, I give a brief history of the development of scientific societies devoted to thrombosis and haemostasis, and emphasize the important role that professor Gaston Baele played as first chairman of the Belgian Society on Thrombosis and Haemostasis.

Born in Aalst, Belgium, on May 2,1938. M.D. KU Leuven in 1963; specialist in Internal Medicine in 1968. Professor ordinarius , Faculty of Medicine, KU Leuven 1981. Head of the Division of Bleeding and Vascular Disorders, University Hospitals Leuven 1990-2003. Elected member of the Scientific and Standardization Committee (SSC)) of the International Society on Thrombosis and Haemostasis (ISTH) in 1973; chairman of SSC 1980-1982. Elected to the Council of ISTH in 1982; chairman of the Council  of ISTH 1988-1990. Chairman of the Scientific Program Committee for the 1987 ISTH congress in Brussels. Editor-in-Chief of Thrombosis and Haemostasis, then the official journal of ISTH, 1993-1999. Distinguished Career Award of the ISTH in 1997. President of the European Thrombosis Research Organization 1986-1988.  Member of the board of BSTH 1992-2000. Chairman of the Ethics Committee of the  Faculty of Medicine  Leuven  1982-2003 and of the University Hospitals  Leuven 2004-2010. Emeritus Professor of Medicine in 2003. Co-author of over 450 papers in PubMed. Authored with Marc Verstraete several books on Thrombosis and Haemostasis, which were translated in many languages.

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Dr. Ay studied medicine at the Medical Univeristy of Vienna, Austria and Ruprecht-Karls-University, Heidelberg, Germany. He earned his degree (MD) from the Medical University of Vienna, Austria in 2006 and received there his medical training and completed specialisation in Internal Medicine, Haematology and Medical Oncology.
Dr. Ay is currently an associate professor in medicine/haemostaseology at the Medical University of Vienna, Austria, and was a visiting research professor at the University of North Carolina at Chapel Hill, NC, USA (2016-2017). His research and clinical work focuses on venous thromboembolism (VTE), anticoagulation and bleeding disorders. Having contributed to over 150 peer-reviewed publications, he was particular successful in contributing to a better understanding of the etiology of VTE in cancer by identifying biomarkers and clinical risk factors for cancer-associated VTE.
He has been an active peer reviewer for major medical journals in the field including the New England Journal of Medicine, British Medical Journal, Circulation, Blood, ATVB, Haematologica, Journal of Thrombosis and Haemostasis (JTH), Thrombosis Research and Thrombosis & Haemostasis (T&H), etc. He served as Co-Chair of the Scientific and Standardization Committee (SSC) Subcommittee of the International Society on Thrombosis and Haemostasis (ISTH) on Haemostasis and Malignancy until 2019, is currently on the Editorial Board of JTH and as an associate editor of Research and Practice in Thrombosis and Haemostasis (RPTH), the open access journal of ISTH.
Dr. Ay is a passionate clinician and researcher, supervisor of diploma and PhD-students and maintains regular teaching activities for students and health care professionals to foster education in the field of thrombosis and haemostasis.

Professor Catherine Lambert is adult hematologist at the Hemostasis and Thrombosis Unit, in the department of Hematology in the Cliniques Universitaires Saint-Luc, 1200 Brussels, Belgium.
She obtained her medical degree in 1999 and completed a PhD on hemophilia care in developing countries in 2020 at the university of UCLouvain.
Her main fields of interest are hemophilia and other bleeding disorders, venous thrombosis, clinical apheresis, thrombotic microangiopathies, immune thrombocytopenia and sickle cell disease.
Catherine Lambert is working at the Hemophilia Treatment Center of the Cliniques universitaires Saint-Luc and is actively involved in clinical studies on the treatment of hemophilia, anticoagulants, and microangiopanthy. She is member of several World Federation of Hemophilia’s committees and collaborates with the hemophilia treatment centre of Abidjan in Côte d’Ivoire. She is the local director of the Joint Accreditation Committee – International Society for Cellular Therapy & European Society for Blood and Marrow Transplantation (JACIE) program. She authored or co-authored more than 70 articles in international peer-reviewed journals.

Peter Verhamme is a Professor at the Vascular Medicine and Haemostasis Unit in the Department of Cardiovascular Medicine at University Hospitals Leuven, Belgium. His main clinical interests and clinical research programmes concern the prevention and treatment of venous and arterial thrombosis.
Professor Verhamme obtained his medical degree at the University of Leuven in 1997 and completed a PhD on oxidised low-density lipoprotein and atherothrombosis.
Professor Verhamme coordinates research programmes at the Centre for Molecular and Vascular Biology, University of Leuven, focusing on the development of new fibrinolytic and antithrombotic strategies, and on the interactions between inflammation, infection and coagulation. He has authored or co-authored more than 250 papers published in various peer-reviewed journals.

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Marc Peeters is Professor of oncology at the Antwerp University, Belgium. He is head of the oncology department at the Antwerp University Hospital and coordinator of the Multidisciplinary Oncology Center Antwerp. He is also chairman of the College of Oncology. Previously, he was Coordinator of the Digestive Oncology Unit at the University Hospital in Ghent, Belgium. He completed his medical studies at the Catholic University in Leuven, Belgium. He underwent additional training in Oncology and Digestive Oncology at the UZ Gasthuisberg, the Institut Gustave Roussy in Villejuif, Paris, the University of Pennsylvania Hospital in Philadelphia, the Royal Marsden Hospital in London, and the Memorial Sloan-Kettering Cancer Center in New York.
Dr. Peeters is board member of the Flemish Society of Gastroenterology, chair of the Belgian Group of Digestive Oncology and member of the Belgian Society of Medical Oncology, the European Society of Medical Oncology, the American Society for Clinical Oncology and the gastrointestinal group of the European Organisation for Research and Treatment of Cancer. Within EORTC, he is co-chair of the metastatic colorectal task force.
His research interests have included the identification of molecular markers and therapy modulation in digestive tumors. He has been involved in many clinical studies on therapeutic agents for gastrointestinal tumors, published numerous articles in peer reviewed journals and was author of several chapters in oncology books.

Background
Bleeding and ischemic complications are the main cause of morbidity and mortality in critically ill cardiogenic shock patients, supported by short-term percutaneous mechanical circulatory support (pMCS) devices. Hence, finding the optimal antithrombotic regimen is challenging. Bleeding not only occurs because of heparin and antiplatelet therapy (both required in the prevention of pump and acute stent thrombosis) but also because of device- and disease related coagulopathy. To prevent clotting-related device failure, most centers target full therapeutic heparin anticoagulation levels in left ventricular (LV) Impella™ supported patients in analogy with Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO). We aimed to investigate the safety (related to bleeding and thrombotic complications) of targeting low-dose versus therapeutic heparin levels in left Impella™-supported cardiogenic shock patients on dual antiplatelet therapy (DAPT).

Methods
In this hypothesis generating pilot study, we investigated 114 patients supported for at least two days by LV Impella™ mechanical support due to cardiogenic shock at three tertiary intensive care units, highly specialized in mechanical support. Low- dose heparin (aPTT 40-60s or anti-Xa 0.2-0.3) was compared to standard of care (aPTT 60-80s or anti-Xa 0.3-0.5). Major adverse cardio- and cerebrovascular events (MACCE; composite of death, myocardial infarction [MI], stroke/transient ischemic attack [TIA]) and BARC bleeding (bleeding academic research consortium classification) during 30 day follow-up were assessed. Inverse probability of treatment weighting (IPTW) analysis was calculated with age, gender, arterial hypertension, diabetes mellitus, smoking, chronic kidney disease, previous stroke, previous myocardial infarction, previous coronary arterial bypass grafting, hypercholesterolemia and DAPT as matching variables. COX regression analysis was conducted to test for robustness.

Results
IPTW revealed 52 patients in the low-dose heparin group and 62 patients in the therapeutic group. Mean age of patients after IPTW was 62±16 years in the intermediate and 62±13 years in the therapeutic group (p=0.99). 25% and 42.2% were male (p=0.92). Overall bleeding events and major (BARC3b) bleeding events were higher in the therapeutic heparin group (overall bleeding: Hazard ratio [HR]=2.58, 95% confidence interval [CI] 1.2-5.5; p=0.015; BARC 3b: HR=4.4, 95% CI 1.4-13.6, p=0.009). Minor bleeding (BARC3a) as well as MACCE and its single components (ischemic events) did not differ between both groups. These findings were robust in the COX regression analysis (Figure 1).

Conclusion
In this pilot analysis, low-dose heparin in 114 LV Impella™ cardiogenic shock patients was associated with less bleeding without increased ischemic events, adjusted for DAPT. Reducing the target heparin levels in critically ill patients supported by LV Impella™ might improve the outcome of this precarious group. These findings need to be validated in randomized clinical trials.

Background
Acute ischemic stroke is one of the leading causes of death and permanent disability worldwide. Prophylactic strategies, which are based on the underlying etiology, are important to avoid a recurrent stroke. Strikingly, up to 25% of all patients still experience a recurrent stroke within the first 5 years after the initial event, highlighting the need for improved stroke prevention. Better understanding of the specific etiological thrombus characteristics could provide useful insights into stroke pathophysiology and could aid in the secondary prevention of ischemic stroke. Few studies have investigated the association between stroke etiology and thrombus composition, but their results remain inconclusive due to low sample sizes and limited histological assessments.1

Aims
The aim of this study was to investigate thrombus composition and stroke etiology using a large sample cohort and by performing a detailed and elaborate quantitative histological analysis, including 7 histological parameters.

Methods
A total of 501 thromboemboli were collected from mechanical thrombectomy-treated ischemic stroke patients in the Groeninge Hospital (Kortrijk, Belgium) and the Centre Hospitalier Universitaire de Lille (Lille, France). Stroke etiology was categorized according to the TOAST classification. Histological analysis was performed using hematoxylin and eosin, Martius Scarlet Blue staining (red blood cells (RBCs) and fibrin), Feulgen staining (extracellular DNA (exDNA)) and immunohistochemical staining for platelets (GPIbα), von Willebrand factor (VWF), leukocytes (CD45) and citrullinated histone H3 (H3Cit). All thrombus components, except exDNA, were quantitatively analyzed. ExDNA was visually scored by three independent observers blinded for thrombus origin and categorized in three categories: ‘absence’, ‘little to moderate’ and ‘high’ amounts of exDNA.

Results
The patient cohort had a median age of 72 (range:  14–97) and 54.5% were female. Stroke etiology was classified as cardioembolic (CE) in 249 patients (49.7%), large artery atherosclerosis (LAA) in 81 patients (16.0%), other known etiologies in 30 patients (6.0%) and cryptogenic in 141 patients (28.1%). CE thromboemboli contain significantly less RBCs (37.9% ±19.0% vs. 51.6% ±19.0%) than LAA thromboemboli respectively, but more platelets (36.9% ±18.2% vs. 29.0% ±14.0%), fibrin (34.6% ±16.9% vs. 24.7% ±13.0%), exDNA (88% vs. 74% of thromboemboli containing little to high amounts of exDNA) and leukocytes (19.7% ±14.1% vs. 14.8% ±10.6%). No differences were observed in VWF (35.5% ±16.6% vs. 33.4% ±15.4%) and H3Cit content (6.6% ±7.6% vs. 5.4 ±6.8%) in CE and LAA thromboemboli, respectively. Intriguingly, cryptogenic thromboemboli have similar gross histopathological characteristics in terms of RBCs and platelets as those of an CE origin, suggesting that the majority of these thromboemboli originate from the heart.

Conclusion
CE and cryptogenic thromboemboli have a different biochemical and cellular composition compared to LAA thromboemboli. Our histological data provide a basis to further improve secondary prevention strategies using antiplatelet therapy, anticoagulation therapy or potentially both.

Background
Coronavirus (SARS-CoV-2) induced pneumonia (COVID-19) is associated with a pro-thrombotic state. In hospitalized patients with COVID-19, D-dimer levels are often high and a predictor of mortality, with an incidence of venous thromboembolism (VTE) up to 30-50%. Therefore, thromboprophylaxis with prophylactic or – for the critically ill – intermediate dose of low molecular weight heparins (LMWHs) became the standard of care for COVID-19 patients at our institution. However, little is known about the incidence of COVID-19 associated VTE and the need for extended thromboprophylaxis after discharge.

Aims
To evaluate the residual thrombotic risk and incidence of VTE in patients following hospitalization for COVID-19.

Methods
In COVID-19 patients, we measured D-dimers and performed venous ultrasound screening at a multidisciplinary outpatient follow-up 6 weeks after discharge. In patients who were hospitalized on an intensive care unit (ICU) or had D-dimer levels ≥2000 ng/mL, CT pulmonary angiogram (CTPA) or ventilation/perfusion lung scan (V/Q) was performed. Patients with known VTE or chronic anticoagulation were excluded. The study was approved by the ethical committee.

Results
We screened 178 patients and ultimately included 148 patients for analysis with a median age of 58 years (IQR 51-67). Median hospital stay for non-ICU and ICU patients was 7 and 27 days respectively. Fifty-seven patients were hospitalized at ICU with a median ICU-stay of 13 days (IQR 8-22); 63% of which required mechanical ventilation. Follow-up took place 50 days (IQR 39-55) after hospital discharge. D-dimer levels (figure) were significantly lower at follow-up (413 ng/mL, IQR 298-599) compared to discharge (922 ng/mL, IQR 668-1578) and to the highest value during hospitalization (1699 ng/mL, IQR 815-3505). Patients admitted to the ICU had significant higher D-dimers upon hospital admission (1114 ng/mL, IQR 625-1396), peak (2749 ng/mL, IQR 1735-10422) and discharge (1236, IQR 818-1931) than non-ICU patients. Only 38% of patients received prophylactic LMWHs after discharge (median 14 days) without major or non-major clinically relevant bleedings. There was one symptomatic case of pulmonary embolism after discharge (0.7%). Systematic screening with ultrasound with or without CTPA or V/Q only revealed one additional asymptomatic VTE (deep vein thrombosis), bringing the total VTE rate after discharge at 1.4%.

Conclusions
We report a very low VTE-incidence of 1.4% in COVID-19 patients after hospitalization with systematic screening 6 weeks after discharge at an outpatient follow-up. This is despite a rather low rate of extend thromboprophylaxis at home, in a center with an adjusted COVID-19 thromboprophylactic protocol. These results suggest that extended thromboprophylaxis after hospitalization is not routinely needed and should be reserved after discharge for high risk patients only.

The capacity of pathogens to trigger thrombosis in the host has been brought into sharp focus by the COVID-19 pandemic. Nevertheless, many pathogens, viral and bacterial, can induce thrombosis during severe infections. Amongst these is the bacterial pathogen Salmonella enterica. This bacterial species can cause severe disseminated infections such as typhoid or invasive non-typhoidal salmonellosis that are associated with severe complications such as thrombosis. In this talk, I will focus on how Salmonella induce thrombosis in mice during a systemic infection. In addition to providing mechanistic insights, the talk will focus on i) the surprising finding that the infection induces thrombi in the spleen and liver with distinct kinetics, despite both organs having similar total bacterial counts; ii) the relationship between bacterial numbers, inflammation and thrombus formation and iii) the cell types and molecular factors that contribute to these processes.

Professor Adam Cunningham gained his PhD from Southampton University for studies on antibody responses to Chlamydia pneumoniae. After a short-term position in The Gambia, funded by the WHO, he had his first post-doctoral position in Birmingham studying the cell wall of Mycobacterium tuberculosis. From here, he started work in Prof. Ian MacLennan’s group examining how antibody responses develop and are regulated. During this time, he incorporated the use of Salmonella and its component antigens into this work, leading to an independent position as a RCUK Roberts Academic Fellow, studying how immune responses develop to pathogens and vaccines. He was made Professor of Functional Immunity in August 2011 and his research is focused on how adaptive immunity to pathogens and their component antigens are induced, maintained and function. These studies help us understand why some responses are protective, whilst others are not or can even be harmful. This includes how immune responses to bacterial infections triggers thrombosis.

Neutrophil extracellular traps (NETs) are expelled from activated neutrophils and consist of nuclear DNA with histones and microbicidal proteins. Neutrophil hyperactivation has detrimental effects on healthy bystander tissue and therefore neutrophils are implicated in many inflammatory diseases.  The discovery of neutrophil extracellular traps (NETs) described a novel antibacterial function of neutrophils.  NETs are extracellular DNA strands containing histones and powerful granular enzymes such as neutrophil elastase, that physically trap and kill pathogens. However, the release of highly charged histones, serine proteases, and myeloperoxidase, concentrated on DNA fibers, into the extracellular space is also highly injurious to the host.  Indeed, aberrant NET production has been implicated in autoimmunity, cardiovascular disease, and others. NETs can bind platelets, red blood cells (RBCs), and plasma proteins, therefore contributing to thrombosis.

NET formation (NETosis) is an active and coordinated biological process involving many enzymatic components.  One enzyme in particular, peptidylarginine deiminase 4 (PAD4), citrullinates histones and is involved in chromatin decondensation during NETosis. We have seen important anti-thrombotic and cardioprotective effects in the absence of NETs using PAD4-deficient mice, which do not decondense chromatin or release NETs in vivo. Studying PAD4-deficient mice has revealed the impact of NETs in thrombotic/inflammatory disease and identified PAD4 as an attractive therapeutic target. This talk summarizes work done to date on NETs/PAD4 in thromboinflammation, and more recently in immunothrombosis.

Kimberly Martinod is an assistant professor in the Department of Cardiovascular Sciences, Faculty of Medicine, at KU Leuven.  She performed her doctoral studies in Denisa Wagner’s lab and received her PhD degree in Immunology from Harvard Medical School for her thesis titled “Neutrophil extracellular traps in thrombosis and inflammation.” As a Transfusion Biology Research Fellow at Boston Children’s Hospital, she investigated the role of peptidylarginine deiminase 4 (PAD4) and NETs in fibrotic tissue remodeling during aging. During her postdoctoral training in the Laboratory for Thrombosis Research at the KU Leuven KULAK campus as a Marie Skłodowska-Curie Postdoctoral Fellow, she studied the interaction between the blood protein von Willebrand factor and neutrophils in their activation leading to NETosis.

Her research group, located at the Center for Molecular and Vascular Biology in Leuven, focuses on the interplay between thrombosis and inflammation in cardiac disease, specifically in the development of heart failure.  She is, as of 2018, a co-chair of the Scientific Subcommittee on Vascular Biology of the International Society on Thrombosis and Haemostasis, leading an international standardization study on the measurement of NETs in human plasma samples.

Acute respiratory distress syndrome (ARDS) is defined as a syndrome of acute onset, with bilateral opacities in chest imaging and respiratory failure not caused by cardiac failure, leading to mild, moderate or severe oxygenation impairment. The syndrome is most commonly a manifestation of sepsis-induced organ dysfunction, characterized by disruption of endothelial barrier integrity and diffuse lung damage. Imbalance between coagulation and inflammation is a predominant characteristic of ARDS, leading to extreme inflammatory response and diffuse fibrin deposition in vascular capillary bed and alveoli. Activated platelets, neutrophils, endothelial cells, neutrophil extracellular traps, microparticles and coagulation proteases, participate in the complex process of immunothrombosis, which is a key event in ARDS pathophysiology. The present review is focused on the elucidation of immunothrombosis in ARDS and the potential therapeutic implications.

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Frantzeska Frantzeskaki (1973) is pulmonologist-intensivist, consultant in 2^nd Department of Critical Care, in Attikon University Hospital, NK University of Athens, Greece. She has completed a MSc on “Thrombosis, hemorrhage and transfusion medicine” and PhD on ARDS, in NK Univesity of Athens, Medical School. Her fields of interest are: Coagulation disorders in sepsis, Pulmonary Hypertension, Lung Transplantation. She has 30 publications in scientific journals. She is member of European Respiratory Society, European Society of ICM and American Thoracic Society.

Patients with severe COVID-19 infections frequently manifest coagulation abnormalities that are associated with respiratory deterioration and death. In addition, many patients with severe COVID-19 infections develop thromboembolic complications, which seem to be related to the coagulopathy. It has been suggested that undiagnosed pulmonary embolism contribute to a sudden deterioration of pulmonary oxygen exchange that is sometimes seen in patients with COVID-19 infections.

The coagulation changes associated with COVID-19 mimics other systemic coagulopathies that are regularly seen during severe infections, such as disseminated intravascular coagulation (DIC) or thrombotic microangiopathy (TMA). However, at the same time, the clinical and laboratory characteristics of the coagulation changes in COVID are distinctly different from the common presentation of these conditions.

Severe COVID-19 infections seem to cause a profound coagulation abnormality caused by inflammation-induced changes in coagulation in combination with severe endothelial cell injury with consequent massive release of von Willebrand factor and plasminogen activators. This coagulopathy likely contributes to pulmonary microvascular thrombosis, broncho-alveolar fibrin deposition (which is a hallmark of adult respiratory distress syndrome (ARDS)) and thromboembolic complications.

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There is ample evidence supporting the use of prophylactic dose low molecular weight (LMW) heparin as prophylaxis for venous thromboembolism in critically ill medical patients. In view of the hypercoagulable state of severe COVID-19 patients and the possibly increased risk of thrombosis, all patients with COVID-19 that are admitted to the hospital should receive this prophylactic treatment. It may be hypothesized that severe COVID-19 patients should receive higher dose thromboprophylaxis because of their hypercoagulable state and this is the subject of several multi-center randomized controlled trials that are ongoing.  Marcel Levi (1964) is chief executive of University College London Hospitals (UCLH) and Professor of Medicine at UCL. He is a consultant in Acute Medicine and Haematology at UCLH. Previously he was Dean of the Faculty of Medicine of the University of Amsterdam and Chief Executive of the Academic Medical Center in Amsterdam. Earlier he worked at the University of Perugia (Italy), in Oxford (UK) and the Center for Transgene Technology and Genetherapy of the University of Leuven, Belgium. He has published more than 700 articles in scientific journals and has been awarded a number of international research awards. He was chairman of the Netherlands Organization for Health Research and is currently chairman of the scientific board of several national charities, including the Dutch Heart Foundation, and the AIDS fund. He became a member of the Royal Netherlands Academy of Science in 2008 and is a fellow of the Royal College of Physicians in the United Kingdom.

In collaboration with Sciensano, the BSTH coordinated the development of guidelines for antithrombotic therapy in patients with COVID-19.

These guidelines were written by a group of national thrombosis experts, and have been published in Acta Clinica Belgica: International Journal of Clinical and Laboratory Medicine.

Anticoagulation in critical care patients and in patients on mechanical cardiopulmonary support
Bleeding and thrombotic complications are leading causes of morbidity and mortality in critically ill patients and those on mechanical cardiopulmonary support which include simple cardiopulmonary bypass and extracorporeal membrane oxygenation (ECMO). Whilst deep vein thrombosis in lower limb is the commonest venous thrombosis (VTE) in these patients, upper limb thrombosis and pulmonary embolism are other common sites for venous thrombotic events. Ischemic stroke and intracardiac thrombosis are main arterial events. Intracranial haemorrhage (ICH) and gastrointestinal bleeding are most common serious bleeding events in these patients. Sepsis, vasopressor use, central catheters, mechanical ventilators, respiratory, cardiac, or renal failure are common ICU related risk factors of VTE. Patients with central venous catheters are at a three-fold greater risk for developing VTE than those without them. Duration of mechanical ventilation and frequent red blood cells transfusion are also risk factors for VTE. Patients on ECMO are at additional risk for bleeding and thrombosis due to artificial surface related haemostatic dysfunction in addition to common risk factors for bleeding and thrombosis in ICU patients.

Maintaining optimal haemostasis and preventing significant bleeding and thrombosis are key aspects of managing patients in these patients. Anticoagulation is essential in patients treated in ICU or on mechanical circulatory support. Anticoagulation (thromboprophylaxis or treatment) is usually achieved with low molecular weight heparin or intravenous unfractionated heparin (UFH), and using the direct thrombin inhibitors bivalirudin or argatroban when UFH is contraindicated or not suitable, such as in the case of allergy to UFH/heparin-induced thrombocytopenia, or in patients with severe acute antithrombin deficiency.

Maintaining optimal anticoagulation is challenging, as the monitoring of UFH can be difficult in these patients due to number of reasons which will be discussed. In addition, for assessing the effect of anticoagulation, it is also important to assess the overall haemostatic profile, to assess the bleeding risk with global haemostatic assays such as Thromboelastography or ROEM. Platelets play a major role in both primary and secondary haemostasis, and thrombocytopaenia and/or impaired platelet function can contribute to the excess bleeding risk. In addition to platelet count, function of the platelet needs to be assessed where possible. Patients requiring intensive care treatment are critically ill with infection and systemic inflammation which promotes disseminated intravascular coagulation (DIC), thus causing both bleeding and thrombosis. Anticoagulation, low platelet count and/or acquired platelet dysfunction due to loss of platelet receptors through the mechanical circulatory support and acquired von Willebrand syndrome (AVWS) due to loss of high molecular weight multimers, all contribute to an increased risk of bleeding.

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Dr Deepa J Arachchillage (MBBS, MRCP, FRCPath, MD) is a consultant haematologist specialised in Haemostasis and Thrombosis and an honorary senior lecturer at Imperial College London, United Kingdom. She was awarded MD (res) from University College London in 2015 for her research related to antiphospholipid syndrome (APS), complement activation and direct acting oral anticoagulants. Her clinical work is based at Hammersmith hospital in Imperial College Healthcare NHS Trust and Royal Brompton Hospital in London. She has published over 50 peer reviewed journal articles as the first author or senior author and written several book chapters. She is a member of the British Society for Haematologists’ haemostasis and thrombosis Task Force and lead author for several BSH guidelines and contributed for international guidelines.
Her principal research interests are inflammation and thrombosis, APS, anticoagulation and acquired bleeding disorders mainly related to cardiac surgeries and extra corporeal membrane oxygenation (ECMO) in both paediatric and adults. She is the chief investigator of several clinal and translational research studies including multicentre study assessing coagulopathy in COVID-19. She is a member of Research Advisory Group for autoimmune rheumatic diseases for Versus Arthritis, UK, and a member of International Extracorporeal life support (ECLS) Scientific Oversight Committee.